views: support vertical-drag-to-end on textfields

ui/views/controls/textfield/textfield_unittest.cc

Index: ui/views/controls/textfield/textfield_unittest.cc
diff --git a/ui/views/controls/textfield/textfield_unittest.cc b/ui/views/controls/textfield/textfield_unittest.cc
index 97595c57cb4e5b61a1c8569801d43f7724a0607d..6a7a292592487d00aabcfaa5ee296ed7605fc240 100644
--- a/ui/views/controls/textfield/textfield_unittest.cc
+++ b/ui/views/controls/textfield/textfield_unittest.cc
@@ -39,6 +39,7 @@
 #include "ui/views/controls/textfield/textfield_model.h"
 #include "ui/views/controls/textfield/textfield_test_api.h"
 #include "ui/views/focus/focus_manager.h"
+#include "ui/views/style/platform_style.h"
 #include "ui/views/test/test_views_delegate.h"
 #include "ui/views/test/views_test_base.h"
 #include "ui/views/test/widget_test.h"
@@ -1195,6 +1196,43 @@ TEST_F(TextfieldTest, DragToSelect) {
   EXPECT_EQ(textfield_->text(), textfield_->GetSelectedText());
 }
 
+TEST_F(TextfieldTest, DragUpOrDownSelectsToEnd) {

[tapted, 2016/04/08 08:53:28]

nit: although the other tests are missing one,... it's usually good to have a
comment explaining the purpose of a test just above 

[Elly Fong-Jones, 2016/04/08 16:46:47]

Done.

+  if (!PlatformStyle::kTextfieldDragVerticallyDragsToEnd)

[tapted, 2016/04/08 08:53:28]

Can we verify the behaviour when this is false as well? (i.e. to verify that
it's *not* selecting more text ?)

[Elly Fong-Jones, 2016/04/08 16:46:48]

Yes. I changed the test to test the correct behavior either way, and tested it
both ways on Mac.

+    return;
+  InitTextfield();
+  textfield_->SetText(ASCIIToUTF16("hello world"));
+  const int kStartX = GetCursorPositionX(5);
+  gfx::Point start_point(kStartX, 0);
+  gfx::Point down_point(kStartX, 500);
+  gfx::Point up_point(kStartX, -500);
+  ui::MouseEvent click_start(ui::ET_MOUSE_PRESSED, start_point, start_point,

[tapted, 2016/04/08 08:53:28]

Can these be simplified with a ui::EventGenerator? 

E.g. they have DragMouseTo(dx, dy) methods to encapsulate a lot of this

I meant to toy with this today, but I ran out of time. I think it will make this
test a lot more readable.

(the other tests in this file should probably use it too, but EventGenerator
came after them)

[Elly Fong-Jones, 2016/04/08 16:46:48]

I spent a bit of time trying to use EventGenerator, and I can't figure out how
to use it, or debug why it's not working. The docs for the constructor say:

  // Creates an EventGenerator with the mouse/touch location centered over
  // |window|. This is currently the only constructor that works on Mac, since
  // a specific window is required (and there is no root window).
  EventGenerator(gfx::NativeWindow root_window, gfx::NativeWindow window);

But I think that since this is a Views build, there is no native window for the
actual textfield control. I tried mirroring the pattern of other uses of
EventGenerator in the views controls unit tests, but they seem to do this:

  EventGenerator(GetContext(), widget_->GetNativeWindow())

I tried doing this, and no events are delivered to my widget, no matter whether
I use screen coordinates or widget-local coordinates for the events. I looked at
the EventGenerator code but it is very complex and I found it pretty much
impossible to debug why my events were not being delivered. Further
investigation revealed that GetContext() returns NULL on non-Aura builds, so
that seems like it should be broken, but it works in other places, so I'm a bit
baffled by that.

Anyway, I guess the short version of how I feel is that if I can't figure out
how to use EventGenerator or why it isn't working, it's likely that future
people who have to maintain this code won't be able to figure it out either, so
I shouldn't use it here. The current code is kind of verbose, but it calls event
handlers directly on the widget and the code is very easy to follow. If you feel
strongly that I should use EventGenerator, I can spend more time trying to
understand it, but otherwise I'd prefer to leave this as it is.

+                             ui::EventTimeForNow(), ui::EF_LEFT_MOUSE_BUTTON,
+                             ui::EF_LEFT_MOUSE_BUTTON);
+  ui::MouseEvent click_down(ui::ET_MOUSE_PRESSED, down_point, down_point,
+                            ui::EventTimeForNow(), ui::EF_LEFT_MOUSE_BUTTON,
+                            ui::EF_LEFT_MOUSE_BUTTON);
+  ui::MouseEvent drag_up(ui::ET_MOUSE_DRAGGED, up_point, up_point,
+                           ui::EventTimeForNow(), ui::EF_LEFT_MOUSE_BUTTON, 0);
+  ui::MouseEvent drag_down(ui::ET_MOUSE_DRAGGED, down_point, down_point,
+                           ui::EventTimeForNow(), ui::EF_LEFT_MOUSE_BUTTON, 0);
+  ui::MouseEvent release_up(ui::ET_MOUSE_RELEASED, up_point, up_point,
+                           ui::EventTimeForNow(), ui::EF_LEFT_MOUSE_BUTTON,
+                           ui::EF_LEFT_MOUSE_BUTTON);
+  ui::MouseEvent release_down(ui::ET_MOUSE_RELEASED, down_point, down_point,
+                              ui::EventTimeForNow(), ui::EF_LEFT_MOUSE_BUTTON,
+                              ui::EF_LEFT_MOUSE_BUTTON);
+
+  textfield_->OnMousePressed(click_start);
+  textfield_->OnMouseDragged(drag_up);
+  textfield_->OnMouseReleased(release_up);
+  EXPECT_EQ(textfield_->GetSelectedText(), base::ASCIIToUTF16("hello"));
+
+  textfield_->OnMousePressed(click_start);
+  textfield_->OnMouseDragged(drag_down);
+  textfield_->OnMouseReleased(release_down);
+  EXPECT_EQ(textfield_->GetSelectedText(), base::ASCIIToUTF16(" world"));
+}
+
 #if defined(OS_WIN)
 TEST_F(TextfieldTest, DragAndDrop_AcceptDrop) {
   InitTextfield();