windowscodecs: GetThumbnail should be supported for ICO frames.

dlls/windowscodecs/icoformat.c

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

dlls/windowscodecs/tests/icoformat.c

@@ -134,9 +134,16 @@ static void test_bad_icondirentry_size(void)
             if (SUCCEEDED(hr))
             {
                 UINT width = 0, height = 0;
+                IWICBitmapSource *thumbnail = NULL;
+
                 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);
                 IWICBitmapFrameDecode_Release(framedecode);
             }