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| // Copyright (c) 2012 Kuba Niegowski
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
'use strict';
var interlaceUtils = require('./interlace');
function getByteWidth(width, bpp, depth) {
var byteWidth = width * bpp;
if (depth !== 8) {
byteWidth = Math.ceil(byteWidth / (8 / depth));
}
return byteWidth;
}
var Filter = module.exports = function(width, height, Bpp, depth, interlace, options, dependencies) {
this._width = width;
this._height = height;
this._Bpp = Bpp;
this._depth = depth;
this._options = options;
if (!('filterType' in options) || options.filterType == -1) {
options.filterType = [0, 1, 2, 3, 4];
} else Iif (typeof options.filterType == 'number') {
options.filterType = [options.filterType];
}
this._filters = {
0: this._filterNone.bind(this),
1: this._filterSub.bind(this),
2: this._filterUp.bind(this),
3: this._filterAvg.bind(this),
4: this._filterPaeth.bind(this)
};
this.read = dependencies.read;
this.write = dependencies.write;
this.complete = dependencies.complete;
this._imageIndex = 0;
this._images = [];
if (interlace) {
var passes = interlaceUtils.getImagePasses(width, height);
for(var i = 0; i < passes.length; i++) {
this._images.push({
byteWidth: getByteWidth(passes[i].width, Bpp, depth),
height: passes[i].height,
lineIndex: 0
});
}
} else {
this._images.push({
byteWidth: getByteWidth(width, Bpp, depth),
height: height,
lineIndex: 0
});
}
};
Filter.prototype.start = function() {
this.read(this._images[this._imageIndex].byteWidth + 1, this._reverseFilterLine.bind(this));
};
Filter.prototype._reverseFilterLine = function(rawData) {
var currentImage = this._images[this._imageIndex];
var line = new Buffer(currentImage.byteWidth);
var filter = rawData[0];
var xComparison = this._depth >= 8 ? ((this._depth === 16) ? this._Bpp * 2 : this._Bpp) : 1;
var xBiggerThan = xComparison - 1;
for (var x = 0; x < currentImage.byteWidth; x++) {
var rawByte = rawData[1 + x];
switch(filter) {
case 0:
line[x] = rawByte;
break;
case 1:
var left = x > xBiggerThan ? line[x - xComparison] : 0;
line[x] = rawByte + left;
break;
case 2:
var up = this._lastLine ? this._lastLine[x] : 0;
line[x] = rawByte + up;
break;
case 3:
var up = this._lastLine ? this._lastLine[x] : 0;
var left = x > xBiggerThan ? line[x - xComparison] : 0;
var add = Math.floor((left + up) / 2);
line[x] = rawByte + add;
break;
case 4:
var up = this._lastLine ? this._lastLine[x] : 0;
var left = x > xBiggerThan ? line[x - xComparison] : 0;
var upLeft = x > xBiggerThan && this._lastLine
? this._lastLine[x - xComparison] : 0;
var add = PaethPredictor(left, up, upLeft);
line[x] = rawByte + add;
break;
}
//if (x === 5) {
// console.log("R", line[3], "G", line[4], "B", line[5]);
//}
}
this.write(line);
currentImage.lineIndex++;
if (currentImage.lineIndex >= currentImage.height) {
this._lastLine = null;
this._imageIndex++;
currentImage = this._images[this._imageIndex];
} else {
this._lastLine = line;
}
if (currentImage) {
this.read(currentImage.byteWidth + 1, this._reverseFilterLine.bind(this));
} else {
this.complete(this._width, this._height);
}
};
Filter.prototype.filter = function(pxData) {
var rawData = new Buffer(((this._width << 2) + 1) * this._height);
for (var y = 0; y < this._height; y++) {
// find best filter for this line (with lowest sum of values)
var filterTypes = this._options.filterType,
min = Infinity,
sel = 0;
for (var i = 0; i < filterTypes.length; i++) {
var sum = this._filters[filterTypes[i]](pxData, y, null);
if (sum < min) {
sel = filterTypes[i];
min = sum;
}
}
this._filters[sel](pxData, y, rawData);
}
return rawData;
};
Filter.prototype._filterNone = function(pxData, y, rawData) {
var pxRowLength = this._width << 2,
rawRowLength = pxRowLength + 1,
sum = 0;
if (!rawData) {
for (var x = 0; x < pxRowLength; x++)
sum += Math.abs(pxData[y * pxRowLength + x]);
} else {
rawData[y * rawRowLength] = 0;
pxData.copy(rawData, rawRowLength * y + 1, pxRowLength * y, pxRowLength * (y + 1));
}
return sum;
};
Filter.prototype._filterSub = function(pxData, y, rawData) {
var pxRowLength = this._width << 2,
rawRowLength = pxRowLength + 1,
sum = 0;
if (rawData)
rawData[y * rawRowLength] = 1;
for (var x = 0; x < pxRowLength; x++) {
var left = x >= 4 ? pxData[y * pxRowLength + x - 4] : 0,
val = pxData[y * pxRowLength + x] - left;
if (!rawData) sum += Math.abs(val);
else rawData[y * rawRowLength + 1 + x] = val;
}
return sum;
};
Filter.prototype._filterUp = function(pxData, y, rawData) {
var pxRowLength = this._width << 2,
rawRowLength = pxRowLength + 1,
sum = 0;
if (rawData)
rawData[y * rawRowLength] = 2;
for (var x = 0; x < pxRowLength; x++) {
var up = y > 0 ? pxData[(y - 1) * pxRowLength + x] : 0,
val = pxData[y * pxRowLength + x] - up;
if (!rawData) sum += Math.abs(val);
else rawData[y * rawRowLength + 1 + x] = val;
}
return sum;
};
Filter.prototype._filterAvg = function(pxData, y, rawData) {
var pxRowLength = this._width << 2,
rawRowLength = pxRowLength + 1,
sum = 0;
if (rawData)
rawData[y * rawRowLength] = 3;
for (var x = 0; x < pxRowLength; x++) {
var left = x >= 4 ? pxData[y * pxRowLength + x - 4] : 0,
up = y > 0 ? pxData[(y - 1) * pxRowLength + x] : 0,
val = pxData[y * pxRowLength + x] - ((left + up) >> 1);
if (!rawData) sum += Math.abs(val);
else rawData[y * rawRowLength + 1 + x] = val;
}
return sum;
};
Filter.prototype._filterPaeth = function(pxData, y, rawData) {
var pxRowLength = this._width << 2,
rawRowLength = pxRowLength + 1,
sum = 0;
if (rawData)
rawData[y * rawRowLength] = 4;
for (var x = 0; x < pxRowLength; x++) {
var left = x >= 4 ? pxData[y * pxRowLength + x - 4] : 0,
up = y > 0 ? pxData[(y - 1) * pxRowLength + x] : 0,
upLeft = x >= 4 && y > 0 ? pxData[(y - 1) * pxRowLength + x - 4] : 0,
val = pxData[y * pxRowLength + x] - PaethPredictor(left, up, upLeft);
if (!rawData) sum += Math.abs(val);
else rawData[y * rawRowLength + 1 + x] = val;
}
return sum;
};
var PaethPredictor = function(left, above, upLeft) {
var p = left + above - upLeft,
pLeft = Math.abs(p - left),
pAbove = Math.abs(p - above),
pUpLeft = Math.abs(p - upLeft);
if (pLeft <= pAbove && pLeft <= pUpLeft) return left;
else if (pAbove <= pUpLeft) return above;
else return upLeft;
};
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