364 lines
16 KiB
JavaScript
364 lines
16 KiB
JavaScript
// JavaScript Image Resizer (c) 2012 - Grant Galitz
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// Released to public domain 29 July 2013: https://github.com/grantgalitz/JS-Image-Resizer/issues/4
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function Resize(widthOriginal, heightOriginal, targetWidth, targetHeight, blendAlpha, interpolationPass, resizeCallback) {
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this.widthOriginal = Math.abs(parseInt(widthOriginal) || 0);
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this.heightOriginal = Math.abs(parseInt(heightOriginal) || 0);
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this.targetWidth = Math.abs(parseInt(targetWidth) || 0);
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this.targetHeight = Math.abs(parseInt(targetHeight) || 0);
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this.colorChannels = (!!blendAlpha) ? 4 : 3;
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this.interpolationPass = !!interpolationPass;
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this.resizeCallback = (typeof resizeCallback == "function") ? resizeCallback : function (returnedArray) {};
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this.targetWidthMultipliedByChannels = this.targetWidth * this.colorChannels;
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this.originalWidthMultipliedByChannels = this.widthOriginal * this.colorChannels;
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this.originalHeightMultipliedByChannels = this.heightOriginal * this.colorChannels;
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this.widthPassResultSize = this.targetWidthMultipliedByChannels * this.heightOriginal;
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this.finalResultSize = this.targetWidthMultipliedByChannels * this.targetHeight;
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this.initialize();
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}
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Resize.prototype.initialize = function () {
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//Perform some checks:
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if (this.widthOriginal > 0 && this.heightOriginal > 0 && this.targetWidth > 0 && this.targetHeight > 0) {
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this.configurePasses();
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} else {
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throw (new Error("Invalid settings specified for the resizer."));
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}
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}
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Resize.prototype.configurePasses = function () {
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if (this.widthOriginal == this.targetWidth) {
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//Bypass the width resizer pass:
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this.resizeWidth = this.bypassResizer;
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} else {
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//Setup the width resizer pass:
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this.ratioWeightWidthPass = this.widthOriginal / this.targetWidth;
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if (this.ratioWeightWidthPass < 1 && this.interpolationPass) {
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this.initializeFirstPassBuffers(true);
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this.resizeWidth = (this.colorChannels == 4) ? this.resizeWidthInterpolatedRGBA : this.resizeWidthInterpolatedRGB;
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} else {
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this.initializeFirstPassBuffers(false);
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this.resizeWidth = (this.colorChannels == 4) ? this.resizeWidthRGBA : this.resizeWidthRGB;
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}
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}
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if (this.heightOriginal == this.targetHeight) {
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//Bypass the height resizer pass:
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this.resizeHeight = this.bypassResizer;
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} else {
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//Setup the height resizer pass:
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this.ratioWeightHeightPass = this.heightOriginal / this.targetHeight;
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if (this.ratioWeightHeightPass < 1 && this.interpolationPass) {
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this.initializeSecondPassBuffers(true);
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this.resizeHeight = this.resizeHeightInterpolated;
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} else {
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this.initializeSecondPassBuffers(false);
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this.resizeHeight = (this.colorChannels == 4) ? this.resizeHeightRGBA : this.resizeHeightRGB;
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}
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}
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}
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Resize.prototype._resizeWidthInterpolatedRGBChannels = function (buffer, fourthChannel) {
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var channelsNum = fourthChannel ? 4 : 3;
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var ratioWeight = this.ratioWeightWidthPass;
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var weight = 0;
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var finalOffset = 0;
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var pixelOffset = 0;
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var firstWeight = 0;
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var secondWeight = 0;
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var outputBuffer = this.widthBuffer;
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//Handle for only one interpolation input being valid for start calculation:
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for (var targetPosition = 0; weight < 1 / 3; targetPosition += channelsNum, weight += ratioWeight) {
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for (finalOffset = targetPosition, pixelOffset = 0; finalOffset < this.widthPassResultSize; pixelOffset += this.originalWidthMultipliedByChannels, finalOffset += this.targetWidthMultipliedByChannels) {
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outputBuffer[finalOffset] = buffer[pixelOffset];
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outputBuffer[finalOffset + 1] = buffer[pixelOffset + 1];
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outputBuffer[finalOffset + 2] = buffer[pixelOffset + 2];
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if (!fourthChannel) continue;
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outputBuffer[finalOffset + 3] = buffer[pixelOffset + 3];
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}
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}
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//Adjust for overshoot of the last pass's counter:
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weight -= 1 / 3;
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for (var interpolationWidthSourceReadStop = this.widthOriginal - 1; weight < interpolationWidthSourceReadStop; targetPosition += channelsNum, weight += ratioWeight) {
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//Calculate weightings:
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secondWeight = weight % 1;
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firstWeight = 1 - secondWeight;
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//Interpolate:
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for (finalOffset = targetPosition, pixelOffset = Math.floor(weight) * channelsNum; finalOffset < this.widthPassResultSize; pixelOffset += this.originalWidthMultipliedByChannels, finalOffset += this.targetWidthMultipliedByChannels) {
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outputBuffer[finalOffset] = (buffer[pixelOffset] * firstWeight) + (buffer[pixelOffset + channelsNum] * secondWeight);
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outputBuffer[finalOffset + 1] = (buffer[pixelOffset + 1] * firstWeight) + (buffer[pixelOffset + channelsNum + 1] * secondWeight);
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outputBuffer[finalOffset + 2] = (buffer[pixelOffset + 2] * firstWeight) + (buffer[pixelOffset + channelsNum + 2] * secondWeight);
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if (!fourthChannel) continue;
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outputBuffer[finalOffset + 3] = (buffer[pixelOffset + 3] * firstWeight) + (buffer[pixelOffset + channelsNum + 3] * secondWeight);
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}
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}
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//Handle for only one interpolation input being valid for end calculation:
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for (interpolationWidthSourceReadStop = this.originalWidthMultipliedByChannels - channelsNum; targetPosition < this.targetWidthMultipliedByChannels; targetPosition += channelsNum) {
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for (finalOffset = targetPosition, pixelOffset = interpolationWidthSourceReadStop; finalOffset < this.widthPassResultSize; pixelOffset += this.originalWidthMultipliedByChannels, finalOffset += this.targetWidthMultipliedByChannels) {
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outputBuffer[finalOffset] = buffer[pixelOffset];
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outputBuffer[finalOffset + 1] = buffer[pixelOffset + 1];
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outputBuffer[finalOffset + 2] = buffer[pixelOffset + 2];
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if (!fourthChannel) continue;
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outputBuffer[finalOffset + 3] = buffer[pixelOffset + 3];
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}
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}
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return outputBuffer;
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}
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Resize.prototype._resizeWidthRGBChannels = function (buffer, fourthChannel) {
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var channelsNum = fourthChannel ? 4 : 3;
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var ratioWeight = this.ratioWeightWidthPass;
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var ratioWeightDivisor = 1 / ratioWeight;
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var weight = 0;
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var amountToNext = 0;
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var actualPosition = 0;
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var currentPosition = 0;
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var line = 0;
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var pixelOffset = 0;
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var outputOffset = 0;
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var nextLineOffsetOriginalWidth = this.originalWidthMultipliedByChannels - channelsNum + 1;
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var nextLineOffsetTargetWidth = this.targetWidthMultipliedByChannels - channelsNum + 1;
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var output = this.outputWidthWorkBench;
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var outputBuffer = this.widthBuffer;
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var trustworthyColorsCount = this.outputWidthWorkBenchOpaquePixelsCount;
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var multiplier = 1;
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var r = 0;
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var g = 0;
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var b = 0;
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var a = 0;
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do {
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for (line = 0; line < this.originalHeightMultipliedByChannels;) {
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output[line++] = 0;
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output[line++] = 0;
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output[line++] = 0;
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if (!fourthChannel) continue;
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output[line++] = 0;
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trustworthyColorsCount[line / channelsNum - 1] = 0;
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}
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weight = ratioWeight;
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do {
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amountToNext = 1 + actualPosition - currentPosition;
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multiplier = Math.min(weight, amountToNext);
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for (line = 0, pixelOffset = actualPosition; line < this.originalHeightMultipliedByChannels; pixelOffset += nextLineOffsetOriginalWidth) {
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r = buffer[pixelOffset];
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g = buffer[++pixelOffset];
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b = buffer[++pixelOffset];
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a = fourthChannel ? buffer[++pixelOffset] : 255;
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// Ignore RGB values if pixel is completely transparent
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output[line++] += (a ? r : 0) * multiplier;
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output[line++] += (a ? g : 0) * multiplier;
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output[line++] += (a ? b : 0) * multiplier;
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if (!fourthChannel) continue;
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output[line++] += a * multiplier;
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trustworthyColorsCount[line / channelsNum - 1] += (a ? multiplier : 0);
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}
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if (weight >= amountToNext) {
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currentPosition = actualPosition = actualPosition + channelsNum;
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weight -= amountToNext;
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} else {
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currentPosition += weight;
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break;
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}
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} while (weight > 0 && actualPosition < this.originalWidthMultipliedByChannels);
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for (line = 0, pixelOffset = outputOffset; line < this.originalHeightMultipliedByChannels; pixelOffset += nextLineOffsetTargetWidth) {
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weight = fourthChannel ? trustworthyColorsCount[line / channelsNum] : 1;
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multiplier = fourthChannel ? (weight ? 1 / weight : 0) : ratioWeightDivisor;
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outputBuffer[pixelOffset] = output[line++] * multiplier;
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outputBuffer[++pixelOffset] = output[line++] * multiplier;
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outputBuffer[++pixelOffset] = output[line++] * multiplier;
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if (!fourthChannel) continue;
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outputBuffer[++pixelOffset] = output[line++] * ratioWeightDivisor;
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}
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outputOffset += channelsNum;
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} while (outputOffset < this.targetWidthMultipliedByChannels);
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return outputBuffer;
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}
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Resize.prototype._resizeHeightRGBChannels = function(buffer, fourthChannel) {
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var ratioWeight = this.ratioWeightHeightPass;
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var ratioWeightDivisor = 1 / ratioWeight;
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var weight = 0;
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var amountToNext = 0;
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var actualPosition = 0;
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var currentPosition = 0;
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var pixelOffset = 0;
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var outputOffset = 0;
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var output = this.outputHeightWorkBench;
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var outputBuffer = this.heightBuffer;
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var trustworthyColorsCount = this.outputHeightWorkBenchOpaquePixelsCount;
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var caret = 0;
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var multiplier = 1;
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var r = 0;
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var g = 0;
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var b = 0;
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var a = 0;
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do {
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for (pixelOffset = 0; pixelOffset < this.targetWidthMultipliedByChannels;) {
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output[pixelOffset++] = 0;
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output[pixelOffset++] = 0;
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output[pixelOffset++] = 0;
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if (!fourthChannel) continue;
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output[pixelOffset++] = 0;
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trustworthyColorsCount[pixelOffset / 4 - 1] = 0;
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}
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weight = ratioWeight;
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do {
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amountToNext = 1 + actualPosition - currentPosition;
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multiplier = Math.min(weight, amountToNext);
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caret = actualPosition;
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for (pixelOffset = 0; pixelOffset < this.targetWidthMultipliedByChannels;) {
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r = buffer[caret++];
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g = buffer[caret++];
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b = buffer[caret++];
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a = fourthChannel ? buffer[caret++] : 255;
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// Ignore RGB values if pixel is completely transparent
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output[pixelOffset++] += (a ? r : 0) * multiplier;
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output[pixelOffset++] += (a ? g : 0) * multiplier;
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output[pixelOffset++] += (a ? b : 0) * multiplier;
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if (!fourthChannel) continue;
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output[pixelOffset++] += a * multiplier;
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trustworthyColorsCount[pixelOffset / 4 - 1] += (a ? multiplier : 0);
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}
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if (weight >= amountToNext) {
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currentPosition = actualPosition = caret;
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weight -= amountToNext;
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} else {
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currentPosition += weight;
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break;
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}
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} while (weight > 0 && actualPosition < this.widthPassResultSize);
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for (pixelOffset = 0; pixelOffset < this.targetWidthMultipliedByChannels;) {
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weight = fourthChannel ? trustworthyColorsCount[pixelOffset / 4] : 1;
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multiplier = fourthChannel ? (weight ? 1 / weight : 0) : ratioWeightDivisor;
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outputBuffer[outputOffset++] = Math.round(output[pixelOffset++] * multiplier);
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outputBuffer[outputOffset++] = Math.round(output[pixelOffset++] * multiplier);
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outputBuffer[outputOffset++] = Math.round(output[pixelOffset++] * multiplier);
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if (!fourthChannel) continue;
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outputBuffer[outputOffset++] = Math.round(output[pixelOffset++] * ratioWeightDivisor);
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}
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} while (outputOffset < this.finalResultSize);
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return outputBuffer;
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}
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Resize.prototype.resizeWidthInterpolatedRGB = function (buffer) {
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return this._resizeWidthInterpolatedRGBChannels(buffer, false);
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}
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Resize.prototype.resizeWidthInterpolatedRGBA = function (buffer) {
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return this._resizeWidthInterpolatedRGBChannels(buffer, true);
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}
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Resize.prototype.resizeWidthRGB = function (buffer) {
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return this._resizeWidthRGBChannels(buffer, false);
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}
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Resize.prototype.resizeWidthRGBA = function (buffer) {
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return this._resizeWidthRGBChannels(buffer, true);
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}
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Resize.prototype.resizeHeightInterpolated = function (buffer) {
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var ratioWeight = this.ratioWeightHeightPass;
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var weight = 0;
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var finalOffset = 0;
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var pixelOffset = 0;
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var pixelOffsetAccumulated = 0;
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var pixelOffsetAccumulated2 = 0;
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var firstWeight = 0;
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var secondWeight = 0;
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var outputBuffer = this.heightBuffer;
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//Handle for only one interpolation input being valid for start calculation:
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for (; weight < 1 / 3; weight += ratioWeight) {
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for (pixelOffset = 0; pixelOffset < this.targetWidthMultipliedByChannels;) {
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outputBuffer[finalOffset++] = Math.round(buffer[pixelOffset++]);
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}
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}
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//Adjust for overshoot of the last pass's counter:
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weight -= 1 / 3;
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for (var interpolationHeightSourceReadStop = this.heightOriginal - 1; weight < interpolationHeightSourceReadStop; weight += ratioWeight) {
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//Calculate weightings:
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secondWeight = weight % 1;
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firstWeight = 1 - secondWeight;
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//Interpolate:
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pixelOffsetAccumulated = Math.floor(weight) * this.targetWidthMultipliedByChannels;
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pixelOffsetAccumulated2 = pixelOffsetAccumulated + this.targetWidthMultipliedByChannels;
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for (pixelOffset = 0; pixelOffset < this.targetWidthMultipliedByChannels; ++pixelOffset) {
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outputBuffer[finalOffset++] = Math.round((buffer[pixelOffsetAccumulated++] * firstWeight) + (buffer[pixelOffsetAccumulated2++] * secondWeight));
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}
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}
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//Handle for only one interpolation input being valid for end calculation:
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while (finalOffset < this.finalResultSize) {
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for (pixelOffset = 0, pixelOffsetAccumulated = interpolationHeightSourceReadStop * this.targetWidthMultipliedByChannels; pixelOffset < this.targetWidthMultipliedByChannels; ++pixelOffset) {
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outputBuffer[finalOffset++] = Math.round(buffer[pixelOffsetAccumulated++]);
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}
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}
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return outputBuffer;
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}
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Resize.prototype.resizeHeightRGB = function (buffer) {
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return this._resizeHeightRGBChannels(buffer, false);
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}
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Resize.prototype.resizeHeightRGBA = function (buffer) {
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return this._resizeHeightRGBChannels(buffer, true);
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}
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Resize.prototype.resize = function (buffer) {
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this.resizeCallback(this.resizeHeight(this.resizeWidth(buffer)));
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}
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Resize.prototype.bypassResizer = function (buffer) {
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//Just return the buffer passsed:
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return buffer;
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}
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Resize.prototype.initializeFirstPassBuffers = function (BILINEARAlgo) {
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//Initialize the internal width pass buffers:
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this.widthBuffer = this.generateFloatBuffer(this.widthPassResultSize);
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if (!BILINEARAlgo) {
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this.outputWidthWorkBench = this.generateFloatBuffer(this.originalHeightMultipliedByChannels);
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if (this.colorChannels > 3) {
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this.outputWidthWorkBenchOpaquePixelsCount = this.generateFloat64Buffer(this.heightOriginal);
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}
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}
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}
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Resize.prototype.initializeSecondPassBuffers = function (BILINEARAlgo) {
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//Initialize the internal height pass buffers:
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this.heightBuffer = this.generateUint8Buffer(this.finalResultSize);
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if (!BILINEARAlgo) {
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this.outputHeightWorkBench = this.generateFloatBuffer(this.targetWidthMultipliedByChannels);
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if (this.colorChannels > 3) {
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this.outputHeightWorkBenchOpaquePixelsCount = this.generateFloat64Buffer(this.targetWidth);
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}
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}
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}
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Resize.prototype.generateFloatBuffer = function (bufferLength) {
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//Generate a float32 typed array buffer:
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try {
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return new Float32Array(bufferLength);
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} catch (error) {
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return [];
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}
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}
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Resize.prototype.generateFloat64Buffer = function (bufferLength) {
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//Generate a float64 typed array buffer:
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try {
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return new Float64Array(bufferLength);
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} catch (error) {
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return [];
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}
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}
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Resize.prototype.generateUint8Buffer = function (bufferLength) {
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//Generate a uint8 typed array buffer:
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try {
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return new Uint8Array(bufferLength);
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} catch (error) {
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return [];
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}
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}
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module.exports = Resize;
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