Add confine bounds code for Ozone X11.

This CL implements ConfineCursorToBounds() for Ozone X11. This is only
active if --ash-constrain-pointer-to-root is passed in.

Bug: 771212
Change-Id: I605c704846a34d61a77a87518f1872355e821773
Reviewed-on: https://chromium-review.googlesource.com/731028
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: kylechar <kylechar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510957}

ui/platform_window/x11/x11_window_base.cc

@@ -44,26 +44,14 @@ X11WindowBase::X11WindowBase(PlatformWindowDelegate* delegate,
       xroot_window_(DefaultRootWindow(xdisplay_)),
       bounds_(bounds) {
   DCHECK(delegate_);
+  pointer_barriers_.fill(None);
 }
 
 X11WindowBase::~X11WindowBase() {
+  UnConfineCursor();
   Destroy();
 }
 
-void X11WindowBase::Destroy() {
-  if (xwindow_ == None)
-    return;
-
-  // Stop processing events.
-  XID xwindow = xwindow_;
-  XDisplay* xdisplay = xdisplay_;
-  xwindow_ = None;
-  delegate_->OnClosed();
-  // |this| might be deleted because of the above call.
-
-  XDestroyWindow(xdisplay, xwindow);
-}
-
 void X11WindowBase::Create() {
   DCHECK(!bounds_.size().IsEmpty());
 
@@ -243,12 +231,64 @@ void X11WindowBase::MoveCursorTo(const gfx::Point& location) {
                bounds_.x() + location.x(), bounds_.y() + location.y());
 }
 
-void X11WindowBase::ConfineCursorToBounds(const gfx::Rect& bounds) {}
+void X11WindowBase::ConfineCursorToBounds(const gfx::Rect& bounds) {
+  UnConfineCursor();
+
+  if (bounds.IsEmpty())
+    return;
+
+  gfx::Rect barrier(bounds);
+  barrier.Offset(bounds_.x(), bounds_.y());
+
+  // Top horizontal barrier.
+  pointer_barriers_[0] = XFixesCreatePointerBarrier(
+      xdisplay_, xroot_window_, barrier.x(), barrier.y(), barrier.right(),
+      barrier.y(), BarrierPositiveY, 0, XIAllDevices);
+  // Bottom horizontal barrier.
+  pointer_barriers_[1] = XFixesCreatePointerBarrier(
+      xdisplay_, xroot_window_, barrier.x(), barrier.bottom(), barrier.right(),
+      barrier.bottom(), BarrierNegativeY, 0, XIAllDevices);
+  // Left vertical barrier.
+  pointer_barriers_[2] = XFixesCreatePointerBarrier(
+      xdisplay_, xroot_window_, barrier.x(), barrier.y(), barrier.x(),
+      barrier.bottom(), BarrierPositiveX, 0, XIAllDevices);
+  // Right vertical barrier.
+  pointer_barriers_[3] = XFixesCreatePointerBarrier(
+      xdisplay_, xroot_window_, barrier.right(), barrier.y(), barrier.right(),
+      barrier.bottom(), BarrierNegativeX, 0, XIAllDevices);
+
+  has_pointer_barriers_ = true;
+}
 
 PlatformImeController* X11WindowBase::GetPlatformImeController() {
   return nullptr;
 }
 
+void X11WindowBase::Destroy() {
+  if (xwindow_ == None)
+    return;
+
+  // Stop processing events.
+  XID xwindow = xwindow_;
+  XDisplay* xdisplay = xdisplay_;
+  xwindow_ = None;
+  delegate_->OnClosed();
+  // |this| might be deleted because of the above call.
+
+  XDestroyWindow(xdisplay, xwindow);
+}
+
+void X11WindowBase::UnConfineCursor() {
+  if (!has_pointer_barriers_)
+    return;
+
+  for (XID pointer_barrier : pointer_barriers_)
+    XFixesDestroyPointerBarrier(xdisplay_, pointer_barrier);
+  pointer_barriers_.fill(None);
+
+  has_pointer_barriers_ = false;
+}
+
 bool X11WindowBase::IsEventForXWindow(const XEvent& xev) const {
   return xwindow_ != None && FindXEventTarget(xev) == xwindow_;
 }

ui/platform_window/x11/x11_window_base.h

@@ -7,6 +7,8 @@
 
 #include <stdint.h>
 
+#include <array>
+
 #include "base/callback.h"
 #include "base/macros.h"
 #include "ui/gfx/geometry/rect.h"
@@ -47,20 +49,21 @@ class X11_WINDOW_EXPORT X11WindowBase : public PlatformWindow {
   PlatformImeController* GetPlatformImeController() override;
 
  protected:
-  void Destroy();
-
   PlatformWindowDelegate* delegate() { return delegate_; }
   XDisplay* xdisplay() { return xdisplay_; }
   XID xwindow() const { return xwindow_; }
 
+  void Destroy();
+  void UnConfineCursor();
+
   // Checks if XEvent is for this XWindow.
   bool IsEventForXWindow(const XEvent& xev) const;
 
   // Processes events for this XWindow.
   void ProcessXWindowEvent(XEvent* xev);
 
  private:
-  PlatformWindowDelegate* delegate_;
+  PlatformWindowDelegate* const delegate_;
 
   XDisplay* xdisplay_;
   XID xwindow_;
@@ -72,6 +75,10 @@ class X11_WINDOW_EXPORT X11WindowBase : public PlatformWindow {
   // The bounds of |xwindow_|.
   gfx::Rect bounds_;
 
+  // Keep track of barriers to confine cursor.
+  bool has_pointer_barriers_ = false;
+  std::array<XID, 4> pointer_barriers_;
+
   bool window_mapped_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(X11WindowBase);