Added SetLayerTransform to PPAPI

content/renderer/pepper/pepper_plugin_instance_impl.cc

Index: content/renderer/pepper/pepper_plugin_instance_impl.cc
diff --git a/content/renderer/pepper/pepper_plugin_instance_impl.cc b/content/renderer/pepper/pepper_plugin_instance_impl.cc
index 6894654d3db4f62dc46c0b073ef27158e58e30a4..a27ed1b273a62782948e8e9bde72eb3a81779b82 100644
--- a/content/renderer/pepper/pepper_plugin_instance_impl.cc
+++ b/content/renderer/pepper/pepper_plugin_instance_impl.cc
@@ -1545,6 +1545,13 @@ bool PepperPluginInstanceImpl::LoadTextInputInterface() {
   return !!plugin_textinput_interface_;
 }
 
+void PepperPluginInstanceImpl::SetLayerTransform(gfx::Transform transform) {
+  transform_ = transform;
+  DCHECK(transform.IsScaleOrTranslation());

[bokan, 2016/04/14 21:45:01]

Any reason this can't be an arbitrary transform? This API could be used outside
of the PDF pinch zoom case.

[piman, 2016/04/14 23:11:35]

Actually, because it's used for the UVs, it can only be a 2D axis-aligned
transform (this is even too loose).

But, any reason to go from 2D scale+origin+translate to gfx::Transform, back to
(essentially) 2D scale+origin+translate?

It seems simpler to just pass those? Actually equivalently, just a 2D scale +
translate (the origin can be backed into the translate) can represent the range
of transforms.

[alessandroa, 2016/04/21 15:39:22]

Acknowledged.

+
+  UpdateLayerTransform();
+}
+
 void PepperPluginInstanceImpl::UpdateLayerTransform() {
   if (!bound_graphics_2d_platform_ || !texture_layer_) {
     // Currently the transform is only applied for Graphics2D.
@@ -1564,11 +1571,24 @@ void PepperPluginInstanceImpl::UpdateLayerTransform() {
   gfx::Size plugin_size_in_dip(view_data_.rect.size.width,
                                view_data_.rect.size.height);
 
+  // Adding the SetLayerTransform from Graphics2D to the UV.
+  // If the transform_ is the identity matrix
+  // then UV will be top_left (0,0) and
+  // lower_right (plugin_size_in_dip.width() / graphics_2d_size_in_dip.width(),
+  //             plugin_size_in_dip.height() / graphics_2d_size_in_dip.height())
+  gfx::PointF translate = gfx::PointF(transform_.matrix().getFloat(0,3),
+                                      transform_.matrix().getFloat(1,3));
+  float scale = transform_.matrix().getFloat(0,0);
+  gfx::PointF top_left =
+      gfx::PointF(-translate.x() / scale, -translate.y() / scale);
+  gfx::PointF lower_right = gfx::PointF(
+      (1 / scale) * plugin_size_in_dip.width() - translate.x() / scale,
+      (1 / scale) * plugin_size_in_dip.height() - translate.y() / scale);
   texture_layer_->SetUV(
-      gfx::PointF(0.0f, 0.0f),
-      gfx::PointF(
-          plugin_size_in_dip.width() / graphics_2d_size_in_dip.width(),
-          plugin_size_in_dip.height() / graphics_2d_size_in_dip.height()));
+      gfx::PointF(top_left.x() / graphics_2d_size_in_dip.width(),
+                  top_left.y() / graphics_2d_size_in_dip.height()),
+      gfx::PointF(lower_right.x() / graphics_2d_size_in_dip.width(),
+                  lower_right.y() / graphics_2d_size_in_dip.height()));
 }
 
 bool PepperPluginInstanceImpl::PluginHasFocus() const {