Scale touch event radius

ash/touch/touch_transformer_controller.cc

 // Copyright 2014 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 "ash/touch/touch_transformer_controller.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/host/ash_window_tree_host.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/display/chromeos/display_configurator.h"
 #include "ui/display/types/chromeos/display_snapshot.h"
 #include "ui/events/device_data_manager.h"
+#include "ui/events/x/device_data_manager_x11.h"
 
 namespace ash {
 
 namespace {
 
 DisplayManager* GetDisplayManager() {
   return Shell::GetInstance()->display_manager();
 }
 
 }  // namespace
 
+
+// This is to compute the scale ratio for the TouchEvent's radius. The
+// configured resolution of the display is not always the same as the touch
+// screen's reporting resolution, e.g. the display could be set as
+// 1920x1080 while the touchscreen is reporting touch position range at
+// 32767x32767. Touch radius is reported in the units the same as touch position
+// so we need to scale the touch radius to be compatible with the display's
+// resolution. We compute the scale as
+// sqrt of (display_area / touchscreen_area)
+double TouchTransformerController::GetTouchRadiusScale(

[oshima, 2014/07/22 21:41:18]

Maybe TouchResolutionScale is better name?

[Yufeng Shen (Slow to review), 2014/07/22 21:52:03]

Done.

+    const DisplayInfo& touch_display) const {
+  if (touch_display.touch_device_id() == 0)
+    return 1.0;
+
+  double min_x, max_x;
+  double min_y, max_y;
+  if (!ui::DeviceDataManagerX11::GetInstance()->GetDataRange(
+          touch_display.touch_device_id(),
+          ui::DeviceDataManagerX11::DT_TOUCH_POSITION_X,
+          &min_x, &max_x) ||
+      !ui::DeviceDataManagerX11::GetInstance()->GetDataRange(
+          touch_display.touch_device_id(),
+          ui::DeviceDataManagerX11::DT_TOUCH_POSITION_Y,
+          &min_y, &max_y)) {
+    return 1.0;
+  }
+
+  double width = touch_display.bounds_in_native().width();
+  double height = touch_display.bounds_in_native().height();
+
+  if (max_x == 0.0 || max_y == 0.0 || width == 0.0 || height == 0.0)
+    return 1.0;
+
+  // [0, max_x] -> touchscreen width = max_x + 1
+  // [0, max_y] -> touchscreen height = max_y + 1
+  max_x += 1.0;
+  max_y += 1.0;
+
+  double ratio = std::sqrt((width * height) / (max_x * max_y));
+
+  VLOG(2) << "Screen width/height: " << width << "/" << height
+          << ", Touchscreen width/height: " << max_x << "/" << max_y
+          << ", Touch radius scale ratio: " << ratio;
+  return ratio;
+}
+
 // This function computes the extended mode TouchTransformer for
 // |touch_display|. The TouchTransformer maps the touch event position
 // from framebuffer size to the display size.
 gfx::Transform
 TouchTransformerController::GetExtendedModeTouchTransformer(
     const DisplayInfo& touch_display, const gfx::Size& fb_size) const {
   gfx::Transform ctm;
   if (touch_display.touch_device_id() == 0 ||
       fb_size.width() == 0.0 ||
       fb_size.height() == 0.0)
@@ skipping 114 matching lines @@
   } else if (display_state == ui::MULTIPLE_DISPLAY_STATE_DUAL_MIRROR ||
              display_state == ui::MULTIPLE_DISPLAY_STATE_DUAL_EXTENDED) {
     // TODO(miletus) : Handle DUAL_EXTENDED with software mirroring.
     DisplayIdPair id_pair = GetDisplayManager()->GetCurrentDisplayIdPair();
     display1_id = id_pair.first;
     display2_id = id_pair.second;
     DCHECK(display1_id != gfx::Display::kInvalidDisplayID &&
            display2_id != gfx::Display::kInvalidDisplayID);
     display1 = GetDisplayManager()->GetDisplayInfo(display1_id);
     display2 = GetDisplayManager()->GetDisplayInfo(display2_id);
+    device_manager->UpdateTouchRadiusScale(display1.touch_device_id(),
+                                           GetTouchRadiusScale(display1));
+    device_manager->UpdateTouchRadiusScale(display2.touch_device_id(),
+                                           GetTouchRadiusScale(display2));
   } else {
     single_display_id = GetDisplayManager()->first_display_id();
     DCHECK(single_display_id != gfx::Display::kInvalidDisplayID);
     single_display = GetDisplayManager()->GetDisplayInfo(single_display_id);
+    device_manager->UpdateTouchRadiusScale(single_display.touch_device_id(),
+                                           GetTouchRadiusScale(single_display));
   }
 
   if (display_state == ui::MULTIPLE_DISPLAY_STATE_DUAL_MIRROR) {
     // In mirror mode, both displays share the same root window so
     // both display ids are associated with the root window.
     aura::Window* root = display_controller->GetPrimaryRootWindow();
     RootWindowController::ForWindow(root)->ash_host()->UpdateDisplayID(
         display1_id, display2_id);
     device_manager->UpdateTouchInfoForDisplay(
         display1_id,
@@ skipping 45 matching lines @@
 
 void TouchTransformerController::OnDisplaysInitialized() {
   UpdateTouchTransformer();
 }
 
 void TouchTransformerController::OnDisplayConfigurationChanged() {
   UpdateTouchTransformer();
 }
 
 }  // namespace ash