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PDFImage_resize: copy in place with alpha and ~5x speed up

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p01 2014-04-23 16:56:22 +02:00
parent bda1865fb8
commit 8f9bd33a57
2 changed files with 49 additions and 28 deletions
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56
src/core/image.js
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@ -198,30 +198,50 @@ var PDFImage = (function PDFImageClosure() {
* @param {Number} h1 Original height.
* @param {Number} w2 New width.
* @param {Number} h2 New height.
* @param {TypedArray} dest (Optional) The destination buffer.
* @param {Number} alpha01 (Optional) Size reserved for the alpha channel.
* @return {TypedArray} Resized image data.
*/
PDFImage.resize = function PDFImage_resize(pixels, bpc, components,
w1, h1, w2, h2) {
w1, h1, w2, h2, dest, alpha01) {
if (components !== 1 && components !== 3) {
error('Unsupported component count for resizing.');
}
var length = w2 * h2 * components;
var temp = (bpc <= 8 ? new Uint8Array(length) :
var temp = dest ? dest : (bpc <= 8 ? new Uint8Array(length) :
(bpc <= 16 ? new Uint16Array(length) : new Uint32Array(length)));
var xRatio = w1 / w2;
var yRatio = h1 / h2;
var px, py, newIndex, oldIndex;
for (var i = 0; i < h2; i++) {
for (var j = 0; j < w2; j++) {
px = Math.floor(j * xRatio);
py = Math.floor(i * yRatio);
newIndex = (i * w2) + j;
oldIndex = ((py * w1) + px);
if (components === 1) {
temp[newIndex] = pixels[oldIndex];
} else if (components === 3) {
newIndex *= 3;
oldIndex *= 3;
temp[newIndex] = pixels[oldIndex];
temp[newIndex + 1] = pixels[oldIndex + 1];
temp[newIndex + 2] = pixels[oldIndex + 2];
var i, j, py, newIndex = 0, oldIndex;
var xScaled = new Uint16Array(w2);
var w1Scanline = w1 * components;
if (alpha01 !== 1) {
alpha01 = 0;
}
for (j = 0; j < w2; j++) {
xScaled[j] = Math.floor(j * xRatio) * components;
}
if (components === 1) {
for (i = 0; i < h2; i++) {
py = Math.floor(i * yRatio) * w1Scanline;
for (j = 0; j < w2; j++) {
oldIndex = py + xScaled[j];
temp[newIndex++] = pixels[oldIndex];
}
}
} else if (components === 3) {
for (i = 0; i < h2; i++) {
py = Math.floor(i * yRatio) * w1Scanline;
for (j = 0; j < w2; j++) {
oldIndex = py + xScaled[j];
temp[newIndex++] = pixels[oldIndex++];
temp[newIndex++] = pixels[oldIndex++];
temp[newIndex++] = pixels[oldIndex++];
newIndex += alpha01;
}
}
}
@ -568,7 +588,7 @@ var PDFImage = (function PDFImageClosure() {
// inline decoding (= inversion) for 1 bpc images
length = width * height;
if (this.needsDecode) {
// invert and scale to {0, 255}
// invert and scale to {0, 255}
for (i = 0; i < length; ++i) {
buffer[i] = (comps[i] - 1) & 255;
}

21
src/shared/colorspace.js
View File

@ -145,16 +145,17 @@ var ColorSpace = (function ColorSpaceClosure() {
if (rgbBuf) {
if (needsResizing) {
rgbBuf = PDFImage.resize(rgbBuf, bpc, 3, originalWidth,
originalHeight, width, height);
}
rgbPos = 0;
destPos = 0;
for (i = 0, ii = width * actualHeight; i < ii; i++) {
dest[destPos++] = rgbBuf[rgbPos++];
dest[destPos++] = rgbBuf[rgbPos++];
dest[destPos++] = rgbBuf[rgbPos++];
destPos += alpha01;
PDFImage.resize(rgbBuf, bpc, 3, originalWidth, originalHeight, width,
height, dest, alpha01);
} else {
rgbPos = 0;
destPos = 0;
for (i = 0, ii = width * actualHeight; i < ii; i++) {
dest[destPos++] = rgbBuf[rgbPos++];
dest[destPos++] = rgbBuf[rgbPos++];
dest[destPos++] = rgbBuf[rgbPos++];
destPos += alpha01;
}
}
}
},