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Pre-scale image in the paintImageMaskXObject

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Yury Delendik 2012-05-27 13:50:46 -05:00
parent e9632120c4
commit 81681e7914
1 changed files with 45 additions and 1 deletions
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46
src/canvas.js
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@ -1094,6 +1094,40 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
}
}
}
function rescaleImage(pixels, widthScale, heightScale) {
var scaledWidth = Math.ceil(width / widthScale);
var scaledHeight = Math.ceil(height / heightScale);
var itemsSum = new Uint32Array(scaledWidth * scaledHeight * 4);
var itemsCount = new Uint32Array(scaledWidth * scaledHeight);
for (var i = 0, position = 0; i < height; i++) {
var lineOffset = (0 | (i / heightScale)) * scaledWidth;
for (var j = 0; j < width; j++) {
var countOffset = lineOffset + (0 | (j / widthScale));
var sumOffset = countOffset << 2;
itemsSum[sumOffset] += pixels[position];
itemsSum[sumOffset + 1] += pixels[position + 1];
itemsSum[sumOffset + 2] += pixels[position + 2];
itemsSum[sumOffset + 3] += pixels[position + 3];
itemsCount[countOffset]++;
position += 4;
}
}
var tmpCanvas = createScratchCanvas(scaledWidth, scaledHeight);
var tmpCtx = tmpCanvas.getContext('2d');
var imgData = tmpCtx.getImageData(0, 0, scaledWidth, scaledHeight);
pixels = imgData.data;
for (var i = 0, j = 0, ii = scaledWidth * scaledHeight; i < ii; i++) {
var count = itemsCount[i];
pixels[j] = itemsSum[j] / count;
pixels[j + 1] = itemsSum[j + 1] / count;
pixels[j + 2] = itemsSum[j + 2] / count;
pixels[j + 3] = itemsSum[j + 3] / count;
j += 4;
}
tmpCtx.putImageData(imgData, 0, 0);
return tmpCanvas;
}
this.save();
@ -1117,7 +1151,17 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
applyStencilMask(pixels, inverseDecode);
tmpCtx.putImageData(imgData, 0, 0);
ctx.drawImage(tmpCanvas, 0, -h);
var currentTransform = ctx.mozCurrentTransformInverse;
var widthScale = Math.max(Math.abs(currentTransform[0]), 1);
var heightScale = Math.max(Math.abs(currentTransform[3]), 1);
if (widthScale >= 2 || heightScale >= 2) {
// canvas does not resize large images to small -- using simple
// algorithm to perform pre-scaling
tmpCanvas = rescaleImage(imgData.data, widthScale, heightScale);
ctx.scale(widthScale, heightScale);
ctx.drawImage(tmpCanvas, 0, -h / heightScale);
} else
ctx.drawImage(tmpCanvas, 0, -h);
this.restore();
},