src/core/jpg.js

@@ -17,6 +17,7 @@ import { assert, BaseException, warn } from "../shared/util.js";
 import { ColorSpaceUtils } from "./colorspace_utils.js";
 import { DeviceCmykCS } from "./colorspace.js";
 import { grayToRGBA } from "../shared/image_utils.js";
+import { readUint16 } from "./core_utils.js";
 
 class JpegError extends BaseException {
   constructor(msg) {
@@ -121,7 +122,6 @@ function getBlockBufferOffset(component, row, col) {
 
 function decodeScan(
   data,
-  view,
   offset,
   frame,
   components,
@@ -151,7 +151,7 @@ function decodeScan(
         if (nextByte === /* DNL = */ 0xdc && parseDNLMarker) {
           offset += 2; // Skip marker length.
 
-          const scanLines = view.getUint16(offset);
+          const scanLines = readUint16(data, offset);
           offset += 2;
           if (scanLines > 0 && scanLines !== frame.scanLines) {
             throw new DNLMarkerError(
@@ -434,7 +434,7 @@ function decodeScan(
 
     // find marker
     bitsCount = 0;
-    fileMarker = findNextFileMarker(data, view, offset);
+    fileMarker = findNextFileMarker(data, offset);
     if (!fileMarker) {
       break; // Reached the end of the image data without finding any marker.
     }
@@ -717,14 +717,14 @@ function buildComponentData(frame, component) {
   return component.blockData;
 }
 
-function findNextFileMarker(data, view, currentPos, startPos = currentPos) {
+function findNextFileMarker(data, currentPos, startPos = currentPos) {
   const maxPos = data.length - 1;
   let newPos = startPos < currentPos ? startPos : currentPos;
 
   if (currentPos >= maxPos) {
     return null; // Don't attempt to read non-existent data and just return.
   }
-  const currentMarker = view.getUint16(currentPos);
+  const currentMarker = readUint16(data, currentPos);
   if (currentMarker >= 0xffc0 && currentMarker <= 0xfffe) {
     return {
       invalid: null,
@@ -732,12 +732,12 @@ function findNextFileMarker(data, view, currentPos, startPos = currentPos) {
       offset: currentPos,
     };
   }
-  let newMarker = view.getUint16(newPos);
+  let newMarker = readUint16(data, newPos);
   while (!(newMarker >= 0xffc0 && newMarker <= 0xfffe)) {
     if (++newPos >= maxPos) {
       return null; // Don't attempt to read non-existent data and just return.
     }
-    newMarker = view.getUint16(newPos);
+    newMarker = readUint16(data, newPos);
   }
   return {
     invalid: currentMarker.toString(16),
@@ -769,12 +769,12 @@ function prepareComponents(frame) {
   frame.mcusPerColumn = mcusPerColumn;
 }
 
-function readDataBlock(data, view, offset) {
-  const length = view.getUint16(offset);
+function readDataBlock(data, offset) {
+  const length = readUint16(data, offset);
   offset += 2;
   let endOffset = offset + length - 2;
 
-  const fileMarker = findNextFileMarker(data, view, endOffset, offset);
+  const fileMarker = findNextFileMarker(data, endOffset, offset);
   if (fileMarker?.invalid) {
     warn(
       "readDataBlock - incorrect length, current marker is: " +
@@ -791,12 +791,12 @@ function readDataBlock(data, view, offset) {
   };
 }
 
-function skipData(data, view, offset) {
-  const length = view.getUint16(offset);
+function skipData(data, offset) {
+  const length = readUint16(data, offset);
   offset += 2;
   const endOffset = offset + length - 2;
 
-  const fileMarker = findNextFileMarker(data, view, endOffset, offset);
+  const fileMarker = findNextFileMarker(data, endOffset, offset);
   if (fileMarker?.invalid) {
     return fileMarker.offset;
   }
@@ -810,16 +810,15 @@ class JpegImage {
   }
 
   static canUseImageDecoder(data, colorTransform = -1) {
-    const view = new DataView(data.buffer, data.byteOffset, data.byteLength);
     let exifOffsets = null;
     let offset = 0;
     let numComponents = null;
-    let fileMarker = view.getUint16(offset);
+    let fileMarker = readUint16(data, offset);
     offset += 2;
     if (fileMarker !== /* SOI (Start of Image) = */ 0xffd8) {
       throw new JpegError("SOI not found");
     }
-    fileMarker = view.getUint16(offset);
+    fileMarker = readUint16(data, offset);
     offset += 2;
 
     markerLoop: while (fileMarker !== /* EOI (End of Image) = */ 0xffd9) {
@@ -827,11 +826,7 @@ class JpegImage {
         case 0xffe1: // APP1 - Exif
           // TODO: Remove this once https://github.com/w3c/webcodecs/issues/870
           //       is fixed.
-          const { appData, oldOffset, newOffset } = readDataBlock(
-            data,
-            view,
-            offset
-          );
+          const { appData, oldOffset, newOffset } = readDataBlock(data, offset);
           offset = newOffset;
 
           // 'Exif\x00\x00'
@@ -850,7 +845,7 @@ class JpegImage {
             // since that can modify the original PDF document.
             exifOffsets = { exifStart: oldOffset + 6, exifEnd: newOffset };
           }
-          fileMarker = view.getUint16(offset);
+          fileMarker = readUint16(data, offset);
           offset += 2;
           continue;
         case 0xffc0: // SOF0 (Start of Frame, Baseline DCT)
@@ -869,8 +864,8 @@ class JpegImage {
           }
           break;
       }
-      offset = skipData(data, view, offset);
-      fileMarker = view.getUint16(offset);
+      offset = skipData(data, offset);
+      fileMarker = readUint16(data, offset);
       offset += 2;
     }
     if (numComponents === 4) {
@@ -883,8 +878,6 @@ class JpegImage {
   }
 
   parse(data, { dnlScanLines = null } = {}) {
-    const view = new DataView(data.buffer, data.byteOffset, data.byteLength);
-    const maxOffset = data.length - 1;
     let offset = 0;
     let jfif = null;
     let adobe = null;
@@ -894,12 +887,12 @@ class JpegImage {
     const huffmanTablesAC = [],
       huffmanTablesDC = [];
 
-    let fileMarker = view.getUint16(offset);
+    let fileMarker = readUint16(data, offset);
     offset += 2;
     if (fileMarker !== /* SOI (Start of Image) = */ 0xffd8) {
       throw new JpegError("SOI not found");
     }
-    fileMarker = view.getUint16(offset);
+    fileMarker = readUint16(data, offset);
     offset += 2;
 
     markerLoop: while (fileMarker !== /* EOI (End of Image) = */ 0xffd9) {
@@ -922,7 +915,7 @@ class JpegImage {
         case 0xffee: // APP14
         case 0xffef: // APP15
         case 0xfffe: // COM (Comment)
-          const { appData, newOffset } = readDataBlock(data, view, offset);
+          const { appData, newOffset } = readDataBlock(data, offset);
           offset = newOffset;
 
           if (fileMarker === 0xffe0) {
@@ -969,7 +962,7 @@ class JpegImage {
           break;
 
         case 0xffdb: // DQT (Define Quantization Tables)
-          const quantizationTablesLength = view.getUint16(offset);
+          const quantizationTablesLength = readUint16(data, offset);
           offset += 2;
           const quantizationTablesEnd = quantizationTablesLength + offset - 2;
           let z;
@@ -986,7 +979,7 @@ class JpegImage {
               // 16 bit values
               for (j = 0; j < 64; j++) {
                 z = dctZigZag[j];
-                tableData[z] = view.getUint16(offset);
+                tableData[z] = readUint16(data, offset);
                 offset += 2;
               }
             } else {
@@ -1008,10 +1001,10 @@ class JpegImage {
           frame.extended = fileMarker === 0xffc1;
           frame.progressive = fileMarker === 0xffc2;
           frame.precision = data[offset++];
-          const sofScanLines = view.getUint16(offset);
+          const sofScanLines = readUint16(data, offset);
           offset += 2;
           frame.scanLines = dnlScanLines || sofScanLines;
-          frame.samplesPerLine = view.getUint16(offset);
+          frame.samplesPerLine = readUint16(data, offset);
           offset += 2;
           frame.components = [];
           frame.componentIds = {};
@@ -1044,7 +1037,7 @@ class JpegImage {
           break;
 
         case 0xffc4: // DHT (Define Huffman Tables)
-          const huffmanLength = view.getUint16(offset);
+          const huffmanLength = readUint16(data, offset);
           offset += 2;
           for (i = 2; i < huffmanLength; ) {
             const huffmanTableSpec = data[offset++];
@@ -1068,7 +1061,7 @@ class JpegImage {
         case 0xffdd: // DRI (Define Restart Interval)
           offset += 2; // Skip marker length.
 
-          resetInterval = view.getUint16(offset);
+          resetInterval = readUint16(data, offset);
           offset += 2;
           break;
 
@@ -1099,7 +1092,6 @@ class JpegImage {
           try {
             const processed = decodeScan(
               data,
-              view,
               offset,
               frame,
               components,
@@ -1141,7 +1133,6 @@ class JpegImage {
           // `startPos = offset - 3` when looking for the next valid marker.
           const nextFileMarker = findNextFileMarker(
             data,
-            view,
             /* currentPos = */ offset - 2,
             /* startPos = */ offset - 3
           );
@@ -1153,7 +1144,7 @@ class JpegImage {
             offset = nextFileMarker.offset;
             break;
           }
-          if (!nextFileMarker || offset >= maxOffset) {
+          if (!nextFileMarker || offset >= data.length - 1) {
             warn(
               "JpegImage.parse - reached the end of the image data " +
                 "without finding an EOI marker (0xFFD9)."
@@ -1164,13 +1155,8 @@ class JpegImage {
             "JpegImage.parse - unknown marker: " + fileMarker.toString(16)
           );
       }
-
-      if (offset < maxOffset) {
-        fileMarker = view.getUint16(offset);
-        offset += 2;
-      } else {
-        fileMarker = 0;
-      }
+      fileMarker = readUint16(data, offset);
+      offset += 2;
     }
 
     if (!frame) {