touchui: Fine-tune selection-controller visibility.

views/touchui/touch_selection_controller_impl.cc

 // Copyright (c) 2011 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.
 
 #include "views/touchui/touch_selection_controller_impl.h"
 
 #include "base/time.h"
 #include "grit/ui_strings.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
@@ skipping 13 matching lines @@
 
 namespace {
 
 // Constants defining the visual attributes of selection handles
 const int kSelectionHandleRadius = 10;
 const int kSelectionHandleCursorHeight = 10;
 const int kSelectionHandleAlpha = 0x7F;
 const SkColor kSelectionHandleColor =
     SkColorSetA(SK_ColorBLUE, kSelectionHandleAlpha);
 
+// The minimum selection size to trigger selection controller.
+const int kMinSelectionSize = 4;
+
 const int kContextMenuCommands[] = {IDS_APP_CUT,
                                     IDS_APP_COPY,
 // TODO(varunjain): PASTE is acting funny due to some gtk clipboard issue.
 // Uncomment the following when that is fixed.
 //                                    IDS_APP_PASTE,
                                     IDS_APP_DELETE,
                                     IDS_APP_SELECT_ALL};
 const int kContextMenuPadding = 2;
 const int kContextMenuTimoutMs = 1000;
 const int kContextMenuVerticalOffset = 10;
@@ skipping 228 matching lines @@
 
   if (dragging_handle_) {
     // We need to reposition only the selection handle that is being dragged.
     // The other handle stays the same. Also, the selection handle being dragged
     // will always be at the end of selection, while the other handle will be at
     // the start.
     dragging_handle_->SetScreenPosition(screen_pos_2);
   } else {
     UpdateContextMenu(p1, p2);
 
-    // Check if there is any selection at all.
-    if (screen_pos_1 == screen_pos_2) {
+    // Check if there is any selection at all. The points may not match exactly,
+    // since the selection range computation may introduce some floating point
+    // errors. So check for a minimum size to decide whether or not there is any
+    // selection.
+    int delta_x = screen_pos_2.x() - screen_pos_1.x();
+    int delta_y = screen_pos_2.y() - screen_pos_1.y();
+    if (abs(delta_x) < kMinSelectionSize && abs(delta_y) < kMinSelectionSize) {
       selection_handle_1_->SetVisible(false);
       selection_handle_2_->SetVisible(false);
       return;
     }
 
     if (client_view_->bounds().Contains(p1)) {
       selection_handle_1_->SetScreenPosition(screen_pos_1);
       selection_handle_1_->SetVisible(true);
     } else {
       selection_handle_1_->SetVisible(false);
@@ skipping 121 matching lines @@
 bool TouchSelectionControllerImpl::IsSelectionHandle2Visible() {
   return selection_handle_2_->IsVisible();
 }
 
 TouchSelectionController* TouchSelectionController::create(
     TouchSelectionClientView* client_view) {
   return new TouchSelectionControllerImpl(client_view);
 }
 
 }  // namespace views