Linux UI: Dynamically respond to changes in the scale factor

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.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 "ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h"
 
 #include <X11/extensions/shape.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xregion.h>
@@ skipping 147 matching lines @@
       window_parent_(NULL),
       custom_window_shape_(false),
       urgency_hint_set_(false),
       has_pointer_grab_(false),
       activatable_(true),
       has_pointer_(false),
       has_window_focus_(false),
       has_pointer_focus_(false),
       modal_dialog_counter_(0),
       close_widget_factory_(this),
-      weak_factory_(this) {}
+      weak_factory_(this) {
+  display::Screen::GetScreen()->AddObserver(this);
+}
 
 DesktopWindowTreeHostX11::~DesktopWindowTreeHostX11() {
   window()->ClearProperty(kHostForRootWindow);
   wm::SetWindowMoveClient(window(), NULL);
   desktop_native_widget_aura_->OnDesktopWindowTreeHostDestroyed(this);
   DestroyDispatcher();
+  display::Screen::GetScreen()->RemoveObserver(this);
 }
 
 // static
 aura::Window* DesktopWindowTreeHostX11::GetContentWindowForXID(XID xid) {
   aura::WindowTreeHost* host =
       aura::WindowTreeHost::GetForAcceleratedWidget(xid);
   return host ? host->window()->GetProperty(kViewsWindowForRootWindow) : NULL;
 }
 
 // static
@@ skipping 1098 matching lines @@
                bounds_in_pixels_.x() + location_in_pixels.x(),
                bounds_in_pixels_.y() + location_in_pixels.y());
 }
 
 void DesktopWindowTreeHostX11::OnCursorVisibilityChangedNative(bool show) {
   // TODO(erg): Conditional on us enabling touch on desktop linux builds, do
   // the same tap-to-click disabling here that chromeos does.
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// DesktopWindowTreeHostX11, display::DisplayObserver implementation:
+
+void DesktopWindowTreeHostX11::OnDisplayAdded(
+    const display::Display& new_display) {}
+
+void DesktopWindowTreeHostX11::OnDisplayRemoved(
+    const display::Display& old_display) {}
+
+void DesktopWindowTreeHostX11::OnDisplayMetricsChanged(
+    const display::Display& display,
+    uint32_t changed_metrics) {
+  if ((changed_metrics & DISPLAY_METRIC_DEVICE_SCALE_FACTOR) &&
+      display::Screen::GetScreen()->GetDisplayNearestWindow(window()).id() ==
+          display.id()) {
+    // When the scale factor changes, also pretend that a resize
+    // occured so that the window layout will be refreshed and a
+    // compositor redraw will be scheduled.  This is weird, but works.
+    // TODO(thomasanderson): Figure out a more direct way of doing
+    // this.
+    RestartDelayedResizeTask();
+  }
+}
+
+////////////////////////////////////////////////////////////////////////////////
 // DesktopWindowTreeHostX11, private:
 
 void DesktopWindowTreeHostX11::InitX11Window(
     const Widget::InitParams& params) {
   unsigned long attribute_mask = CWBackPixmap | CWBitGravity;
   XSetWindowAttributes swa;
   memset(&swa, 0, sizeof(swa));
   swa.background_pixmap = None;
   swa.bit_gravity = NorthWestGravity;
 
@@ skipping 686 matching lines @@
                                  xev->xconfigure.width, xev->xconfigure.height);
       bool size_changed = bounds_in_pixels_.size() != bounds_in_pixels.size();
       bool origin_changed =
           bounds_in_pixels_.origin() != bounds_in_pixels.origin();
       previous_bounds_in_pixels_ = bounds_in_pixels_;
       bounds_in_pixels_ = bounds_in_pixels;
 
       if (origin_changed)
         OnHostMovedInPixels(bounds_in_pixels_.origin());
 
-      if (size_changed) {
-        delayed_resize_task_.Reset(base::Bind(
-            &DesktopWindowTreeHostX11::DelayedResize,
-            close_widget_factory_.GetWeakPtr(), bounds_in_pixels.size()));
-        base::ThreadTaskRunnerHandle::Get()->PostTask(
-            FROM_HERE, delayed_resize_task_.callback());
-      }
+      if (size_changed)
+        RestartDelayedResizeTask();
       break;
     }
     case GenericEvent: {
       ui::TouchFactory* factory = ui::TouchFactory::GetInstance();
       if (!factory->ShouldProcessXI2Event(xev))
         break;
 
       XIEnterEvent* enter_event = static_cast<XIEnterEvent*>(xev->xcookie.data);
       switch (static_cast<XIEvent*>(xev->xcookie.data)->evtype) {
         case XI_Enter:
@@ skipping 252 matching lines @@
       &DesktopWindowTreeHostX11::EnableEventListening,
       weak_factory_.GetWeakPtr()));
 }
 
 void DesktopWindowTreeHostX11::EnableEventListening() {
   DCHECK_GT(modal_dialog_counter_, 0UL);
   if (!--modal_dialog_counter_)
     targeter_for_modal_.reset();
 }
 
+void DesktopWindowTreeHostX11::RestartDelayedResizeTask() {
+  delayed_resize_task_.Reset(
+      base::Bind(&DesktopWindowTreeHostX11::DelayedResize,
+                 close_widget_factory_.GetWeakPtr(), bounds_in_pixels_.size()));
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, delayed_resize_task_.callback());
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopWindowTreeHost, public:
 
 // static
 DesktopWindowTreeHost* DesktopWindowTreeHost::Create(
     internal::NativeWidgetDelegate* native_widget_delegate,
     DesktopNativeWidgetAura* desktop_native_widget_aura) {
   return new DesktopWindowTreeHostX11(native_widget_delegate,
                                       desktop_native_widget_aura);
 }
 
 }  // namespace views