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Remove manual clamping code in src/core/jpx.js

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Since we're now using `Uint8ClampedArray`, rather than `Uint8Array`, doing manual clamping shouldn't be necessary given that that is now handled natively.

This shouldn't have any measurable performance impact, but just to sanity check that I've done some quick benchmarking with the following manifest file:
```json
[
    {  "id": "S2-eq",
       "file": "pdfs/S2.pdf",
       "md5": "d0b6137846df6e0fe058f234a87fb588",
       "rounds": 100,
       "type": "eq"
    }
]
```
which gave the following results against the current `master` (repeated benchmark runs didn't result in any meaningful differences):
```
-- Grouped By browser, stat --
browser | stat         | Count | Baseline(ms) | Current(ms) | +/- |    %  | Result(P<.05)
------- | ------------ | ----- | ------------ | ----------- | --- | ----- | -------------
firefox | Overall      |   100 |          592 |         592 |   1 |  0.12 |
firefox | Page Request |   100 |            3 |           3 |   0 | -9.88 |
firefox | Rendering    |   100 |          588 |         589 |   1 |  0.18 |
```
This commit is contained in:
Jonas Jenwald 2017-08-15 16:45:33 +02:00
parent f6636d6b19
commit 563b68e74d
1 changed files with 12 additions and 24 deletions
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36
src/core/jpx.js
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@ -1396,8 +1396,8 @@ var JpxImage = (function JpxImageClosure() {
};
// Section G.2.2 Inverse multi component transform
var shift, offset, max, min, maxK;
var pos = 0, j, jj, y0, y1, y2, r, g, b, k, val;
var shift, offset;
var pos = 0, j, jj, y0, y1, y2;
if (tile.codingStyleDefaultParameters.multipleComponentTransform) {
var fourComponents = componentsCount === 4;
var y0items = transformedTiles[0].items;
@ -1410,9 +1410,6 @@ var JpxImage = (function JpxImageClosure() {
// compute shift and offset only once.
shift = components[0].precision - 8;
offset = (128 << shift) + 0.5;
max = 255 * (1 << shift);
maxK = max * 0.5;
min = -maxK;
var component0 = tile.components[0];
var alpha01 = componentsCount - 3;
@ -1423,12 +1420,9 @@ var JpxImage = (function JpxImageClosure() {
y0 = y0items[j] + offset;
y1 = y1items[j];
y2 = y2items[j];
r = y0 + 1.402 * y2;
g = y0 - 0.34413 * y1 - 0.71414 * y2;
b = y0 + 1.772 * y1;
out[pos++] = r <= 0 ? 0 : r >= max ? 255 : r >> shift;
out[pos++] = g <= 0 ? 0 : g >= max ? 255 : g >> shift;
out[pos++] = b <= 0 ? 0 : b >= max ? 255 : b >> shift;
out[pos++] = (y0 + 1.402 * y2) >> shift;
out[pos++] = (y0 - 0.34413 * y1 - 0.71414 * y2) >> shift;
out[pos++] = (y0 + 1.772 * y1) >> shift;
}
} else {
// inverse reversible multiple component transform
@ -1436,18 +1430,16 @@ var JpxImage = (function JpxImageClosure() {
y0 = y0items[j] + offset;
y1 = y1items[j];
y2 = y2items[j];
g = y0 - ((y2 + y1) >> 2);
r = g + y2;
b = g + y1;
out[pos++] = r <= 0 ? 0 : r >= max ? 255 : r >> shift;
out[pos++] = g <= 0 ? 0 : g >= max ? 255 : g >> shift;
out[pos++] = b <= 0 ? 0 : b >= max ? 255 : b >> shift;
let g = y0 - ((y2 + y1) >> 2);
out[pos++] = (g + y2) >> shift;
out[pos++] = g >> shift;
out[pos++] = (g + y1) >> shift;
}
}
if (fourComponents) {
for (j = 0, pos = 3; j < jj; j++, pos += 4) {
k = y3items[j];
out[pos] = k <= min ? 0 : k >= maxK ? 255 : (k + offset) >> shift;
out[pos] = (y3items[j] + offset) >> shift;
}
}
} else { // no multi-component transform
@ -1455,12 +1447,8 @@ var JpxImage = (function JpxImageClosure() {
var items = transformedTiles[c].items;
shift = components[c].precision - 8;
offset = (128 << shift) + 0.5;
max = (127.5 * (1 << shift));
min = -max;
for (pos = c, j = 0, jj = items.length; j < jj; j++) {
val = items[j];
out[pos] = val <= min ? 0 :
val >= max ? 255 : (val + offset) >> shift;
out[pos] = (items[j] + offset) >> shift;
pos += componentsCount;
}
}