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

content/browser/android/content_view_core_impl.cc

Index: content/browser/android/content_view_core_impl.cc
diff --git a/content/browser/android/content_view_core_impl.cc b/content/browser/android/content_view_core_impl.cc
index 4b6a7b16b27be88a8b7fbb25baa82ef6ea940c3a..2577720b1e1b88db69edc5d6a24d6c1f70b23b17 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -58,6 +58,7 @@
 #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"
@@ -225,7 +226,9 @@ ContentViewCoreImpl::ContentViewCoreImpl(
       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.";
 
@@ -977,6 +980,29 @@ jboolean ContentViewCoreImpl::OnTouchEvent(JNIEnv* env,
                            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);
 }