yetangitu/pdf.js
1
0
Fork 0
Code Issues Pull requests Releases Wiki Activity

Optimized putBinaryImageData for GRAYSCALE_1BPP

Browse source 
The following changes make putBinaryImageData 2.2x faster.

* Use a Uint32Array to draw whole pixels instead component by component

* Unroll the inner most loop

* Added lazy PDFJS.hasCanvasTypedArrays, PDFJS.isLittleEndian and compatibility
Uint32ArrayView for browsers using the old CanvasPixelArray
This commit is contained in:
p01 2014-03-20 16:57:11 +01:00
parent 26d57a5c9c
commit 4e6ebf2de0
2 changed files with 112 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

67
src/display/canvas.js
View file

@ -14,10 +14,10 @@
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* globals ColorSpace, DeviceCmykCS, DeviceGrayCS, DeviceRgbCS, error,
FONT_IDENTITY_MATRIX, IDENTITY_MATRIX, ImageData, ImageKind,
isArray, isNum, TilingPattern, OPS, Promise, Util, warn, assert,
info, shadow, TextRenderingMode, getShadingPatternFromIR */
/* globals ColorSpace, DeviceCmykCS, DeviceGrayCS, DeviceRgbCS, error, PDFJS,
FONT_IDENTITY_MATRIX, Uint32ArrayView, IDENTITY_MATRIX, ImageData,
ImageKind, isArray, isNum, TilingPattern, OPS, Promise, Util, warn,
assert, info, shadow, TextRenderingMode, getShadingPatternFromIR */
'use strict';
@ -463,45 +463,48 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
// Grayscale, 1 bit per pixel (i.e. black-and-white).
var destDataLength = dest.length;
var srcLength = src.byteLength;
for (var i = 3; i < destDataLength; i += 4) {
dest[i] = 255;
}
var dest32 = PDFJS.hasCanvasTypedArrays ? new Uint32Array(dest.buffer) :
new Uint32ArrayView(dest);
var dest32DataLength = dest32.length;
var fullSrcDiff = (width + 7) >> 3;
var white = 0xFFFFFFFF;
var black = (PDFJS.isLittleEndian || !PDFJS.hasCanvasTypedArrays) ?
0xFF000000 : 0x000000FF;
for (var i = 0; i < totalChunks; i++) {
var thisChunkHeight =
(i < fullChunks) ? fullChunkHeight : partialChunkHeight;
var destPos = 0;
for (var j = 0; j < thisChunkHeight; j++) {
var srcDiff = srcLength - srcPos;
var k = 0;
var kEnd = (srcDiff > fullSrcDiff) ? width : srcDiff * 8 - 7;
var kEndUnrolled = kEnd & ~7;
var mask = 0;
var srcByte = 0;
for (var k = 0; k < width; k++, destPos += 4) {
if (mask === 0) {
if (srcPos >= srcLength) {
break;
}
srcByte = src[srcPos++];
mask = 128;
}
if ((srcByte & mask)) {
dest[destPos] = 255;
dest[destPos + 1] = 255;
dest[destPos + 2] = 255;
} else {
dest[destPos] = 0;
dest[destPos + 1] = 0;
dest[destPos + 2] = 0;
}
for (; k < kEndUnrolled; k += 8) {
srcByte = src[srcPos++];
dest32[destPos++] = (srcByte & 128) ? white : black;
dest32[destPos++] = (srcByte & 64) ? white : black;
dest32[destPos++] = (srcByte & 32) ? white : black;
dest32[destPos++] = (srcByte & 16) ? white : black;
dest32[destPos++] = (srcByte & 8) ? white : black;
dest32[destPos++] = (srcByte & 4) ? white : black;
dest32[destPos++] = (srcByte & 2) ? white : black;
dest32[destPos++] = (srcByte & 1) ? white : black;
}
for (; k < kEnd; k++) {
if (mask === 0) {
srcByte = src[srcPos++];
mask = 128;
}
dest32[destPos++] = (srcByte & mask) ? white : black;
mask >>= 1;
}
}
if (destPos < destDataLength) {
// We ran out of input. Make all remaining pixels transparent.
destPos += 3;
do {
dest[destPos] = 0;
destPos += 4;
} while (destPos < destDataLength);
// We ran out of input. Make all remaining pixels transparent.
while (destPos < dest32DataLength) {
dest32[destPos++] = 0;
}
ctx.putImageData(chunkImgData, 0, i * fullChunkHeight);