WIP - Gutterless resize on Windows

content/browser/renderer_host/render_widget_host_impl.cc

 // Copyright (c) 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/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 #include <set>
 #include <utility>
 
@@ skipping 60 matching lines @@
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/geometry/vector2d_conversions.h"
 #include "ui/gfx/skbitmap_operations.h"
 #include "ui/snapshot/snapshot.h"
 
 #if defined(OS_WIN)
 #include "content/common/plugin_constants_win.h"
 #endif
 
 #if defined(OS_MACOSX)
-#include "ui/accelerated_widget_mac/window_resize_helper_mac.h"
+#include "ui/base/window_resize_helper.h"

[ericrk, 2015/12/10 23:08:43]

The logic here doesn't seem to be necessary on Windows. Still trying to figure
out why the render_widget_host_impl as well as the actual bridged_native_widget
need to both have 50ms waits on mac. On windows these both cancel eachother out
(waiting in one place removes the need to wait in the other) - however, putting
the wait here introduced significant stuttering on windows.

[piman, 2015/12/11 07:53:12]

Well, if you want the UI *and* the renderer to stick to the edge, after a resize
you need to:
- resize the UI elements, including the container for the renderer (which will
send the resize to the renderer)
- wait for a frame from the renderer at the new size (WaitForSurface here)
- draw a UI frame with that renderer frame
- wait for the swap (the one in bridged_native_widget)

all of these without new resizes being serviced (i.e. blocking the message
loop).


The code here is to handle the renderer parts, on Mac, which is a little
different than Aura - the ui::Compositor only renders the renderer parts, not
the whole UI, and is resized by the renderer's frame, instead of the UI.
The 2 timeouts are meant to be nested within each other, so it could be why it
appears that they're redundant (but they may not be in all cases, e.g.
considering a slow renderer vs a slow GPU).

For Aura, the renderer parts would need to interact with the resize_lock logic
in DelegatedFrameHost/RenderWidgetHostViewAura (which was originally created for
Chrome OS, by throttling resizes rather than blocking the thread, because we
could. This code was disabled on linux/windows - see
RenderWidgetHostViewAura::DelegatedFrameCanCreateResizeLock).

[ericrk, 2015/12/15 00:25:03]

Thanks - I think it's best to save this for a follow-up? We can discuss when
you're back.

 #endif
 
 using base::Time;
 using base::TimeDelta;
 using base::TimeTicks;
 using blink::WebGestureEvent;
 using blink::WebInputEvent;
 using blink::WebKeyboardEvent;
 using blink::WebMouseEvent;
 using blink::WebMouseWheelEvent;
@@ skipping 801 matching lines @@
     Send(new ViewMsg_Repaint(routing_id_, view_size));
   }
 
   // Pump a nested message loop until we time out or get a frame of the right
   // size.
   TimeTicks start_time = TimeTicks::Now();
   TimeDelta time_left = TimeDelta::FromMilliseconds(kPaintMsgTimeoutMS);
   TimeTicks timeout_time = start_time + time_left;
   while (1) {
     TRACE_EVENT0("renderer_host", "WaitForSurface::WaitForSingleTaskToRun");
-    if (ui::WindowResizeHelperMac::Get()->WaitForSingleTaskToRun(time_left)) {
+    if (ui::WindowResizeHelper::Get()->WaitForSingleTaskToRun(time_left)) {
       // For auto-resized views, current_size_ determines the view_size and it
       // may have changed during the handling of an UpdateRect message.
       if (auto_resize_enabled_)
         view_size = current_size_;
       if (view_->HasAcceleratedSurface(view_size))
         break;
     }
     time_left = timeout_time - TimeTicks::Now();
     if (time_left <= TimeDelta::FromSeconds(0)) {
       TRACE_EVENT0("renderer_host", "WaitForSurface::Timeout");
@@ skipping 1327 matching lines @@
 }
 
 #if defined(OS_WIN)
 gfx::NativeViewAccessible
     RenderWidgetHostImpl::GetParentNativeViewAccessible() {
   return delegate_ ? delegate_->GetParentNativeViewAccessible() : NULL;
 }
 #endif
 
 }  // namespace content