Sakurai/pdf.js
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Merge pull request #4212 from yurydelendik/jank4181

Browse Source 
Removes scrolling jank after bw image optimization
This commit is contained in:
Brendan Dahl 2014-01-30 10:14:27 -08:00
commit 7be0924ac4
1 changed files with 30 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
src/display/canvas.js
View File

@ -442,13 +442,14 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
// will (conceptually) put pixels past the bounds of the canvas. But // will (conceptually) put pixels past the bounds of the canvas. But
// that's ok; any such pixels are ignored. // that's ok; any such pixels are ignored.
var height = imgData.height, width = imgData.width;
var fullChunkHeight = 16; var fullChunkHeight = 16;
var fracChunks = imgData.height / fullChunkHeight; var fracChunks = height / fullChunkHeight;
var fullChunks = Math.floor(fracChunks); var fullChunks = Math.floor(fracChunks);
var totalChunks = Math.ceil(fracChunks); var totalChunks = Math.ceil(fracChunks);
var partialChunkHeight = imgData.height - fullChunks * fullChunkHeight; var partialChunkHeight = height - fullChunks * fullChunkHeight;
var chunkImgData = ctx.createImageData(imgData.width, fullChunkHeight); var chunkImgData = ctx.createImageData(width, fullChunkHeight);
var srcPos = 0; var srcPos = 0;
var src = imgData.data; var src = imgData.data;
var dst = chunkImgData.data; var dst = chunkImgData.data;
@ -460,8 +461,11 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
// Grayscale, 1 bit per pixel (i.e. black-and-white). // Grayscale, 1 bit per pixel (i.e. black-and-white).
var srcData = imgData.data; var srcData = imgData.data;
var destData = chunkImgData.data; var destData = chunkImgData.data;
var alpha = 255; var destDataLength = destData.length;
var origLength = imgData.origLength; var origLength = imgData.origLength;
for (var i = 3; i < destDataLength; i += 4) {
destData[i] = 255;
}
for (var i = 0; i < totalChunks; i++) { for (var i = 0; i < totalChunks; i++) {
var thisChunkHeight = var thisChunkHeight =
(i < fullChunks) ? fullChunkHeight : partialChunkHeight; (i < fullChunks) ? fullChunkHeight : partialChunkHeight;
@ -469,25 +473,37 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
for (var j = 0; j < thisChunkHeight; j++) { for (var j = 0; j < thisChunkHeight; j++) {
var mask = 0; var mask = 0;
var srcByte = 0; var srcByte = 0;
for (var k = 0; k < imgData.width; k++) { for (var k = 0; k < width; k++, destPos += 4) {
if (srcPos >= origLength) {
// We ran out of input. Make all remaining pixels transparent.
alpha = 0;
}
if (mask === 0) { if (mask === 0) {
if (srcPos >= origLength) {
break;
}
srcByte = srcData[srcPos++]; srcByte = srcData[srcPos++];
mask = 128; mask = 128;
} }
var c = (+!!(srcByte & mask)) * 255; if ((srcByte & mask)) {
destData[destPos++] = c; destData[destPos] = 255;
destData[destPos++] = c; destData[destPos + 1] = 255;
destData[destPos++] = c; destData[destPos + 2] = 255;
destData[destPos++] = alpha; } else {
destData[destPos] = 0;
destData[destPos + 1] = 0;
destData[destPos + 2] = 0;
}
mask >>= 1; mask >>= 1;
} }
} }
if (destPos < destDataLength) {
// We ran out of input. Make all remaining pixels transparent.
destPos += 3;
do {
destData[destPos] = 0;
destPos += 4;
} while (destPos < destDataLength);
}
ctx.putImageData(chunkImgData, 0, i * fullChunkHeight); ctx.putImageData(chunkImgData, 0, i * fullChunkHeight);
} }