[Android] Select text when stylus first button is pressed.

content/browser/android/content_view_core_impl.cc

 // Copyright 2012 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 "content/browser/android/content_view_core_impl.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
@@ skipping 40 matching lines @@
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/menu_item.h"
 #include "content/public/common/page_transition_types.h"
 #include "content/public/common/user_agent.h"
 #include "jni/ContentViewCore_jni.h"
 #include "third_party/WebKit/public/web/WebBindings.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/base/android/view_android.h"
 #include "ui/base/android/window_android.h"
+#include "ui/events/gesture_detection/motion_event.h"
 #include "ui/gfx/android/java_bitmap.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/size_f.h"
 
 using base::android::AttachCurrentThread;
 using base::android::ConvertJavaStringToUTF16;
 using base::android::ConvertJavaStringToUTF8;
 using base::android::ConvertUTF16ToJavaString;
 using base::android::ConvertUTF8ToJavaString;
@@ skipping 147 matching lines @@
     ui::WindowAndroid* window_android,
     jobject java_bridge_retained_object_set)
     : WebContentsObserver(web_contents),
       java_ref_(env, obj),
       web_contents_(static_cast<WebContentsImpl*>(web_contents)),
       root_layer_(cc::SolidColorLayer::Create()),
       dpi_scale_(GetPrimaryDisplayDeviceScaleFactor()),
       view_android_(view_android),
       window_android_(window_android),
       device_orientation_(0),
-      accessibility_enabled_(false) {
+      accessibility_enabled_(false),
+      mouse_drag_start_x_(0),
+      mouse_drag_start_y_(0) {
   CHECK(web_contents) <<
       "A ContentViewCoreImpl should be created with a valid WebContents.";
 
   root_layer_->SetBackgroundColor(GetBackgroundColor(env, obj));
   gfx::Size physical_size(
       Java_ContentViewCore_getPhysicalBackingWidthPix(env, obj),
       Java_ContentViewCore_getPhysicalBackingHeightPix(env, obj));
   root_layer_->SetBounds(physical_size);
   root_layer_->SetIsDrawable(true);
 
@@ skipping 731 matching lines @@
                            pointer_id_0,
                            pointer_id_1,
                            touch_major_0,
                            touch_major_1,
                            raw_pos_x,
                            raw_pos_y,
                            android_tool_type_0,
                            android_tool_type_1,
                            android_button_state);
 
+  // Select text and show handles if necessary.
+  if (rwhv->ShouldTriggerOrUntriggerTextSelection(event)) {
+    Java_ContentViewCore_showSelectionHandlesAutomatically(env, obj);
+    switch (event.GetAction()) {
+      case ui::MotionEvent::ACTION_DOWN:
+        web_contents_->Unselect();
+        mouse_drag_start_x_ = pos_x_0;

[jdduke (slow), 2014/06/23 15:09:59]

All of this logic should live close to where we determine the selection state
(based on the ACTION_DOWN state of the stylus).  Otherwise it makes it very
difficult to reason about event flow.  My suggestion would be to expose
|Select()| and |SelectBetweenCoordinates()| on ContentViewCoreImpl, and then we
can hook into those methods from RWHVAndroid and move this code there.  The
reason I suggested using GestureScrollBegin/Update is that there is built-in
slop with detecting scrolls, i.e., it allows you to tap/press OR scroll, but not
both, so you have a clean separation between the "SelectWord" and
"SelectBetweenCoordinates" paths.  If you use ACTION_MOVE, you could be sending
(multiple) SelectBetweenCoordinates message(s) and then a SelectWord message
when you get the long press event.

[jdduke (slow), 2014/06/23 15:24:50]

Hmm, it appears |GetWebContents()| is a proper public method on ContentViewCore,
so we could probably just use it directly in RWHVAndroid instead of adding
delegating methods.

[Changwan Ryu, 2014/06/24 09:29:48]

Done

+        mouse_drag_start_y_ = pos_y_0;
+        break;
+      case ui::MotionEvent::ACTION_MOVE:
+      case ui::MotionEvent::ACTION_UP:
+        if (rwhv->IsGestureTextSelectionTriggered()) {
+          SelectBetweenCoordinates(env, obj, mouse_drag_start_x_,
+                                   mouse_drag_start_y_, pos_x_0, pos_y_0);
+        }
+        break;
+      case ui::MotionEvent::ACTION_CANCEL:
+        web_contents_->Unselect();
+        break;
+      default:
+        break;
+    }
+  }
   return rwhv->OnTouchEvent(event);
 }
 
 float ContentViewCoreImpl::GetDpiScale() const {
   return dpi_scale_;
 }
 
 jboolean ContentViewCoreImpl::SendMouseMoveEvent(JNIEnv* env,
                                                  jobject obj,
                                                  jlong time_ms,
@@ skipping 687 matching lines @@
       reinterpret_cast<ui::WindowAndroid*>(window_android),
       retained_objects_set);
   return reinterpret_cast<intptr_t>(view);
 }
 
 bool RegisterContentViewCore(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace content