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