half-working alpha on windowswin32-alpha

doesn't redraw the "background" properly - compositor bug?

http://stackoverflow.com/questions/4052940/how-to-make-an-opengl-
rendering-context-with-transparent-background

2 files changed, 25 insertions, 3 deletions

diff --git a/video/out/opengl/context_w32.c b/video/out/opengl/context_w32.c
index 5157cd97a5..02b748db42 100644
--- a/video/out/opengl/context_w32.c
+++ b/video/out/opengl/context_w32.c
@@ -49,6 +49,22 @@ static int GLAPIENTRY w32_swap_interval(int interval)
     return 0;
 }
 
+static void enable_transparency(struct MPGLContext *ctx,
+                                PIXELFORMATDESCRIPTOR *pfd)
+{
+    HWND win = vo_w32_hwnd(ctx->vo);
+    pfd->dwFlags |= PFD_SUPPORT_COMPOSITION;
+    pfd->cAlphaBits = 8;
+    pfd->cColorBits += pfd->cAlphaBits;
+
+    DWM_BLURBEHIND bb = {
+        .hRgnBlur = CreateRectRgn(0, 0, -1, -1),
+        .dwFlags = DWM_BB_ENABLE | DWM_BB_BLURREGION,
+        .fEnable = TRUE,
+    };
+    DwmEnableBlurBehindWindow(win, &bb);
+}
+
 static bool create_dc(struct MPGLContext *ctx, int flags)
 {
     struct w32_context *w32_ctx = ctx->priv;
@@ -70,6 +86,10 @@ static bool create_dc(struct MPGLContext *ctx, int flags)
     pfd.iPixelType = PFD_TYPE_RGBA;
     pfd.cColorBits = 24;
     pfd.iLayerType = PFD_MAIN_PLANE;
+
+    if (flags & VOFLAG_ALPHA)
+        enable_transparency(ctx, &pfd);
+
     int pf = ChoosePixelFormat(hdc, &pfd);
 
     if (!pf) {
@@ -221,6 +241,7 @@ static void create_ctx(void *ptr)
         ctx->gl->fb_g = pfd.cGreenBits;
         ctx->gl->fb_b = pfd.cBlueBits;
     }
+    ctx->gl->fb_premultiplied = true;
 
     wglMakeCurrent(w32_ctx->hdc, NULL);
 }
diff --git a/video/out/w32_common.c b/video/out/w32_common.c
index 025b744838..463696cc8a 100644
--- a/video/out/w32_common.c
+++ b/video/out/w32_common.c
@@ -688,8 +688,8 @@ static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam,
         // This message is used to wakeup the GUI thread, see wakeup_gui_thread.
         mp_dispatch_queue_process(w32->dispatch, 0);
         break;
-    case WM_ERASEBKGND: // no need to erase background separately
-        return 1;
+    //case WM_ERASEBKGND: // no need to erase background separately
+    //    return 1;
     case WM_PAINT:
         signal_events(w32, VO_EVENT_EXPOSE);
         break;
@@ -1192,6 +1192,7 @@ static void *gui_thread(void *ptr)
         .hIcon = LoadIconW(hInstance, L"IDI_ICON1"),
         .hCursor = LoadCursor(NULL, IDC_ARROW),
         .lpszClassName = classname,
+        .hbrBackground = CreateSolidBrush(0x00000000),
     };
     RegisterClassExW(&wcex);
 
@@ -1209,7 +1210,7 @@ static void *gui_thread(void *ptr)
                                       0, 0, r.right, r.bottom,
                                       w32->parent, 0, hInstance, NULL);
     } else {
-        w32->window = CreateWindowExW(0, classname,
+        w32->window = CreateWindowExW(WS_EX_APPWINDOW, classname,
                                       classname,
                                       update_style(w32, 0),
                                       CW_USEDEFAULT, SW_HIDE, 100, 100,