Destructuring args.

* Adding chroma subsampling for mozjpeg

* Adding separate chroma quality.

* Preact sometimes removes the inline styles, this fixes it.

* Simplifying chroma subsample

* Adding comments

codecs/mozjpeg_enc/README.md

@@ -39,5 +39,9 @@ struct MozJpegOptions {
   bool trellis_opt_zero;
   bool trellis_opt_table;
   int trellis_loops;
+  bool auto_subsample;
+  int chroma_subsample;
+  bool separate_chroma_quality;
+  int chroma_quality;
 };
 ```

codecs/mozjpeg_enc/example.html

@@ -21,7 +21,7 @@
     console.log('Version:', module.version().toString(16));
     const image = await loadImage('../example.png');
     const result = module.encode(image.data, image.width, image.height, {
-      quality: 40,
+      quality: 75,
       baseline: false,
       arithmetic: false,
       progressive: true,
@@ -29,10 +29,14 @@
       smoothing: 0,
       color_space: 3,
       quant_table: 3,
-      trellis_multipass: true,
-      trellis_opt_zero: true,
-      trellis_opt_table: true,
+      trellis_multipass: false,
+      trellis_opt_zero: false,
+      trellis_opt_table: false,
       trellis_loops: 1,
+      auto_subsample: true,
+      chroma_subsample: 2,
+      separate_chroma_quality: false,
+      chroma_quality: 75,
     });
 
     const blob = new Blob([result], {type: 'image/jpeg'});

codecs/mozjpeg_enc/mozjpeg_enc.cpp

@@ -29,6 +29,10 @@ struct MozJpegOptions {
   bool trellis_opt_zero;
   bool trellis_opt_table;
   int trellis_loops;
+  bool auto_subsample;
+  int chroma_subsample;
+  bool separate_chroma_quality;
+  int chroma_quality;
 };
 
 int version() {
@@ -119,9 +123,6 @@ val encode(std::string image_in, int image_width, int image_height, MozJpegOptio
    */
   jpeg_set_defaults(&cinfo);
 
-  /* Now you can set any non-default parameters you wish to.
-   * Here we just illustrate the use of quality (quantization table) scaling:
-   */
   jpeg_set_colorspace(&cinfo, (J_COLOR_SPACE) opts.color_space);
 
   if (opts.quant_table != -1) {
@@ -142,11 +143,23 @@ val encode(std::string image_in, int image_width, int image_height, MozJpegOptio
   jpeg_c_set_bool_param(&cinfo, JBOOLEAN_TRELLIS_Q_OPT, opts.trellis_opt_table);
   jpeg_c_set_int_param(&cinfo, JINT_TRELLIS_NUM_LOOPS, opts.trellis_loops);
 
+  // A little hacky to build a string for this, but it means we can use set_quality_ratings which
+  // does some useful heuristic stuff.
   std::string quality_str = std::to_string(opts.quality);
+
+  if (opts.separate_chroma_quality && opts.color_space == JCS_YCbCr) {
+    quality_str += "," + std::to_string(opts.chroma_quality);
+  }
+
   char const *pqual = quality_str.c_str();
 
   set_quality_ratings(&cinfo, (char*) pqual, opts.baseline);
 
+  if (!opts.auto_subsample && opts.color_space == JCS_YCbCr) {
+    cinfo.comp_info[0].h_samp_factor = opts.chroma_subsample;
+    cinfo.comp_info[0].v_samp_factor = opts.chroma_subsample;
+  }
+
   if (!opts.baseline && opts.progressive) {
     jpeg_simple_progression(&cinfo);
   } else {
@@ -209,6 +222,10 @@ EMSCRIPTEN_BINDINGS(my_module) {
     .field("trellis_opt_zero", &MozJpegOptions::trellis_opt_zero)
     .field("trellis_opt_table", &MozJpegOptions::trellis_opt_table)
     .field("trellis_loops", &MozJpegOptions::trellis_loops)
+    .field("chroma_subsample", &MozJpegOptions::chroma_subsample)
+    .field("auto_subsample", &MozJpegOptions::auto_subsample)
+    .field("separate_chroma_quality", &MozJpegOptions::separate_chroma_quality)
+    .field("chroma_quality", &MozJpegOptions::chroma_quality)
     ;
 
   function("version", &version);

src/codecs/mozjpeg/encoder-meta.ts

@@ -17,6 +17,10 @@ export interface EncodeOptions {
   trellis_opt_zero: boolean;
   trellis_opt_table: boolean;
   trellis_loops: number;
+  auto_subsample: boolean;
+  chroma_subsample: number;
+  separate_chroma_quality: boolean;
+  chroma_quality: number;
 }
 
 export interface EncoderState { type: typeof type; options: EncodeOptions; }
@@ -38,4 +42,8 @@ export const defaultOptions: EncodeOptions = {
   trellis_opt_zero: false,
   trellis_opt_table: false,
   trellis_loops: 1,
+  auto_subsample: true,
+  chroma_subsample: 2,
+  separate_chroma_quality: false,
+  chroma_quality: 75,
 };

src/codecs/mozjpeg/options.tsx

@@ -39,8 +39,13 @@ export default class MozJPEGEncoderOptions extends Component<Props, State> {
       trellis_multipass: inputFieldChecked(form.trellis_multipass, options.trellis_multipass),
       trellis_opt_zero: inputFieldChecked(form.trellis_opt_zero, options.trellis_opt_zero),
       trellis_opt_table: inputFieldChecked(form.trellis_opt_table, options.trellis_opt_table),
+      auto_subsample: inputFieldChecked(form.auto_subsample, options.auto_subsample),
+      separate_chroma_quality:
+        inputFieldChecked(form.separate_chroma_quality, options.separate_chroma_quality),
       // .value
       quality: inputFieldValueAsNumber(form.quality, options.quality),
+      chroma_quality: inputFieldValueAsNumber(form.chroma_quality, options.chroma_quality),
+      chroma_subsample: inputFieldValueAsNumber(form.chroma_subsample, options.chroma_subsample),
       smoothing: inputFieldValueAsNumber(form.smoothing, options.smoothing),
       color_space: inputFieldValueAsNumber(form.color_space, options.color_space),
       quant_table: inputFieldValueAsNumber(form.quant_table, options.quant_table),
@@ -75,6 +80,72 @@ export default class MozJPEGEncoderOptions extends Component<Props, State> {
         <Expander>
           {showAdvanced ?
             <div>
+              <label class={style.optionTextFirst}>
+                Channels:
+                <Select
+                  name="color_space"
+                  value={options.color_space}
+                  onChange={this.onChange}
+                >
+                  <option value={MozJpegColorSpace.GRAYSCALE}>Grayscale</option>
+                  <option value={MozJpegColorSpace.RGB}>RGB</option>
+                  <option value={MozJpegColorSpace.YCbCr}>YCbCr</option>
+                </Select>
+              </label>
+              <Expander>
+                {options.color_space === MozJpegColorSpace.YCbCr ?
+                  <div>
+                    <label class={style.optionInputFirst}>
+                      <Checkbox
+                        name="auto_subsample"
+                        checked={options.auto_subsample}
+                        onChange={this.onChange}
+                      />
+                      Auto subsample chroma
+                    </label>
+                    <Expander>
+                      {options.auto_subsample ? null :
+                        <div class={style.optionOneCell}>
+                          <Range
+                            name="chroma_subsample"
+                            min="1"
+                            max="4"
+                            value={options.chroma_subsample}
+                            onInput={this.onChange}
+                          >
+                            Subsample chroma by:
+                          </Range>
+                        </div>
+                      }
+                    </Expander>
+                    <label class={style.optionInputFirst}>
+                      <Checkbox
+                        name="separate_chroma_quality"
+                        checked={options.separate_chroma_quality}
+                        onChange={this.onChange}
+                      />
+                      Separate chroma quality
+                    </label>
+                    <Expander>
+                      {options.separate_chroma_quality ?
+                        <div class={style.optionOneCell}>
+                          <Range
+                            name="chroma_quality"
+                            min="0"
+                            max="100"
+                            value={options.chroma_quality}
+                            onInput={this.onChange}
+                          >
+                            Chroma quality:
+                          </Range>
+                        </div>
+                        : null
+                      }
+                    </Expander>
+                  </div>
+                  : null
+                }
+              </Expander>
               <label class={style.optionInputFirst}>
                 <Checkbox
                   name="baseline"
@@ -119,18 +190,6 @@ export default class MozJPEGEncoderOptions extends Component<Props, State> {
                   Smoothing:
                 </Range>
               </div>
-              <label class={style.optionTextFirst}>
-                Channels:
-                <Select
-                  name="color_space"
-                  value={options.color_space}
-                  onChange={this.onChange}
-                >
-                  <option value={MozJpegColorSpace.GRAYSCALE}>Grayscale</option>
-                  <option value={MozJpegColorSpace.RGB}>RGB</option>
-                  <option value={MozJpegColorSpace.YCbCr}>YCbCr</option>
-                </Select>
-              </label>
               <label class={style.optionTextFirst}>
                 Quantization:
                 <Select

src/codecs/webp/options.tsx

@@ -26,8 +26,10 @@ const losslessPresets:[number, number][] = [
 ];
 const losslessPresetDefault = 6;
 
-function determineLosslessQuality(quality: number): number {
-  const index = losslessPresets.findIndex(item => item[1] === quality);
+function determineLosslessQuality(quality: number, method: number): number {
+  const index = losslessPresets.findIndex(
+    ([presetMethod, presetQuality]) => presetMethod === method && presetQuality === quality,
+  );
   if (index !== -1) return index;
   // Quality doesn't match one of the presets.
   // This can happen when toggling 'lossless'.
@@ -45,7 +47,7 @@ export default class WebPEncoderOptions extends Component<Props, State> {
     const lossless = inputFieldCheckedAsNumber(form.lossless);
     const { options } = this.props;
     const losslessPresetValue = inputFieldValueAsNumber(
-      form.lossless_preset, determineLosslessQuality(options.quality),
+      form.lossless_preset, determineLosslessQuality(options.quality, options.method),
     );
 
     const newOptions: EncodeOptions = {
@@ -97,7 +99,7 @@ export default class WebPEncoderOptions extends Component<Props, State> {
             name="lossless_preset"
             min="0"
             max="9"
-            value={determineLosslessQuality(options.quality)}
+            value={determineLosslessQuality(options.quality, options.method)}
             onInput={this.onChange}
           >
             Effort:

src/components/App/index.tsx

@@ -4,7 +4,7 @@ import { bind, linkRef, Fileish } from '../../lib/initial-util';
 import * as style from './style.scss';
 import { FileDropEvent } from './custom-els/FileDrop';
 import './custom-els/FileDrop';
-import SnackBarElement from '../../lib/SnackBar';
+import SnackBarElement, { SnackOptions } from '../../lib/SnackBar';
 import '../../lib/SnackBar';
 import Intro from '../intro';
 import '../custom-els/LoadingSpinner';
@@ -39,7 +39,7 @@ export default class App extends Component<Props, State> {
     import('../compress').then((module) => {
       this.setState({ Compress: module.default });
     }).catch(() => {
-      this.showError('Failed to load app');
+      this.showSnack('Failed to load app');
     });
 
     // In development, persist application state across hot reloads:
@@ -66,9 +66,9 @@ export default class App extends Component<Props, State> {
   }
 
   @bind
-  private showError(error: string) {
+  private showSnack(message: string, options: SnackOptions = {}): Promise<string> {
     if (!this.snackbar) throw Error('Snackbar missing');
-    this.snackbar.showSnackbar({ message: error });
+    return this.snackbar.showSnackbar(message, options);
   }
 
   render({}: Props, { file, Compress }: State) {
@@ -76,9 +76,9 @@ export default class App extends Component<Props, State> {
       <div id="app" class={style.app}>
         <file-drop accept="image/*" onfiledrop={this.onFileDrop} class={style.drop}>
           {(!file)
-            ? <Intro onFile={this.onIntroPickFile} onError={this.showError} />
+            ? <Intro onFile={this.onIntroPickFile} showSnack={this.showSnack} />
             : (Compress)
-              ? <Compress file={file} onError={this.showError} />
+              ? <Compress file={file} showSnack={this.showSnack} />
               : <loading-spinner class={style.appLoader}/>
           }
           <snack-bar ref={linkRef(this, 'snackbar')} />

src/components/Options/index.tsx

@@ -1,7 +1,7 @@
 import { h, Component } from 'preact';
 
 import * as style from './style.scss';
-import { bind, Fileish } from '../../lib/initial-util';
+import { bind } from '../../lib/initial-util';
 import { cleanSet, cleanMerge } from '../../lib/clean-modify';
 import OptiPNGEncoderOptions from '../../codecs/optipng/options';
 import MozJpegEncoderOptions from '../../codecs/mozjpeg/options';
@@ -35,13 +35,10 @@ import {
 import { QuantizeOptions } from '../../codecs/imagequant/processor-meta';
 import { ResizeOptions } from '../../codecs/resize/processor-meta';
 import { PreprocessorState } from '../../codecs/preprocessors';
-import FileSize from './FileSize';
-import { DownloadIcon } from '../../lib/icons';
 import { SourceImage } from '../App';
 import Checkbox from '../checkbox';
 import Expander from '../expander';
 import Select from '../select';
-import '../custom-els/LoadingSpinner';
 
 const encoderOptionsComponentMap = {
   [identity.type]: undefined,
@@ -60,55 +57,29 @@ const encoderOptionsComponentMap = {
 };
 
 interface Props {
-  orientation: 'horizontal' | 'vertical';
-  loading: boolean;
+  mobileView: boolean;
   source?: SourceImage;
-  imageIndex: number;
-  imageFile?: Fileish;
-  downloadUrl?: string;
   encoderState: EncoderState;
   preprocessorState: PreprocessorState;
   onEncoderTypeChange(newType: EncoderType): void;
   onEncoderOptionsChange(newOptions: EncoderOptions): void;
   onPreprocessorOptionsChange(newOptions: PreprocessorState): void;
-  onCopyToOtherClick(): void;
 }
 
 interface State {
   encoderSupportMap?: EncoderSupportMap;
-  showLoadingState: boolean;
 }
 
-const loadingReactionDelay = 500;
-
 export default class Options extends Component<Props, State> {
   state: State = {
     encoderSupportMap: undefined,
-    showLoadingState: false,
   };
 
-  /** The timeout ID between entering the loading state, and changing UI */
-  private loadingTimeoutId: number = 0;
-
   constructor() {
     super();
     encodersSupported.then(encoderSupportMap => this.setState({ encoderSupportMap }));
   }
 
-  componentDidUpdate(prevProps: Props, prevState: State) {
-    if (prevProps.loading && !this.props.loading) {
-      // Just stopped loading
-      clearTimeout(this.loadingTimeoutId);
-      this.setState({ showLoadingState: false });
-    } else if (!prevProps.loading && this.props.loading) {
-      // Just started loading
-      this.loadingTimeoutId = self.setTimeout(
-        () => this.setState({ showLoadingState: true }),
-        loadingReactionDelay,
-      );
-    }
-  }
-
   @bind
   onEncoderTypeChange(event: Event) {
     const el = event.currentTarget as HTMLSelectElement;
@@ -143,30 +114,20 @@ export default class Options extends Component<Props, State> {
     );
   }
 
-  @bind
-  onCopyToOtherClick(event: Event) {
-    event.preventDefault();
-    this.props.onCopyToOtherClick();
-  }
-
   render(
     {
       source,
-      imageIndex,
-      imageFile,
-      downloadUrl,
-      orientation,
       encoderState,
       preprocessorState,
       onEncoderOptionsChange,
     }: Props,
-    { encoderSupportMap, showLoadingState }: State,
+    { encoderSupportMap }: State,
   ) {
     // tslint:disable variable-name
     const EncoderOptionComponent = encoderOptionsComponentMap[encoderState.type];
 
     return (
-      <div class={style.options}>
+      <div class={style.optionsScroller}>
         <Expander>
           {encoderState.type === identity.type ? null :
             <div>
@@ -211,67 +172,30 @@ export default class Options extends Component<Props, State> {
 
         <h3 class={style.optionsTitle}>Compress</h3>
 
-        <div class={style.optionsScroller}>
-          <section class={`${style.optionOneCell} ${style.optionsSection}`}>
-            {encoderSupportMap ?
-              <Select value={encoderState.type} onChange={this.onEncoderTypeChange} large>
-                {encoders.filter(encoder => encoderSupportMap[encoder.type]).map(encoder => (
-                  <option value={encoder.type}>{encoder.label}</option>
-                ))}
-              </Select>
-              :
-              <Select large><option>Loading…</option></Select>
-            }
-          </section>
-
-          <Expander>
-            {EncoderOptionComponent ?
-              <EncoderOptionComponent
-                options={
-                  // Casting options, as encoderOptionsComponentMap[encodeData.type] ensures
-                  // the correct type, but typescript isn't smart enough.
-                  encoderState.options as any
-                }
-                onChange={onEncoderOptionsChange}
-              />
-            : null}
-          </Expander>
-        </div>
-
-        <div class={style.optionsCopy}>
-          <button onClick={this.onCopyToOtherClick} class={style.copyButton}>
-            {imageIndex === 1 && '← '}
-            Copy settings across
-            {imageIndex === 0 && ' →'}
-          </button>
-        </div>
-
-        <div class={style.results}>
-          <div class={style.resultData}>
-            {!imageFile || showLoadingState ? 'Working…' :
-              <FileSize
-                blob={imageFile}
-                compareTo={(source && imageFile !== source.file) ? source.file : undefined}
-              />
-            }
-          </div>
-
-          <div class={style.download}>
-            {(downloadUrl && imageFile) && (
-              <a
-                class={`${style.downloadLink} ${showLoadingState ? style.downloadLinkDisable : ''}`}
-                href={downloadUrl}
-                download={imageFile.name}
-                title="Download"
-              >
-                <DownloadIcon class={style.downloadIcon} />
-              </a>
-            )}
-            {showLoadingState && <loading-spinner class={style.spinner} />}
-          </div>
-
-        </div>
+        <section class={`${style.optionOneCell} ${style.optionsSection}`}>
+          {encoderSupportMap ?
+            <Select value={encoderState.type} onChange={this.onEncoderTypeChange} large>
+              {encoders.filter(encoder => encoderSupportMap[encoder.type]).map(encoder => (
+                <option value={encoder.type}>{encoder.label}</option>
+              ))}
+            </Select>
+            :
+            <Select large><option>Loading…</option></Select>
+          }
+        </section>
 
+        <Expander>
+          {EncoderOptionComponent ?
+            <EncoderOptionComponent
+              options={
+                // Casting options, as encoderOptionsComponentMap[encodeData.type] ensures
+                // the correct type, but typescript isn't smart enough.
+                encoderState.options as any
+              }
+              onChange={onEncoderOptionsChange}
+            />
+          : null}
+        </Expander>
       </div>
     );
   }

src/components/Options/style.scss

@@ -1,15 +1,5 @@
 $horizontalPadding: 15px;
 
-.options {
-  color: #fff;
-  width: 300px;
-  opacity: 0.9;
-  font-size: 1.2rem;
-  max-height: 100%;
-  display: flex;
-  flex-flow: column;
-}
-
 .options-title {
   background: rgba(0, 0, 0, 0.9);
   margin: 0;
@@ -65,102 +55,3 @@ $horizontalPadding: 15px;
   overflow-x: hidden;
   overflow-y: auto;
 }
-
-.results {
-  display: grid;
-  grid-template-columns: 1fr auto;
-  background: rgba(0, 0, 0, 0.9);
-  font-size: 1.4rem;
-}
-
-.result-data {
-  display: flex;
-  align-items: center;
-  padding: 0 $horizontalPadding;
-}
-
-.size-delta {
-  font-size: 1.1rem;
-  font-style: italic;
-  position: relative;
-  top: -1px;
-  margin-left: 0.3em;
-}
-
-.size-increase {
-  color: #e35050;
-}
-
-.size-decrease {
-  color: #50e3c2;
-}
-
-.options-copy {
-  display: grid;
-  background: rgba(0, 0, 0, 0.9);
-  padding: 5px;
-}
-
-.copy-button {
-  composes: unbutton from '../../lib/util.scss';
-  background: #484848;
-  border-radius: 4px;
-  color: #fff;
-  text-align: left;
-  padding: 5px 10px;
-}
-
-@keyframes action-enter {
-  from {
-    transform: rotate(-90deg);
-    opacity: 0;
-    animation-timing-function: ease-out;
-  }
-}
-
-@keyframes action-leave {
-  from {
-    transform: rotate(0deg);
-    opacity: 1;
-    animation-timing-function: ease-out;
-  }
-}
-
-.download {
-  background: #34B9EB;
-  --size: 38px;
-  width: var(--size);
-  height: var(--size);
-  display: grid;
-  align-items: center;
-  justify-items: center;
-}
-
-.download-link {
-  animation: action-enter 0.2s;
-  grid-area: 1/1;
-}
-
-.download-link-disable {
-  pointer-events: none;
-  opacity: 0;
-  transform: rotate(90deg);
-  animation: action-leave 0.2s;
-}
-
-.download-icon {
-  color: #fff;
-  display: block;
-  --size: 24px;
-  width: var(--size);
-  height: var(--size);
-  padding: 7px;
-  filter: drop-shadow(0 1px 0 rgba(0, 0, 0, 0.7));
-}
-
-.spinner {
-  --color: #fff;
-  --delay: 0;
-  --size: 22px;
-  grid-area: 1/1;
-}

src/components/Output/custom-els/TwoUp/styles.css

@@ -56,7 +56,7 @@ two-up[legacy-clip-compat] > :not(.two-up-handle) {
   box-shadow: 0 1px 4px rgba(0,0,0,0.1);
   color: var(--thumb-color);
   box-sizing: border-box;
-  padding: 0 48%;
+  padding: 0 calc(var(--thumb-size) * 0.24);
 }
 
 .scrubber svg {

src/components/Output/index.tsx

@@ -10,7 +10,7 @@ import { twoUpHandle } from './custom-els/TwoUp/styles.css';
 
 interface Props {
   originalImage?: ImageData;
-  orientation: 'horizontal' | 'vertical';
+  mobileView: boolean;
   leftCompressed?: ImageData;
   rightCompressed?: ImageData;
   leftImgContain: boolean;
@@ -180,10 +180,7 @@ export default class Output extends Component<Props, State> {
   }
 
   render(
-    {
-      orientation, leftCompressed, rightCompressed, leftImgContain, rightImgContain,
-      originalImage,
-    }: Props,
+    { mobileView, leftImgContain, rightImgContain, originalImage }: Props,
     { scale, editingScale, altBackground }: State,
   ) {
     const leftDraw = this.leftDrawable();
@@ -194,7 +191,7 @@ export default class Output extends Component<Props, State> {
         <two-up
           legacy-clip-compat
           class={style.twoUp}
-          orientation={orientation}
+          orientation={mobileView ? 'vertical' : 'horizontal'}
           // Event redirecting. See onRetargetableEvent.
           onTouchStartCapture={this.onRetargetableEvent}
           onTouchEndCapture={this.onRetargetableEvent}

src/components/Output/style.scss

@@ -1,7 +1,3 @@
-/*
-Note: These styles are temporary. They will be replaced before going live.
-*/
-
 .output {
   composes: abs-fill from '../../lib/util.scss';
 
@@ -47,6 +43,12 @@ Note: These styles are temporary. They will be replaced before going live.
   flex-wrap: wrap;
   contain: content;
 
+  // Allow clicks to fall through to the pinch zoom area
+  pointer-events: none;
+  & > * {
+    pointer-events: auto;
+  }
+
   @media (min-width: 860px) {
     top: auto;
     left: 320px;
@@ -127,4 +129,8 @@ Note: These styles are temporary. They will be replaced before going live.
 
 .output-canvas {
   flex-shrink: 0;
+  // This fixes a severe painting bug in Chrome.
+  // We should try to remove this once the issue is fixed.
+  // https://bugs.chromium.org/p/chromium/issues/detail?id=870222#c10
+  will-change: auto;
 }

src/components/compress/custom-els/MultiPanel/index.ts

@@ -1,19 +1,75 @@
-import './styles.css';
+import * as style from './styles.css';
+import { transitionHeight } from '../../../../lib/util';
 
-function getClosestHeading(el: Element) {
-  const closestEl = el.closest('multi-panel > *');
-  if (closestEl && closestEl.classList.contains('panel-heading')) {
-    return closestEl;
+interface CloseAllOptions {
+  exceptFirst?: boolean;
+}
+
+const openOneOnlyAttr = 'open-one-only';
+
+function getClosestHeading(el: Element): HTMLElement | undefined {
+  // Look for the child of multi-panel, but stop at interactive elements like links & buttons
+  const closestEl = el.closest('multi-panel > *, a, button');
+  if (closestEl && closestEl.classList.contains(style.panelHeading)) {
+    return closestEl as HTMLElement;
   }
   return undefined;
 }
 
+async function close(heading: HTMLElement) {
+  const content = heading.nextElementSibling as HTMLElement;
+
+  // if there is no content, nothing to expand
+  if (!content) return;
+
+  const from = content.getBoundingClientRect().height;
+
+  heading.removeAttribute('content-expanded');
+  content.setAttribute('aria-expanded', 'false');
+
+  // Wait a microtask so other calls to open/close can get the final sizes.
+  await null;
+
+  await transitionHeight(content, {
+    from,
+    to: 0,
+    duration: 300,
+  });
+
+  content.style.height = '';
+}
+
+async function open(heading: HTMLElement) {
+  const content = heading.nextElementSibling as HTMLElement;
+
+  // if there is no content, nothing to expand
+  if (!content) return;
+
+  const from = content.getBoundingClientRect().height;
+
+  heading.setAttribute('content-expanded', '');
+  content.setAttribute('aria-expanded', 'true');
+
+  const to = content.getBoundingClientRect().height;
+
+  // Wait a microtask so other calls to open/close can get the final sizes.
+  await null;
+
+  await transitionHeight(content, {
+    from, to,
+    duration: 300,
+  });
+
+  content.style.height = '';
+}
+
 /**
  * A multi-panel view that the user can add any number of 'panels'.
  * 'a panel' consists of two elements. Even index element becomes heading,
  * and odd index element becomes the expandable content.
  */
 export default class MultiPanel extends HTMLElement {
+  static get observedAttributes() { return [openOneOnlyAttr]; }
 
   constructor() {
     super();
@@ -31,12 +87,18 @@ export default class MultiPanel extends HTMLElement {
     this._childrenChange();
   }
 
+  attributeChangedCallback(name: string, oldValue: string | null, newValue: string | null) {
+    if (name === openOneOnlyAttr && newValue === null) {
+      this._closeAll({ exceptFirst: true });
+    }
+  }
+
   // Click event handler
   private _onClick(event: MouseEvent) {
-    const el = event.target as Element;
+    const el = event.target as HTMLElement;
     const heading = getClosestHeading(el);
     if (!heading) return;
-    this._expand(heading);
+    this._toggle(heading);
   }
 
   // KeyDown event handler
@@ -53,7 +115,8 @@ export default class MultiPanel extends HTMLElement {
     // don’t handle modifier shortcuts used by assistive technology.
     if (event.altKey) return;
 
-    let newHeading:HTMLElement | undefined;
+    let newHeading: HTMLElement | undefined;
+
     switch (event.key) {
       case 'ArrowLeft':
       case 'ArrowUp':
@@ -77,7 +140,7 @@ export default class MultiPanel extends HTMLElement {
       case 'Enter':
       case ' ':
       case 'Spacebar':
-        this._expand(heading);
+        this._toggle(heading);
         break;
 
       // Any other key press is ignored and passed back to the browser.
@@ -93,26 +156,32 @@ export default class MultiPanel extends HTMLElement {
     }
   }
 
-  private _expand(heading: Element) {
+  private _toggle(heading: HTMLElement) {
     if (!heading) return;
-    const content = heading.nextElementSibling;
-
-    // if there is no content, nothing to expand
-    if (!content) return;
 
     // toggle expanded and aria-expanded attributes
-    if (content.hasAttribute('expanded')) {
-      content.removeAttribute('expanded');
-      content.setAttribute('aria-expanded', 'false');
+    if (heading.hasAttribute('content-expanded')) {
+      close(heading);
     } else {
-      content.setAttribute('expanded', '');
-      content.setAttribute('aria-expanded', 'true');
+      if (this.openOneOnly) this._closeAll();
+      open(heading);
     }
   }
 
+  private _closeAll(options: CloseAllOptions = {}): void {
+    const { exceptFirst = false } = options;
+    let els = [...this.children].filter(el => el.matches('[content-expanded]')) as HTMLElement[];
+
+    if (exceptFirst) {
+      els = els.slice(1);
+    }
+
+    for (const el of els) close(el);
+  }
+
   // children of multi-panel should always be even number (heading/content pair)
   private _childrenChange() {
-    let preserveTabIndex : boolean = false;
+    let preserveTabIndex = false;
     let heading = this.firstElementChild;
 
     while (heading) {
@@ -123,31 +192,23 @@ export default class MultiPanel extends HTMLElement {
       // it means it has odd number of elements. log error and set heading to end the loop.
       if (!content) {
         console.error('<multi-panel> requires an even number of element children.');
-        heading = null;
-        continue;
+        break;
       }
 
       // When odd number of elements were inserted in the middle,
       // what was heading before may become content after the insertion.
       // Remove classes and attributes to prepare for this change.
-      heading.classList.remove('panel-content');
-
-      if (content.classList.contains('panel-heading')) {
-        content.classList.remove('panel-heading');
-      }
-      if (heading.hasAttribute('expanded') && heading.hasAttribute('aria-expanded')) {
-        heading.removeAttribute('expanded');
-        heading.removeAttribute('aria-expanded');
-      }
+      heading.classList.remove(style.panelContent);
+      content.classList.remove(style.panelHeading);
+      heading.removeAttribute('aria-expanded');
+      heading.removeAttribute('content-expanded');
 
       // If appreciable, remove tabindex from content which used to be header.
-      if (content.hasAttribute('tabindex')) {
-        content.removeAttribute('tabindex');
-      }
+      content.removeAttribute('tabindex');
 
       // Assign heading and content classes
-      heading.classList.add('panel-heading');
-      content.classList.add('panel-content');
+      heading.classList.add(style.panelHeading);
+      content.classList.add(style.panelContent);
 
       // Assign ids and aria-X for heading/content pair.
       heading.id = `panel-heading-${randomId}`;
@@ -163,6 +224,13 @@ export default class MultiPanel extends HTMLElement {
         heading.setAttribute('tabindex', '-1');
       }
 
+      // It's possible that the heading & content expanded attributes are now out of sync. Resync
+      // them using the heading as the source of truth.
+      content.setAttribute(
+        'aria-expanded',
+        heading.hasAttribute('content-expanded') ? 'true' : 'false',
+      );
+
       // next sibling of content = next heading
       heading = content.nextElementSibling;
     }
@@ -171,6 +239,9 @@ export default class MultiPanel extends HTMLElement {
     if (!preserveTabIndex && this.firstElementChild) {
       this.firstElementChild.setAttribute('tabindex', '0');
     }
+
+    // In case we're openOneOnly, and an additional open item has been added:
+    if (this.openOneOnly) this._closeAll({ exceptFirst: true });
   }
 
   // returns heading that is before currently selected one.
@@ -208,7 +279,7 @@ export default class MultiPanel extends HTMLElement {
   private _lastHeading() {
     // if the last element is heading, return last element
     const lastEl = this.lastElementChild as HTMLElement;
-    if (lastEl && lastEl.classList.contains('panel-heading')) {
+    if (lastEl && lastEl.classList.contains(style.panelHeading)) {
       return lastEl;
     }
     // otherwise return 2nd from the last
@@ -217,6 +288,21 @@ export default class MultiPanel extends HTMLElement {
       return lastContent.previousElementSibling as HTMLElement;
     }
   }
+
+  /**
+   * If true, only one panel can be open at once. When one opens, others close.
+   */
+  get openOneOnly() {
+    return this.hasAttribute(openOneOnlyAttr);
+  }
+
+  set openOneOnly(val: boolean) {
+    if (val) {
+      this.setAttribute(openOneOnlyAttr, '');
+    } else {
+      this.removeAttribute(openOneOnlyAttr);
+    }
+  }
 }
 
 customElements.define('multi-panel', MultiPanel);

src/components/compress/custom-els/MultiPanel/missing-types.d.ts

@@ -0,0 +1,9 @@
+interface MultiPanelAttributes extends JSX.HTMLAttributes {
+  'open-one-only'?: boolean;
+}
+
+declare namespace JSX {
+  interface IntrinsicElements {
+    'multi-panel': MultiPanelAttributes;
+  }
+}

src/components/compress/custom-els/MultiPanel/styles.css

@@ -0,0 +1,10 @@
+.panel-heading {
+  background: gray;
+}
+.panel-content {
+  height: 0px;
+  overflow: auto;
+}
+.panel-content[aria-expanded=true] {
+  height: auto;
+}

src/components/compress/index.tsx

@@ -24,18 +24,18 @@ import {
     EncoderOptions,
     encoderMap,
 } from '../../codecs/encoders';
-
 import {
   PreprocessorState,
   defaultPreprocessorState,
 } from '../../codecs/preprocessors';
-
 import { decodeImage } from '../../codecs/decoders';
 import { cleanMerge, cleanSet } from '../../lib/clean-modify';
 import Processor from '../../codecs/processor';
 import { VectorResizeOptions, BitmapResizeOptions } from '../../codecs/resize/processor-meta';
-
-type Orientation = 'horizontal' | 'vertical';
+import './custom-els/MultiPanel';
+import Results from '../results';
+import { ExpandIcon, CopyAcrossIconProps } from '../../lib/icons';
+import SnackBarElement from 'src/lib/SnackBar';
 
 export interface SourceImage {
   file: File | Fileish;
@@ -59,7 +59,7 @@ interface EncodedImage {
 
 interface Props {
   file: File | Fileish;
-  onError: (msg: string) => void;
+  showSnack: SnackBarElement['showSnackbar'];
 }
 
 interface State {
@@ -69,7 +69,7 @@ interface State {
   loading: boolean;
   loadingCounter: number;
   error?: string;
-  orientation: Orientation;
+  mobileView: boolean;
 }
 
 interface UpdateImageOptions {
@@ -137,7 +137,7 @@ async function processSvg(blob: Blob): Promise<HTMLImageElement> {
   const parser = new DOMParser();
   const text = await blobToText(blob);
   const document = parser.parseFromString(text, 'image/svg+xml');
-  const svg = document.documentElement;
+  const svg = document.documentElement!;
 
   if (svg.hasAttribute('width') && svg.hasAttribute('height')) {
     return blobToImg(blob);
@@ -155,8 +155,14 @@ async function processSvg(blob: Blob): Promise<HTMLImageElement> {
   return blobToImg(new Blob([newSource], { type: 'image/svg+xml' }));
 }
 
+// These are only used in the mobile view
+const resultTitles = ['Top', 'Bottom'];
+// These are only used in the desktop view
+const buttonPositions =
+  ['download-left', 'download-right'] as ('download-left' | 'download-right')[];
+
 export default class Compress extends Component<Props, State> {
-  widthQuery = window.matchMedia('(min-width: 500px)');
+  widthQuery = window.matchMedia('(max-width: 599px)');
 
   state: State = {
     source: undefined,
@@ -178,7 +184,7 @@ export default class Compress extends Component<Props, State> {
         loading: false,
       },
     ],
-    orientation: this.widthQuery.matches ? 'horizontal' : 'vertical',
+    mobileView: this.widthQuery.matches,
   };
 
   private readonly encodeCache = new ResultCache();
@@ -193,7 +199,7 @@ export default class Compress extends Component<Props, State> {
 
   @bind
   private onMobileWidthChange() {
-    this.setState({ orientation: this.widthQuery.matches ? 'horizontal' : 'vertical' });
+    this.setState({ mobileView: this.widthQuery.matches });
   }
 
   private onEncoderTypeChange(index: 0 | 1, newType: EncoderType): void {
@@ -245,12 +251,24 @@ export default class Compress extends Component<Props, State> {
     }
   }
 
-  private onCopyToOtherClick(index: 0 | 1) {
+  private async onCopyToOtherClick(index: 0 | 1) {
     const otherIndex = (index + 1) % 2;
+    const oldSettings = this.state.images[otherIndex];
 
     this.setState({
       images: cleanSet(this.state.images, otherIndex, this.state.images[index]),
     });
+
+    const result = await this.props.showSnack('Settings copied across', {
+      timeout: 5000,
+      actions: ['undo', 'dismiss'],
+    });
+
+    if (result !== 'undo') return;
+
+    this.setState({
+      images: cleanSet(this.state.images, otherIndex, oldSettings),
+    });
   }
 
   @bind
@@ -313,7 +331,7 @@ export default class Compress extends Component<Props, State> {
       console.error(err);
       // Another file has been opened before this one processed.
       if (this.state.loadingCounter !== loadingCounter) return;
-      this.props.onError('Invalid image');
+      this.props.showSnack('Invalid image');
       this.setState({ loading: false });
     }
   }
@@ -372,7 +390,7 @@ export default class Compress extends Component<Props, State> {
         }
       } catch (err) {
         if (err.name === 'AbortError') return;
-        this.props.onError(`Processing error (type=${image.encoderState.type}): ${err}`);
+        this.props.showSnack(`Processing error (type=${image.encoderState.type}): ${err}`);
         throw err;
       }
     }
@@ -395,36 +413,73 @@ export default class Compress extends Component<Props, State> {
     this.setState({ images });
   }
 
-  render({ }: Props, { loading, images, source, orientation }: State) {
+  render({ }: Props, { loading, images, source, mobileView }: State) {
     const [leftImage, rightImage] = images;
     const [leftImageData, rightImageData] = images.map(i => i.data);
 
+    const options = images.map((image, index) => (
+      <Options
+        source={source}
+        mobileView={mobileView}
+        preprocessorState={image.preprocessorState}
+        encoderState={image.encoderState}
+        onEncoderTypeChange={this.onEncoderTypeChange.bind(this, index)}
+        onEncoderOptionsChange={this.onEncoderOptionsChange.bind(this, index)}
+        onPreprocessorOptionsChange={this.onPreprocessorOptionsChange.bind(this, index)}
+      />
+    ));
+
+    const copyDirections =
+      (mobileView ? ['down', 'up'] : ['right', 'left']) as CopyAcrossIconProps['copyDirection'][];
+
+    const results = images.map((image, index) => (
+      <Results
+        downloadUrl={image.downloadUrl}
+        imageFile={image.file}
+        source={source}
+        loading={loading || image.loading}
+        copyDirection={copyDirections[index]}
+        onCopyToOtherClick={this.onCopyToOtherClick.bind(this, index)}
+        buttonPosition={mobileView ? 'stack-right' : buttonPositions[index]}
+      >
+        {!mobileView ? null : [
+          <ExpandIcon class={style.expandIcon} key="expand-icon"/>,
+          `${resultTitles[index]} (${encoderMap[image.encoderState.type].label})`,
+        ]}
+      </Results>
+    ));
+
     return (
-      <div class={`${style.compress} ${style[orientation]}`}>
+      <div class={style.compress}>
         <Output
           originalImage={source && source.data}
-          orientation={orientation}
+          mobileView={mobileView}
           leftCompressed={leftImageData}
           rightCompressed={rightImageData}
           leftImgContain={leftImage.preprocessorState.resize.fitMethod === 'cover'}
           rightImgContain={rightImage.preprocessorState.resize.fitMethod === 'cover'}
         />
-        {images.map((image, index) => (
-          <Options
-            loading={loading || image.loading}
-            source={source}
-            orientation={orientation}
-            imageIndex={index}
-            imageFile={image.file}
-            downloadUrl={image.downloadUrl}
-            preprocessorState={image.preprocessorState}
-            encoderState={image.encoderState}
-            onEncoderTypeChange={this.onEncoderTypeChange.bind(this, index)}
-            onEncoderOptionsChange={this.onEncoderOptionsChange.bind(this, index)}
-            onPreprocessorOptionsChange={this.onPreprocessorOptionsChange.bind(this, index)}
-            onCopyToOtherClick={this.onCopyToOtherClick.bind(this, index)}
-          />
-        ))}
+        {mobileView
+          ? (
+            <div class={style.options}>
+              <multi-panel class={style.multiPanel} open-one-only>
+                {results[0]}
+                {options[0]}
+                {results[1]}
+                {options[1]}
+              </multi-panel>
+            </div>
+          ) : ([
+            <div class={style.options} key="options0">
+              {options[0]}
+              {results[0]}
+            </div>,
+            <div class={style.options} key="options1">
+              {options[1]}
+              {results[1]}
+            </div>,
+          ])
+        }
       </div>
     );
   }

src/components/compress/style.scss

@@ -3,20 +3,72 @@
   height: 100%;
   contain: strict;
   display: grid;
+  align-items: end;
+  align-content: end;
+  grid-template-rows: 1fr auto;
 
-  &.horizontal {
+  @media (min-width: 600px) {
     grid-template-columns: 1fr auto;
-    grid-template-rows: calc(100% - 75px);
-
-    @media (min-width: 860px) {
-      grid-template-rows: 100%;
-    }
-    align-items: end;
-    align-content: end;
-  }
-
-  &.vertical {
-    // TODO: make the mobile view work
-    background: red;
+    grid-template-rows: 100%;
   }
 }
+
+.options {
+  color: #fff;
+  opacity: 0.9;
+  font-size: 1.2rem;
+  display: flex;
+  flex-flow: column;
+  max-width: 400px;
+  margin: 0 auto;
+  width: calc(100% - 60px);
+  max-height: calc(100% - 143px);
+  overflow: hidden;
+
+  @media (min-width: 600px) {
+    max-height: calc(100% - 75px);
+    width: 300px;
+    margin: 0;
+  }
+
+  @media (min-width: 860px) {
+    max-height: 100%;
+  }
+}
+
+.multi-panel {
+  position: relative;
+  display: flex;
+  flex-flow: column;
+
+  // Reorder so headings appear after content:
+  & > :nth-child(1) {
+    order: 2;
+    margin-bottom: 10px;
+  }
+
+  & > :nth-child(2) {
+    order: 1;
+  }
+
+  & > :nth-child(3) {
+    order: 4;
+  }
+
+  & > :nth-child(4) {
+    order: 3;
+  }
+}
+
+.expand-icon {
+  transform: rotate(180deg);
+  margin-left: -12px;
+}
+
+[content-expanded] .expand-icon {
+  transform: none;
+}
+
+:focus .expand-icon {
+  fill: #34B9EB;
+}

src/components/expander/index.tsx

@@ -1,6 +1,6 @@
 import { h, Component, ComponentChild, ComponentChildren } from 'preact';
 import * as style from './style.scss';
-import { linkRef } from '../../lib/initial-util';
+import { transitionHeight } from '../../lib/util';
 
 interface Props {
   children: ComponentChildren;
@@ -13,7 +13,6 @@ export default class Expander extends Component<Props, State> {
   state: State = {
     outgoingChildren: [],
   };
-  private el?: HTMLDivElement;
   private lastElHeight: number = 0;
 
   componentWillReceiveProps(nextProps: Props) {
@@ -32,10 +31,10 @@ export default class Expander extends Component<Props, State> {
 
     // Only interested if going from empty to not-empty, or not-empty to empty.
     if ((children[0] && nextChildren[0]) || (!children[0] && !nextChildren[0])) return;
-    this.lastElHeight = this.el!.getBoundingClientRect().height;
+    this.lastElHeight = this.base!.getBoundingClientRect().height;
   }
 
-  componentDidUpdate(previousProps: Props) {
+  async componentDidUpdate(previousProps: Props) {
     const children = this.props.children as ComponentChild[];
     const previousChildren = previousProps.children as ComponentChild[];
 
@@ -43,37 +42,20 @@ export default class Expander extends Component<Props, State> {
     if ((children[0] && previousChildren[0]) || (!children[0] && !previousChildren[0])) return;
 
     // What height do we need to transition to?
-    this.el!.style.transition = 'none';
-    this.el!.style.height = '';
-    const newHeight = children[0] ? this.el!.getBoundingClientRect().height : 0;
+    this.base!.style.height = '';
+    this.base!.style.overflow = 'hidden';
+    const newHeight = children[0] ? this.base!.getBoundingClientRect().height : 0;
 
-    if (this.lastElHeight === newHeight) {
-      this.el!.style.transition = '';
-      return;
-    }
+    await transitionHeight(this.base!, {
+      duration: 300,
+      from: this.lastElHeight,
+      to: newHeight,
+    });
 
-    // Set the currently rendered height absolutely.
-    this.el!.style.height = this.lastElHeight + 'px';
-    this.el!.style.transition = '';
-    this.el!.style.overflow = 'hidden';
-    // Force a style calc so the browser picks up the start value.
-    getComputedStyle(this.el!).height;
-    // Animate to the new height.
-    this.el!.style.height = newHeight + 'px';
-
-    const listener = () => {
-      // Unset the height & overflow, so element changes do the right thing.
-      this.el!.style.height = '';
-      this.el!.style.overflow = '';
-      this.el!.removeEventListener('transitionend', listener);
-      this.el!.removeEventListener('transitioncancel', listener);
-      if (this.state.outgoingChildren[0]) {
-        this.setState({ outgoingChildren: [] });
-      }
-    };
-
-    this.el!.addEventListener('transitionend', listener);
-    this.el!.addEventListener('transitioncancel', listener);
+    // Unset the height & overflow, so element changes do the right thing.
+    this.base!.style.height = '';
+    this.base!.style.overflow = '';
+    if (this.state.outgoingChildren[0]) this.setState({ outgoingChildren: [] });
   }
 
   render(props: Props, { outgoingChildren }: State) {
@@ -81,10 +63,7 @@ export default class Expander extends Component<Props, State> {
     const childrenExiting = !children[0] && outgoingChildren[0];
 
     return (
-      <div
-        ref={linkRef(this, 'el')}
-        class={`${style.expander} ${childrenExiting ? style.childrenExiting : ''}`}
-      >
+      <div class={childrenExiting ? style.childrenExiting : ''}>
         {children[0] ? children : outgoingChildren}
       </div>
     );

src/components/expander/style.scss

@@ -1,7 +1,3 @@
-.expander {
-  transition: height 200ms ease-in-out;
-}
-
 .children-exiting {
   & > * {
     pointer-events: none;

src/components/intro/index.tsx

@@ -12,6 +12,7 @@ import artworkIcon from './imgs/demos/artwork-icon.jpg';
 import deviceScreenIcon from './imgs/demos/device-screen-icon.jpg';
 import logoIcon from './imgs/demos/logo-icon.png';
 import * as style from './style.scss';
+import SnackBarElement from '../../lib/SnackBar';
 
 const demos = [
   {
@@ -42,7 +43,7 @@ const demos = [
 
 interface Props {
   onFile: (file: File | Fileish) => void;
-  onError: (error: string) => void;
+  showSnack: SnackBarElement['showSnackbar'];
 }
 interface State {
   fetchingDemoIndex?: number;
@@ -79,7 +80,7 @@ export default class Intro extends Component<Props, State> {
       this.props.onFile(file);
     } catch (err) {
       this.setState({ fetchingDemoIndex: undefined });
-      this.props.onError("Couldn't fetch demo image");
+      this.props.showSnack("Couldn't fetch demo image");
     }
   }
 

src/components/output/custom-els/MultiPanel/styles.css

@@ -1,11 +0,0 @@
-multi-panel > .panel-heading {
-  background:gray;
-}
-multi-panel > .panel-content {
-  height:0px;
-  overflow:scroll;
-  transition: height 1s;
-}
-multi-panel > .panel-content[expanded] {
-  height:auto;
-}

src/components/results/index.tsx

@@ -0,0 +1,105 @@
+import { h, Component, ComponentChildren, ComponentChild } from 'preact';
+
+import * as style from './style.scss';
+import FileSize from './FileSize';
+import { DownloadIcon, CopyAcrossIcon, CopyAcrossIconProps } from '../../lib/icons';
+import '../custom-els/LoadingSpinner';
+import { SourceImage } from '../compress';
+import { Fileish, bind } from '../../lib/initial-util';
+
+interface Props {
+  loading: boolean;
+  source?: SourceImage;
+  imageFile?: Fileish;
+  downloadUrl?: string;
+  children: ComponentChildren;
+  copyDirection: CopyAcrossIconProps['copyDirection'];
+  buttonPosition: keyof typeof buttonPositionClass;
+  onCopyToOtherClick(): void;
+}
+
+interface State {
+  showLoadingState: boolean;
+}
+
+const buttonPositionClass = {
+  'stack-right': style.stackRight,
+  'download-right': style.downloadRight,
+  'download-left': style.downloadLeft,
+};
+
+const loadingReactionDelay = 500;
+
+export default class Results extends Component<Props, State> {
+  state: State = {
+    showLoadingState: false,
+  };
+
+  /** The timeout ID between entering the loading state, and changing UI */
+  private loadingTimeoutId: number = 0;
+
+  componentDidUpdate(prevProps: Props, prevState: State) {
+    if (prevProps.loading && !this.props.loading) {
+      // Just stopped loading
+      clearTimeout(this.loadingTimeoutId);
+      this.setState({ showLoadingState: false });
+    } else if (!prevProps.loading && this.props.loading) {
+      // Just started loading
+      this.loadingTimeoutId = self.setTimeout(
+        () => this.setState({ showLoadingState: true }),
+        loadingReactionDelay,
+      );
+    }
+  }
+
+  @bind
+  private onCopyToOtherClick(event: Event) {
+    event.preventDefault();
+    this.props.onCopyToOtherClick();
+  }
+
+  render(
+    { source, imageFile, downloadUrl, children, copyDirection, buttonPosition }: Props,
+    { showLoadingState }: State,
+  ) {
+
+    return (
+      <div class={`${style.results} ${buttonPositionClass[buttonPosition]}`}>
+        <div class={style.resultData}>
+          {(children as ComponentChild[])[0]
+            ? <div class={style.resultTitle}>{children}</div>
+            : null
+          }
+          {!imageFile || showLoadingState ? 'Working…' :
+            <FileSize
+              blob={imageFile}
+              compareTo={(source && imageFile !== source.file) ? source.file : undefined}
+            />
+          }
+        </div>
+
+        <button
+          class={style.copyToOther}
+          title="Copy settings to other side"
+          onClick={this.onCopyToOtherClick}
+        >
+          <CopyAcrossIcon class={style.copyIcon} copyDirection={copyDirection} />
+        </button>
+
+        <div class={style.download}>
+          {(downloadUrl && imageFile) && (
+            <a
+              class={`${style.downloadLink} ${showLoadingState ? style.downloadLinkDisable : ''}`}
+              href={downloadUrl}
+              download={imageFile.name}
+              title="Download"
+            >
+              <DownloadIcon class={style.downloadIcon} />
+            </a>
+          )}
+          {showLoadingState && <loading-spinner class={style.spinner} />}
+        </div>
+      </div>
+    );
+  }
+}

src/components/results/style.scss

@@ -0,0 +1,131 @@
+@keyframes action-enter {
+  from {
+    transform: rotate(-90deg);
+    opacity: 0;
+    animation-timing-function: ease-out;
+  }
+}
+
+@keyframes action-leave {
+  from {
+    transform: rotate(0deg);
+    opacity: 1;
+    animation-timing-function: ease-out;
+  }
+}
+
+.results {
+  display: grid;
+  grid-template-columns: [text] 1fr [copy-button] auto [download-button] auto;
+  background: rgba(0, 0, 0, 0.9);
+  font-size: 1rem;
+
+  @media (min-width: 400px) {
+    font-size: 1.2rem;
+  }
+
+  @media (min-width: 600px) {
+    font-size: 1.4rem;
+  }
+
+  &:focus {
+    outline: none;
+  }
+}
+
+.result-data {
+  grid-row: 1;
+  grid-column: text;
+  display: flex;
+  align-items: center;
+  padding: 0 10px;
+  white-space: nowrap;
+  overflow: hidden;
+}
+
+.download-right {
+  grid-template-columns: [copy-button] auto [text] 1fr [download-button] auto;
+}
+
+.download-left {
+  grid-template-columns: [download-button] auto [text] 1fr [copy-button] auto;
+}
+
+.stack-right {
+  & .result-data {
+    padding: 0 15px;
+  }
+}
+
+.result-title {
+  display: flex;
+  align-items: center;
+  margin-right: 0.4em;
+}
+
+.size-delta {
+  font-size: 0.8em;
+  font-style: italic;
+  position: relative;
+  top: -1px;
+  margin-left: 0.3em;
+}
+
+.size-increase {
+  color: #e35050;
+}
+
+.size-decrease {
+  color: #50e3c2;
+}
+
+.download {
+  grid-row: 1;
+  grid-column: download-button;
+  background: #34B9EB;
+  --size: 38px;
+  width: var(--size);
+  height: var(--size);
+  display: grid;
+  align-items: center;
+  justify-items: center;
+}
+
+.download-link {
+  animation: action-enter 0.2s;
+  grid-area: 1/1;
+}
+
+.download-link-disable {
+  pointer-events: none;
+  opacity: 0;
+  transform: rotate(90deg);
+  animation: action-leave 0.2s;
+}
+
+.download-icon,
+.copy-icon {
+  color: #fff;
+  display: block;
+  --size: 24px;
+  width: var(--size);
+  height: var(--size);
+  padding: 7px;
+  filter: drop-shadow(0 1px 0 rgba(0, 0, 0, 0.7));
+}
+
+.spinner {
+  --color: #fff;
+  --delay: 0;
+  --size: 22px;
+  grid-area: 1/1;
+}
+
+.copy-to-other {
+  grid-row: 1;
+  grid-column: copy-button;
+  composes: unbutton from '../../lib/util.scss';
+  composes: download;
+
+  background: #656565;
+}

src/custom-els/RangeInput/index.ts

@@ -1,5 +1,6 @@
 import { bind } from '../../lib/initial-util';
 import * as style from './styles.css';
+import { PointerTracker } from '../../lib/PointerTracker';
 
 const RETARGETED_EVENTS = ['focus', 'blur'];
 const UPDATE_EVENTS = ['input', 'change'];
@@ -26,6 +27,17 @@ class RangeInputElement extends HTMLElement {
     this._input.type = 'range';
     this._input.className = style.input;
 
+    const tracker = new PointerTracker(this._input, {
+      start: (): boolean => {
+        if (tracker.currentPointers.length !== 0) return false;
+        this._input.classList.add(style.touchActive);
+        return true;
+      },
+      end: () => {
+        this._input.classList.remove(style.touchActive);
+      },
+    });
+
     for (const event of RETARGETED_EVENTS) {
       this._input.addEventListener(event, this._retargetEvent, true);
     }
@@ -45,6 +57,8 @@ class RangeInputElement extends HTMLElement {
 
     this.insertBefore(this._input, this.firstChild);
     this._valueDisplay = this.querySelector('.' + style.valueDisplay) as HTMLDivElement;
+    // Set inline styles (this is useful when used with frameworks which might clear inline styles)
+    this._update();
   }
 
   get labelPrecision(): string {

src/custom-els/RangeInput/styles.css

@@ -84,11 +84,11 @@ range-input::before {
   overflow: hidden;
 }
 
-.input:active + .thumb-wrapper .value-display {
+.touch-active + .thumb-wrapper .value-display {
   opacity: 1;
   transform: scale(1);
 }
 
-.input:active + .thumb-wrapper .thumb {
+.touch-active + .thumb-wrapper .thumb {
   box-shadow: 0 1px 3px rgba(0,0,0,0.5);
 }

src/lib/SnackBar/index.ts

@@ -1,114 +1,96 @@
-import './styles.css';
-
-const DEFAULT_TIMEOUT = 2750;
+import * as style from './styles.css';
 
 export interface SnackOptions {
-  message: string;
   timeout?: number;
-  actionText?: string;
-  actionHandler?: () => boolean | null;
+  actions?: string[];
 }
 
-export interface SnackShowResult {
-  action: boolean;
-}
+function createSnack(message: string, options: SnackOptions): [Element, Promise<string>] {
+  const {
+    timeout = 0,
+    actions = [],
+  } = options;
 
-class Snack {
-  private _onremove: ((result: SnackShowResult) => void)[] = [];
-  private _options: SnackOptions;
-  private _element: Element = document.createElement('div');
-  private _text: Element = document.createElement('div');
-  private _button: Element = document.createElement('button');
-  private _showing = false;
-  private _closeTimer?: number;
-  private _result: SnackShowResult = {
-    action: false,
-  };
+  // Provide a default 'dismiss' action
+  if (!timeout && actions.length === 0) actions.push('dismiss');
 
-  constructor (options: SnackOptions, callback?: (result: SnackShowResult) => void) {
-    this._options = options;
+  const el = document.createElement('div');
+  el.className = style.snackbar;
+  el.setAttribute('aria-live', 'assertive');
+  el.setAttribute('aria-atomic', 'true');
+  el.setAttribute('aria-hidden', 'false');
 
-    this._element.className = 'snackbar';
-    this._element.setAttribute('aria-live', 'assertive');
-    this._element.setAttribute('aria-atomic', 'true');
-    this._element.setAttribute('aria-hidden', 'true');
+  const text = document.createElement('div');
+  text.className = style.text;
+  text.textContent = message;
+  el.appendChild(text);
 
-    this._text.className = 'snackbar--text';
-    this._text.textContent = options.message;
-    this._element.appendChild(this._text);
+  const result = new Promise<string>((resolve) => {
+    let timeoutId: number;
 
-    if (options.actionText) {
-      this._button.className = 'snackbar--button';
-      this._button.textContent = options.actionText;
-      this._button.addEventListener('click', () => {
-        if (this._showing) {
-          if (options.actionHandler && options.actionHandler() === false) return;
-          this._result.action = true;
-        }
-        this.hide();
+    // Add action buttons
+    for (const action of actions) {
+      const button = document.createElement('button');
+      button.className = style.button;
+      button.textContent = action;
+      button.addEventListener('click', () => {
+        clearTimeout(timeoutId);
+        resolve(action);
       });
-      this._element.appendChild(this._button);
+      el.appendChild(button);
     }
 
-    if (callback) {
-      this._onremove.push(callback);
+    // Add timeout
+    if (timeout) {
+      timeoutId = self.setTimeout(
+        () => resolve(''),
+        timeout,
+      );
     }
-  }
+  });
 
-  cancelTimer () {
-    if (this._closeTimer != null) clearTimeout(this._closeTimer);
-  }
-
-  show (parent: Element): Promise<SnackShowResult> {
-    if (this._showing) return Promise.resolve(this._result);
-    this._showing = true;
-    this.cancelTimer();
-    if (parent !== this._element.parentNode) {
-      parent.appendChild(this._element);
-    }
-    this._element.removeAttribute('aria-hidden');
-    this._closeTimer = setTimeout(this.hide.bind(this), this._options.timeout || DEFAULT_TIMEOUT);
-    return new Promise((resolve) => {
-      this._onremove.push(resolve);
-    });
-  }
-
-  hide () {
-    if (!this._showing) return;
-    this._showing = false;
-    this.cancelTimer();
-    this._element.addEventListener('animationend', this.remove.bind(this));
-    this._element.setAttribute('aria-hidden', 'true');
-  }
-
-  remove () {
-    this.cancelTimer();
-    const parent = this._element.parentNode;
-    if (parent) parent.removeChild(this._element);
-    this._onremove.forEach(f => f(this._result));
-    this._onremove = [];
-  }
+  return [el, result];
 }
 
 export default class SnackBarElement extends HTMLElement {
-  private _snackbars: Snack[] = [];
-  private _processingStack = false;
+  private _snackbars: [string, SnackOptions, (action: Promise<string>) => void][] = [];
+  private _processingQueue = false;
 
-  showSnackbar (options: SnackOptions): Promise<SnackShowResult> {
-    return new Promise((resolve) => {
-      const snack = new Snack(options, resolve);
-      this._snackbars.push(snack);
-      this._processStack();
+  /**
+   * Show a snackbar. Returns a promise for the name of the action clicked, or an empty string if no
+   * action is clicked.
+   */
+  showSnackbar(message: string, options: SnackOptions = {}): Promise<string> {
+    return new Promise<string>((resolve) => {
+      this._snackbars.push([message, options, resolve]);
+      if (!this._processingQueue) this._processQueue();
     });
   }
 
-  private async _processStack () {
-    if (this._processingStack === true || this._snackbars.length === 0) return;
-    this._processingStack = true;
-    await this._snackbars[0].show(this);
-    this._snackbars.shift();
-    this._processingStack = false;
-    this._processStack();
+  private async _processQueue() {
+    this._processingQueue = true;
+
+    while (this._snackbars[0]) {
+      const [message, options, resolver] = this._snackbars[0];
+      const [el, result] = createSnack(message, options);
+      // Pass the result back to the original showSnackbar call.
+      resolver(result);
+      this.appendChild(el);
+
+      // Wait for the user to click an action, or for the snack to timeout.
+      await result;
+
+      // Transition the snack away.
+      el.setAttribute('aria-hidden', 'true');
+      await new Promise((resolve) => {
+        el.addEventListener('animationend', () => resolve());
+      });
+      el.remove();
+
+      this._snackbars.shift();
+    }
+
+    this._processingQueue = false;
   }
 }
 

src/lib/SnackBar/styles.css

@@ -22,7 +22,6 @@ snack-bar {
   transform-origin: center;
   color: #eee;
   z-index: 100;
-  pointer-events: none;
   cursor: default;
   will-change: transform;
   animation: snackbar-show 300ms ease forwards 1;
@@ -53,13 +52,13 @@ snack-bar {
   }
 }
 
-.snackbar--text {
+.text {
   flex: 1 1 auto;
   padding: 16px;
   font-size: 100%;
 }
 
-.snackbar--button {
+.button {
   position: relative;
   flex: 0 1 auto;
   padding: 8px;
@@ -75,16 +74,15 @@ snack-bar {
   font-size: 100%;
   text-transform: uppercase;
   text-align: center;
-  pointer-events: all;
   cursor: pointer;
   overflow: hidden;
   transition: background-color 200ms ease;
   outline: none;
 }
-.snackbar--button:hover {
+.button:hover {
   background-color: rgba(0,0,0,0.15);
 }
-.snackbar--button:focus:before {
+.button:focus:before {
   content: '';
   position: absolute;
   left: 50%;

src/lib/icons.tsx

@@ -41,3 +41,34 @@ export const CheckedIcon = (props: JSX.HTMLAttributes) => (
     <path d="M21.3 0H2.7A2.7 2.7 0 0 0 0 2.7v18.6A2.7 2.7 0 0 0 2.7 24h18.6a2.7 2.7 0 0 0 2.7-2.7V2.7A2.7 2.7 0 0 0 21.3 0zm-12 18.7L2.7 12l1.8-1.9L9.3 15 19.5 4.8l1.8 1.9z"/>
   </Icon>
 );
+
+export const ExpandIcon = (props: JSX.HTMLAttributes) => (
+  <Icon {...props}>
+    <path d="M16.6 8.6L12 13.2 7.4 8.6 6 10l6 6 6-6z"/>
+  </Icon>
+);
+
+const copyAcrossRotations = {
+  up: 90, right: 180, down: -90, left: 0,
+};
+
+export interface CopyAcrossIconProps extends JSX.HTMLAttributes {
+  copyDirection: keyof typeof copyAcrossRotations;
+}
+
+export const CopyAcrossIcon = (props: CopyAcrossIconProps) => {
+  const { copyDirection, ...otherProps } = props;
+  const id = 'point-' + copyDirection;
+  const rotation = copyAcrossRotations[copyDirection];
+
+  return (
+    <Icon {...otherProps}>
+      <defs>
+        <clipPath id={id}>
+          <path d="M-12-12v24h24v-24zM4.5 2h-4v3l-5-5 5-5v3h4z" transform={`translate(12 13) rotate(${rotation})`}/>
+        </clipPath>
+      </defs>
+      <path clip-path={`url(#${id})`} d="M19 3h-4.2c-.4-1.2-1.5-2-2.8-2s-2.4.8-2.8 2H5a2 2 0 0 0-2 2v14c0 1.1.9 2 2 2h14a2 2 0 0 0 2-2V5a2 2 0 0 0-2-2zm-7 0a1 1 0 0 1 0 2c-.6 0-1-.4-1-1s.4-1 1-1z"/>
+    </Icon>
+  );
+};

src/lib/util.ts

@@ -258,3 +258,43 @@ export function konami(): Promise<void> {
     window.addEventListener('keydown', listener);
   });
 }
+
+interface TransitionOptions {
+  from?: number;
+  to?: number;
+  duration?: number;
+  easing?: string;
+}
+
+export async function transitionHeight(el: HTMLElement, opts: TransitionOptions): Promise<void> {
+  const {
+    from = el.getBoundingClientRect().height,
+    to = el.getBoundingClientRect().height,
+    duration = 1000,
+    easing = 'ease-in-out',
+  } = opts;
+
+  if (from === to || duration === 0) {
+    el.style.height = to + 'px';
+    return;
+  }
+
+  el.style.height = from + 'px';
+  // Force a style calc so the browser picks up the start value.
+  getComputedStyle(el).transform;
+  el.style.transition = `height ${duration}ms ${easing}`;
+  el.style.height = to + 'px';
+
+  return new Promise<void>((resolve) => {
+    const listener = (event: Event) => {
+      if (event.target !== el) return;
+      el.style.transition = '';
+      el.removeEventListener('transitionend', listener);
+      el.removeEventListener('transitioncancel', listener);
+      resolve();
+    };
+
+    el.addEventListener('transitionend', listener);
+    el.addEventListener('transitioncancel', listener);
+  });
+}

webpack.config.js

@@ -25,6 +25,7 @@ module.exports = function (_, env) {
     path.join(__dirname, 'src/components'),
     path.join(__dirname, 'src/codecs'),
     path.join(__dirname, 'src/custom-els'),
+    path.join(__dirname, 'src/lib'),
   ];
 
   return {
@@ -107,7 +108,7 @@ module.exports = function (_, env) {
               loader: 'typings-for-css-modules-loader',
               options: {
                 modules: true,
-                localIdentName: '[local]__[hash:base64:5]',
+                localIdentName: isProd ? '[hash:base64:5]' : '[local]__[hash:base64:5]',
                 namedExport: true,
                 camelCase: true,
                 importLoaders: 1,
@@ -199,8 +200,11 @@ module.exports = function (_, env) {
 
       new OptimizeCssAssetsPlugin({
         cssProcessorOptions: {
-          zindex: false,
-          discardComments: { removeAll: true }
+          postcssReduceIdents: {
+            counterStyle: false,
+            gridTemplate: false,
+            keyframes: false
+          }
         }
       }),