Add support for horizontal scrolling in 'scrollIntoView' in ui_utils.js

web/text_layer_builder.js

@@ -13,10 +13,12 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+/* globals CustomStyle, PDFFindController, scrollIntoView */
 
 'use strict';
 
-/* globals CustomStyle, PDFFindController, scrollIntoView */
+var FIND_SCROLL_OFFSET_TOP = -50;
+var FIND_SCROLL_OFFSET_LEFT = -400;
 
 /**
  * TextLayerBuilder provides text-selection
@@ -310,7 +312,8 @@ var TextLayerBuilder = function textLayerBuilder(options) {
       var isSelected = isSelectedPage && i === selectedMatchIdx;
       var highlightSuffix = (isSelected ? ' selected' : '');
       if (isSelected && !this.isViewerInPresentationMode) {
-        scrollIntoView(textDivs[begin.divIdx], { top: -50 });
+        scrollIntoView(textDivs[begin.divIdx], { top: FIND_SCROLL_OFFSET_TOP,
+                                               left: FIND_SCROLL_OFFSET_LEFT });
       }
 
       // Match inside new div.

web/ui_utils.js

@@ -100,7 +100,8 @@ function getOutputScale(ctx) {
 /**
  * Scrolls specified element into view of its parent.
  * element {Object} The element to be visible.
- * spot {Object} The object with the top property -- offset from the top edge.
+ * spot {Object} An object with optional top and left properties,
+ *               specifying the offset from the top left edge.
  */
 function scrollIntoView(element, spot) {
   // Assuming offsetParent is available (it's not available when viewer is in
@@ -108,21 +109,32 @@ function scrollIntoView(element, spot) {
   // producing the error. See also animationStartedClosure.
   var parent = element.offsetParent;
   var offsetY = element.offsetTop + element.clientTop;
+  var offsetX = element.offsetLeft + element.clientLeft;
   if (!parent) {
     console.error('offsetParent is not set -- cannot scroll');
     return;
   }
-  while (parent.clientHeight == parent.scrollHeight) {
+  while (parent.clientHeight === parent.scrollHeight) {
     if (parent.dataset._scaleY) {
       offsetY /= parent.dataset._scaleY;
+      offsetX /= parent.dataset._scaleX;
     }
     offsetY += parent.offsetTop;
+    offsetX += parent.offsetLeft;
     parent = parent.offsetParent;
-    if (!parent)
+    if (!parent) {
       return; // no need to scroll
+    }
+  }
+  if (spot) {
+    if (spot.top !== undefined) {
+      offsetY += spot.top;
+    }
+    if (spot.left !== undefined) {
+      offsetX += spot.left;
+      parent.scrollLeft = offsetX;
+    }
   }
-  if (spot)
-    offsetY += spot.top;
   parent.scrollTop = offsetY;
 }