pdf.js/src/display/transport_stream.js

/* 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.
 */

import { assert, createPromiseCapability } from '../shared/util';

 /** @implements {IPDFStream} */
var PDFDataTransportStream = (function PDFDataTransportStreamClosure() {
  function PDFDataTransportStream(params, pdfDataRangeTransport) {
    assert(pdfDataRangeTransport);

    this._queuedChunks = [];
    var initialData = params.initialData;
    if (initialData && initialData.length > 0) {
      let buffer = new Uint8Array(initialData).buffer;
      this._queuedChunks.push(buffer);
    }

    this._pdfDataRangeTransport = pdfDataRangeTransport;
    this._isStreamingSupported = !params.disableStream;
    this._isRangeSupported = !params.disableRange;
    this._contentLength = params.length;

    this._fullRequestReader = null;
    this._rangeReaders = [];

    this._pdfDataRangeTransport.addRangeListener((begin, chunk) => {
      this._onReceiveData({ begin, chunk, });
    });

    this._pdfDataRangeTransport.addProgressListener((loaded) => {
      this._onProgress({ loaded, });
    });

    this._pdfDataRangeTransport.addProgressiveReadListener((chunk) => {
      this._onReceiveData({ chunk, });
    });

    this._pdfDataRangeTransport.transportReady();
  }
  PDFDataTransportStream.prototype = {
    _onReceiveData: function PDFDataTransportStream_onReceiveData(args) {
       let buffer = new Uint8Array(args.chunk).buffer;
       if (args.begin === undefined) {
         if (this._fullRequestReader) {
           this._fullRequestReader._enqueue(buffer);
         } else {
           this._queuedChunks.push(buffer);
         }
       } else {
         var found = this._rangeReaders.some(function (rangeReader) {
           if (rangeReader._begin !== args.begin) {
             return false;
           }
           rangeReader._enqueue(buffer);
           return true;
         });
         assert(found);
       }
    },

    _onProgress: function PDFDataTransportStream_onDataProgress(evt) {
       if (this._rangeReaders.length > 0) {
         // Reporting to first range reader.
         var firstReader = this._rangeReaders[0];
         if (firstReader.onProgress) {
           firstReader.onProgress({ loaded: evt.loaded, });
         }
       }
    },

    _removeRangeReader:
        function PDFDataTransportStream_removeRangeReader(reader) {
      var i = this._rangeReaders.indexOf(reader);
      if (i >= 0) {
        this._rangeReaders.splice(i, 1);
      }
    },

    getFullReader: function PDFDataTransportStream_getFullReader() {
      assert(!this._fullRequestReader);
      var queuedChunks = this._queuedChunks;
      this._queuedChunks = null;
      return new PDFDataTransportStreamReader(this, queuedChunks);
    },

    getRangeReader: function PDFDataTransportStream_getRangeReader(begin, end) {
      var reader = new PDFDataTransportStreamRangeReader(this, begin, end);
      this._pdfDataRangeTransport.requestDataRange(begin, end);
      this._rangeReaders.push(reader);
      return reader;
    },

    cancelAllRequests:
        function PDFDataTransportStream_cancelAllRequests(reason) {
      if (this._fullRequestReader) {
        this._fullRequestReader.cancel(reason);
      }
      var readers = this._rangeReaders.slice(0);
      readers.forEach(function (rangeReader) {
        rangeReader.cancel(reason);
      });
      this._pdfDataRangeTransport.abort();
    },
  };

  /** @implements {IPDFStreamReader} */
  function PDFDataTransportStreamReader(stream, queuedChunks) {
    this._stream = stream;
    this._done = false;
    this._filename = null;
    this._queuedChunks = queuedChunks || [];
    this._requests = [];
    this._headersReady = Promise.resolve();
    stream._fullRequestReader = this;

    this.onProgress = null; // not used
  }
  PDFDataTransportStreamReader.prototype = {
    _enqueue: function PDFDataTransportStreamReader_enqueue(chunk) {
      if (this._done) {
        return; // ignore new data
      }
      if (this._requests.length > 0) {
        var requestCapability = this._requests.shift();
        requestCapability.resolve({ value: chunk, done: false, });
        return;
      }
      this._queuedChunks.push(chunk);
    },

    get headersReady() {
      return this._headersReady;
    },

    get filename() {
      return this._filename;
    },

    get isRangeSupported() {
      return this._stream._isRangeSupported;
    },

    get isStreamingSupported() {
      return this._stream._isStreamingSupported;
    },

    get contentLength() {
      return this._stream._contentLength;
    },

    async read() {
      if (this._queuedChunks.length > 0) {
        var chunk = this._queuedChunks.shift();
        return { value: chunk, done: false, };
      }
      if (this._done) {
        return { value: undefined, done: true, };
      }
      var requestCapability = createPromiseCapability();
      this._requests.push(requestCapability);
      return requestCapability.promise;
    },

    cancel: function PDFDataTransportStreamReader_cancel(reason) {
      this._done = true;
      this._requests.forEach(function (requestCapability) {
        requestCapability.resolve({ value: undefined, done: true, });
      });
      this._requests = [];
    },
  };

  /** @implements {IPDFStreamRangeReader} */
  function PDFDataTransportStreamRangeReader(stream, begin, end) {
    this._stream = stream;
    this._begin = begin;
    this._end = end;
    this._queuedChunk = null;
    this._requests = [];
    this._done = false;

    this.onProgress = null;
  }
  PDFDataTransportStreamRangeReader.prototype = {
    _enqueue: function PDFDataTransportStreamRangeReader_enqueue(chunk) {
      if (this._done) {
        return; // ignore new data
      }
      if (this._requests.length === 0) {
        this._queuedChunk = chunk;
      } else {
        var requestsCapability = this._requests.shift();
        requestsCapability.resolve({ value: chunk, done: false, });
        this._requests.forEach(function (requestCapability) {
          requestCapability.resolve({ value: undefined, done: true, });
        });
        this._requests = [];
      }
      this._done = true;
      this._stream._removeRangeReader(this);
    },

    get isStreamingSupported() {
      return false;
    },

    async read() {
      if (this._queuedChunk) {
        let chunk = this._queuedChunk;
        this._queuedChunk = null;
        return { value: chunk, done: false, };
      }
      if (this._done) {
        return { value: undefined, done: true, };
      }
      var requestCapability = createPromiseCapability();
      this._requests.push(requestCapability);
      return requestCapability.promise;
    },

    cancel: function PDFDataTransportStreamRangeReader_cancel(reason) {
      this._done = true;
      this._requests.forEach(function (requestCapability) {
        requestCapability.resolve({ value: undefined, done: true, });
      });
      this._requests = [];
      this._stream._removeRangeReader(this);
    },
  };

  return PDFDataTransportStream;
})();

export {
  PDFDataTransportStream,
};