/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
/* Copyright 2012 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* globals assert, ColorSpace, DecodeStream, error, info, isArray, ImageKind,
isStream, JpegStream, JpxImage, Name, Promise, Stream, warn */
'use strict';
var PDFImage = (function PDFImageClosure() {
/**
* Decode the image in the main thread if it supported. Resovles the promise
* when the image data is ready.
*/
function handleImageData(handler, xref, res, image) {
if (image instanceof JpegStream && image.isNativelyDecodable(xref, res)) {
// For natively supported jpegs send them to the main thread for decoding.
var dict = image.dict;
var colorSpace = dict.get('ColorSpace', 'CS');
colorSpace = ColorSpace.parse(colorSpace, xref, res);
var numComps = colorSpace.numComps;
var decodePromise = handler.sendWithPromise('JpegDecode',
[image.getIR(), numComps]);
return decodePromise.then(function (message) {
var data = message.data;
return new Stream(data, 0, data.length, image.dict);
});
} else {
return Promise.resolve(image);
}
}
/**
* Decode and clamp a value. The formula is different from the spec because we
* don't decode to float range [0,1], we decode it in the [0,max] range.
*/
function decodeAndClamp(value, addend, coefficient, max) {
value = addend + value * coefficient;
// Clamp the value to the range
return (value < 0 ? 0 : (value > max ? max : value));
}
function PDFImage(xref, res, image, inline, smask, mask, isMask) {
this.image = image;
var dict = image.dict;
if (dict.has('Filter')) {
var filter = dict.get('Filter').name;
if (filter === 'JPXDecode') {
var jpxImage = new JpxImage();
jpxImage.parseImageProperties(image.stream);
image.stream.reset();
image.bitsPerComponent = jpxImage.bitsPerComponent;
image.numComps = jpxImage.componentsCount;
} else if (filter === 'JBIG2Decode') {
image.bitsPerComponent = 1;
image.numComps = 1;
}
}
// TODO cache rendered images?
this.width = dict.get('Width', 'W');
this.height = dict.get('Height', 'H');
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;
this.matte = dict.get('Matte') || false;
var bitsPerComponent = image.bitsPerComponent;
if (!bitsPerComponent) {
bitsPerComponent = dict.get('BitsPerComponent', 'BPC');
if (!bitsPerComponent) {
if (this.imageMask) {
bitsPerComponent = 1;
} else {
error('Bits per component missing in image: ' + this.imageMask);
}
}
}
this.bpc = bitsPerComponent;
if (!this.imageMask) {
var colorSpace = dict.get('ColorSpace', 'CS');
if (!colorSpace) {
info('JPX images (which do not require color spaces)');
switch (image.numComps) {
case 1:
colorSpace = Name.get('DeviceGray');
break;
case 3:
colorSpace = Name.get('DeviceRGB');
break;
case 4:
colorSpace = Name.get('DeviceCMYK');
break;
default:
error('JPX images with ' + this.numComps +
' color components not supported.');
}
}
this.colorSpace = ColorSpace.parse(colorSpace, xref, res);
this.numComps = this.colorSpace.numComps;
}
this.decode = dict.get('Decode', 'D');
this.needsDecode = false;
if (this.decode &&
((this.colorSpace && !this.colorSpace.isDefaultDecode(this.decode)) ||
(isMask && !ColorSpace.isDefaultDecode(this.decode, 1)))) {
this.needsDecode = true;
// Do some preprocessing to avoid more math.
var max = (1 << bitsPerComponent) - 1;
this.decodeCoefficients = [];
this.decodeAddends = [];
for (var i = 0, j = 0; i < this.decode.length; i += 2, ++j) {
var dmin = this.decode[i];
var dmax = this.decode[i + 1];
this.decodeCoefficients[j] = dmax - dmin;
this.decodeAddends[j] = max * dmin;
}
}
if (smask) {
this.smask = new PDFImage(xref, res, smask, false);
} else if (mask) {
if (isStream(mask)) {
this.mask = new PDFImage(xref, res, mask, false, null, null, true);
} else {
// Color key mask (just an array).
this.mask = mask;
}
}
}
/**
* Handles processing of image data and returns the Promise that is resolved
* with a PDFImage when the image is ready to be used.
*/
PDFImage.buildImage = function PDFImage_buildImage(handler, xref,
res, image, inline) {
var imagePromise = handleImageData(handler, xref, res, image);
var smaskPromise;
var maskPromise;
var smask = image.dict.get('SMask');
var mask = image.dict.get('Mask');
if (smask) {
smaskPromise = handleImageData(handler, xref, res, smask);
maskPromise = Promise.resolve(null);
} else {
smaskPromise = Promise.resolve(null);
if (mask) {
if (isStream(mask)) {
maskPromise = handleImageData(handler, xref, res, mask);
} else if (isArray(mask)) {
maskPromise = Promise.resolve(mask);
} else {
warn('Unsupported mask format.');
maskPromise = Promise.resolve(null);
}
} else {
maskPromise = Promise.resolve(null);
}
}
return Promise.all([imagePromise, smaskPromise, maskPromise]).then(
function(results) {
var imageData = results[0];
var smaskData = results[1];
var maskData = results[2];
return new PDFImage(xref, res, imageData, inline, smaskData, maskData);
});
};
/**
* Resize an image using the nearest neighbor algorithm. Currently only
* supports one and three component images.
* @param {TypedArray} pixels The original image with one component.
* @param {Number} bpc Number of bits per component.
* @param {Number} components Number of color components, 1 or 3 is supported.
* @param {Number} w1 Original width.
* @param {Number} h1 Original height.
* @param {Number} w2 New width.
* @param {Number} h2 New height.
* @param {TypedArray} dest (Optional) The destination buffer.
* @param {Number} alpha01 (Optional) Size reserved for the alpha channel.
* @return {TypedArray} Resized image data.
*/
PDFImage.resize = function PDFImage_resize(pixels, bpc, components,
w1, h1, w2, h2, dest, alpha01) {
if (components !== 1 && components !== 3) {
error('Unsupported component count for resizing.');
}
var length = w2 * h2 * components;
var temp = dest ? dest : (bpc <= 8 ? new Uint8Array(length) :
(bpc <= 16 ? new Uint16Array(length) : new Uint32Array(length)));
var xRatio = w1 / w2;
var yRatio = h1 / h2;
var i, j, py, newIndex = 0, oldIndex;
var xScaled = new Uint16Array(w2);
var w1Scanline = w1 * components;
if (alpha01 !== 1) {
alpha01 = 0;
}
for (j = 0; j < w2; j++) {
xScaled[j] = Math.floor(j * xRatio) * components;
}
if (components === 1) {
for (i = 0; i < h2; i++) {
py = Math.floor(i * yRatio) * w1Scanline;
for (j = 0; j < w2; j++) {
oldIndex = py + xScaled[j];
temp[newIndex++] = pixels[oldIndex];
}
}
} else if (components === 3) {
for (i = 0; i < h2; i++) {
py = Math.floor(i * yRatio) * w1Scanline;
for (j = 0; j < w2; j++) {
oldIndex = py + xScaled[j];
temp[newIndex++] = pixels[oldIndex++];
temp[newIndex++] = pixels[oldIndex++];
temp[newIndex++] = pixels[oldIndex++];
newIndex += alpha01;
}
}
}
return temp;
};
PDFImage.createMask =
function PDFImage_createMask(imgArray, width, height,
imageIsFromDecodeStream, inverseDecode) {
// |imgArray| might not contain full data for every pixel of the mask, so
// we need to distinguish between |computedLength| and |actualLength|.
// In particular, if inverseDecode is true, then the array we return must
// have a length of |computedLength|.
var computedLength = ((width + 7) >> 3) * height;
var actualLength = imgArray.byteLength;
var haveFullData = computedLength === actualLength;
var data, i;
if (imageIsFromDecodeStream && (!inverseDecode || haveFullData)) {
// imgArray came from a DecodeStream and its data is in an appropriate
// form, so we can just transfer it.
data = imgArray;
} else if (!inverseDecode) {
data = new Uint8Array(actualLength);
data.set(imgArray);
} else {
data = new Uint8Array(computedLength);
data.set(imgArray);
for (i = actualLength; i < computedLength; i++) {
data[i] = 0xff;
}
}
// If necessary, invert the original mask data (but not any extra we might
// have added above). It's safe to modify the array -- whether it's the
// original or a copy, we're about to transfer it anyway, so nothing else
// in this thread can be relying on its contents.
if (inverseDecode) {
for (i = 0; i < actualLength; i++) {
data[i] = ~data[i];
}
}
return {data: data, width: width, height: height};
};
PDFImage.prototype = {
get drawWidth() {
return Math.max(this.width,
this.smask && this.smask.width || 0,
this.mask && this.mask.width || 0);
},
get drawHeight() {
return Math.max(this.height,
this.smask && this.smask.height || 0,
this.mask && this.mask.height || 0);
},
decodeBuffer: function PDFImage_decodeBuffer(buffer) {
var bpc = this.bpc;
var numComps = this.numComps;
var decodeAddends = this.decodeAddends;
var decodeCoefficients = this.decodeCoefficients;
var max = (1 << bpc) - 1;
var i, ii;
if (bpc === 1) {
// If the buffer needed decode that means it just needs to be inverted.
for (i = 0, ii = buffer.length; i < ii; i++) {
buffer[i] = +!(buffer[i]);
}
return;
}
var index = 0;
for (i = 0, ii = this.width * this.height; i < ii; i++) {
for (var j = 0; j < numComps; j++) {
buffer[index] = decodeAndClamp(buffer[index], decodeAddends[j],
decodeCoefficients[j], max);
index++;
}
}
},
getComponents: function PDFImage_getComponents(buffer) {
var bpc = this.bpc;
// This image doesn't require any extra work.
if (bpc === 8) {
return buffer;
}
var width = this.width;
var height = this.height;
var numComps = this.numComps;
var length = width * height * numComps;
var bufferPos = 0;
var output = (bpc <= 8 ? new Uint8Array(length) :
(bpc <= 16 ? new Uint16Array(length) : new Uint32Array(length)));
var rowComps = width * numComps;
var max = (1 << bpc) - 1;
var i = 0, ii, buf;
if (bpc === 1) {
// Optimization for reading 1 bpc images.
var mask, loop1End, loop2End;
for (var j = 0; j < height; j++) {
loop1End = i + (rowComps & ~7);
loop2End = i + rowComps;
// 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;
}
// handle remaing bits
if (i < loop2End) {
buf = buffer[bufferPos++];
mask = 128;
while (i < loop2End) {
output[i++] = +!!(buf & mask);
mask >>= 1;
}
}
}
} else {
// The general case that handles all other bpc values.
var bits = 0;
buf = 0;
for (i = 0, ii = length; i < ii; ++i) {
if (i % rowComps === 0) {
buf = 0;
bits = 0;
}
while (bits < bpc) {
buf = (buf << 8) | buffer[bufferPos++];
bits += 8;
}
var remainingBits = bits - bpc;
var value = buf >> remainingBits;
output[i] = (value < 0 ? 0 : (value > max ? max : value));
buf = buf & ((1 << remainingBits) - 1);
bits = remainingBits;
}
}
return output;
},
fillOpacity: function PDFImage_fillOpacity(rgbaBuf, width, height,
actualHeight, image) {
var smask = this.smask;
var mask = this.mask;
var alphaBuf, sw, sh, i, ii, j;
if (smask) {
sw = smask.width;
sh = smask.height;
alphaBuf = new Uint8Array(sw * sh);
smask.fillGrayBuffer(alphaBuf);
if (sw !== width || sh !== height) {
alphaBuf = PDFImage.resize(alphaBuf, smask.bpc, 1, sw, sh, width,
height);
}
} else if (mask) {
if (mask instanceof PDFImage) {
sw = mask.width;
sh = mask.height;
alphaBuf = new Uint8Array(sw * sh);
mask.numComps = 1;
mask.fillGrayBuffer(alphaBuf);
// Need to invert values in rgbaBuf
for (i = 0, ii = sw * sh; i < ii; ++i) {
alphaBuf[i] = 255 - alphaBuf[i];
}
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.
alphaBuf = new Uint8Array(width * height);
var numComps = this.numComps;
for (i = 0, ii = width * height; i < ii; ++i) {
var opacity = 0;
var imageOffset = i * numComps;
for (j = 0; j < numComps; ++j) {
var color = image[imageOffset + j];
var maskOffset = j * 2;
if (color < mask[maskOffset] || color > mask[maskOffset + 1]) {
opacity = 255;
break;
}
}
alphaBuf[i] = opacity;
}
} else {
error('Unknown mask format.');
}
}
if (alphaBuf) {
for (i = 0, j = 3, ii = width * actualHeight; i < ii; ++i, j += 4) {
rgbaBuf[j] = alphaBuf[i];
}
} else {
// No mask.
for (i = 0, j = 3, ii = width * actualHeight; i < ii; ++i, j += 4) {
rgbaBuf[j] = 255;
}
}
},
undoPreblend: function PDFImage_undoPreblend(buffer, width, height) {
var matte = this.smask && this.smask.matte;
if (!matte) {
return;
}
var matteRgb = this.colorSpace.getRgb(matte, 0);
var matteR = matteRgb[0];
var matteG = matteRgb[1];
var matteB = matteRgb[2];
var length = width * height * 4;
var r, g, b;
for (var i = 0; i < length; i += 4) {
var alpha = buffer[i + 3];
if (alpha === 0) {
// according formula we have to get Infinity in all components
// making it white (typical paper color) should be okay
buffer[i] = 255;
buffer[i + 1] = 255;
buffer[i + 2] = 255;
continue;
}
var k = 255 / alpha;
r = (buffer[i] - matteR) * k + matteR;
g = (buffer[i + 1] - matteG) * k + matteG;
b = (buffer[i + 2] - matteB) * k + matteB;
buffer[i] = r <= 0 ? 0 : r >= 255 ? 255 : r | 0;
buffer[i + 1] = g <= 0 ? 0 : g >= 255 ? 255 : g | 0;
buffer[i + 2] = b <= 0 ? 0 : b >= 255 ? 255 : b | 0;
}
},
createImageData: function PDFImage_createImageData(forceRGBA) {
var drawWidth = this.drawWidth;
var drawHeight = this.drawHeight;
var imgData = { // other fields are filled in below
width: drawWidth,
height: drawHeight
};
var numComps = this.numComps;
var originalWidth = this.width;
var originalHeight = this.height;
var bpc = this.bpc;
// Rows start at byte boundary.
var rowBytes = (originalWidth * numComps * bpc + 7) >> 3;
var imgArray;
if (!forceRGBA) {
// If it is a 1-bit-per-pixel grayscale (i.e. black-and-white) image
// without any complications, we pass a same-sized copy to the main
// thread rather than expanding by 32x to RGBA form. This saves *lots*
// of memory for many scanned documents. It's also much faster.
//
// Similarly, if it is a 24-bit-per pixel RGB image without any
// complications, we avoid expanding by 1.333x to RGBA form.
var kind;
if (this.colorSpace.name === 'DeviceGray' && bpc === 1) {
kind = ImageKind.GRAYSCALE_1BPP;
} else if (this.colorSpace.name === 'DeviceRGB' && bpc === 8 &&
!this.needsDecode) {
kind = ImageKind.RGB_24BPP;
}
if (kind && !this.smask && !this.mask &&
drawWidth === originalWidth && drawHeight === originalHeight) {
imgData.kind = kind;
imgArray = this.getImageBytes(originalHeight * rowBytes);
// If imgArray came from a DecodeStream, we're safe to transfer it
// (and thus neuter it) because it will constitute the entire
// DecodeStream's data. But if it came from a Stream, we need to
// copy it because it'll only be a portion of the Stream's data, and
// the rest will be read later on.
if (this.image instanceof DecodeStream) {
imgData.data = imgArray;
} else {
var newArray = new Uint8Array(imgArray.length);
newArray.set(imgArray);
imgData.data = newArray;
}
if (this.needsDecode) {
// Invert the buffer (which must be grayscale if we reached here).
assert(kind === ImageKind.GRAYSCALE_1BPP);
var buffer = imgData.data;
for (var i = 0, ii = buffer.length; i < ii; i++) {
buffer[i] ^= 0xff;
}
}
return imgData;
}
if (this.image instanceof JpegStream && !this.smask && !this.mask) {
imgData.kind = ImageKind.RGB_24BPP;
imgData.data = this.getImageBytes(originalHeight * rowBytes,
drawWidth, drawHeight, true);
return imgData;
}
}
imgArray = this.getImageBytes(originalHeight * rowBytes);
// imgArray can be incomplete (e.g. after CCITT fax encoding).
var actualHeight = 0 | (imgArray.length / rowBytes *
drawHeight / originalHeight);
var comps = this.getComponents(imgArray);
// If opacity data is present, use RGBA_32BPP form. Otherwise, use the
// more compact RGB_24BPP form if allowable.
var alpha01, maybeUndoPreblend;
if (!forceRGBA && !this.smask && !this.mask) {
imgData.kind = ImageKind.RGB_24BPP;
imgData.data = new Uint8Array(drawWidth * drawHeight * 3);
alpha01 = 0;
maybeUndoPreblend = false;
} else {
imgData.kind = ImageKind.RGBA_32BPP;
imgData.data = new Uint8Array(drawWidth * drawHeight * 4);
alpha01 = 1;
maybeUndoPreblend = true;
// Color key masking (opacity) must be performed before decoding.
this.fillOpacity(imgData.data, drawWidth, drawHeight, actualHeight,
comps);
}
if (this.needsDecode) {
this.decodeBuffer(comps);
}
this.colorSpace.fillRgb(imgData.data, originalWidth, originalHeight,
drawWidth, drawHeight, actualHeight, bpc, comps,
alpha01);
if (maybeUndoPreblend) {
this.undoPreblend(imgData.data, drawWidth, actualHeight);
}
return imgData;
},
fillGrayBuffer: function PDFImage_fillGrayBuffer(buffer) {
var numComps = this.numComps;
if (numComps !== 1) {
error('Reading gray scale from a color image: ' + numComps);
}
var width = this.width;
var height = this.height;
var bpc = this.bpc;
// rows start at byte boundary
var rowBytes = (width * numComps * bpc + 7) >> 3;
var imgArray = this.getImageBytes(height * rowBytes);
var comps = this.getComponents(imgArray);
var i, length;
if (bpc === 1) {
// inline decoding (= inversion) for 1 bpc images
length = width * height;
if (this.needsDecode) {
// invert and scale to {0, 255}
for (i = 0; i < length; ++i) {
buffer[i] = (comps[i] - 1) & 255;
}
} else {
// scale to {0, 255}
for (i = 0; i < length; ++i) {
buffer[i] = (-comps[i]) & 255;
}
}
return;
}
if (this.needsDecode) {
this.decodeBuffer(comps);
}
length = width * height;
// we aren't using a colorspace so we need to scale the value
var scale = 255 / ((1 << bpc) - 1);
for (i = 0; i < length; ++i) {
buffer[i] = (scale * comps[i]) | 0;
}
},
getImageBytes: function PDFImage_getImageBytes(length,
drawWidth, drawHeight,
forceRGB) {
this.image.reset();
this.image.drawWidth = drawWidth || this.width;
this.image.drawHeight = drawHeight || this.height;
this.image.forceRGB = !!forceRGB;
return this.image.getBytes(length);
}
};
return PDFImage;
})();