Move HiDPI-related Pepper interfaces to stable

ppapi/cpp/graphics_2d.h

Index: ppapi/cpp/graphics_2d.h
diff --git a/ppapi/cpp/graphics_2d.h b/ppapi/cpp/graphics_2d.h
index 0ce664163eda867c92e6ca3a428ad68261c1c38f..31d04f2bbe07993a70967597cd9b8c771c5cc7d9 100644
--- a/ppapi/cpp/graphics_2d.h
+++ b/ppapi/cpp/graphics_2d.h
@@ -260,6 +260,32 @@ class Graphics2D : public Resource {
   // for it.
   int32_t Flush(const CompletionCallback& cc);
 
+  /// Returns true if SetScale and GetScale are supported. False if not.
+  static bool SupportsScale();

[dmichael (off chromium), 2013/03/28 21:38:29]

Hmm, I don't think we usually have this kind of function in the C++ wrappers. It
also seems like it would be unnecessary...  if we're running on a version of
Chrome that doesn't support these, then the View should give us a device scale
of 1.0, and a scale-aware plugin will just work as if it's on a device with
scale 1.0.

Is there a use case for this function I'm not thinking of?

[Josh Horwich, 2013/03/29 20:54:23]

I originally was worried about cases where view did give a scale, but for
whatever reason the graphics2d scale interface wasn't available (since
technically one could implement a Pepper host that supports view1_1 but
graphics2d_1_0), so a plugin could decide to revert to "DIPs only" if it knew
that SetScale wasn't actually available.

However, this is probably overkill in practice (and they could check SetScale's
result too I suppose) so I'll remove it.

+
+  /// SetScale() sets the scale factor that will be applied when painting the
+  /// graphics context onto the output device. Typically, if rendering at device
+  /// resolution is desired, the context would be created with the width and
+  /// height scaled up by the view's GetDeviceScale and SetScale called with a
+  /// scale of 1.0 / GetDeviceScale(). For example, if the view resource passed
+  /// to DidChangeView has a rectangle of (w=200, h=100) and a device scale of
+  /// 2.0, one would call Create with a size of (w=400, h=200) and then call
+  /// SetScale with 0.5. One would then treat each pixel in the context as a
+  /// single device pixel.
+  ///
+  /// @param[in] scale The scale to apply when painting.
+  ///
+  /// @return Returns <code>true</code> on success or <code>false</code>
+  /// if the resource is invalid or the scale factor is 0 or less.
+  bool SetScale(float scale);
+
+  /// GetScale() gets the scale factor that will be applied when painting the
+  /// graphics context onto the output device.
+  ///
+  /// @return Returns the scale factor for the graphics context. If the resource
+  /// is invalid, 0.0 will be returned.
+  float GetScale();

[dmichael (off chromium), 2013/03/28 21:38:29]

It would be good to mention somewhere that the default is always 1.0

[Josh Horwich, 2013/03/29 20:54:23]

Done.

+
  private:
   Size size_;
 };