windowscodecs: Implement GetThumbnail in the ICO frame decoder.

dlls/windowscodecs/icoformat.c

@@ -200,8 +200,8 @@ static HRESULT WINAPI IcoFrameDecode_GetColorContexts(IWICBitmapFrameDecode *ifa
 static HRESULT WINAPI IcoFrameDecode_GetThumbnail(IWICBitmapFrameDecode *iface,
     IWICBitmapSource **ppIThumbnail)
 {
-    FIXME("(%p,%p)\n", iface, ppIThumbnail);
-    return E_NOTIMPL;
+    TRACE("(%p,%p)\n", iface, ppIThumbnail);
+    return IWICBitmapFrameDecode_QueryInterface(iface, &IID_IWICBitmapSource, (void **)ppIThumbnail);
 }
 
 static const IWICBitmapFrameDecodeVtbl IcoFrameDecode_Vtbl = {

dlls/windowscodecs/tests/icoformat.c

@@ -133,17 +133,24 @@ static void test_bad_icondirentry_size(void)
 
             if (SUCCEEDED(hr))
             {
-                UINT width = 0, height = 0;
-                IWICBitmapSource *thumbnail = NULL;
+                UINT width, height;
+                IWICBitmapSource *thumbnail;
 
+                width = height = 0;
                 hr = IWICBitmapFrameDecode_GetSize(framedecode, &width, &height);
                 ok(hr == S_OK, "GetFrameSize failed, hr=%x\n", hr);
                 ok(width == 16 && height == 16, "framesize=%ux%u\n", width, height);
 
                 hr = IWICBitmapFrameDecode_GetThumbnail(framedecode, &thumbnail);
-                todo_wine ok(hr == S_OK, "GetThumbnail failed, hr=%x\n", hr);
-
-                if (thumbnail) IWICBitmapSource_Release(thumbnail);
+                ok(hr == S_OK, "GetThumbnail failed, hr=%x\n", hr);
+                if (hr == S_OK)
+                {
+                    width = height = 0;
+                    hr = IWICBitmapSource_GetSize(thumbnail, &width, &height);
+                    ok(hr == S_OK, "GetFrameSize failed, hr=%x\n", hr);
+                    ok(width == 16 && height == 16, "framesize=%ux%u\n", width, height);
+                    IWICBitmapSource_Release(thumbnail);
+                }
                 IWICBitmapFrameDecode_Release(framedecode);
             }