Fixing lossless slider for webP. Previously you couldn't select "9" :D (#236)

* MozJPEG chroma subsampling and quality (#235)

* Adding chroma subsampling for mozjpeg

* Adding separate chroma quality.

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

* Simplifying chroma subsample

* Adding comments

* Fixing lossless slider for webP. Previously you couldn't select "9" :D

* Destructuring args.

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/custom-els/RangeInput/index.ts

@@ -57,6 +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 {