From eef5ed5c11ee8fbdef0ea4a19666c1e6463d5503 Mon Sep 17 00:00:00 2001
From: fkaelberer <o_0_o@gmx.de>
Date: Wed, 5 Mar 2014 09:42:16 +0100
Subject: [PATCH] Optimizations for 1bpc images
---
src/core/image.js | 73 +++++++++++++++++++++++++++++++++++------------
1 file changed, 54 insertions(+), 19 deletions(-)
diff --git a/src/core/image.js b/src/core/image.js
index 0ac02cdca..d264bba29 100644
--- a/src/core/image.js
+++ b/src/core/image.js
@@ -64,9 +64,10 @@ var PDFImage = (function PDFImageClosure() {
this.width = dict.get('Width', 'W');
this.height = dict.get('Height', 'H');
- if (this.width < 1 || this.height < 1)
+ if (this.width < 1 || this.height < 1) {
error('Invalid image width: ' + this.width + ' or height: ' +
this.height);
+ }
this.interpolate = dict.get('Interpolate', 'I') || false;
this.imageMask = dict.get('ImageMask', 'IM') || false;
@@ -76,10 +77,11 @@ var PDFImage = (function PDFImageClosure() {
if (!bitsPerComponent) {
bitsPerComponent = dict.get('BitsPerComponent', 'BPC');
if (!bitsPerComponent) {
- if (this.imageMask)
+ if (this.imageMask) {
bitsPerComponent = 1;
- else
+ } else {
error('Bits per component missing in image: ' + this.imageMask);
+ }
}
}
this.bpc = bitsPerComponent;
@@ -285,23 +287,34 @@ var PDFImage = (function PDFImageClosure() {
if (bpc === 1) {
// Optimization for reading 1 bpc images.
- var mask = 0;
- var buf = 0;
+ var i = 0, buf, mask, loop1End, loop2End;
+ for (var j = 0; j < height; j++) {
+ loop1End = i + (rowComps & ~7);
+ loop2End = i + rowComps;
- for (var i = 0, ii = length; i < ii; ++i) {
- if (i % rowComps === 0) {
- mask = 0;
- buf = 0;
- } else {
- mask >>= 1;
+ // unroll loop for all full bytes
+ while (i < loop1End) {
+ buf = buffer[bufferPos++];
+ output[i] = (buf >> 7) & 1;
+ output[i + 1] = (buf >> 6) & 1;
+ output[i + 2] = (buf >> 5) & 1;
+ output[i + 3] = (buf >> 4) & 1;
+ output[i + 4] = (buf >> 3) & 1;
+ output[i + 5] = (buf >> 2) & 1;
+ output[i + 6] = (buf >> 1) & 1;
+ output[i + 7] = buf & 1;
+ i += 8;
}
- if (mask <= 0) {
+ // handle remaing bits
+ if (i < loop2End) {
buf = buffer[bufferPos++];
mask = 128;
+ while (i < loop2End) {
+ output[i++] = +!!(buf & mask);
+ mask >>= 1;
+ }
}
-
- output[i] = +!!(buf & mask);
}
} else {
// The general case that handles all other bpc values.
@@ -337,9 +350,10 @@ var PDFImage = (function PDFImageClosure() {
var sh = smask.height;
alphaBuf = new Uint8Array(sw * sh);
smask.fillGrayBuffer(alphaBuf);
- if (sw != width || sh != height)
+ if (sw != width || sh != height) {
alphaBuf = PDFImage.resize(alphaBuf, smask.bpc, 1, sw, sh, width,
height);
+ }
} else if (mask) {
if (mask instanceof PDFImage) {
var sw = mask.width;
@@ -349,12 +363,14 @@ var PDFImage = (function PDFImageClosure() {
mask.fillGrayBuffer(alphaBuf);
// Need to invert values in rgbaBuf
- for (var i = 0, ii = sw * sh; i < ii; ++i)
+ for (var i = 0, ii = sw * sh; i < ii; ++i) {
alphaBuf[i] = 255 - alphaBuf[i];
+ }
- if (sw != width || sh != height)
+ if (sw != width || sh != height) {
alphaBuf = PDFImage.resize(alphaBuf, mask.bpc, 1, sw, sh, width,
height);
+ }
} else if (isArray(mask)) {
// Color key mask: if any of the compontents are outside the range
// then they should be painted.
@@ -422,7 +438,7 @@ var PDFImage = (function PDFImageClosure() {
var drawHeight = this.drawHeight;
var imgData = { // other fields are filled in below
width: drawWidth,
- height: drawHeight,
+ height: drawHeight
};
var numComps = this.numComps;
@@ -507,14 +523,33 @@ var PDFImage = (function PDFImageClosure() {
var imgArray = this.getImageBytes(height * rowBytes);
var comps = this.getComponents(imgArray);
+
+ if (bpc === 1) {
+ // inline decoding (= inversion) for 1 bpc images
+ var length = width * height;
+ if (this.needsDecode) {
+ // invert and scale to {0, 255}
+ for (var i = 0; i < length; ++i) {
+ buffer[i] = (comps[i] - 1) & 255;
+ }
+ } else {
+ // scale to {0, 255}
+ for (var i = 0; i < length; ++i) {
+ buffer[i] = (-comps[i]) & 255;
+ }
+ }
+ return;
+ }
+
if (this.needsDecode) {
this.decodeBuffer(comps);
}
var length = width * height;
// we aren't using a colorspace so we need to scale the value
var scale = 255 / ((1 << bpc) - 1);
- for (var i = 0; i < length; ++i)
+ for (var i = 0; i < length; ++i) {
buffer[i] = (scale * comps[i]) | 0;
+ }
},
getImageBytes: function PDFImage_getImageBytes(length) {
this.image.reset();