Fix tab dragging in unity2d

Unity 2d creates non-rectangled or 'shaped' X11 windows. These windows have a
big bounding box according to XGetGeometry but should actually only interact
with part of the screen, which confuses the tab strip dragging code. This
checks if a point is actually inside the ShapeInput list when this extension
is supported by the X display

BUG=114985


Review URL: https://chromiumcodereview.appspot.com/10990010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@159111 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 52 insertions, 7 deletions

diff --git a/ui/base/x/x11_util.cc b/ui/base/x/x11_util.cc
index 8a1d5e6..4cc5dc3 100644
--- a/ui/base/x/x11_util.cc
+++ b/ui/base/x/x11_util.cc
@@ -19,6 +19,7 @@
 
 #include <X11/extensions/Xrandr.h>
 #include <X11/extensions/randr.h>
+#include <X11/extensions/shape.h>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ -310,19 +311,21 @@ class XButtonMap {
 };
 
 bool IsRandRAvailable() {
-  static bool is_randr_available = false;
-  static bool is_randr_availability_cached = false;
-  if (is_randr_availability_cached)
-    return is_randr_available;
-
   int randr_version_major = 0;
   int randr_version_minor = 0;
-  is_randr_available = XRRQueryVersion(
+  static bool is_randr_available = XRRQueryVersion(
       GetXDisplay(), &randr_version_major, &randr_version_minor);
-  is_randr_availability_cached = true;
   return is_randr_available;
 }
 
+bool IsShapeAvailable() {
+  int dummy;
+  static bool is_shape_available =
+    XShapeQueryExtension(ui::GetXDisplay(), &dummy, &dummy);
+  return is_shape_available;
+
+}
+
 }  // namespace
 
 bool XDisplayExists() {
@@ -612,6 +615,45 @@ bool GetWindowRect(XID window, gfx::Rect* rect) {
   return true;
 }
 
+
+bool WindowContainsPoint(XID window, gfx::Point screen_loc) {
+  gfx::Rect window_rect;
+  if (!GetWindowRect(window, &window_rect))
+    return false;
+
+  if (!window_rect.Contains(screen_loc))
+    return false;
+
+  if (!IsShapeAvailable())
+    return true;
+
+  // According to http://www.x.org/releases/X11R7.6/doc/libXext/shapelib.html,
+  // if an X display supports the shape extension the bounds of a window are
+  // defined as the intersection of the window bounds and the interior
+  // rectangles. This means to determine if a point is inside a window for the
+  // purpose of input handling we have to check the rectangles in the ShapeInput
+  // list.
+  int dummy;
+  int input_rects_size = 0;
+  XRectangle* input_rects = XShapeGetRectangles(
+      ui::GetXDisplay(), window, ShapeInput, &input_rects_size, &dummy);
+  if (!input_rects)
+    return true;
+  bool is_in_input_rects = false;
+  for (int i = 0; i < input_rects_size; ++i) {
+    gfx::Rect input_rect =
+        gfx::Rect(input_rects[i].x, input_rects[i].y,
+                  input_rects[i].width, input_rects[i].height);
+    if (input_rect.Contains(screen_loc)) {
+      is_in_input_rects = true;
+      break;
+    }
+  }
+  XFree(input_rects);
+  return is_in_input_rects;
+}
+
+
 bool PropertyExists(XID window, const std::string& property_name) {
   Atom type = None;
   int format = 0;  // size in bits of each item in 'property'
diff --git a/ui/base/x/x11_util.h b/ui/base/x/x11_util.h
index 053008f..b1a6e4d 100644
--- a/ui/base/x/x11_util.h
+++ b/ui/base/x/x11_util.h
@@ -145,6 +145,9 @@ UI_EXPORT bool IsWindowVisible(XID window);
 // Returns the bounds of |window|.
 UI_EXPORT bool GetWindowRect(XID window, gfx::Rect* rect);
 
+// Returns true if |window| contains the point |screen_loc|.
+UI_EXPORT bool WindowContainsPoint(XID window, gfx::Point screen_loc);
+
 // Return true if |window| has any property with |property_name|.
 UI_EXPORT bool PropertyExists(XID window, const std::string& property_name);