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When an image has a non-zero SMaskInData it means that the image has an alpha channel. With JPX images, the colorspace isn't required (by spec) so when we don't have it, the JPX decoder will handle the conversion in RGBA format.
65 lines
1.8 KiB
JavaScript
65 lines
1.8 KiB
JavaScript
/* Copyright 2012 Mozilla Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import { DecodeStream } from "./decode_stream.js";
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import { JpxImage } from "./jpx.js";
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import { shadow } from "../shared/util.js";
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/**
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* For JPEG 2000's we use a library to decode these images and
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* the stream behaves like all the other DecodeStreams.
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*/
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class JpxStream extends DecodeStream {
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constructor(stream, maybeLength, params) {
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super(maybeLength);
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this.stream = stream;
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this.dict = stream.dict;
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this.maybeLength = maybeLength;
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this.params = params;
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}
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get bytes() {
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// If `this.maybeLength` is null, we'll get the entire stream.
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return shadow(this, "bytes", this.stream.getBytes(this.maybeLength));
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}
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ensureBuffer(requested) {
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// No-op, since `this.readBlock` will always parse the entire image and
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// directly insert all of its data into `this.buffer`.
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}
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readBlock(decoderOptions) {
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this.decodeImage(null, decoderOptions);
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}
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decodeImage(bytes, decoderOptions) {
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if (this.eof) {
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return this.buffer;
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}
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bytes ||= this.bytes;
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this.buffer = JpxImage.decode(bytes, decoderOptions);
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this.bufferLength = this.buffer.length;
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this.eof = true;
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return this.buffer;
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}
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get canAsyncDecodeImageFromBuffer() {
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return this.stream.isAsync;
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}
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}
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export { JpxStream };
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