Moves rendering queue logic from PDFView

web/pdf_rendering_queue.js

@@ -0,0 +1,151 @@
+/* -*- 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 CLEANUP_TIMEOUT */
+
+'use strict';
+
+var RenderingStates = {
+  INITIAL: 0,
+  RUNNING: 1,
+  PAUSED: 2,
+  FINISHED: 3
+};
+
+var PDFRenderingQueue = (function PDFRenderingQueueClosure() {
+  function PDFRenderingQueue() {
+    this.pdfViewer = null;
+    this.pdfThumbnailViewer = null;
+    this.onIdle = null;
+
+    this.highestPriorityPage = null;
+    this.idleTimeout = null;
+    this.printing = false;
+    this.isThumbnailViewEnabled = false;
+  }
+
+  PDFRenderingQueue.prototype = {
+    setViewer: function PDFRenderingQueue_setViewer(pdfViewer) {
+      this.pdfViewer = pdfViewer;
+    },
+
+    setThumbnailViewer:
+        function PDFRenderingQueue_setThumbnailViewer(pdfThumbnailViewer) {
+      this.pdfThumbnailViewer = pdfThumbnailViewer;
+    },
+
+    isHighestPriority: function PDFRenderingQueue_isHighestPriority(view) {
+      return this.highestPriorityPage === view.renderingId;
+    },
+
+    renderHighestPriority: function
+        PDFRenderingQueue_renderHighestPriority(currentlyVisiblePages) {
+      if (this.idleTimeout) {
+        clearTimeout(this.idleTimeout);
+        this.idleTimeout = null;
+      }
+
+      // Pages have a higher priority than thumbnails, so check them first.
+      if (this.pdfViewer.forceRendering(currentlyVisiblePages)) {
+        return;
+      }
+      // No pages needed rendering so check thumbnails.
+      if (this.pdfThumbnailViewer && this.isThumbnailViewEnabled) {
+        if (this.pdfThumbnailViewer.forceRendering()) {
+          return;
+        }
+      }
+
+      if (this.printing) {
+        // If printing is currently ongoing do not reschedule cleanup.
+        return;
+      }
+
+      if (this.onIdle) {
+        this.idleTimeout = setTimeout(this.onIdle.bind(this), CLEANUP_TIMEOUT);
+      }
+    },
+
+    getHighestPriority: function
+        PDFRenderingQueue_getHighestPriority(visible, views, scrolledDown) {
+      // The state has changed figure out which page has the highest priority to
+      // render next (if any).
+      // Priority:
+      // 1 visible pages
+      // 2 if last scrolled down page after the visible pages
+      // 2 if last scrolled up page before the visible pages
+      var visibleViews = visible.views;
+
+      var numVisible = visibleViews.length;
+      if (numVisible === 0) {
+        return false;
+      }
+      for (var i = 0; i < numVisible; ++i) {
+        var view = visibleViews[i].view;
+        if (!this.isViewFinished(view)) {
+          return view;
+        }
+      }
+
+      // All the visible views have rendered, try to render next/previous pages.
+      if (scrolledDown) {
+        var nextPageIndex = visible.last.id;
+        // ID's start at 1 so no need to add 1.
+        if (views[nextPageIndex] &&
+            !this.isViewFinished(views[nextPageIndex])) {
+          return views[nextPageIndex];
+        }
+      } else {
+        var previousPageIndex = visible.first.id - 2;
+        if (views[previousPageIndex] &&
+          !this.isViewFinished(views[previousPageIndex])) {
+          return views[previousPageIndex];
+        }
+      }
+      // Everything that needs to be rendered has been.
+      return null;
+    },
+
+    isViewFinished: function PDFRenderingQueue_isViewFinished(view) {
+      return view.renderingState === RenderingStates.FINISHED;
+    },
+
+    // Render a page or thumbnail view. This calls the appropriate function
+    // based on the views state. If the view is already rendered it will return
+    // false.
+    renderView: function PDFRenderingQueue_renderView(view) {
+      var state = view.renderingState;
+      switch (state) {
+        case RenderingStates.FINISHED:
+          return false;
+        case RenderingStates.PAUSED:
+          this.highestPriorityPage = view.renderingId;
+          view.resume();
+          break;
+        case RenderingStates.RUNNING:
+          this.highestPriorityPage = view.renderingId;
+          break;
+        case RenderingStates.INITIAL:
+          this.highestPriorityPage = view.renderingId;
+          view.draw(this.renderHighestPriority.bind(this));
+          break;
+      }
+      return true;
+    },
+  };
+
+  return PDFRenderingQueue;
+})();