Rescale regular images manually if they are too big.
This commit is contained in:
Brendan Dahl
parent
bcbc21a51c
commit
39038b7377
148
src/canvas.js
148
src/canvas.js
@ -224,6 +224,60 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
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}
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}
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function rescaleImage(pixels, width, height, widthScale, heightScale) {
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var scaledWidth = Math.ceil(width / widthScale);
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var scaledHeight = Math.ceil(height / heightScale);
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var itemsSum = new Float32Array(scaledWidth * scaledHeight * 3);
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var itemsCount = new Float32Array(scaledWidth * scaledHeight);
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var maxAlphas = new Uint8Array(scaledWidth * scaledHeight);
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for (var i = 0, position = 0; i < height; i++) {
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var lineOffset = (0 | (i / heightScale)) * scaledWidth;
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for (var j = 0; j < width; j++) {
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var countOffset = lineOffset + (0 | (j / widthScale));
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var sumOffset = countOffset * 3;
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var maxAlpha = maxAlphas[countOffset];
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var currentAlpha = pixels[position + 3];
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if (maxAlpha < currentAlpha) {
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// lowering total alpha
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var scale = 1 - (currentAlpha - maxAlpha) / 255;
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itemsSum[sumOffset] *= scale;
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itemsSum[sumOffset + 1] *= scale;
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itemsSum[sumOffset + 2] *= scale;
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maxAlphas[countOffset] = maxAlpha = currentAlpha;
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}
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if (maxAlpha > currentAlpha) {
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var scale = 1 - (maxAlpha - currentAlpha) / 255;
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itemsSum[sumOffset] += pixels[position] * scale;
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itemsSum[sumOffset + 1] += pixels[position + 1] * scale;
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itemsSum[sumOffset + 2] += pixels[position + 2] * scale;
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itemsCount[countOffset] += scale;
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} else {
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itemsSum[sumOffset] += pixels[position];
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itemsSum[sumOffset + 1] += pixels[position + 1];
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itemsSum[sumOffset + 2] += pixels[position + 2];
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itemsCount[countOffset]++;
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}
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position += 4;
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}
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}
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var tmpCanvas = createScratchCanvas(scaledWidth, scaledHeight);
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var tmpCtx = tmpCanvas.getContext('2d');
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var imgData = tmpCtx.getImageData(0, 0, scaledWidth, scaledHeight);
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pixels = imgData.data;
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var j = 0, q = 0;
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for (var i = 0, ii = scaledWidth * scaledHeight; i < ii; i++) {
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var count = itemsCount[i];
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pixels[j] = itemsSum[q++] / count;
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pixels[j + 1] = itemsSum[q++] / count;
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pixels[j + 2] = itemsSum[q++] / count;
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pixels[j + 3] = maxAlphas[i];
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j += 4;
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}
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tmpCtx.putImageData(imgData, 0, 0);
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return tmpCanvas;
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}
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var LINE_CAP_STYLES = ['butt', 'round', 'square'];
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var LINE_JOIN_STYLES = ['miter', 'round', 'bevel'];
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var NORMAL_CLIP = {};
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@ -1175,47 +1229,8 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
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}
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}
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}
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function rescaleImage(pixels, widthScale, heightScale) {
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var scaledWidth = Math.ceil(width / widthScale);
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var scaledHeight = Math.ceil(height / heightScale);
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var itemsSum = new Uint32Array(scaledWidth * scaledHeight * 4);
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var itemsCount = new Uint32Array(scaledWidth * scaledHeight);
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for (var i = 0, position = 0; i < height; i++) {
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var lineOffset = (0 | (i / heightScale)) * scaledWidth;
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for (var j = 0; j < width; j++) {
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var countOffset = lineOffset + (0 | (j / widthScale));
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var sumOffset = countOffset << 2;
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itemsSum[sumOffset] += pixels[position];
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itemsSum[sumOffset + 1] += pixels[position + 1];
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itemsSum[sumOffset + 2] += pixels[position + 2];
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itemsSum[sumOffset + 3] += pixels[position + 3];
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itemsCount[countOffset]++;
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position += 4;
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}
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}
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var tmpCanvas = createScratchCanvas(scaledWidth, scaledHeight);
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var tmpCtx = tmpCanvas.getContext('2d');
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var imgData = tmpCtx.getImageData(0, 0, scaledWidth, scaledHeight);
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pixels = imgData.data;
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for (var i = 0, j = 0, ii = scaledWidth * scaledHeight; i < ii; i++) {
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var count = itemsCount[i];
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pixels[j] = itemsSum[j] / count;
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pixels[j + 1] = itemsSum[j + 1] / count;
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pixels[j + 2] = itemsSum[j + 2] / count;
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pixels[j + 3] = itemsSum[j + 3] / count;
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j += 4;
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}
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tmpCtx.putImageData(imgData, 0, 0);
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return tmpCanvas;
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}
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this.save();
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var ctx = this.ctx;
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var w = width, h = height;
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// scale the image to the unit square
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ctx.scale(1 / w, -1 / h);
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var tmpCanvas = createScratchCanvas(w, h);
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var tmpCtx = tmpCanvas.getContext('2d');
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@ -1231,20 +1246,7 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
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applyStencilMask(pixels, inverseDecode);
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var currentTransform = ctx.mozCurrentTransformInverse;
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var widthScale = Math.max(Math.abs(currentTransform[0]), 1);
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var heightScale = Math.max(Math.abs(currentTransform[3]), 1);
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if (widthScale >= 2 || heightScale >= 2) {
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// canvas does not resize well large images to small -- using simple
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// algorithm to perform pre-scaling
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tmpCanvas = rescaleImage(imgData.data, widthScale, heightScale);
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ctx.scale(widthScale, heightScale);
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ctx.drawImage(tmpCanvas, 0, -h / heightScale);
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} else {
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tmpCtx.putImageData(imgData, 0, 0);
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ctx.drawImage(tmpCanvas, 0, -h);
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}
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this.restore();
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this.paintImage(imgData);
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},
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paintImageXObject: function CanvasGraphics_paintImageXObject(objId) {
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@ -1252,23 +1254,45 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
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if (!imgData)
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error('Dependent image isn\'t ready yet');
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this.save();
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this.paintImage(imgData);
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},
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paintImage: function CanvasGraphics_paintImage(imgData) {
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var width = imgData.width;
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var height = imgData.height;
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var ctx = this.ctx;
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var w = imgData.width;
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var h = imgData.height;
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this.save();
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// scale the image to the unit square
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ctx.scale(1 / w, -1 / h);
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ctx.scale(1 / width, -1 / height);
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var tmpCanvas = createScratchCanvas(w, h);
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var currentTransform = ctx.mozCurrentTransformInverse;
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var widthScale = Math.max(Math.abs(currentTransform[0]), 1);
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var heightScale = Math.max(Math.abs(currentTransform[3]), 1);
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var tmpCanvas = createScratchCanvas(width, height);
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var tmpCtx = tmpCanvas.getContext('2d');
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this.putBinaryImageData(tmpCtx, imgData, w, h);
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ctx.drawImage(tmpCanvas, 0, -h);
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if (widthScale >= 2 || heightScale >= 2) {
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// canvas does not resize well large images to small -- using simple
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// algorithm to perform pre-scaling
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tmpCanvas = rescaleImage(imgData.data,
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width, height,
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widthScale, heightScale);
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ctx.scale(widthScale, heightScale);
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ctx.drawImage(tmpCanvas, 0, -height / heightScale);
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} else {
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if (typeof ImageData !== 'undefined' && imgData instanceof ImageData) {
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tmpCtx.putImageData(imgData, 0, 0);
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} else {
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this.putBinaryImageData(tmpCtx, imgData);
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}
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ctx.drawImage(tmpCanvas, 0, -height);
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}
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this.restore();
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},
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putBinaryImageData: function CanvasGraphics_putBinaryImageData(ctx, imgData,
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w, h) {
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putBinaryImageData: function CanvasGraphics_putBinaryImageData(ctx,
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imgData) {
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var w = imgData.width, h = imgData.height;
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var tmpImgData = 'createImageData' in ctx ? ctx.createImageData(w, h) :
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ctx.getImageData(0, 0, w, h);
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