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Special-case 24-bit RGB image-handling.

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This commit is contained in:
Nicholas Nethercote 2014-02-24 19:37:19 -08:00
parent f11a6ae238
commit f62c1c469f
3 changed files with 51 additions and 23 deletions
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52
src/core/image.js
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@ -417,7 +417,7 @@ var PDFImage = (function PDFImageClosure() {
buffer[i + 2] = clamp((buffer[i + 2] - matteRgb[2]) * k + matteRgb[2]);
}
},
createImageData: function PDFImage_createImageData() {
createImageData: function PDFImage_createImageData(forceRGBA) {
var drawWidth = this.drawWidth;
var drawHeight = this.drawHeight;
var imgData = { // other fields are filled in below
@ -430,32 +430,42 @@ var PDFImage = (function PDFImageClosure() {
var originalHeight = this.height;
var bpc = this.bpc;
// rows start at byte boundary;
// Rows start at byte boundary.
var rowBytes = (originalWidth * numComps * bpc + 7) >> 3;
var imgArray = this.getImageBytes(originalHeight * rowBytes);
// imgArray can be incomplete (e.g. after CCITT fax encoding)
if (!forceRGBA) {
// 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.
//
// Similarly, if it is a 24-bit-per pixel RGB image without any
// complications, we avoid expanding by 1.333x to RGBA form.
var kind;
if (this.colorSpace.name === 'DeviceGray' && bpc === 1) {
kind = 'grayscale_1bpp';
} else if (this.colorSpace.name === 'DeviceRGB' && bpc === 8) {
kind = 'rgb_24bpp';
}
if (kind && !this.smask && !this.mask && !this.needsDecode &&
drawWidth === originalWidth && drawHeight === originalHeight) {
imgData.kind = kind;
// 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;
}
}
// imgArray can be incomplete (e.g. after CCITT fax encoding).
var actualHeight = 0 | (imgArray.length / rowBytes *
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);