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Create color maps for single component color spaces.

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This commit is contained in:
Brendan Dahl 2013-03-20 17:59:28 -07:00
parent 921f3211a4
commit fea4507c24
1 changed files with 29 additions and 2 deletions
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31
src/colorspace.js
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@ -74,8 +74,35 @@ var ColorSpace = (function ColorSpaceClosure() {
if (this.isPassthrough(bits)) {
return src.subarray(srcOffset);
}
var destLength = this.getOutputLength(count * this.numComps);
var dest = new Uint8Array(destLength);
var dest = new Uint8Array(count * 3);
var numComponentColors = 1 << bits;
// Optimization: create a color map when there is just one component and
// we are converting more colors than the size of the color map. We
// don't build the map if the colorspace is gray or rgb since those
// methods are faster than building a map. This mainly offers big speed
// ups for indexed and alternate colorspaces.
if (this.numComps === 1 && count > numComponentColors &&
this.name !== 'DeviceGray' && this.name !== 'DeviceRGB') {
// TODO it may be worth while to cache the color map. While running
// testing I never hit a cache so I will leave that out for now (perhaps
// we are reparsing colorspaces too much?).
var allColors = bits <= 8 ? new Uint8Array(numComponentColors) :
new Uint16Array(numComponentColors);
for (var i = 0; i < numComponentColors; i++) {
allColors[i] = i;
}
var colorMap = new Uint8Array(numComponentColors * 3);
this.getRgbBuffer(allColors, 0, numComponentColors, colorMap, 0, bits);
var destOffset = 0;
for (var i = 0; i < count; ++i) {
var key = src[srcOffset++] * 3;
dest[destOffset++] = colorMap[key];
dest[destOffset++] = colorMap[key + 1];
dest[destOffset++] = colorMap[key + 2];
}
return dest;
}
this.getRgbBuffer(src, srcOffset, count, dest, 0, bits);
return dest;
}