Scroll while selecting

chrome/browser/resources/pdf/pdf.js

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 'use strict';
 
 /**
  * @return {number} Width of a scrollbar in pixels
  */
 function getScrollbarWidth() {
@@ skipping 390 matching lines @@
         break;
       case 'setTranslatedStrings':
         this.passwordScreen_.text = message.data.getPasswordString;
         this.progressBar_.text = message.data.loadingString;
         this.progressBar_.style.visibility = 'visible';
         this.errorScreen_.text = message.data.loadFailedString;
         break;
       case 'cancelStreamUrl':
         chrome.streamsPrivate.abort(this.streamDetails_.streamUrl);
         break;
+      case 'isSelecting':
+        if (message.data.isSelecting == this.isSelecting_)
+          break;
+        this.isSelecting_ = message.data.isSelecting_;
+        if (this.isSelecting_) {
+          this.plugin_.addEventListener('mousemove',
+                                        selectionDragListener,
+                                        false);
+        } else {
+          this.plugin_.removeEventListener('mousemove',
+                                           selectionDragListener,
+                                           false);
+        }
+        break;
     }
   },
 
+  getDragScrollVelocity_: function(pos, max_pos) {
+    // This gives a higher velocity as the pos approaches 0 or max_pos.
+    var velocity = Math.abs(ACCEL_COEFFICIENT * pos - (max_pos / 2));
+    // This gives a range in which there is no velocity for the given pos.
+    velocity -= DRAG_START_COEFFICIENT;
+    // Bound the velocity between 0 and MAX_VELOCITY.
+    velocity = Math.max(0, min(MAX_VELOCITY, velocity));
+  }
+
+  selectionDragListener_: function(event) {
+    var relative_x = event.x - this.plugin_.clientLeft;
+    var relative_y = event.y - this.plugin_.clientTop;
+    var x_velocity = this.getDragScrollVelocity_(relative_x, this.plugin_.width);
+    var y_velocity = this.getDragScrollVelocity_(relative_y, this.plugin_.height);
+    if (event.x )
+  },
+
   /**
    * @private
    * A callback that's called before the zoom changes. Notify the plugin to stop
    * reacting to scroll events while zoom is taking place to avoid flickering.
    */
   beforeZoom_: function() {
     this.plugin_.postMessage({
       type: 'stopScrolling'
     });
   },
@@ skipping 183 matching lines @@
               this.streamDetails_.tabId != -1);
   },
 
   /**
    * @type {Viewport} the viewport of the PDF viewer.
    */
   get viewport() {
     return this.viewport_;
   }
 };