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Reduce memory consumption of simple black and white images.

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Nicholas Nethercote 2014-01-22 16:47:51 -08:00
parent 0049407762
commit a966909754
3 changed files with 110 additions and 53 deletions
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60
src/core/image.js
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@ -267,10 +267,10 @@ var PDFImage = (function PDFImageClosure() {
var bpc = this.bpc;
// This image doesn't require any extra work.
if (bpc === 8)
if (bpc === 8) {
return buffer;
}
var bufferLength = buffer.length;
var width = this.width;
var height = this.height;
var numComps = this.numComps;
@ -417,7 +417,14 @@ var PDFImage = (function PDFImageClosure() {
buffer[i + 2] = clamp((buffer[i + 2] - matteRgb[2]) * k + matteRgb[2]);
}
},
fillRgbaBuffer: function PDFImage_fillRgbaBuffer(buffer, width, height) {
createImageData: function PDFImage_createImageData() {
var drawWidth = this.drawWidth;
var drawHeight = this.drawHeight;
var imgData = { // other fields are filled in below
width: drawWidth,
height: drawHeight,
};
var numComps = this.numComps;
var originalWidth = this.width;
var originalHeight = this.height;
@ -429,21 +436,46 @@ var PDFImage = (function PDFImageClosure() {
// imgArray can be incomplete (e.g. after CCITT fax encoding)
var actualHeight = 0 | (imgArray.length / rowBytes *
height / originalHeight);
drawHeight / originalHeight);
// If it is a 1-bit-per-pixel grayscale (i.e. black-and-white) image
// without any complications, we pass a same-sized copy to the main
// thread rather than expanding by 32x to RGBA form. This saves *lots* of
// memory for many scanned documents. It's also much faster.
if (this.colorSpace.name === 'DeviceGray' && bpc === 1 &&
!this.smask && !this.mask && !this.needsDecode &&
drawWidth === originalWidth && drawHeight === originalHeight) {
imgData.kind = 'grayscale_1bpp';
// We must make a copy of imgArray, otherwise it'll be neutered upon
// transfer which will break any code that subsequently reuses it.
var newArray = new Uint8Array(imgArray.length);
newArray.set(imgArray);
imgData.data = newArray;
imgData.origLength = imgArray.length;
return imgData;
}
var comps = this.getComponents(imgArray);
var rgbaBuf = new Uint8Array(drawWidth * drawHeight * 4);
// Handle opacity here since color key masking needs to be performed on
// undecoded values.
this.fillOpacity(buffer, width, height, actualHeight, comps);
this.fillOpacity(rgbaBuf, drawWidth, drawHeight, actualHeight, comps);
if (this.needsDecode) {
this.decodeBuffer(comps);
}
this.colorSpace.fillRgb(buffer, originalWidth, originalHeight, width,
height, actualHeight, bpc, comps);
this.colorSpace.fillRgb(rgbaBuf, originalWidth, originalHeight, drawWidth,
drawHeight, actualHeight, bpc, comps);
this.undoPreblend(buffer, width, actualHeight);
this.undoPreblend(rgbaBuf, drawWidth, actualHeight);
imgData.kind = 'rgba_32bpp';
imgData.data = rgbaBuf;
return imgData;
},
fillGrayBuffer: function PDFImage_fillGrayBuffer(buffer) {
var numComps = this.numComps;
@ -468,18 +500,6 @@ var PDFImage = (function PDFImageClosure() {
for (var i = 0; i < length; ++i)
buffer[i] = (scale * comps[i]) | 0;
},
getImageData: function PDFImage_getImageData() {
var drawWidth = this.drawWidth;
var drawHeight = this.drawHeight;
var imgData = {
width: drawWidth,
height: drawHeight,
data: new Uint8Array(drawWidth * drawHeight * 4)
};
var pixels = imgData.data;
this.fillRgbaBuffer(pixels, drawWidth, drawHeight);
return imgData;
},
getImageBytes: function PDFImage_getImageBytes(length) {
this.image.reset();
return this.image.getBytes(length);