Adding resize preprocessor (#152)

* Adding resize preprocessor

* Using ! on form

* Haha oops

* Using createImageBitmapPolyfill

* Updating package.json

* Oops again

* Ooops again

package-lock.json

@@ -6681,6 +6681,11 @@
         "invert-kv": "^1.0.0"
       }
     },
+    "linkstate": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/linkstate/-/linkstate-1.1.1.tgz",
+      "integrity": "sha512-5SICdxQG9FpWk44wSEoM2WOCUNuYfClp10t51XAIV5E7vUILF/dTYxf0vJw6bW2dUd2wcQon+LkNtRijpNLrig=="
+    },
     "listr": {
       "version": "0.14.1",
       "resolved": "https://registry.npmjs.org/listr/-/listr-0.14.1.tgz",

package.json

@@ -67,6 +67,7 @@
     "comlink": "^3.0.3",
     "comlink-loader": "^1.0.0",
     "preact": "^8.3.1",
+    "linkstate": "^1.1.1",
     "pretty-bytes": "^5.1.0"
   }
 }

src/codecs/preprocessors.ts

@@ -1,15 +1,21 @@
 import { QuantizeOptions, defaultOptions as quantizerDefaultOptions } from './imagequant/quantizer';
+import { ResizeOptions, defaultOptions as resizeDefaultOptions } from './resize/resize';
 
 interface Enableable {
   enabled: boolean;
 }
 export interface PreprocessorState {
   quantizer: Enableable & QuantizeOptions;
+  resize: Enableable & ResizeOptions;
 }
 
-export const defaultPreprocessorState = {
+export const defaultPreprocessorState: PreprocessorState = {
   quantizer: {
     enabled: false,
     ...quantizerDefaultOptions,
   },
+  resize: {
+    enabled: false,
+    ...resizeDefaultOptions,
+  },
 };

src/codecs/resize/options.tsx

@@ -0,0 +1,128 @@
+import { h, Component } from 'preact';
+import linkState from 'linkstate';
+import { bind, inputFieldValueAsNumber } from '../../lib/util';
+import { ResizeOptions } from './resize';
+
+interface Props {
+  options: ResizeOptions;
+  aspect: number;
+  onChange(newOptions: ResizeOptions): void;
+}
+
+interface State {
+  maintainAspect: boolean;
+}
+
+export default class ResizerOptions extends Component<Props, State> {
+  state: State = {
+    maintainAspect: true,
+  };
+
+  form?: HTMLFormElement;
+
+  reportOptions() {
+    const width = this.form!.width as HTMLInputElement;
+    const height = this.form!.height as HTMLInputElement;
+
+    if (!width.checkValidity() || !height.checkValidity()) return;
+
+    const options: ResizeOptions = {
+      width: inputFieldValueAsNumber(width),
+      height: inputFieldValueAsNumber(height),
+      method: this.form!.resizeMethod.value,
+      fitMethod: this.form!.fitMethod.value,
+    };
+    this.props.onChange(options);
+  }
+
+  @bind
+  onChange(event: Event) {
+    this.reportOptions();
+  }
+
+  componentDidUpdate(prevProps: Props, prevState: State) {
+    if (!prevState.maintainAspect && this.state.maintainAspect) {
+      this.form!.height.value = Math.round(Number(this.form!.width.value) / this.props.aspect);
+      this.reportOptions();
+    }
+  }
+
+  @bind
+  onWidthInput(event: Event) {
+    if (!this.state.maintainAspect) return;
+
+    const width = inputFieldValueAsNumber(this.form!.width);
+    this.form!.height.value = Math.round(width / this.props.aspect);
+  }
+
+  @bind
+  onHeightInput(event: Event) {
+    if (!this.state.maintainAspect) return;
+
+    const height = inputFieldValueAsNumber(this.form!.height);
+    this.form!.width.value = Math.round(height * this.props.aspect);
+  }
+
+  render({ options, aspect }: Props, { maintainAspect }: State) {
+    return (
+      <form ref={el => this.form = el}>
+        <label>
+          Method:
+          <select
+            name="resizeMethod"
+            value={options.method}
+            onChange={this.onChange}
+          >
+            <option value="browser-pixelated">Browser pixelated</option>
+            <option value="browser-low">Browser low quality</option>
+            <option value="browser-medium">Browser medium quality</option>
+            <option value="browser-high">Browser high quality</option>
+          </select>
+        </label>
+        <label>
+          Width:
+          <input
+            required
+            name="width"
+            type="number"
+            min="1"
+            value={'' + options.width}
+            onChange={this.onChange}
+            onInput={this.onWidthInput}
+          />
+        </label>
+        <label>
+          Height:
+          <input
+            required
+            name="height"
+            type="number"
+            min="1"
+            value={'' + options.height}
+            onChange={this.onChange}
+          />
+        </label>
+        <label>
+          <input
+            name="maintainAspect"
+            type="checkbox"
+            checked={maintainAspect}
+            onChange={linkState(this, 'maintainAspect')}
+          />
+          Maintain aspect ratio
+        </label>
+        <label style={{ display: maintainAspect ? 'none' : '' }}>
+          Fit method:
+          <select
+            name="fitMethod"
+            value={options.fitMethod}
+            onChange={this.onChange}
+          >
+            <option value="stretch">Stretch</option>
+            <option value="cover">Cover</option>
+          </select>
+        </label>
+      </form>
+    );
+  }
+}

src/codecs/resize/resize.ts

@@ -0,0 +1,46 @@
+import { bitmapToImageData, createImageBitmapPolyfill } from '../../lib/util';
+
+type CreateImageBitmapResize = 'pixelated' | 'low' | 'medium' | 'high';
+
+export async function resize(data: ImageData, opts: ResizeOptions): Promise<ImageData> {
+  let sx = 0;
+  let sy = 0;
+  let sw = data.width;
+  let sh = data.height;
+
+  if (opts.fitMethod === 'cover') {
+    const currentAspect = data.width / data.height;
+    const endAspect = opts.width / opts.height;
+    if (endAspect > currentAspect) {
+      sh = opts.height / (opts.width / data.width);
+      sy = (data.height - sh) / 2;
+    } else {
+      sw = opts.width / (opts.height / data.height);
+      sx = (data.width - sw) / 2;
+    }
+  }
+
+  const bmp = await createImageBitmapPolyfill(data, sx, sy, sw, sh, {
+    resizeQuality: opts.method.slice('browser-'.length) as CreateImageBitmapResize,
+    resizeWidth: opts.width,
+    resizeHeight: opts.height,
+  });
+
+  return bitmapToImageData(bmp);
+}
+
+export interface ResizeOptions {
+  width: number;
+  height: number;
+  method: 'browser-pixelated' | 'browser-low' | 'browser-medium' | 'browser-high';
+  fitMethod: 'stretch' | 'cover';
+}
+
+export const defaultOptions: ResizeOptions = {
+  // Width and height will always default to the image size.
+  // This is set elsewhere.
+  width: 1,
+  height: 1,
+  method: 'browser-high',
+  fitMethod: 'stretch',
+};

src/components/App/index.tsx

@@ -10,6 +10,7 @@ import ResultCache from './result-cache';
 
 import * as quantizer from '../../codecs/imagequant/quantizer';
 import * as optiPNG from '../../codecs/optipng/encoder';
+import * as resizer from '../../codecs/resize/resize';
 import * as mozJPEG from '../../codecs/mozjpeg/encoder';
 import * as webP from '../../codecs/webp/encoder';
 import * as identity from '../../codecs/identity/encoder';
@@ -79,6 +80,9 @@ async function preprocessImage(
   preprocessData: PreprocessorState,
 ): Promise<ImageData> {
   let result = source.data;
+  if (preprocessData.resize.enabled) {
+    result = await resizer.resize(result, preprocessData.resize);
+  }
   if (preprocessData.quantizer.enabled) {
     result = await quantizer.quantize(result, preprocessData.quantizer);
   }
@@ -227,10 +231,21 @@ export default class App extends Component<Props, State> {
       // compute the corresponding ImageData once since it only changes when the file changes:
       const data = await bitmapToImageData(bmp);
 
-      this.setState({
+      let newState = {
+        ...this.state,
         source: { data, bmp, file },
         loading: false,
+      };
+
+      // Default resize values come from the image:
+      for (const i of [0, 1]) {
+        newState = cleanMerge(newState, `images.${i}.preprocessorState.resize`, {
+          width: data.width,
+          height: data.height,
         });
+      }
+
+      this.setState(newState);
     } catch (err) {
       console.error(err);
       this.showError(`Invalid image`);
@@ -314,17 +329,22 @@ export default class App extends Component<Props, State> {
   }
 
   render({ }: Props, { loading, images, source, orientation }: State) {
+    const [leftImage, rightImage] = images;
     const [leftImageBmp, rightImageBmp] = images.map(i => i.bmp);
     const anyLoading = loading || images.some(image => image.loading);
 
     return (
       <file-drop accept="image/*" onfiledrop={this.onFileDrop}>
         <div id="app" class={`${style.app} ${style[orientation]}`}>
-          {(leftImageBmp && rightImageBmp) ? (
+          {(leftImageBmp && rightImageBmp && source) ? (
             <Output
               orientation={orientation}
+              imgWidth={source.bmp.width}
+              imgHeight={source.bmp.height}
               leftImg={leftImageBmp}
               rightImg={rightImageBmp}
+              leftImgContain={leftImage.preprocessorState.resize.fitMethod === 'cover'}
+              rightImgContain={rightImage.preprocessorState.resize.fitMethod === 'cover'}
             />
           ) : (
             <div class={style.welcome}>
@@ -332,9 +352,10 @@ export default class App extends Component<Props, State> {
               <input type="file" onChange={this.onFileChange} />
             </div>
           )}
-          {(leftImageBmp && rightImageBmp) && images.map((image, index) => (
+          {(leftImageBmp && rightImageBmp && source) && images.map((image, index) => (
             <Options
               orientation={orientation}
+              sourceAspect={source.bmp.width / source.bmp.height}
               imageIndex={index}
               imageFile={image.file}
               sourceImageFile={source && source.file}

src/components/Options/index.tsx

@@ -10,6 +10,7 @@ import WebPEncoderOptions from '../../codecs/webp/options';
 import BrowserWebPEncoderOptions from '../../codecs/browser-webp/options';
 
 import QuantizerOptionsComponent from '../../codecs/imagequant/options';
+import ResizeOptionsComponent from '../../codecs/resize/options';
 
 import * as identity from '../../codecs/identity/encoder';
 import * as optiPNG from '../../codecs/optipng/encoder';
@@ -33,9 +34,8 @@ import {
     encoderMap,
 } from '../../codecs/encoders';
 import { QuantizeOptions } from '../../codecs/imagequant/quantizer';
-
+import { ResizeOptions } from '../../codecs/resize/resize';
 import { PreprocessorState } from '../../codecs/preprocessors';
-
 import FileSize from '../FileSize';
 import { DownloadIcon } from '../../lib/icons';
 
@@ -62,6 +62,7 @@ const titles = {
 
 interface Props {
   orientation: 'horizontal' | 'vertical';
+  sourceAspect: number;
   imageIndex: number;
   sourceImageFile?: File;
   imageFile?: File;
@@ -112,9 +113,17 @@ export default class Options extends Component<Props, State> {
     );
   }
 
+  @bind
+  onResizeOptionsChange(opts: ResizeOptions) {
+    this.props.onPreprocessorOptionsChange(
+      cleanMerge(this.props.preprocessorState, 'resize', opts),
+    );
+  }
+
   render(
     {
       sourceImageFile,
+      sourceAspect,
       imageIndex,
       imageFile,
       downloadUrl,
@@ -161,7 +170,23 @@ export default class Options extends Component<Props, State> {
           </section>
 
           {encoderState.type !== 'identity' && (
-            <div key="quantization" class={style.quantization}>
+            <div key="preprocessors" class={style.preprocessors}>
+              <label class={style.toggle}>
+                <input
+                  name="resize.enable"
+                  type="checkbox"
+                  checked={!!preprocessorState.resize.enabled}
+                  onChange={this.onPreprocessorEnabledChange}
+                />
+                Resize
+              </label>
+              {preprocessorState.resize.enabled &&
+                <ResizeOptionsComponent
+                  aspect={sourceAspect}
+                  options={preprocessorState.resize}
+                  onChange={this.onResizeOptionsChange}
+                />
+              }
               <label class={style.toggle}>
                 <input
                   name="quantizer.enable"
@@ -169,7 +194,7 @@ export default class Options extends Component<Props, State> {
                   checked={!!preprocessorState.quantizer.enabled}
                   onChange={this.onPreprocessorEnabledChange}
                 />
-                Enable Quantization
+                Quantize
               </label>
               {preprocessorState.quantizer.enabled &&
                 <QuantizerOptionsComponent

src/components/Options/style.scss

@@ -153,7 +153,7 @@ Note: These styles are temporary. They will be replaced before going live.
 }
 
 
-.quantization {
+.preprocessors {
   padding: 5px 0;
   margin: 5px 0;
   box-shadow: inset 0 -.5px 0 rgba(0,0,0,0.25), 0 .5px 0 rgba(255,255,255,0.15);

src/components/Output/index.tsx

@@ -11,6 +11,10 @@ interface Props {
   orientation: 'horizontal' | 'vertical';
   leftImg: ImageBitmap;
   rightImg: ImageBitmap;
+  imgWidth: number;
+  imgHeight: number;
+  leftImgContain: boolean;
+  rightImgContain: boolean;
 }
 
 interface State {
@@ -145,7 +149,7 @@ export default class Output extends Component<Props, State> {
   }
 
   render(
-    { orientation, leftImg, rightImg }: Props,
+    { orientation, leftImg, rightImg, imgWidth, imgHeight, leftImgContain, rightImgContain }: Props,
     { scale, editingScale, altBackground }: State,
   ) {
     return (
@@ -165,18 +169,26 @@ export default class Output extends Component<Props, State> {
             ref={linkRef(this, 'pinchZoomLeft')}
           >
             <canvas
-              class={style.outputCanvas}
               ref={linkRef(this, 'canvasLeft')}
               width={leftImg.width}
               height={leftImg.height}
+              style={{
+                width: imgWidth,
+                height: imgHeight,
+                objectFit: leftImgContain ? 'contain' : '',
+              }}
             />
           </pinch-zoom>
           <pinch-zoom ref={linkRef(this, 'pinchZoomRight')}>
             <canvas
-              class={style.outputCanvas}
               ref={linkRef(this, 'canvasRight')}
               width={rightImg.width}
               height={rightImg.height}
+              style={{
+                width: imgWidth,
+                height: imgHeight,
+                objectFit: rightImgContain ? 'contain' : '',
+              }}
             />
           </pinch-zoom>
         </two-up>

src/components/Output/style.scss

@@ -134,7 +134,3 @@ Note: These styles are temporary. They will be replaced before going live.
     border-bottom-right-radius: 0;
   }
 }
-
-.outputCanvas {
-  image-rendering: pixelated;
-}

src/lib/util.ts

@@ -154,8 +154,35 @@ export async function sniffMimeType(blob: Blob): Promise<string> {
   return '';
 }
 
-export function createImageBitmapPolyfill(blob: Blob): Promise<ImageBitmap> {
+type CreateImageBitmapInput = HTMLImageElement | SVGImageElement | HTMLVideoElement |
-  return createImageBitmap(blob);
+  HTMLCanvasElement | ImageBitmap | ImageData | Blob;
+
+export function createImageBitmapPolyfill(
+  image: CreateImageBitmapInput,
+  options?: ImageBitmapOptions,
+): Promise<ImageBitmap>;
+export function createImageBitmapPolyfill(
+  image: CreateImageBitmapInput,
+  sx: number,
+  sy: number,
+  sw: number,
+  sh: number,
+  options?: ImageBitmapOptions,
+): Promise<ImageBitmap>;
+export function createImageBitmapPolyfill(
+  image: CreateImageBitmapInput,
+  sxOrOptions?: number | ImageBitmapOptions,
+  sy?: number,
+  sw?: number,
+  sh?: number,
+  options?: ImageBitmapOptions,
+): Promise<ImageBitmap> {
+  if (sxOrOptions === undefined || typeof sxOrOptions !== 'number') {
+    // sxOrOptions is absent or an options object
+    return createImageBitmap(image, sxOrOptions);
+  }
+  // sxOrOptions is a number
+  return createImageBitmap(image, sxOrOptions, sy!, sw!, sh!, options);
 }
 
 /**