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Use changingTemplateX, Y and Bit in JBIG2's decodeBitmap

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p01 2014-03-07 17:26:56 +01:00
parent e2a4328ff2
commit 0bca56cbb2
1 changed files with 18 additions and 7 deletions
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25
src/core/jbig2.js
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@ -255,9 +255,17 @@ var Jbig2Image = (function Jbig2ImageClosure() {
changingTemplateEntries.push(k); changingTemplateEntries.push(k);
} }
} }
changingTemplateEntries = new Uint8Array(changingTemplateEntries);
var changingEntriesLength = changingTemplateEntries.length; var changingEntriesLength = changingTemplateEntries.length;
var changingTemplateX = new Int8Array(changingEntriesLength);
var changingTemplateY = new Int8Array(changingEntriesLength);
var changingTemplateBit = new Uint16Array(changingEntriesLength);
for (var c = 0; c < changingEntriesLength; c++) {
k = changingTemplateEntries[c];
changingTemplateX[c] = template[k].x;
changingTemplateY[c] = template[k].y;
changingTemplateBit[c] = 1 << (templateLength - 1 - k);
}
// Get the safe bounding box edges from the width, height, minX, maxX, minY // Get the safe bounding box edges from the width, height, minX, maxX, minY
var sbb_left = -minX; var sbb_left = -minX;
@ -293,16 +301,19 @@ var Jbig2Image = (function Jbig2ImageClosure() {
// If yes, we can just shift the bits that are reusable and only // If yes, we can just shift the bits that are reusable and only
// fetch the remaining ones. // fetch the remaining ones.
contextLabel = (contextLabel << 1) & reuseMask; contextLabel = (contextLabel << 1) & reuseMask;
for (c = 0; c < changingEntriesLength; c++) { for (k = 0; k < changingEntriesLength; k++) {
k = changingTemplateEntries[c]; i0 = i + changingTemplateY[k];
i0 = i + templateY[k]; j0 = j + changingTemplateX[k];
j0 = j + templateX[k]; bit = bitmap[i0][j0];
contextLabel |= bitmap[i0][j0] << (templateLength - 1 - k); if (bit) {
bit = changingTemplateBit[k];
contextLabel |= bit;
}
} }
} else { } else {
// compute the contextLabel from scratch // compute the contextLabel from scratch
contextLabel = 0; contextLabel = 0;
var shift = templateLength - 1; shift = templateLength - 1;
for (k = 0; k < templateLength; k++, shift--) { for (k = 0; k < templateLength; k++, shift--) {
j0 = j + templateX[k]; j0 = j + templateX[k];
if (j0 >= 0 && j0 < width) { if (j0 >= 0 && j0 < width) {