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extract code to own method for faster JPX decoding

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This commit is contained in:
fkaelberer 2013-10-16 09:47:03 +02:00
parent 7ad19c3355
commit f6841d1720
1 changed files with 15 additions and 24 deletions
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39
src/core/jpx.js
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@ -1692,6 +1692,19 @@ var JpxImage = (function JpxImageClosure() {
} }
return ll; return ll;
}; };
Transform.prototype.expand = function expand(buffer, bufferPadding, step) {
// Section F.3.7 extending... using max extension of 4
var i1 = bufferPadding - 1, j1 = bufferPadding + 1;
var i2 = bufferPadding + step - 2, j2 = bufferPadding + step;
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
};
Transform.prototype.iterate = function Transform_iterate(ll, hl, lh, hh, Transform.prototype.iterate = function Transform_iterate(ll, hl, lh, hh,
u0, v0) { u0, v0) {
var llWidth = ll.width, llHeight = ll.height, llItems = ll.items; var llWidth = ll.width, llHeight = ll.height, llItems = ll.items;
@ -1745,18 +1758,7 @@ var JpxImage = (function JpxImageClosure() {
for (var u = 0; u < width; u++, k++, l++) for (var u = 0; u < width; u++, k++, l++)
buffer[l] = items[k]; buffer[l] = items[k];
// Section F.3.7 extending... using max extension of 4 this.expand(buffer, bufferPadding, width);
var i1 = bufferPadding - 1, j1 = bufferPadding + 1;
var i2 = bufferPadding + width - 2, j2 = bufferPadding + width;
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
this.filter(buffer, bufferPadding, width, u0, bufferOut); this.filter(buffer, bufferPadding, width, u0, bufferOut);
k = v * width; k = v * width;
@ -1780,18 +1782,7 @@ var JpxImage = (function JpxImageClosure() {
for (var v = 0; v < height; v++, k += width, l++) for (var v = 0; v < height; v++, k += width, l++)
buffer[l] = items[k]; buffer[l] = items[k];
// Section F.3.7 extending... using max extension of 4 this.expand(buffer, bufferPadding, height);
var i1 = bufferPadding - 1, j1 = bufferPadding + 1;
var i2 = bufferPadding + height - 2, j2 = bufferPadding + height;
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
buffer[i1--] = buffer[j1++];
buffer[j2++] = buffer[i2--];
this.filter(buffer, bufferPadding, height, v0, bufferOut); this.filter(buffer, bufferPadding, height, v0, bufferOut);
k = u; k = u;