[Pkg-javascript-commits] [pdf.js] 156/246: Reduces amount of used memory during PNG creation.
David Prévot
taffit at moszumanska.debian.org
Sun Sep 7 15:36:36 UTC 2014
This is an automated email from the git hooks/post-receive script.
taffit pushed a commit to branch master
in repository pdf.js.
commit 56f0539045540231964ef20bc16f5c4964993752
Author: Yury Delendik <ydelendik at mozilla.com>
Date: Sat Aug 9 15:53:05 2014 -0500
Reduces amount of used memory during PNG creation.
---
src/display/svg.js | 98 ++++++++++++++++++++++++++++++------------------------
1 file changed, 55 insertions(+), 43 deletions(-)
diff --git a/src/display/svg.js b/src/display/svg.js
index 46048f5..13b2648 100644
--- a/src/display/svg.js
+++ b/src/display/svg.js
@@ -30,7 +30,12 @@ function createScratchSVG(width, height) {
}
var convertImgDataToPng = (function convertImgDataToPngClosure() {
- var crcTable = [];
+ var PNG_HEADER =
+ new Uint8Array([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);
+
+ var CHUNK_WRAPPER_SIZE = 12;
+
+ var crcTable = new Int32Array(256);
for (var i = 0; i < 256; i++) {
var c = i;
for (var h = 0; h < 8; h++) {
@@ -53,32 +58,32 @@ var convertImgDataToPng = (function convertImgDataToPngClosure() {
return crc ^ -1;
}
- function createPngChunk(type, data) {
- var chunk = new Uint8Array(12 + data.length);
- var p = 0;
+ function writePngChunk(type, body, data, offset) {
+ var p = offset;
- var len = data.length;
- chunk[p] = len >> 24 & 0xff;
- chunk[p + 1] = len >> 16 & 0xff;
- chunk[p + 2] = len >> 8 & 0xff;
- chunk[p + 3] = len & 0xff;
+ var len = body.length;
- chunk[p + 4] = type.charCodeAt(0) & 0xff;
- chunk[p + 5] = type.charCodeAt(1) & 0xff;
- chunk[p + 6] = type.charCodeAt(2) & 0xff;
- chunk[p + 7] = type.charCodeAt(3) & 0xff;
+ data[p] = len >> 24 & 0xff;
+ data[p + 1] = len >> 16 & 0xff;
+ data[p + 2] = len >> 8 & 0xff;
+ data[p + 3] = len & 0xff;
+ p += 4;
- chunk.set(data, 8);
+ data[p] = type.charCodeAt(0) & 0xff;
+ data[p + 1] = type.charCodeAt(1) & 0xff;
+ data[p + 2] = type.charCodeAt(2) & 0xff;
+ data[p + 3] = type.charCodeAt(3) & 0xff;
+ p += 4;
- p = 8 + len;
+ data.set(body, p);
+ p += body.length;
- var crc = crc32(chunk, 4, p);
- chunk[p] = crc >> 24 & 0xff;
- chunk[p + 1] = crc >> 16 & 0xff;
- chunk[p + 2] = crc >> 8 & 0xff;
- chunk[p + 3] = crc & 0xff;
+ var crc = crc32(data, offset + 4, p);
- return chunk;
+ data[p] = crc >> 24 & 0xff;
+ data[p + 1] = crc >> 16 & 0xff;
+ data[p + 2] = crc >> 8 & 0xff;
+ data[p + 3] = crc & 0xff;
}
function adler32(data, start, end) {
@@ -119,18 +124,26 @@ var convertImgDataToPng = (function convertImgDataToPngClosure() {
throw new Error('invalid format');
}
+ // prefix every row with predictor 0
var literals = new Uint8Array((1 + lineSize) * height);
var offsetLiterals = 0, offsetBytes = 0;
- for (var y = 0; y < height; ++y) {
- literals[offsetLiterals++] = 0;
+ var y, i;
+ for (y = 0; y < height; ++y) {
+ literals[offsetLiterals++] = 0; // no prediction
literals.set(bytes.subarray(offsetBytes, offsetBytes + lineSize),
offsetLiterals);
offsetBytes += lineSize;
offsetLiterals += lineSize;
}
+
if (kind === ImageKind.GRAYSCALE_1BPP) {
- for (var i = 0, ii = bytes.length; i < ii; i++) {
- bytes[i] ^= 0xFF;
+ // inverting for B/W
+ offsetLiterals = 0;
+ for (y = 0; y < height; y++) {
+ offsetLiterals++; // skipping predictor
+ for (i = 0; i < lineSize; i++) {
+ literals[offsetLiterals++] ^= 0xFF;
+ }
}
}
@@ -153,14 +166,15 @@ var convertImgDataToPng = (function convertImgDataToPngClosure() {
var len = literals.length;
var maxBlockLength = 0xFFFF;
- var idat = new Uint8Array(2 + len +
- Math.ceil(len / maxBlockLength) * 5 + 4);
+ var deflateBlocks = Math.ceil(len / maxBlockLength);
+ var idat = new Uint8Array(2 + len + deflateBlocks * 5 + 4);
var pi = 0;
idat[pi++] = 0x78; // compression method and flags
idat[pi++] = 0x9c; // flags
var pos = 0;
while (len > maxBlockLength) {
+ // writing non-final DEFLATE blocks type 0 and length of 65535
idat[pi++] = 0x00;
idat[pi++] = 0xff;
idat[pi++] = 0xff;
@@ -172,12 +186,12 @@ var convertImgDataToPng = (function convertImgDataToPngClosure() {
len -= maxBlockLength;
}
+ // writing non-final DEFLATE blocks type 0
idat[pi++] = 0x01;
idat[pi++] = len & 0xff;
idat[pi++] = len >> 8 & 0xff;
idat[pi++] = (~len & 0xffff) & 0xff;
idat[pi++] = (~len & 0xffff) >> 8 & 0xff;
-
idat.set(literals.subarray(pos), pi);
pi += literals.length - pos;
@@ -187,28 +201,26 @@ var convertImgDataToPng = (function convertImgDataToPngClosure() {
idat[pi++] = adler >> 8 & 0xff;
idat[pi++] = adler & 0xff;
- var chunks = [
- new Uint8Array([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]),
- createPngChunk('IHDR', ihdr),
- createPngChunk('IDAT', idat),
- createPngChunk('IEND', new Uint8Array(0))
- ];
+ // PNG will consists: header, IHDR+data, IDAT+data, and IEND.
+ var pngLength = PNG_HEADER.length + CHUNK_WRAPPER_SIZE * 3 +
+ ihdr.length + idat.length;
+ var data = new Uint8Array(pngLength);
+ var offset = 0;
+ data.set(PNG_HEADER, offset);
+ offset += PNG_HEADER.length;
+ writePngChunk('IHDR', ihdr, data, offset);
+ offset += CHUNK_WRAPPER_SIZE + ihdr.length;
+ writePngChunk('IDATA', idat, data, offset);
+ offset += CHUNK_WRAPPER_SIZE + idat.length;
+ writePngChunk('IEND', new Uint8Array(0), data, offset);
- var data = [];
- for (var j = 0; j < 3; j++) {
- data.push.apply(data, chunks[j]);
- }
- data = new Uint8Array(data);
return PDFJS.createObjectURL(data, 'image/png');
}
return function convertImgDataToPng(imgData) {
var kind = (imgData.kind === undefined ?
ImageKind.GRAYSCALE_1BPP : imgData.kind);
- var url = encode(imgData, kind);
- if (url) {
- return url;
- }
+ return encode(imgData, kind);
};
})();
--
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