GTK: Try to position info bubbles onscreen.

chrome/browser/gtk/info_bubble_gtk.cc

Index: chrome/browser/gtk/info_bubble_gtk.cc
diff --git a/chrome/browser/gtk/info_bubble_gtk.cc b/chrome/browser/gtk/info_bubble_gtk.cc
index 1072fb2c772610613646d9fc34cf6e39abc6eebf..68fbc2d3470b9ee904f7fa46bf7ce5c9bd4bffea 100644
--- a/chrome/browser/gtk/info_bubble_gtk.cc
+++ b/chrome/browser/gtk/info_bubble_gtk.cc
@@ -21,13 +21,17 @@ namespace {
 
 // The height of the arrow, and the width will be about twice the height.
 const int kArrowSize = 5;
+
 // Number of pixels to the start of the arrow from the edge of the window.
 const int kArrowX = 13;
+
 // Number of pixels between the tip of the arrow and the region we're
 // pointing to.
 const int kArrowToContentPadding = -6;
+
 // We draw flat diagonal corners, each corner is an NxN square.
 const int kCornerSize = 3;
+
 // Margins around the content.
 const int kTopMargin = kArrowSize + kCornerSize + 6;
 const int kBottomMargin = kCornerSize + 6;
@@ -37,87 +41,6 @@ const int kRightMargin = kCornerSize + 6;
 const GdkColor kBackgroundColor = GDK_COLOR_RGB(0xff, 0xff, 0xff);
 const GdkColor kFrameColor = GDK_COLOR_RGB(0x63, 0x63, 0x63);
 
-enum FrameType {
-  FRAME_MASK,
-  FRAME_STROKE,
-};
-
-// Make the points for our polygon frame, either for fill (the mask), or for
-// when we stroke the border.  NOTE: This seems a bit overcomplicated, but it
-// requires a bunch of careful fudging to get the pixels rasterized exactly
-// where we want them, the arrow to have a 1 pixel point, etc.
-// TODO(deanm): Windows draws with Skia and uses some PNG images for the
-// corners.  This is a lot more work, but they get anti-aliasing.
-std::vector<GdkPoint> MakeFramePolygonPoints(int width,
-                                             int height,
-                                             FrameType type) {
-  using gtk_util::MakeBidiGdkPoint;
-  std::vector<GdkPoint> points;
-
-  bool ltr = l10n_util::GetTextDirection() == l10n_util::LEFT_TO_RIGHT;
-  // If we have a stroke, we have to offset some of our points by 1 pixel.
-  // We have to inset by 1 pixel when we draw horizontal lines that are on the
-  // bottom or when we draw vertical lines that are closer to the end (end is
-  // right for ltr).
-  int y_off = (type == FRAME_MASK) ? 0 : -1;
-  // We use this one for LTR.
-  int x_off_l = ltr ? y_off : 0;
-  // We use this one for RTL.
-  int x_off_r = !ltr ? -y_off : 0;
-
-  // Top left corner.
-  points.push_back(MakeBidiGdkPoint(
-      x_off_r, kArrowSize + kCornerSize - 1, width, ltr));
-  points.push_back(MakeBidiGdkPoint(
-      kCornerSize + x_off_r - 1, kArrowSize, width, ltr));
-
-  // The arrow.
-  points.push_back(MakeBidiGdkPoint(
-      kArrowX - kArrowSize + x_off_r, kArrowSize, width, ltr));
-  points.push_back(MakeBidiGdkPoint(
-      kArrowX + x_off_r, 0, width, ltr));
-  points.push_back(MakeBidiGdkPoint(
-      kArrowX + 1 + x_off_l, 0, width, ltr));
-  points.push_back(MakeBidiGdkPoint(
-      kArrowX + kArrowSize + 1 + x_off_l, kArrowSize, width, ltr));
-
-  // Top right corner.
-  points.push_back(MakeBidiGdkPoint(
-      width - kCornerSize + 1 + x_off_l, kArrowSize, width, ltr));
-  points.push_back(MakeBidiGdkPoint(
-      width + x_off_l, kArrowSize + kCornerSize - 1, width, ltr));
-
-  // Bottom right corner.
-  points.push_back(MakeBidiGdkPoint(
-      width + x_off_l, height - kCornerSize, width, ltr));
-  points.push_back(MakeBidiGdkPoint(
-      width - kCornerSize + x_off_r, height + y_off, width, ltr));
-
-  // Bottom left corner.
-  points.push_back(MakeBidiGdkPoint(
-      kCornerSize + x_off_l, height + y_off, width, ltr));
-  points.push_back(MakeBidiGdkPoint(
-      x_off_r, height - kCornerSize, width, ltr));
-
-  return points;
-}
-
-gboolean HandleExpose(GtkWidget* widget,
-                      GdkEventExpose* event,
-                      gpointer unused) {
-  GdkDrawable* drawable = GDK_DRAWABLE(event->window);
-  GdkGC* gc = gdk_gc_new(drawable);
-  gdk_gc_set_rgb_fg_color(gc, &kFrameColor);
-
-  // Stroke the frame border.
-  std::vector<GdkPoint> points = MakeFramePolygonPoints(
-      widget->allocation.width, widget->allocation.height, FRAME_STROKE);
-  gdk_draw_polygon(drawable, gc, FALSE, &points[0], points.size());
-
-  g_object_unref(gc);
-  return FALSE;  // Propagate so our children paint, etc.
-}
-
 }  // namespace
 
 // static
@@ -138,7 +61,8 @@ InfoBubbleGtk::InfoBubbleGtk(GtkThemeProvider* provider)
       theme_provider_(provider),
       accel_group_(gtk_accel_group_new()),
       toplevel_window_(NULL),
-      mask_region_(NULL) {
+      mask_region_(NULL),
+      arrow_location_(ARROW_LOCATION_TOP_LEFT) {
 }
 
 InfoBubbleGtk::~InfoBubbleGtk() {
@@ -168,8 +92,6 @@ void InfoBubbleGtk::Init(GtkWindow* toplevel_window,
 
   window_ = gtk_window_new(GTK_WINDOW_POPUP);
   gtk_widget_set_app_paintable(window_, TRUE);
-  // Have GTK double buffer around the expose signal.
-  gtk_widget_set_double_buffered(window_, TRUE);
 
   // Attach our accelerator group to the window with an escape accelerator.
   gtk_accel_group_connect(accel_group_, GDK_Escape,
@@ -202,7 +124,7 @@ void InfoBubbleGtk::Init(GtkWindow* toplevel_window,
                                  GDK_BUTTON_RELEASE_MASK);
 
   g_signal_connect(window_, "expose-event",
-                   G_CALLBACK(HandleExpose), NULL);
+                   G_CALLBACK(HandleExposeThunk), this);
   g_signal_connect(window_, "size-allocate",
                    G_CALLBACK(HandleSizeAllocateThunk), this);
   g_signal_connect(window_, "button-press-event",
@@ -240,17 +162,135 @@ void InfoBubbleGtk::Init(GtkWindow* toplevel_window,
   theme_provider_->InitThemesFor(this);
 }
 
+// NOTE: This seems a bit overcomplicated, but it requires a bunch of careful
+// fudging to get the pixels rasterized exactly where we want them, the arrow to
+// have a 1 pixel point, etc.
+// TODO(deanm): Windows draws with Skia and uses some PNG images for the
+// corners.  This is a lot more work, but they get anti-aliasing.
+// static
+std::vector<GdkPoint> InfoBubbleGtk::MakeFramePolygonPoints(
+    ArrowLocationGtk arrow_location,
+    int width,
+    int height,
+    FrameType type) {
+  using gtk_util::MakeBidiGdkPoint;
+  std::vector<GdkPoint> points;
+
+  // This name isn't completely accurate; the arrow location can differ from its
+  // expected location for LTR/RTL if needed for the bubble to fit onscreen.
+  bool ltr = (arrow_location == ARROW_LOCATION_TOP_LEFT);
+
+  // If we have a stroke, we have to offset some of our points by 1 pixel.
+  // We have to inset by 1 pixel when we draw horizontal lines that are on the
+  // bottom or when we draw vertical lines that are closer to the end (end is
+  // right for ltr).
+  int y_off = (type == FRAME_MASK) ? 0 : -1;
+  // We use this one for LTR.
+  int x_off_l = ltr ? y_off : 0;
+  // We use this one for RTL.
+  int x_off_r = !ltr ? -y_off : 0;
+
+  // Top left corner.
+  points.push_back(MakeBidiGdkPoint(
+      x_off_r, kArrowSize + kCornerSize - 1, width, ltr));
+  points.push_back(MakeBidiGdkPoint(
+      kCornerSize + x_off_r - 1, kArrowSize, width, ltr));
+
+  // The arrow.
+  points.push_back(MakeBidiGdkPoint(
+      kArrowX - kArrowSize + x_off_r, kArrowSize, width, ltr));
+  points.push_back(MakeBidiGdkPoint(
+      kArrowX + x_off_r, 0, width, ltr));
+  points.push_back(MakeBidiGdkPoint(
+      kArrowX + 1 + x_off_l, 0, width, ltr));
+  points.push_back(MakeBidiGdkPoint(
+      kArrowX + kArrowSize + 1 + x_off_l, kArrowSize, width, ltr));
+
+  // Top right corner.
+  points.push_back(MakeBidiGdkPoint(
+      width - kCornerSize + 1 + x_off_l, kArrowSize, width, ltr));
+  points.push_back(MakeBidiGdkPoint(
+      width + x_off_l, kArrowSize + kCornerSize - 1, width, ltr));
+
+  // Bottom right corner.
+  points.push_back(MakeBidiGdkPoint(
+      width + x_off_l, height - kCornerSize, width, ltr));
+  points.push_back(MakeBidiGdkPoint(
+      width - kCornerSize + x_off_r, height + y_off, width, ltr));
+
+  // Bottom left corner.
+  points.push_back(MakeBidiGdkPoint(
+      kCornerSize + x_off_l, height + y_off, width, ltr));
+  points.push_back(MakeBidiGdkPoint(
+      x_off_r, height - kCornerSize, width, ltr));
+
+  return points;
+}
+
+InfoBubbleGtk::ArrowLocationGtk InfoBubbleGtk::GetArrowLocation(
+    int arrow_x, int width) {
+  bool ltr = (l10n_util::GetTextDirection() == l10n_util::LEFT_TO_RIGHT);
+  int screen_width = gdk_screen_get_width(gdk_screen_get_default());
+
+  bool left_is_onscreen = (arrow_x - kArrowX + width < screen_width);
+  bool right_is_onscreen = (arrow_x + kArrowX - width >= 0);
+
+  // Use the expected location for our LTR/RTL-ness if it fits onscreen, use
+  // whatever fits otherwise, and use the expected location if neither fits.
+  if (left_is_onscreen && (ltr || !right_is_onscreen))
+    return ARROW_LOCATION_TOP_LEFT;
+  if (right_is_onscreen && (!ltr || !left_is_onscreen))
+    return ARROW_LOCATION_TOP_RIGHT;
+  return (ltr ? ARROW_LOCATION_TOP_LEFT : ARROW_LOCATION_TOP_RIGHT);
+}
+
+bool InfoBubbleGtk::UpdateArrowLocation() {
+  gint toplevel_x = 0, toplevel_y = 0;
+  gdk_window_get_position(
+      GTK_WIDGET(toplevel_window_)->window, &toplevel_x, &toplevel_y);
+
+  ArrowLocationGtk old_location = arrow_location_;
+  arrow_location_ = GetArrowLocation(
+      toplevel_x + rect_.x() + (rect_.width() / 2),  // arrow_x
+      window_->allocation.width);
+
+  if (arrow_location_ != old_location) {
+    UpdateWindowShape();
+    MoveWindow();
+    // We need to redraw the entire window to repaint its border.
+    gtk_widget_queue_draw(window_);
+    return true;
+  }
+  return false;
+}
+
+void InfoBubbleGtk::UpdateWindowShape() {
+  if (mask_region_) {
+    gdk_region_destroy(mask_region_);
+    mask_region_ = NULL;
+  }
+  std::vector<GdkPoint> points = MakeFramePolygonPoints(
+      arrow_location_, window_->allocation.width, window_->allocation.height,
+      FRAME_MASK);
+  mask_region_ = gdk_region_polygon(&points[0],
+                                    points.size(),
+                                    GDK_EVEN_ODD_RULE);
+  gdk_window_shape_combine_region(window_->window, mask_region_, 0, 0);
+}
+
 void InfoBubbleGtk::MoveWindow() {
   gint toplevel_x = 0, toplevel_y = 0;
   gdk_window_get_position(
       GTK_WIDGET(toplevel_window_)->window, &toplevel_x, &toplevel_y);
 
   gint screen_x = 0;
-  if (l10n_util::GetTextDirection() == l10n_util::RIGHT_TO_LEFT) {
+  if (arrow_location_ == ARROW_LOCATION_TOP_LEFT) {
+    screen_x = toplevel_x + rect_.x() + (rect_.width() / 2) - kArrowX;
+  } else if (arrow_location_ == ARROW_LOCATION_TOP_RIGHT) {
     screen_x = toplevel_x + rect_.x() + (rect_.width() / 2) -
                window_->allocation.width + kArrowX;
   } else {
-    screen_x = toplevel_x + rect_.x() + (rect_.width() / 2) - kArrowX;
+    NOTREACHED();
   }
 
   gint screen_y = toplevel_y + rect_.y() + rect_.height() +
@@ -325,23 +365,29 @@ gboolean InfoBubbleGtk::HandleEscape() {
   return TRUE;
 }
 
+gboolean InfoBubbleGtk::HandleExpose() {
+  GdkDrawable* drawable = GDK_DRAWABLE(window_->window);
+  GdkGC* gc = gdk_gc_new(drawable);
+  gdk_gc_set_rgb_fg_color(gc, &kFrameColor);
+
+  // Stroke the frame border.
+  std::vector<GdkPoint> points = MakeFramePolygonPoints(
+      arrow_location_, window_->allocation.width, window_->allocation.height,
+      FRAME_STROKE);
+  gdk_draw_polygon(drawable, gc, FALSE, &points[0], points.size());
+
+  g_object_unref(gc);
+  return FALSE;  // Propagate so our children paint, etc.
+}
+
 // When our size is initially allocated or changed, we need to recompute
 // and apply our shape mask region.
 void InfoBubbleGtk::HandleSizeAllocate() {
-  if (l10n_util::GetTextDirection() == l10n_util::RIGHT_TO_LEFT)
-    MoveWindow();
-
-  DCHECK(window_->allocation.x == 0 && window_->allocation.y == 0);
-  if (mask_region_) {
-    gdk_region_destroy(mask_region_);
-    mask_region_ = NULL;
+  if (!UpdateArrowLocation()) {
+    UpdateWindowShape();
+    if (arrow_location_ == ARROW_LOCATION_TOP_RIGHT)
+      MoveWindow();
   }
-  std::vector<GdkPoint> points = MakeFramePolygonPoints(
-      window_->allocation.width, window_->allocation.height, FRAME_MASK);
-  mask_region_ = gdk_region_polygon(&points[0],
-                                    points.size(),
-                                    GDK_EVEN_ODD_RULE);
-  gdk_window_shape_combine_region(window_->window, mask_region_, 0, 0);
 }
 
 gboolean InfoBubbleGtk::HandleButtonPress(GdkEventButton* event) {
@@ -374,7 +420,8 @@ gboolean InfoBubbleGtk::HandleDestroy() {
 }
 
 gboolean InfoBubbleGtk::HandleToplevelConfigure(GdkEventConfigure* event) {
-  MoveWindow();
+  if (!UpdateArrowLocation())
+    MoveWindow();
   StackWindow();
   return FALSE;
 }