Fix painting glitch with text and NPAPI plugins. This was a regression from r167042. The problem wa…

content/renderer/webplugin_delegate_proxy.cc

Index: content/renderer/webplugin_delegate_proxy.cc
===================================================================
--- content/renderer/webplugin_delegate_proxy.cc	(revision 186240)
+++ content/renderer/webplugin_delegate_proxy.cc	(working copy)
@@ -195,6 +195,33 @@
   bool multibyte_response_expected_;
 };
 
+// Returns true if the given Silverlight 'background' value corresponds to
+// one that should make the plugin transparent. See:
+// http://msdn.microsoft.com/en-us/library/cc838148(VS.95).aspx
+// for possible values.
+static bool SilverlightColorIsTransparent(const std::string& color) {
+  if (StartsWithASCII(color, "#", false)) {
+    // If it's #ARGB or #AARRGGBB check the alpha; if not it's an RGB form and
+    // it's not transparent.
+    if ((color.length() == 5 && !StartsWithASCII(color, "#F", false)) ||
+        (color.length() == 9 && !StartsWithASCII(color, "#FF", false)))
+      return true;
+  } else if (StartsWithASCII(color, "sc#", false)) {
+    // It's either sc#A,R,G,B or sc#R,G,B; if the former, check the alpha.
+    if (color.length() < 4)
+      return false;
+    std::string value_string = color.substr(3, std::string::npos);
+    std::vector<std::string> components;
+    base::SplitString(value_string, ',', &components);
+    if (components.size() == 4 && !StartsWithASCII(components[0], "1", false))
+      return true;
+  } else if (LowerCaseEqualsASCII(color, "transparent")) {
+    return true;
+  }
+  // Anything else is a named, opaque color or an RGB form with no alpha.
+  return false;
+}
+
 }  // namespace
 
 WebPluginDelegateProxy::WebPluginDelegateProxy(
@@ -214,6 +241,7 @@
       npobject_(NULL),
       sad_plugin_(NULL),
       invalidate_pending_(false),
+      transparent_(false),
       front_buffer_index_(0),
       page_url_(render_view_->webview()->mainFrame()->document().url()) {
 }
@@ -372,6 +400,18 @@
 
   plugin_ = plugin;
 
+  bool flash = LowerCaseEqualsASCII(mime_type_, kFlashPluginSwfMimeType);
+  bool silverlight =
+      StartsWithASCII(mime_type_, "application/x-silverlight", false);
+  for (size_t i = 0; i < arg_names.size(); ++i) {
+    if ((flash && LowerCaseEqualsASCII(arg_names[i], "wmode") &&
+        LowerCaseEqualsASCII(arg_values[i], "transparent")) ||
+        (silverlight && LowerCaseEqualsASCII(arg_names[i], "background") &&
+         SilverlightColorIsTransparent(arg_values[i]))) {
+      transparent_ = true;
+    }
+  }

[piman, 2013/03/06 00:58:57]

Do we really need all that logic? The plugin should already tell us if it's
transparent or opaque, by calling NPN_SetValue(_, NPPVpluginTransparentBool, _)
- see webkit/plugins/npapi/plugin_host.cc . Could we pipe that to the renderer?

[jam, 2013/03/06 01:58:36]

good point, switched to it.

we used to default to windowless being transparent, and now I've changed that. 
seems low risk since we didn't use that flag elsewhere, and the current change
is basically a no-op if NPN_SetValue isn't called.

+
   result = false;
   Send(new PluginMsg_Init(instance_id_, params, &result));
 
@@ -725,7 +765,8 @@
   const SkBitmap& bitmap =
       front_buffer_canvas()->getDevice()->accessBitmap(false);
   SkPaint paint;
-  paint.setXfermodeMode(SkXfermode::kSrcATop_Mode);
+  paint.setXfermodeMode(
+      transparent_ ? SkXfermode::kSrcATop_Mode : SkXfermode::kSrc_Mode);
   SkIRect src_rect = gfx::RectToSkIRect(offset_rect);
   canvas->drawBitmapRect(bitmap,
                          &src_rect,