Add support for transparency on Windows (issue #99).

- Enable the use of Skia instead of GDI for text rendering.
- Add a new CefWindowInfo::m_bTransparentPainting member.
- Add transparent popup window and off-screen rendering examples to cefclient.

git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@334 5089003a-bbd8-11dd-ad1f-f1f9622dbc98

cef.gypi

@@ -10,6 +10,8 @@
         'cef_directory' : '<!(echo %CEF_DIRECTORY%)',
         # Keep the build output in the CEF directory.
         'build_dir_prefix': '..\\<!(echo %CEF_DIRECTORY%)\\',
+        # Use SKIA text rendering for transparency support.
+        'enable_skia_text': 1,
       }, { # OS!="win"
         'cef_directory' : '<!(echo $CEF_DIRECTORY)',
       }],

cef_paths.gypi

@@ -82,6 +82,7 @@
       'tests/cefclient/res/modalmain.html',
       'tests/cefclient/res/osrplugin.html',
       'tests/cefclient/res/small.ico',
+      'tests/cefclient/res/transparency.html',
       'tests/cefclient/res/uiplugin.html',
       'tests/cefclient/resource_util_win.cpp',
       'tests/cefclient/uiplugin.cpp',

include/internal/cef_types_win.h

@@ -74,6 +74,9 @@ typedef struct _cef_window_info_t
   // |m_hWndParent| to the window that will act as the parent for popup menus,
   // dialog boxes, etc.
   BOOL m_bWindowRenderingDisabled;
+
+  // Set to true to enable transparent painting.
+  BOOL m_bTransparentPainting;
   
   // Handle for the new browser window.
   cef_window_handle_t m_hWnd;

include/internal/cef_win.h

@@ -99,6 +99,7 @@ struct CefWindowInfoTraits {
     target->m_hWndParent = src->m_hWndParent;
     target->m_hMenu = src->m_hMenu;
     target->m_bWindowRenderingDisabled = src->m_bWindowRenderingDisabled;
+    target->m_bTransparentPainting = src->m_bTransparentPainting;
     target->m_hWnd = src->m_hWnd;
   }
 };
@@ -144,6 +145,11 @@ public:
     m_bWindowRenderingDisabled = TRUE;
     m_hWndParent = hWndParent;
   }
+
+  void SetTransparentPainting(BOOL transparentPainting)
+  {
+    m_bTransparentPainting = transparentPainting;
+  }
 };
 
 

libcef/browser_impl_win.cc

@@ -8,6 +8,7 @@
 #include "browser_settings.h"
 #include "printing/units.h"
 
+#include "base/win/windows_version.h"
 #include "skia/ext/vector_canvas.h"
 #include "skia/ext/vector_platform_device_emf_win.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebDocument.h"
@@ -18,14 +19,37 @@
 #include "ui/base/win/hwnd_util.h"
 #include "webkit/glue/webpreferences.h"
 
+#include <dwmapi.h>
 #include <shellapi.h>
 #include <shlwapi.h>
 #include <wininet.h>
 #include <winspool.h>
 
+#pragma comment(lib, "dwmapi.lib")
+
 using WebKit::WebRect;
 using WebKit::WebSize;
 
+namespace {
+
+bool IsAeroGlassEnabled() {
+  if (base::win::GetVersion() < base::win::VERSION_VISTA)
+    return false;
+  
+  BOOL enabled = FALSE;
+  return SUCCEEDED(DwmIsCompositionEnabled(&enabled)) && enabled;
+}
+
+void SetAeroGlass(HWND hWnd) {
+  if (!IsAeroGlassEnabled())
+    return;
+
+  // Make the whole window transparent.
+  MARGINS mgMarInset = { -1, -1, -1, -1 };
+  DwmExtendFrameIntoClientArea(hWnd, &mgMarInset);
+}
+
+} // namespace
 
 LPCTSTR CefBrowserImpl::GetWndClass()
 {
@@ -100,6 +124,13 @@ LRESULT CALLBACK CefBrowserImpl::WndProc(HWND hwnd, UINT message,
 
   case WM_ERASEBKGND:
     return 0;
+
+  case WM_DWMCOMPOSITIONCHANGED:
+    // Message sent to top-level windows when composition has been enabled or
+    // disabled.
+    if (browser->window_info_.m_bTransparentPainting)
+      SetAeroGlass(hwnd);
+    break;
   }
 
   return DefWindowProc(hwnd, message, wParam, lParam);
@@ -148,6 +179,12 @@ void CefBrowserImpl::UIT_CreateBrowser(const CefString& url)
         ::GetModuleHandle(NULL), NULL);
     DCHECK(window_info_.m_hWnd != NULL);
 
+    if (window_info_.m_bTransparentPainting &&
+        !(window_info_.m_dwStyle & WS_CHILD)) {
+      // Transparent top-level windows will be given "sheet of glass" effect.
+      SetAeroGlass(window_info_.m_hWnd);
+    }
+
     // Set window user data to this object for future reference from the window
     // procedure
     ui::SetWindowUserData(window_info_.m_hWnd, this);
@@ -174,6 +211,9 @@ void CefBrowserImpl::UIT_CreateBrowser(const CefString& url)
                           paint_delegate_.get(), dev_tools_agent_.get(),
                           prefs));
 
+  if (window_info_.m_bTransparentPainting)
+    webviewhost_->webview()->setIsTransparent(true);
+
   if (!settings_.developer_tools_disabled)
     dev_tools_agent_->SetWebView(webviewhost_->webview());
 

libcef/webwidget_host_win.cc

@@ -16,6 +16,7 @@
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebSize.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebString.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebVector.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/win/WebInputEventFactory.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/win/WebScreenInfoFactory.h"
 #include "ui/base/ime/composition_text.h"
@@ -709,6 +710,17 @@ void WebWidgetHost::PaintRect(const gfx::Rect& rect) {
 #endif
   DCHECK(canvas_.get());
 
+  if (!popup() && ((WebKit::WebView*)webwidget_)->isTransparent()) {
+    // When using transparency mode clear the rectangle before painting.
+    SkPaint clearpaint;
+    clearpaint.setARGB(0,0,0,0);
+    clearpaint.setXfermodeMode(SkXfermode::kClear_Mode);
+
+    SkRect skrc;
+    skrc.set(rect.x(), rect.y(), rect.right(), rect.bottom());
+    canvas_->drawRect(skrc, clearpaint);
+  }
+
   set_painting(true);
   webwidget_->paint(canvas_.get(), rect);
   set_painting(false);

tests/cefclient/cefclient.h

@@ -33,4 +33,8 @@ void RunDOMAccessTest(CefRefPtr<CefBrowser> browser);
 void RunDragDropTest(CefRefPtr<CefBrowser> browser);
 void RunModalDialogTest(CefRefPtr<CefBrowser> browser);
 
+#if defined(OS_WIN)
+void RunTransparentPopupTest(CefRefPtr<CefBrowser> browser);
+#endif
+
 #endif // _CEFCLIENT_H

tests/cefclient/cefclient.rc

@@ -38,6 +38,7 @@ IDS_DOMACCESS BINARY "res\\domaccess.html"
 IDS_MODALMAIN BINARY "res\\modalmain.html"
 IDS_MODALDIALOG BINARY "res\\modaldialog.html"
 IDS_EXTENSIONPERF BINARY "res\\extensionperf.html"
+IDS_TRANSPARENCY BINARY "res\\transparency.html"
 
 /////////////////////////////////////////////////////////////////////////////
 //
@@ -78,10 +79,12 @@ BEGIN
         MENUITEM "JavaScript Execute",          ID_TESTS_JAVASCRIPT_EXECUTE
         MENUITEM "Plugin",                      ID_TESTS_PLUGIN
         MENUITEM "Popup Window",                ID_TESTS_POPUP
+        MENUITEM "Transparent Popup Window",    ID_TESTS_TRANSPARENT_POPUP
         MENUITEM "Request",                     ID_TESTS_REQUEST
         MENUITEM "Scheme Handler",              ID_TESTS_SCHEME_HANDLER
         MENUITEM "UI App Example",              ID_TESTS_UIAPP
         MENUITEM "Off-Screen Rendering Example",ID_TESTS_OSRAPP
+        MENUITEM "Transparent Off-Screen Rendering Example",ID_TESTS_TRANSPARENT_OSRAPP
         MENUITEM "Local Storage",               ID_TESTS_LOCALSTORAGE
         MENUITEM "XMLHttpRequest",              ID_TESTS_XMLHTTPREQUEST
         MENUITEM "WebURLRequest",               ID_TESTS_WEBURLREQUEST

tests/cefclient/cefclient_win.cpp

@@ -374,7 +374,7 @@ LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
         // Initialize window info to the defaults for a child window
         info.SetAsChild(hWnd, rect);
 
-        // Creat the new child child browser window
+        // Creat the new child browser window
         CefBrowser::CreateBrowser(info,
             static_cast<CefRefPtr<CefClient> >(g_handler),
             "http://www.google.com", settings);
@@ -495,6 +495,10 @@ LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
           if(browser.get())
             RunPopupTest(browser);
           return 0;
+        case ID_TESTS_TRANSPARENT_POPUP: // Test a transparent popup window
+          if(browser.get())
+            RunTransparentPopupTest(browser);
+          return 0;
         case ID_TESTS_REQUEST: // Test a request
           if(browser.get())
             RunRequestTest(browser);
@@ -509,7 +513,11 @@ LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
           return 0;
         case ID_TESTS_OSRAPP: // Test the OSR app
           if(browser.get())
-            RunOSRPluginTest(browser);
+            RunOSRPluginTest(browser, false);
+          return 0;
+        case ID_TESTS_TRANSPARENT_OSRAPP: // Test the OSR app with transparency
+          if(browser.get())
+            RunOSRPluginTest(browser, true);
           return 0;
         case ID_TESTS_DOMACCESS: // Test DOM access
           if(browser.get())
@@ -665,3 +673,20 @@ std::string AppGetWorkingDirectory()
 {
 	return szWorkingDir;
 }
+
+void RunTransparentPopupTest(CefRefPtr<CefBrowser> browser)
+{
+  CefWindowInfo info;
+  CefBrowserSettings settings;
+
+  // Initialize window info to the defaults for a popup window
+  info.SetAsPopup(NULL, "TransparentPopup");
+  info.SetTransparentPainting(TRUE);
+  info.m_nWidth = 500;
+  info.m_nHeight = 500;
+
+  // Creat the popup browser window
+  CefBrowser::CreateBrowser(info,
+      static_cast<CefRefPtr<CefClient> >(g_handler),
+      "http://tests/transparency", settings);
+}

tests/cefclient/client_handler.cpp

@@ -35,7 +35,7 @@ void ClientHandler::OnAfterCreated(CefRefPtr<CefBrowser> browser)
   REQUIRE_UI_THREAD();
 
   AutoLock lock_scope(this);
-  if(!browser->IsPopup())
+  if(!m_Browser.get())
   {
     // We need to keep the main child window, but not popup windows
     m_Browser = browser;
@@ -47,7 +47,7 @@ bool ClientHandler::DoClose(CefRefPtr<CefBrowser> browser)
 {
   REQUIRE_UI_THREAD();
 
-  if (!browser->IsPopup()) {
+  if (m_BrowserHwnd == browser->GetWindowHandle()) {
     // Since the main window contains the browser window, we need to close
     // the parent window instead of the browser window.
     CloseMainWindow();
@@ -78,7 +78,7 @@ void ClientHandler::OnLoadStart(CefRefPtr<CefBrowser> browser,
 {
   REQUIRE_UI_THREAD();
 
-  if(!browser->IsPopup() && frame->IsMain()) {
+  if(m_BrowserHwnd == browser->GetWindowHandle() && frame->IsMain()) {
     // We've just started loading a page
     SetLoading(true);
   }
@@ -90,7 +90,7 @@ void ClientHandler::OnLoadEnd(CefRefPtr<CefBrowser> browser,
 {
   REQUIRE_UI_THREAD();
 
-  if(!browser->IsPopup() && frame->IsMain()) {
+  if(m_BrowserHwnd == browser->GetWindowHandle() && frame->IsMain()) {
     // We've just finished loading a page
     SetLoading(false);
 

tests/cefclient/client_handler.h

@@ -54,11 +54,11 @@ public:
 
   // CefLifeSpanHandler methods
   virtual bool OnBeforePopup(CefRefPtr<CefBrowser> parentBrowser,
-                               const CefPopupFeatures& popupFeatures,
+                             const CefPopupFeatures& popupFeatures,
-                               CefWindowInfo& windowInfo,
+                             CefWindowInfo& windowInfo,
-                               const CefString& url,
+                             const CefString& url,
-                               CefRefPtr<CefClient>& client,
+                             CefRefPtr<CefClient>& client,
-                               CefBrowserSettings& settings) OVERRIDE;
+                             CefBrowserSettings& settings) OVERRIDE;
   virtual void OnAfterCreated(CefRefPtr<CefBrowser> browser) OVERRIDE;
   virtual bool DoClose(CefRefPtr<CefBrowser> browser) OVERRIDE;
   virtual void OnBeforeClose(CefRefPtr<CefBrowser> browser) OVERRIDE;

tests/cefclient/client_handler_win.cpp

@@ -24,7 +24,7 @@ bool ClientHandler::OnBeforePopup(CefRefPtr<CefBrowser> parentBrowser,
 
 #ifdef TEST_REDIRECT_POPUP_URLS
   std::string urlStr = url;
-  if(urlStr.find("resources/inspector/devtools.html") == std::string::npos) {
+  if(urlStr.find("chrome-devtools:") == std::string::npos) {
     // Show all popup windows excluding DevTools in the current window.
     windowInfo.m_dwStyle &= ~WS_VISIBLE;
     client = new ClientPopupHandler(m_Browser);
@@ -95,6 +95,10 @@ bool ClientHandler::OnBeforeResourceLoad(CefRefPtr<CefBrowser> browser,
     resourceStream = GetBinaryResourceReader(IDS_MODALDIALOG);
     response->SetMimeType("text/html");
     response->SetStatus(200);
+  } else if(url == "http://tests/transparency") {
+    resourceStream = GetBinaryResourceReader(IDS_TRANSPARENCY);
+    response->SetMimeType("text/html");
+    response->SetStatus(200);
   }
 
   return false;
@@ -120,7 +124,7 @@ void ClientHandler::OnTitleChange(CefRefPtr<CefBrowser> browser,
 
   // Set the frame window title bar
   CefWindowHandle hwnd = browser->GetWindowHandle();
-  if(!browser->IsPopup())
+  if(m_BrowserHwnd == hwnd)
   {
     // The frame window will be the parent of the browser window
     hwnd = GetParent(hwnd);

tests/cefclient/osrplugin.cpp

@@ -4,9 +4,11 @@
 // found in the LICENSE file.
 
 #include "include/cef.h"
-#include "osrplugin.h"
 #include "cefclient.h"
 #include "client_popup_handler.h"
+#include "osrplugin.h"
+#include "resource.h"
+#include "resource_util.h"
 #include "string_util.h"
 #include "util.h"
 #include <gl/gl.h>
@@ -28,6 +30,12 @@ float g_spinY = 0.0f;
 int g_width = -1, g_height = -1;
 CefRefPtr<CefBrowser> g_offscreenBrowser;
 
+// If set to true alpha transparency will be used.
+bool g_offscreenTransparent = false;
+
+#define GL_IMAGE_FORMAT (g_offscreenTransparent?GL_RGBA:GL_RGB)
+#define GL_BYTE_COUNT (g_offscreenTransparent?4:3)
+
 // Class holding pointers for the client plugin window.
 class ClientPlugin
 {
@@ -48,6 +56,7 @@ public:
 class ClientOSRHandler : public CefClient,
                          public CefLifeSpanHandler,
                          public CefLoadHandler,
+                         public CefRequestHandler,
                          public CefDisplayHandler,
                          public CefRenderHandler
 {
@@ -73,6 +82,8 @@ public:
       { return this; }
   virtual CefRefPtr<CefLoadHandler> GetLoadHandler() OVERRIDE
       { return this; }
+  virtual CefRefPtr<CefRequestHandler> GetRequestHandler() OVERRIDE
+      { return this; }
   virtual CefRefPtr<CefDisplayHandler> GetDisplayHandler() OVERRIDE
       { return this; }
   virtual CefRefPtr<CefRenderHandler> GetRenderHandler() OVERRIDE
@@ -134,6 +145,27 @@ public:
     }
   }
 
+  // CefRequestHandler methods
+
+  virtual bool OnBeforeResourceLoad(CefRefPtr<CefBrowser> browser,
+                                    CefRefPtr<CefRequest> request,
+                                    CefString& redirectUrl,
+                                    CefRefPtr<CefStreamReader>& resourceStream,
+                                    CefRefPtr<CefResponse> response,
+                                    int loadFlags) OVERRIDE
+  {
+    REQUIRE_IO_THREAD();
+
+    std::string url = request->GetURL();
+    if(url == "http://tests/transparency") {
+      resourceStream = GetBinaryResourceReader(IDS_TRANSPARENCY);
+      response->SetMimeType("text/html");
+      response->SetStatus(200);
+    }
+
+    return false;
+  }
+
   // CefDisplayHandler methods
 
   virtual void OnNavStateChange(CefRefPtr<CefBrowser> browser,
@@ -254,32 +286,55 @@ public:
     REQUIRE_UI_THREAD();
 
     wglMakeCurrent(plugin_->hDC, plugin_->hRC);
-    
+
+    if (g_offscreenTransparent) {
+      // Enable alpha blending.
+      glEnable(GL_BLEND);
+    }
+
+    // Enable 2D textures.
+    glEnable(GL_TEXTURE_2D);
+
     glBindTexture(GL_TEXTURE_2D, g_textureID);
     
     if (type == PET_VIEW) {
       // Paint the view.
-      SetRGB(buffer, g_width, g_height, true);
+      if (g_offscreenTransparent)
+        SetRGBA(buffer, g_width, g_height, true);
+      else
+        SetRGB(buffer, g_width, g_height, true);
 
       // Update the whole texture. This is done for simplicity instead of
       // updating just the dirty region.
-      glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, g_width, g_height, GL_RGB,
+      glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, g_width, g_height,
-          GL_UNSIGNED_BYTE, view_buffer_);
+          GL_IMAGE_FORMAT, GL_UNSIGNED_BYTE, view_buffer_);
     }
     
     if(popup_rect_.width > 0) {
       if (type == PET_POPUP) {
         // Paint the popup.
-        SetRGB(buffer, popup_rect_.width, popup_rect_.height, false);
+        if (g_offscreenTransparent)
+          SetRGBA(buffer, popup_rect_.width, popup_rect_.height, false);
+        else
+          SetRGB(buffer, popup_rect_.width, popup_rect_.height, false);
       }
 
       if (popup_buffer_) {
         // Update the popup region.
         glTexSubImage2D(GL_TEXTURE_2D, 0, popup_rect_.x,
             g_height-popup_rect_.y-popup_rect_.height, popup_rect_.width,
-            popup_rect_.height, GL_RGB, GL_UNSIGNED_BYTE, popup_buffer_);
+            popup_rect_.height, GL_IMAGE_FORMAT, GL_UNSIGNED_BYTE,
+            popup_buffer_);
       }
     }
+
+    // Disable 2D textures.
+    glDisable(GL_TEXTURE_2D);
+
+    if (g_offscreenTransparent) {
+      // Disable alpha blending.
+      glDisable(GL_BLEND);
+    }
   }
 
   virtual void OnCursorChange(CefRefPtr<CefBrowser> browser,
@@ -305,18 +360,10 @@ private:
     AppGetBrowser()->GetMainFrame()->ExecuteJavaScript(ss.str(), "", 0);
   }
 
-  // Set the contents of the RGB buffer.
-  void SetRGB(const void* src, int width, int height, bool view)
-  {
-    SetBufferSize(width, height, view);
-    ConvertToRGB((unsigned char*)src, view?view_buffer_:popup_buffer_, width,
-        height);
-  }
-
   // Size the RGB buffer.
   void SetBufferSize(int width, int height, bool view)
   {
-    int dst_size = width * height * 3;
+    int dst_size = width * height * GL_BYTE_COUNT;
       
     // Allocate a new buffer if necesary.
     if (view) {
@@ -336,6 +383,38 @@ private:
     }
   }
 
+  // Set the contents of the RGBA buffer.
+  void SetRGBA(const void* src, int width, int height, bool view)
+  {
+    SetBufferSize(width, height, view);
+    ConvertToRGBA((unsigned char*)src, view?view_buffer_:popup_buffer_, width,
+        height);
+  }
+
+  // Convert from BGRA to RGBA format and from upper-left to lower-left origin.
+  static void ConvertToRGBA(const unsigned char* src, unsigned char* dst,
+                           int width, int height)
+  {
+    int sp = 0, dp = (height-1) * width * 4;
+    for(int i = 0; i < height; i++) {
+      for(int j = 0; j < width; j++, dp += 4, sp += 4) {
+        dst[dp] = src[sp+2]; // R
+        dst[dp+1] = src[sp+1]; // G
+        dst[dp+2] = src[sp]; // B
+        dst[dp+3] = src[sp+3]; // A
+      }
+      dp -= width * 8;
+    }
+  }
+
+  // Set the contents of the RGB buffer.
+  void SetRGB(const void* src, int width, int height, bool view)
+  {
+    SetBufferSize(width, height, view);
+    ConvertToRGB((unsigned char*)src, view?view_buffer_:popup_buffer_, width,
+        height);
+  }
+
   // Convert from BGRA to RGB format and from upper-left to lower-left origin.
   static void ConvertToRGB(const unsigned char* src, unsigned char* dst,
                            int width, int height)
@@ -392,10 +471,14 @@ void EnableGL(HWND hWnd, HDC * hDC, HGLRC * hRC)
   wglMakeCurrent(*hDC, *hRC);
 
   glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
-  glEnable(GL_TEXTURE_2D);
 
   // Necessary for non-power-of-2 textures to render correctly.
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+
+  if (g_offscreenTransparent) {
+    // Alpha blending style.
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+  }
 }
 
 // Disable GL.
@@ -424,6 +507,14 @@ void SizeGL(ClientPlugin* plugin, int width, int height)
   glLoadIdentity();
   glOrtho(0, 0, width, height, 0.1, 100.0);
 
+  if (g_offscreenTransparent) {
+    // Enable alpha blending.
+    glEnable(GL_BLEND);
+  }
+
+  // Enable 2D textures.
+  glEnable(GL_TEXTURE_2D);
+
   // Delete the existing exture.
   if(g_textureID != -1)
     glDeleteTextures(1, &g_textureID);
@@ -435,12 +526,20 @@ void SizeGL(ClientPlugin* plugin, int width, int height)
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 
   // Start with all white contents.
-  int size = width * height * 3;
+  int size = width * height * GL_BYTE_COUNT;
   unsigned char* buffer = new unsigned char[size];
   memset(buffer, 255, size);
-  
+
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0,
-      GL_RGB, GL_UNSIGNED_BYTE, buffer);
+      GL_IMAGE_FORMAT, GL_UNSIGNED_BYTE, buffer);
+
+  // Disable 2D textures.
+  glDisable(GL_TEXTURE_2D);
+
+  if (g_offscreenTransparent) {
+    // Disable alpha blending.
+    glDisable(GL_BLEND);
+  }
 
   delete [] buffer;
   
@@ -468,21 +567,43 @@ void RenderGL(ClientPlugin* plugin)
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   //glTranslatef(0.0f, 0.0f, -3.0f);
+
+  // Draw the background gradient.
+  glPushAttrib(GL_ALL_ATTRIB_BITS);
+  glBegin(GL_QUADS);
+  glColor4f(1.0,0.0,0.0,1.0); // red
+  glVertex2f(-1.0,-1.0);
+  glVertex2f(1.0,-1.0);
+  glColor4f(0.0,0.0,1.0,1.0); // blue
+  glVertex2f(1.0, 1.0);
+  glVertex2f(-1.0, 1.0);
+  glEnd();
+  glPopAttrib();
   
   // Rotate the view based on the mouse spin.
   glRotatef(-g_spinX, 1.0f, 0.0f, 0.0f);
   glRotatef(-g_spinY, 0.0f, 1.0f, 0.0f);
 
-  // Enable alpha blending.
+  if (g_offscreenTransparent) {
-  //glEnable(GL_BLEND);
+    // Enable alpha blending.
-  //glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+    glEnable(GL_BLEND);
+  }
+
+  // Enable 2D textures.
+  glEnable(GL_TEXTURE_2D);
 
   // Draw the facets with the texture.
   glBindTexture(GL_TEXTURE_2D, g_textureID);
   glInterleavedArrays(GL_T2F_V3F, 0, vertices);
   glDrawArrays(GL_QUADS, 0, 4);
 
-  //glDisable(GL_BLEND);
+  // Disable 2D textures.
+  glDisable(GL_TEXTURE_2D);
+
+  if (g_offscreenTransparent) {
+    // Disable alpha blending.
+    glDisable(GL_BLEND);
+  }
 
   SwapBuffers(plugin->hDC);
 }
@@ -556,6 +677,8 @@ NPError NPP_SetWindowImpl(NPP instance, NPWindow* window_info) {
     CefWindowInfo windowInfo;
     CefBrowserSettings settings;
     windowInfo.SetAsOffScreen(plugin->hWnd);
+    if (g_offscreenTransparent)
+      windowInfo.SetTransparentPainting(TRUE);
     CefBrowser::CreateBrowser(windowInfo, new ClientOSRHandler(plugin),
         "http://www.google.com", settings);
   }
@@ -774,4 +897,9 @@ CefRefPtr<CefBrowser> GetOffScreenBrowser()
   return g_offscreenBrowser;
 }
 
+void SetOffScreenTransparent(bool transparent)
+{
+  g_offscreenTransparent = transparent;
+}
+
 #endif // OS_WIN

tests/cefclient/osrplugin.h

@@ -22,6 +22,8 @@ NPError API_CALL NP_OSRShutdown(void);
 
 CefRefPtr<CefBrowser> GetOffScreenBrowser();
 
+void SetOffScreenTransparent(bool transparent);
+
 #endif // OS_WIN
 
 #endif // _CEFCLIENT_OSRPLUGIN_H

tests/cefclient/osrplugin_test.cpp

@@ -26,7 +26,7 @@ void InitOSRPluginTest()
   CefRegisterPlugin(plugin_info);
 }
 
-void RunOSRPluginTest(CefRefPtr<CefBrowser> browser)
+void RunOSRPluginTest(CefRefPtr<CefBrowser> browser, bool transparent)
 {
   class Listener : public CefDOMEventListener
   {
@@ -58,9 +58,10 @@ void RunOSRPluginTest(CefRefPtr<CefBrowser> browser)
         CefString value = url->GetValue();
         if (!value.empty())
           browser->GetMainFrame()->LoadURL(value);
-      } else if(elementId == "testWindowedPlugin") {
+      } else if(elementId == "testTransparency") {
-        // Run the windowed plugin test.
+        // Transparency test.
-        RunPluginTest(browser);
+        browser->GetMainFrame()->LoadURL(
+            "http://tests/transparency");
       } else if(elementId == "testWindowlessPlugin") {
         // Load flash, which is a windowless plugin.
         browser->GetMainFrame()->LoadURL(
@@ -101,7 +102,7 @@ void RunOSRPluginTest(CefRefPtr<CefBrowser> browser)
       RegisterClickListener(document, listener, "stop");
       RegisterClickListener(document, listener, "reload");
       RegisterClickListener(document, listener, "go");
-      RegisterClickListener(document, listener, "testWindowedPlugin");
+      RegisterClickListener(document, listener, "testTransparency");
       RegisterClickListener(document, listener, "testWindowlessPlugin");
       RegisterClickListener(document, listener, "viewSource");
     }
@@ -124,5 +125,6 @@ void RunOSRPluginTest(CefRefPtr<CefBrowser> browser)
   static_cast<ClientHandler*>(client.get())->AddDOMVisitor(
       "http://tests/osrapp", new Visitor());
 
+  SetOffScreenTransparent(transparent);
   browser->GetMainFrame()->LoadURL("http://tests/osrapp");
 }

tests/cefclient/osrplugin_test.h

@@ -11,6 +11,6 @@
 void InitOSRPluginTest();
 
 // Run the test.
-void RunOSRPluginTest(CefRefPtr<CefBrowser> browser);
+void RunOSRPluginTest(CefRefPtr<CefBrowser> browser, bool transparent);
 
 #endif // _CEFCLIENT_OSRPLUGIN_TEST_H

tests/cefclient/res/osrplugin.html

@@ -24,8 +24,8 @@
              <ul>
                <li>Click and drag the view with the left mouse button while holding the shift key.</li>
                <li>Enter a URL and click the "Go!" button to browse to a new Website.</li>
-               <li><a href="#" id="testWindowedPlugin">Click here</a> to test a windowed plugin. Windowed plugins must handle the WM_PRINTCLIENT message.</li>
+               <li><a href="#" id="testTransparency">Click here</a> to test transparency.</li>
-               <li><a href="#" id="testWindowlessPlugin">Click here</a> to test a windowless plugin. Windowless plugins can be used without modification.</li>
+               <li><a href="#" id="testWindowlessPlugin">Click here</a> to test a windowless plugin.</li>
              </ul>
           </td>
       </tr>

tests/cefclient/res/transparency.html

@@ -0,0 +1,36 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html>
+<head>
+<title>Transparency Examples</title>
+<style type="text/css">
+body {
+font-family: Verdana, Arial;
+}
+img {
+opacity:0.4;
+}
+img:hover {
+opacity:1.0;
+}
+#transbox {
+width: 300px;
+margin: 0 50px;
+background-color: #fff;
+border: 2px solid black;
+opacity: 0.3;
+font-size: 18px;
+font-weight: bold;
+}
+</style>
+</head>
+<body>
+
+<h1>Image Transparency</h1>
+Hover over an image to make it fully opaque.<br>
+<img src="http://www.w3schools.com/css/klematis.jpg" width="150" height="113" alt="klematis" />
+<img src="http://www.w3schools.com/css/klematis2.jpg" width="150" height="113" alt="klematis" />
+
+<h1>Div Transparency</h1>
+<div id="transbox">This is some text in a transparent box.</div>
+</body>
+</html>

tests/cefclient/resource.h

@@ -53,6 +53,8 @@
 #define ID_TESTS_OSRAPP                 32793
 #define ID_TESTS_MODALDIALOG            32794
 #define ID_TESTS_JAVASCRIPT_PERFORMANCE 32795
+#define ID_TESTS_TRANSPARENT_POPUP      32796
+#define ID_TESTS_TRANSPARENT_OSRAPP     32797
 #define IDC_STATIC                      -1
 #define IDS_LOGO                        1000
 #define IDS_UIPLUGIN                    1001
@@ -64,6 +66,7 @@
 #define IDS_MODALMAIN                   1007
 #define IDS_MODALDIALOG                 1008
 #define IDS_EXTENSIONPERF               1009
+#define IDS_TRANSPARENCY                1010
 
 // Avoid files associated with MacOS
 #define _X86_