Windows implementation of multiline RenderText

Multi-line text rendering in the Chromium UI is currently done by slicing the string into multiple lines by using text metrics from cross-platform libraries and rendering text by using different RenderText instances - one for each line. This approach has poor performance and is very bug-prone.

This CL adds a cross-platform interface and data structures to RenderText to support multi-line text rendering. This CL also implements the required platform-specific bits for Windows. Support for other platforms will be implemented in subsequent CLs.

Multi-line rendering as implemented in this CL is limited. Newline characters are ignored. RTL and complex scripts are supported, while there are be issues with selection highlights. Text-space <-> view-space mappings do not support RTL/complex scripts.

BUG=248597

Review URL: https://chromiumcodereview.appspot.com/16867016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@223394 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 10 insertions, 2 deletions

diff --git a/ui/views/examples/multiline_example.h b/ui/views/examples/multiline_example.h
index bc5d8c8..2757c4a 100644
--- a/ui/views/examples/multiline_example.h
+++ b/ui/views/examples/multiline_example.h
@@ -7,6 +7,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/strings/string16.h"
+#include "ui/views/controls/button/checkbox.h"
 #include "ui/views/controls/textfield/textfield_controller.h"
 #include "ui/views/examples/example_base.h"
 
@@ -16,9 +17,10 @@ class Label;
 
 namespace examples {
 
-// An example that compares the multi-line rendering of different controls.
+// An example that compares the multiline rendering of different controls.
 class MultilineExample : public ExampleBase,
-                         public TextfieldController {
+                         public TextfieldController,
+                         public ButtonListener {
  public:
   MultilineExample();
   virtual ~MultilineExample();
@@ -26,6 +28,9 @@ class MultilineExample : public ExampleBase,
   // ExampleBase:
   virtual void CreateExampleView(View* container) OVERRIDE;
 
+  // ButtonListener:
+  virtual void ButtonPressed(Button* sender, const ui::Event& event) OVERRIDE;
+
  private:
   class RenderTextView;
 
@@ -39,6 +44,9 @@ class MultilineExample : public ExampleBase,
   Label* label_;
   Textfield* textfield_;
 
+  // Checkbox to enable and disable text rendering in |label_|.
+  Checkbox* label_checkbox_;
+
   DISALLOW_COPY_AND_ASSIGN(MultilineExample);
 };