Sakurai/pdf.js
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Merge pull request #4356 from fkaelberer/Optimize_1bpc_images

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Optimizations for 1 bpc images
This commit is contained in:
Yury Delendik 2014-03-05 06:01:52 -06:00
commit 65ce7ca88d
1 changed files with 54 additions and 19 deletions
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73
src/core/image.js
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@ -64,9 +64,10 @@ var PDFImage = (function PDFImageClosure() {
this.width = dict.get('Width', 'W');
this.height = dict.get('Height', 'H');
if (this.width < 1 || this.height < 1)
if (this.width < 1 || this.height < 1) {
error('Invalid image width: ' + this.width + ' or height: ' +
this.height);
}
this.interpolate = dict.get('Interpolate', 'I') || false;
this.imageMask = dict.get('ImageMask', 'IM') || false;
@ -76,10 +77,11 @@ var PDFImage = (function PDFImageClosure() {
if (!bitsPerComponent) {
bitsPerComponent = dict.get('BitsPerComponent', 'BPC');
if (!bitsPerComponent) {
if (this.imageMask)
if (this.imageMask) {
bitsPerComponent = 1;
else
} else {
error('Bits per component missing in image: ' + this.imageMask);
}
}
}
this.bpc = bitsPerComponent;
@ -285,23 +287,34 @@ var PDFImage = (function PDFImageClosure() {
if (bpc === 1) {
// Optimization for reading 1 bpc images.
var mask = 0;
var buf = 0;
var i = 0, buf, mask, loop1End, loop2End;
for (var j = 0; j < height; j++) {
loop1End = i + (rowComps & ~7);
loop2End = i + rowComps;
for (var i = 0, ii = length; i < ii; ++i) {
if (i % rowComps === 0) {
mask = 0;
buf = 0;
} else {
mask >>= 1;
// unroll loop for all full bytes
while (i < loop1End) {
buf = buffer[bufferPos++];
output[i] = (buf >> 7) & 1;
output[i + 1] = (buf >> 6) & 1;
output[i + 2] = (buf >> 5) & 1;
output[i + 3] = (buf >> 4) & 1;
output[i + 4] = (buf >> 3) & 1;
output[i + 5] = (buf >> 2) & 1;
output[i + 6] = (buf >> 1) & 1;
output[i + 7] = buf & 1;
i += 8;
}
if (mask <= 0) {
// handle remaing bits
if (i < loop2End) {
buf = buffer[bufferPos++];
mask = 128;
while (i < loop2End) {
output[i++] = +!!(buf & mask);
mask >>= 1;
}
}
output[i] = +!!(buf & mask);
}
} else {
// The general case that handles all other bpc values.
@ -337,9 +350,10 @@ var PDFImage = (function PDFImageClosure() {
var sh = smask.height;
alphaBuf = new Uint8Array(sw * sh);
smask.fillGrayBuffer(alphaBuf);
if (sw != width || sh != height)
if (sw != width || sh != height) {
alphaBuf = PDFImage.resize(alphaBuf, smask.bpc, 1, sw, sh, width,
height);
}
} else if (mask) {
if (mask instanceof PDFImage) {
var sw = mask.width;
@ -349,12 +363,14 @@ var PDFImage = (function PDFImageClosure() {
mask.fillGrayBuffer(alphaBuf);
// Need to invert values in rgbaBuf
for (var i = 0, ii = sw * sh; i < ii; ++i)
for (var i = 0, ii = sw * sh; i < ii; ++i) {
alphaBuf[i] = 255 - alphaBuf[i];
}
if (sw != width || sh != height)
if (sw != width || sh != height) {
alphaBuf = PDFImage.resize(alphaBuf, mask.bpc, 1, sw, sh, width,
height);
}
} else if (isArray(mask)) {
// Color key mask: if any of the compontents are outside the range
// then they should be painted.
@ -422,7 +438,7 @@ var PDFImage = (function PDFImageClosure() {
var drawHeight = this.drawHeight;
var imgData = { // other fields are filled in below
width: drawWidth,
height: drawHeight,
height: drawHeight
};
var numComps = this.numComps;
@ -507,14 +523,33 @@ var PDFImage = (function PDFImageClosure() {
var imgArray = this.getImageBytes(height * rowBytes);
var comps = this.getComponents(imgArray);
if (bpc === 1) {
// inline decoding (= inversion) for 1 bpc images
var length = width * height;
if (this.needsDecode) {
// invert and scale to {0, 255}
for (var i = 0; i < length; ++i) {
buffer[i] = (comps[i] - 1) & 255;
}
} else {
// scale to {0, 255}
for (var i = 0; i < length; ++i) {
buffer[i] = (-comps[i]) & 255;
}
}
return;
}
if (this.needsDecode) {
this.decodeBuffer(comps);
}
var length = width * height;
// we aren't using a colorspace so we need to scale the value
var scale = 255 / ((1 << bpc) - 1);
for (var i = 0; i < length; ++i)
for (var i = 0; i < length; ++i) {
buffer[i] = (scale * comps[i]) | 0;
}
},
getImageBytes: function PDFImage_getImageBytes(length) {
this.image.reset();