Sakurai/pdf.js
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Merge pull request #1226 from notmasteryet/tree-80

Browse Source 
Rewrite predictor code to avoid writing into subarrays.
This commit is contained in:
Artur Adib 2012-02-17 07:56:02 -08:00
commit dd53edffad
1 changed files with 26 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
src/stream.js
View File

@ -623,7 +623,6 @@ var PredictorStream = (function PredictorStreamClosure() {
var bufferLength = this.bufferLength; var bufferLength = this.bufferLength;
var buffer = this.ensureBuffer(bufferLength + rowBytes); var buffer = this.ensureBuffer(bufferLength + rowBytes);
var currentRow = buffer.subarray(bufferLength, bufferLength + rowBytes);
var bits = this.bits; var bits = this.bits;
var colors = this.colors; var colors = this.colors;
@ -632,6 +631,7 @@ var PredictorStream = (function PredictorStreamClosure() {
var inbuf = 0, outbuf = 0; var inbuf = 0, outbuf = 0;
var inbits = 0, outbits = 0; var inbits = 0, outbits = 0;
var pos = bufferLength;
if (bits === 1) { if (bits === 1) {
for (var i = 0; i < rowBytes; ++i) { for (var i = 0; i < rowBytes; ++i) {
@ -639,19 +639,21 @@ var PredictorStream = (function PredictorStreamClosure() {
inbuf = (inbuf << 8) | c; inbuf = (inbuf << 8) | c;
// bitwise addition is exclusive or // bitwise addition is exclusive or
// first shift inbuf and then add // first shift inbuf and then add
currentRow[i] = (c ^ (inbuf >> colors)) & 0xFF; buffer[pos++] = (c ^ (inbuf >> colors)) & 0xFF;
// truncate inbuf (assumes colors < 16) // truncate inbuf (assumes colors < 16)
inbuf &= 0xFFFF; inbuf &= 0xFFFF;
} }
} else if (bits === 8) { } else if (bits === 8) {
for (var i = 0; i < colors; ++i) for (var i = 0; i < colors; ++i)
currentRow[i] = rawBytes[i]; buffer[pos++] = rawBytes[i];
for (; i < rowBytes; ++i) for (; i < rowBytes; ++i) {
currentRow[i] = currentRow[i - colors] + rawBytes[i]; buffer[pos] = buffer[pos - colors] + rawBytes[i];
pos++;
}
} else { } else {
var compArray = new Uint8Array(colors + 1); var compArray = new Uint8Array(colors + 1);
var bitMask = (1 << bits) - 1; var bitMask = (1 << bits) - 1;
var j = 0, k = 0; var j = 0, k = bufferLength;
var columns = this.columns; var columns = this.columns;
for (var i = 0; i < columns; ++i) { for (var i = 0; i < columns; ++i) {
for (var kk = 0; kk < colors; ++kk) { for (var kk = 0; kk < colors; ++kk) {
@ -665,13 +667,13 @@ var PredictorStream = (function PredictorStreamClosure() {
outbuf = (outbuf << bits) | compArray[kk]; outbuf = (outbuf << bits) | compArray[kk];
outbits += bits; outbits += bits;
if (outbits >= 8) { if (outbits >= 8) {
currentRow[k++] = (outbuf >> (outbits - 8)) & 0xFF; buffer[k++] = (outbuf >> (outbits - 8)) & 0xFF;
outbits -= 8; outbits -= 8;
} }
} }
} }
if (outbits > 0) { if (outbits > 0) {
currentRow[k++] = (outbuf << (8 - outbits)) + buffer[k++] = (outbuf << (8 - outbits)) +
(inbuf & ((1 << (8 - outbits)) - 1)); (inbuf & ((1 << (8 - outbits)) - 1));
} }
} }
@ -690,32 +692,35 @@ var PredictorStream = (function PredictorStreamClosure() {
var bufferLength = this.bufferLength; var bufferLength = this.bufferLength;
var buffer = this.ensureBuffer(bufferLength + rowBytes); var buffer = this.ensureBuffer(bufferLength + rowBytes);
var currentRow = buffer.subarray(bufferLength, bufferLength + rowBytes);
var prevRow = buffer.subarray(bufferLength - rowBytes, bufferLength); var prevRow = buffer.subarray(bufferLength - rowBytes, bufferLength);
if (prevRow.length == 0) if (prevRow.length == 0)
prevRow = new Uint8Array(rowBytes); prevRow = new Uint8Array(rowBytes);
var j = bufferLength;
switch (predictor) { switch (predictor) {
case 0: case 0:
for (var i = 0; i < rowBytes; ++i) for (var i = 0; i < rowBytes; ++i)
currentRow[i] = rawBytes[i]; buffer[j++] = rawBytes[i];
break; break;
case 1: case 1:
for (var i = 0; i < pixBytes; ++i) for (var i = 0; i < pixBytes; ++i)
currentRow[i] = rawBytes[i]; buffer[j++] = rawBytes[i];
for (; i < rowBytes; ++i) for (; i < rowBytes; ++i) {
currentRow[i] = (currentRow[i - pixBytes] + rawBytes[i]) & 0xFF; buffer[j] = (buffer[j - pixBytes] + rawBytes[i]) & 0xFF;
j++;
}
break; break;
case 2: case 2:
for (var i = 0; i < rowBytes; ++i) for (var i = 0; i < rowBytes; ++i)
currentRow[i] = (prevRow[i] + rawBytes[i]) & 0xFF; buffer[j++] = (prevRow[i] + rawBytes[i]) & 0xFF;
break; break;
case 3: case 3:
for (var i = 0; i < pixBytes; ++i) for (var i = 0; i < pixBytes; ++i)
currentRow[i] = (prevRow[i] >> 1) + rawBytes[i]; buffer[j++] = (prevRow[i] >> 1) + rawBytes[i];
for (; i < rowBytes; ++i) { for (; i < rowBytes; ++i) {
currentRow[i] = (((prevRow[i] + currentRow[i - pixBytes]) >> 1) + buffer[j] = (((prevRow[i] + buffer[j - pixBytes]) >> 1) +
rawBytes[i]) & 0xFF; rawBytes[i]) & 0xFF;
j++;
} }
break; break;
case 4: case 4:
@ -724,12 +729,12 @@ var PredictorStream = (function PredictorStreamClosure() {
for (var i = 0; i < pixBytes; ++i) { for (var i = 0; i < pixBytes; ++i) {
var up = prevRow[i]; var up = prevRow[i];
var c = rawBytes[i]; var c = rawBytes[i];
currentRow[i] = up + c; buffer[j++] = up + c;
} }
for (; i < rowBytes; ++i) { for (; i < rowBytes; ++i) {
var up = prevRow[i]; var up = prevRow[i];
var upLeft = prevRow[i - pixBytes]; var upLeft = prevRow[i - pixBytes];
var left = currentRow[i - pixBytes]; var left = buffer[j - pixBytes];
var p = left + up - upLeft; var p = left + up - upLeft;
var pa = p - left; var pa = p - left;
@ -744,11 +749,11 @@ var PredictorStream = (function PredictorStreamClosure() {
var c = rawBytes[i]; var c = rawBytes[i];
if (pa <= pb && pa <= pc) if (pa <= pb && pa <= pc)
currentRow[i] = left + c; buffer[j++] = left + c;
else if (pb <= pc) else if (pb <= pc)
currentRow[i] = up + c; buffer[j++] = up + c;
else else
currentRow[i] = upLeft + c; buffer[j++] = upLeft + c;
} }
break; break;
default: default: