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Fix the interface of JpegStream/JpxStream/Jbig2Stream to agree with the other DecodeStreams

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The interface of all of the "image" streams look kind of weird, and I'm actually a bit surprised that there hasn't been any errors because of it.
For example: None of them actually implement `readBlock` methods, and it seems more luck that anything else that we're not calling `getBytes()` (without providing a length) for those streams, since that would trigger a code-path in `getBytes` that assumes `readBlock` to exist.

To address this long-standing issue, the `ensureBuffer` methods are thus renamed to `readBlock`. Furthermore, the new `ensureBuffer` methods are now no-ops.
Finally, this patch also replaces `var` with `let` in a number of places.
This commit is contained in:
Jonas Jenwald 2017-10-26 13:15:57 +02:00
parent 36593d6bbc
commit de5297b9ea
3 changed files with 68 additions and 56 deletions
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43
src/core/jpeg_stream.js
View file

@ -21,15 +21,15 @@ import { JpegImage } from './jpg';
/**
* Depending on the type of JPEG a JpegStream is handled in different ways. For
* JPEG's that are supported natively such as DeviceGray and DeviceRGB the image
* data is stored and then loaded by the browser. For unsupported JPEG's we use
* data is stored and then loaded by the browser. For unsupported JPEG's we use
* a library to decode these images and the stream behaves like all the other
* DecodeStreams.
*/
var JpegStream = (function JpegStreamClosure() {
let JpegStream = (function JpegStreamClosure() {
function JpegStream(stream, maybeLength, dict, params) {
// Some images may contain 'junk' before the SOI (start-of-image) marker.
// Note: this seems to mainly affect inline images.
var ch;
let ch;
while ((ch = stream.getByte()) !== -1) {
if (ch === 0xFF) { // Find the first byte of the SOI marker (0xFFD8).
stream.skip(-1); // Reset the stream position to the SOI.
@ -48,27 +48,32 @@ var JpegStream = (function JpegStreamClosure() {
Object.defineProperty(JpegStream.prototype, 'bytes', {
get: function JpegStream_bytes() {
// If this.maybeLength is null, we'll get the entire stream.
// If `this.maybeLength` is null, we'll get the entire stream.
return shadow(this, 'bytes', this.stream.getBytes(this.maybeLength));
},
configurable: true,
});
JpegStream.prototype.ensureBuffer = function JpegStream_ensureBuffer(req) {
if (this.bufferLength) {
JpegStream.prototype.ensureBuffer = function(requested) {
// No-op, since `this.readBlock` will always parse the entire image and
// directly insert all of its data into `this.buffer`.
};
JpegStream.prototype.readBlock = function() {
if (this.eof) {
return;
}
var jpegImage = new JpegImage();
let jpegImage = new JpegImage();
// Checking if values need to be transformed before conversion.
var decodeArr = this.dict.getArray('Decode', 'D');
let decodeArr = this.dict.getArray('Decode', 'D');
if (this.forceRGB && Array.isArray(decodeArr)) {
var bitsPerComponent = this.dict.get('BitsPerComponent') || 8;
var decodeArrLength = decodeArr.length;
var transform = new Int32Array(decodeArrLength);
var transformNeeded = false;
var maxValue = (1 << bitsPerComponent) - 1;
for (var i = 0; i < decodeArrLength; i += 2) {
let bitsPerComponent = this.dict.get('BitsPerComponent') || 8;
let decodeArrLength = decodeArr.length;
let transform = new Int32Array(decodeArrLength);
let transformNeeded = false;
let maxValue = (1 << bitsPerComponent) - 1;
for (let i = 0; i < decodeArrLength; i += 2) {
transform[i] = ((decodeArr[i + 1] - decodeArr[i]) * 256) | 0;
transform[i + 1] = (decodeArr[i] * maxValue) | 0;
if (transform[i] !== 256 || transform[i + 1] !== 0) {
@ -81,26 +86,26 @@ var JpegStream = (function JpegStreamClosure() {
}
// Fetching the 'ColorTransform' entry, if it exists.
if (isDict(this.params)) {
var colorTransform = this.params.get('ColorTransform');
let colorTransform = this.params.get('ColorTransform');
if (Number.isInteger(colorTransform)) {
jpegImage.colorTransform = colorTransform;
}
}
jpegImage.parse(this.bytes);
var data = jpegImage.getData(this.drawWidth, this.drawHeight,
let data = jpegImage.getData(this.drawWidth, this.drawHeight,
this.forceRGB);
this.buffer = data;
this.bufferLength = data.length;
this.eof = true;
};
JpegStream.prototype.getBytes = function JpegStream_getBytes(length) {
this.ensureBuffer();
JpegStream.prototype.getBytes = function(length) {
this.readBlock();
return this.buffer;
};
JpegStream.prototype.getIR = function JpegStream_getIR(forceDataSchema) {
JpegStream.prototype.getIR = function(forceDataSchema = false) {
return createObjectURL(this.bytes, 'image/jpeg', forceDataSchema);
};