Reuse submenu arrow images for trees (like the edit bookmark tree).

ui/views/controls/tree/tree_view.cc

Index: ui/views/controls/tree/tree_view.cc
diff --git a/ui/views/controls/tree/tree_view.cc b/ui/views/controls/tree/tree_view.cc
index cb252dd9e97002779d228f3dd74c75ebf6a3e9d9..7e964f96c66ea799acd3547c60ee57475be07fbd 100644
--- a/ui/views/controls/tree/tree_view.cc
+++ b/ui/views/controls/tree/tree_view.cc
@@ -16,9 +16,12 @@
 #include "ui/events/event.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 #include "ui/gfx/canvas.h"
+#include "ui/gfx/color_utils.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/image/image.h"
+#include "ui/gfx/image/image_skia_operations.h"
+#include "ui/gfx/paint_vector_icon.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/native_theme/native_theme.h"
 #include "ui/resources/grit/ui_resources.h"
@@ -29,6 +32,7 @@
 #include "ui/views/controls/tree/tree_view_controller.h"
 #include "ui/views/resources/grit/views_resources.h"
 #include "ui/views/style/platform_style.h"
+#include "ui/views/vector_icons.h"
 
 using ui::TreeModel;
 using ui::TreeModelNode;
@@ -823,31 +827,22 @@ void TreeView::PaintRow(gfx::Canvas* canvas,
 void TreeView::PaintExpandControl(gfx::Canvas* canvas,
                                   const gfx::Rect& node_bounds,
                                   bool expanded) {
-  int center_x;
-  if (base::i18n::IsRTL()) {
-    center_x = node_bounds.right() - kArrowRegionSize +
-               (kArrowRegionSize - 4) / 2;
-  } else {
-    center_x = node_bounds.x() + (kArrowRegionSize - 4) / 2;
-  }
-  int center_y = node_bounds.y() + node_bounds.height() / 2;
-  const SkColor arrow_color = GetNativeTheme()->GetSystemColor(
-      ui::NativeTheme::kColorId_TreeArrow);
-  // TODO: this should come from an image.
-  if (!expanded) {
-    int delta = base::i18n::IsRTL() ? 1 : -1;
-    for (int i = 0; i < 4; ++i) {
-      canvas->FillRect(gfx::Rect(center_x + delta * (2 - i),
-                                 center_y - (3 - i), 1, (3 - i) * 2 + 1),
-                       arrow_color);
-    }
-  } else {
-    center_y -= 2;
-    for (int i = 0; i < 4; ++i) {
-      canvas->FillRect(gfx::Rect(center_x - (3 - i), center_y + i,
-                                 (3 - i) * 2 + 1, 1), arrow_color);
-    }
+  gfx::ImageSkia arrow = gfx::CreateVectorIcon(
+      kSubmenuArrowIcon,
+      color_utils::DeriveDefaultIconColor(
+          GetNativeTheme()->GetSystemColor(text_color_id(false, false))));

[Peter Kasting, 2017/02/15 01:05:31]

Any particular reason to move away from kColorId_TreeArrow?  If this is
equivalent or better, I'm fine with it, but in that case, this was the only user
of that color, so we should rip it out entirely.

If we keep this derivation, should we be matching the conditions on line 816
above here?

[Evan Stade, 2017/02/15 01:28:58]

Ah, forgot about that color. I think we should remove it. The derived version is
better because it will be more consistent with other ui (it will come out to
5a5a5a instead of 7a7a7a).
the selection highlight doesn't extend to the arrow, so I don't think we should
be changing its color ever. I'm ambivalent about using text_color_id() vs just
kColorId_TreeText

[Evan Stade, 2017/02/15 16:07:37]

done

+  if (expanded) {
+    arrow = gfx::ImageSkiaOperations::CreateRotatedImage(
+        arrow, base::i18n::IsRTL() ? SkBitmapOperations::ROTATION_270_CW
+                                   : SkBitmapOperations::ROTATION_90_CW);
   }
+  gfx::Rect arrow_bounds = node_bounds;
+  arrow_bounds.Inset(gfx::Insets((node_bounds.height() - arrow.height()) / 2,
+                                 (kArrowRegionSize - arrow.width()) / 2));
+  canvas->DrawImageInt(arrow, base::i18n::IsRTL()
+                                  ? arrow_bounds.right() - arrow.width()
+                                  : arrow_bounds.x(),
+                       arrow_bounds.y());

[Peter Kasting, 2017/02/15 01:05:31]

Nit: I think this is equivalent, and seems shorter and more readable:

  gfx::Rect arrow_bounds(kArrowRegionSize, node_bounds.height());
  arrow_bounds.ClampToCenteredSize(arrow.size());
  canvas->DrawImageInt(arrow, node_bounds.GetMirroredXForRect(arrow_bounds),
                       node_bounds.y() + arrow_bounds.y());

[Evan Stade, 2017/02/15 01:28:58]

the arrow square isn't centered in the node bounds.

[Peter Kasting, 2017/02/15 02:05:28]

I know.  The code I wrote won't center it in the node bounds.  It will center it
vertically within the node height, and horizontally within a
kArrowRegionSize-width space pinned to the leading edge of the control (mirrored
for RTL).

 }
 
 TreeView::InternalNode* TreeView::GetInternalNodeForModelNode(