Merge pull request #16077 from calixteman/large_image

Render large images even if they're larger than the canvas limits (bug 1720282)

src/core/evaluator.js

@@ -642,7 +642,7 @@ class PartialEvaluator {
         return;
       }
 
-      imgData = PDFImage.createMask({
+      imgData = await PDFImage.createMask({
         imgArray,
         width: w,
         height: h,
@@ -716,7 +716,7 @@ class PartialEvaluator {
       });
       // We force the use of RGBA_32BPP images here, because we can't handle
       // any other kind.
-      imgData = imageObj.createImageData(
+      imgData = await imageObj.createImageData(
         /* forceRGBA = */ true,
         /* isOffscreenCanvasSupported = */ false
       );
@@ -760,8 +760,8 @@ class PartialEvaluator {
       pdfFunctionFactory: this._pdfFunctionFactory,
       localColorSpaceCache,
     })
-      .then(imageObj => {
+      .then(async imageObj => {
-        imgData = imageObj.createImageData(
+        imgData = await imageObj.createImageData(
           /* forceRGBA = */ false,
           /* isOffscreenCanvasSupported = */ this.options
             .isOffscreenCanvasSupported

src/core/image.js

@@ -28,6 +28,7 @@ import {
 import { BaseStream } from "./base_stream.js";
 import { ColorSpace } from "./colorspace.js";
 import { DecodeStream } from "./decode_stream.js";
+import { ImageResizer } from "./image_resizer.js";
 import { JpegStream } from "./jpeg_stream.js";
 import { JpxImage } from "./jpx.js";
 import { Name } from "./primitives.js";
@@ -352,7 +353,7 @@ class PDFImage {
     return { data, width, height, interpolate };
   }
 
-  static createMask({
+  static async createMask({
     imgArray,
     width,
     height,
@@ -371,6 +372,25 @@ class PDFImage {
     }
 
     if (isOffscreenCanvasSupported) {
+      if (ImageResizer.needsToBeResized(width, height)) {
+        const data = new Uint8ClampedArray(width * height * 4);
+        convertBlackAndWhiteToRGBA({
+          src: imgArray,
+          dest: data,
+          width,
+          height,
+          nonBlackColor: 0,
+          inverseDecode,
+        });
+        return ImageResizer.createImage({
+          kind: ImageKind.RGBA_32BPP,
+          data,
+          width,
+          height,
+          interpolate,
+        });
+      }
+
       const canvas = new OffscreenCanvas(width, height);
       const ctx = canvas.getContext("2d");
       const imgData = ctx.createImageData(width, height);
@@ -652,7 +672,7 @@ class PDFImage {
     }
   }
 
-  createImageData(forceRGBA = false, isOffscreenCanvasSupported = false) {
+  async createImageData(forceRGBA = false, isOffscreenCanvasSupported = false) {
     const drawWidth = this.drawWidth;
     const drawHeight = this.drawHeight;
     const imgData = {
@@ -671,6 +691,9 @@ class PDFImage {
 
     // Rows start at byte boundary.
     const rowBytes = (originalWidth * numComps * bpc + 7) >> 3;
+    const mustBeResized =
+      isOffscreenCanvasSupported &&
+      ImageResizer.needsToBeResized(drawWidth, drawHeight);
 
     if (!forceRGBA) {
       // If it is a 1-bit-per-pixel grayscale (i.e. black-and-white) image
@@ -699,6 +722,18 @@ class PDFImage {
       ) {
         const data = this.getImageBytes(originalHeight * rowBytes, {});
         if (isOffscreenCanvasSupported) {
+          if (mustBeResized) {
+            return ImageResizer.createImage(
+              {
+                data,
+                kind,
+                width: drawWidth,
+                height: drawHeight,
+                interpolate: this.interpolate,
+              },
+              this.needsDecode
+            );
+          }
           return this.createBitmap(kind, originalWidth, originalHeight, data);
         }
         imgData.kind = kind;
@@ -719,7 +754,7 @@ class PDFImage {
       }
       if (this.image instanceof JpegStream && !this.smask && !this.mask) {
         let imageLength = originalHeight * rowBytes;
-        if (isOffscreenCanvasSupported) {
+        if (isOffscreenCanvasSupported && !mustBeResized) {
           let isHandled = false;
           switch (this.colorSpace.name) {
             case "DeviceGray":
@@ -763,6 +798,10 @@ class PDFImage {
                 drawHeight,
                 forceRGB: true,
               });
+              if (mustBeResized) {
+                // The image is too big so we resize it.
+                return ImageResizer.createImage(imgData);
+              }
               return imgData;
           }
         }
@@ -783,7 +822,7 @@ class PDFImage {
     let alpha01, maybeUndoPreblend;
 
     let canvas, ctx, canvasImgData, data;
-    if (isOffscreenCanvasSupported) {
+    if (isOffscreenCanvasSupported && !mustBeResized) {
       canvas = new OffscreenCanvas(drawWidth, drawHeight);
       ctx = canvas.getContext("2d");
       canvasImgData = ctx.createImageData(drawWidth, drawHeight);
@@ -793,7 +832,7 @@ class PDFImage {
     imgData.kind = ImageKind.RGBA_32BPP;
 
     if (!forceRGBA && !this.smask && !this.mask) {
-      if (!isOffscreenCanvasSupported) {
+      if (!isOffscreenCanvasSupported || mustBeResized) {
         imgData.kind = ImageKind.RGB_24BPP;
         data = new Uint8ClampedArray(drawWidth * drawHeight * 3);
         alpha01 = 0;
@@ -804,7 +843,7 @@ class PDFImage {
       }
       maybeUndoPreblend = false;
     } else {
-      if (!isOffscreenCanvasSupported) {
+      if (!isOffscreenCanvasSupported || mustBeResized) {
         data = new Uint8ClampedArray(drawWidth * drawHeight * 4);
       }
 
@@ -833,7 +872,7 @@ class PDFImage {
       this.undoPreblend(data, drawWidth, actualHeight);
     }
 
-    if (isOffscreenCanvasSupported) {
+    if (isOffscreenCanvasSupported && !mustBeResized) {
       ctx.putImageData(canvasImgData, 0, 0);
       const bitmap = canvas.transferToImageBitmap();
 
@@ -847,6 +886,9 @@ class PDFImage {
     }
 
     imgData.data = data;
+    if (mustBeResized) {
+      return ImageResizer.createImage(imgData);
+    }
     return imgData;
   }
 

src/core/image_resizer.js

@@ -0,0 +1,384 @@
+/* Copyright 2023 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { FeatureTest, ImageKind, shadow } from "../shared/util.js";
+
+const MIN_IMAGE_DIM = 2048;
+
+// In Chrome, there aren't max dimensions but only a max area. So an image with
+// a very large dimensions is acceptable but it probably doesn't hurt to reduce
+// it when considering that it will finally rendered on a small canvas.
+const MAX_IMAGE_DIM = 65537;
+const MAX_ERROR = 128;
+
+// Large images are encoded in using the BMP format (it's a way faster than
+// encoding in PNG because there are no checksums to compute).
+// Unfortunately, createImageBitmap will create a task in the main thread in
+// order to build the bitmap, hence the main thread is blocked during the
+// decoding which can be a bit long (see bug 1817244).
+// When bug 1759728 is fixed we can remove the BMP workaround and at least it
+// should be a way faster to create the bitmap.
+
+class ImageResizer {
+  constructor(imgData, isMask) {
+    this._imgData = imgData;
+    this._isMask = isMask;
+  }
+
+  static needsToBeResized(width, height) {
+    if (width <= this._goodSquareLength && height <= this._goodSquareLength) {
+      return false;
+    }
+
+    const { MAX_DIM } = this;
+    if (width > MAX_DIM || height > MAX_DIM) {
+      return true;
+    }
+
+    const area = width * height;
+    if (this._hasMaxArea) {
+      return area > this.MAX_AREA;
+    }
+
+    if (area < this._goodSquareLength ** 2) {
+      return false;
+    }
+
+    // We try as much as possible to avoid to compute the max area.
+    if (this._areGoodDims(width, height)) {
+      this._goodSquareLength = Math.max(
+        this._goodSquareLength,
+        Math.floor(Math.sqrt(width * height))
+      );
+      return false;
+    }
+
+    // TODO: the computation can be a bit long because we potentially allocate
+    // some large canvas, so in the Firefox case this value (and MAX_DIM) can be
+    // infered from prefs (MAX_AREA = gfx.max-alloc-size / 4, 4 is because of
+    // RGBA).
+    this._goodSquareLength = this._guessMax(
+      this._goodSquareLength,
+      MAX_DIM,
+      MAX_ERROR,
+      0
+    );
+    const maxArea = (this.MAX_AREA = this._goodSquareLength ** 2);
+
+    return area > maxArea;
+  }
+
+  static get MAX_DIM() {
+    return shadow(
+      this,
+      "MAX_DIM",
+      this._guessMax(MIN_IMAGE_DIM, MAX_IMAGE_DIM, 0, 1)
+    );
+  }
+
+  static get MAX_AREA() {
+    this._hasMaxArea = true;
+    return shadow(
+      this,
+      "MAX_AREA",
+      this._guessMax(
+        ImageResizer._goodSquareLength,
+        this.MAX_DIM,
+        MAX_ERROR,
+        0
+      ) ** 2
+    );
+  }
+
+  static set MAX_AREA(area) {
+    this._hasMaxArea = true;
+    shadow(this, "MAX_AREA", area);
+  }
+
+  static _areGoodDims(width, height) {
+    try {
+      // This code is working in either Firefox or Chrome.
+      // There is a faster solution using transferToImageBitmap which is faster
+      // in Firefox (when the dimensions are wrong the resulting bitmap has its
+      // dimensions equal to 1) but it doesn't find the correct values in
+      // Chrome.
+      const canvas = new OffscreenCanvas(width, height);
+      const ctx = canvas.getContext("2d");
+      ctx.fillRect(0, 0, 1, 1);
+      const opacity = ctx.getImageData(0, 0, 1, 1).data[3];
+      canvas.width = canvas.height = 1;
+      return opacity !== 0;
+    } catch (e) {
+      return false;
+    }
+  }
+
+  static _guessMax(start, end, tolerance, defaultHeight) {
+    // We don't really need to have exact values.
+    // When we're here then we're in a corner case: we've a very large image.
+    // So we could potentially downscale an image which fits in the canvas,
+    // it's maybe a pity in term of perfs but we'll reduce the memory use.
+    // The tolerance is the acceptable error we can make on the limit we want.
+    // On Chrome, when the tolerance 0 then it can take ~5s to compute the max
+    // area... and having a tolerance of 128 divides the time by 2.
+    while (start + tolerance + 1 < end) {
+      const middle = Math.floor((start + end) / 2);
+      const height = defaultHeight || middle;
+      if (this._areGoodDims(middle, height)) {
+        start = middle;
+      } else {
+        end = middle;
+      }
+    }
+    return start;
+  }
+
+  static async createImage(imgData, isMask = false) {
+    return new ImageResizer(imgData, isMask)._createImage();
+  }
+
+  async _createImage() {
+    const data = this._encodeBMP();
+    const blob = new Blob([data.buffer], {
+      type: "image/bmp",
+    });
+    const bitmapPromise = createImageBitmap(blob);
+
+    const { MAX_AREA, MAX_DIM } = ImageResizer;
+    const { _imgData: imgData } = this;
+    const { width, height } = imgData;
+    const minFactor = Math.max(
+      width / MAX_DIM,
+      height / MAX_DIM,
+      Math.sqrt((width * height) / MAX_AREA)
+    );
+
+    const firstFactor = Math.max(minFactor, 2);
+
+    // Add 1 to the ratio and round it with 1 digit.
+    // We add 1.25 in order to have a final image under the limits
+    // (and not just at the limits) to reduce memory use.
+    const factor = Math.round(10 * (minFactor + 1.25)) / 10 / firstFactor;
+
+    const N = Math.floor(Math.log2(factor));
+    const steps = new Array(N + 2).fill(2);
+    steps[0] = firstFactor;
+    steps.splice(-1, 1, factor / (1 << N));
+
+    let newWidth = width;
+    let newHeight = height;
+    let bitmap = await bitmapPromise;
+
+    for (const step of steps) {
+      const prevWidth = newWidth;
+      const prevHeight = newHeight;
+      newWidth = Math.floor(newWidth / step);
+      newHeight = Math.floor(newHeight / step);
+      const canvas = new OffscreenCanvas(newWidth, newHeight);
+      const ctx = canvas.getContext("2d");
+      ctx.drawImage(
+        bitmap,
+        0,
+        0,
+        prevWidth,
+        prevHeight,
+        0,
+        0,
+        newWidth,
+        newHeight
+      );
+      bitmap = canvas.transferToImageBitmap();
+    }
+
+    imgData.data = null;
+    imgData.bitmap = bitmap;
+    imgData.width = newWidth;
+    imgData.height = newHeight;
+
+    return imgData;
+  }
+
+  _encodeBMP() {
+    const { width, height, kind } = this._imgData;
+    let data = this._imgData.data;
+    let bitPerPixel;
+    let colorTable = new Uint8Array(0);
+    let maskTable = colorTable;
+    let compression = 0;
+
+    // Each row of the image must be padded in order to have a final size which
+    // is a multiple of 4.
+
+    switch (kind) {
+      case ImageKind.GRAYSCALE_1BPP: {
+        bitPerPixel = 1;
+        colorTable = new Uint8Array(
+          this._isMask
+            ? [255, 255, 255, 255, 0, 0, 0, 0]
+            : [0, 0, 0, 0, 255, 255, 255, 255]
+        );
+        const rowLen = (width + 7) >> 3;
+        const rowSize = (rowLen + 3) & -4;
+        if (rowLen !== rowSize) {
+          const newData = new Uint8Array(rowSize * height);
+          let k = 0;
+          for (
+            let i = 0, ii = height * rowLen;
+            i < ii;
+            i += rowLen, k += rowSize
+          ) {
+            newData.set(data.subarray(i, i + rowLen), k);
+          }
+          data = newData;
+        }
+        break;
+      }
+      case ImageKind.RGB_24BPP: {
+        bitPerPixel = 24;
+        if (width & 3) {
+          const rowLen = 3 * width;
+          const rowSize = (rowLen + 3) & -4;
+          const extraLen = rowSize - rowLen;
+          const newData = new Uint8Array(rowSize * height);
+          let k = 0;
+          for (let i = 0, ii = height * rowLen; i < ii; i += rowLen) {
+            const row = data.subarray(i, i + rowLen);
+            for (let j = 0; j < rowLen; j += 3) {
+              newData[k++] = row[j + 2];
+              newData[k++] = row[j + 1];
+              newData[k++] = row[j];
+            }
+            k += extraLen;
+          }
+          data = newData;
+        } else {
+          for (let i = 0, ii = data.length; i < ii; i += 3) {
+            // Just swap R and B.
+            const tmp = data[i];
+            data[i] = data[i + 2];
+            data[i + 2] = tmp;
+          }
+        }
+        break;
+      }
+      case ImageKind.RGBA_32BPP:
+        bitPerPixel = 32;
+        compression = 3;
+        maskTable = new Uint8Array(
+          4 /* R mask */ +
+            4 /* G mask */ +
+            4 /* B mask */ +
+            4 /* A mask */ +
+            52 /* Windows color space stuff */
+        );
+        const view = new DataView(maskTable.buffer);
+        if (FeatureTest.isLittleEndian) {
+          view.setUint32(0, 0x000000ff, true);
+          view.setUint32(4, 0x0000ff00, true);
+          view.setUint32(8, 0x00ff0000, true);
+          view.setUint32(12, 0xff000000, true);
+        } else {
+          view.setUint32(0, 0xff000000, true);
+          view.setUint32(4, 0x00ff0000, true);
+          view.setUint32(8, 0x0000ff00, true);
+          view.setUint32(12, 0x000000ff, true);
+        }
+        break;
+      default:
+        throw new Error("invalid format");
+    }
+
+    let i = 0;
+    const headerLength = 40 + maskTable.length;
+    const fileLength = 14 + headerLength + colorTable.length + data.length;
+    const bmpData = new Uint8Array(fileLength);
+    const view = new DataView(bmpData.buffer);
+
+    // Signature.
+    view.setUint16(i, 0x4d42, true);
+    i += 2;
+
+    // File size.
+    view.setUint32(i, fileLength, true);
+    i += 4;
+
+    // Reserved.
+    view.setUint32(i, 0, true);
+    i += 4;
+
+    // Data offset.
+    view.setUint32(i, 14 + headerLength + colorTable.length, true);
+    i += 4;
+
+    // Header size.
+    view.setUint32(i, headerLength, true);
+    i += 4;
+
+    // Width.
+    view.setInt32(i, width, true);
+    i += 4;
+
+    // Height.
+    // Negative height indicates that the image is stored from top to bottom.
+    view.setInt32(i, -height, true);
+    i += 4;
+
+    // Number of planes (must be 1).
+    view.setUint16(i, 1, true);
+    i += 2;
+
+    // Number of bit per pixel.
+    view.setUint16(i, bitPerPixel, true);
+    i += 2;
+
+    // Compression method.
+    view.setUint32(i, compression, true);
+    i += 4;
+
+    // The image size.
+    view.setUint32(i, 0, true);
+    i += 4;
+
+    // Horizontal resolution.
+    view.setInt32(i, 0, true);
+    i += 4;
+
+    // Vertical resolution.
+    view.setInt32(i, 0, true);
+    i += 4;
+
+    // Number of colors in the palette (0 to default).
+    view.setUint32(i, colorTable.length / 4, true);
+    i += 4;
+
+    // Number of important colors used (0 to default).
+    view.setUint32(i, 0, true);
+    i += 4;
+
+    bmpData.set(maskTable, i);
+    i += maskTable.length;
+
+    bmpData.set(colorTable, i);
+    i += colorTable.length;
+
+    bmpData.set(data, i);
+
+    return bmpData;
+  }
+}
+
+ImageResizer._goodSquareLength = MIN_IMAGE_DIM;
+
+export { ImageResizer };

test/pdfs/issue6741.pdf.link

@@ -0,0 +1,2 @@
+https://github.com/mozilla/pdf.js/files/57455/DC000933-uncompressed.pdf
+

test/pdfs/issue8076.pdf.link

@@ -0,0 +1,2 @@
+https://github.com/mozilla/pdf.js/files/1135236/eID_Broschuere-page16.pdf
+

test/test_manifest.json

@@ -7378,5 +7378,21 @@
       "md5": "1eec7137e471a3d68a20855a04293b5b",
       "link": true,
       "type": "other"
+   },
+   {
+      "id": "issue6741",
+      "file": "pdfs/issue6741.pdf",
+      "md5": "ddbe6ccc7ae414c7ffa6c4110536730d",
+      "rounds": 1,
+      "link": true,
+      "type": "eq"
+   },
+   {
+      "id": "issue8076",
+      "file": "pdfs/issue8076.pdf",
+      "md5": "4a866bff4209956a6cfa2e2c9456f421",
+      "rounds": 1,
+      "link": true,
+      "type": "eq"
    }
 ]