Add flush helper to ClipboardCore

src/System.Private.Windows.Core/src/System/Private/Windows/Ole/ClipboardCore.cs

@@ -48,6 +48,32 @@ internal static HRESULT Clear(
         return result;
     }
 
+    /// <summary>
+    ///  Flushes data to the Clipboard.
+    /// </summary>
+    /// <returns>An <see cref="HRESULT"/> indicating the success or failure of the operation.</returns>
+    internal static HRESULT Flush(
+        int retryTimes = OleRetryCount,
+        int retryDelay = OleRetryDelay)
+    {
+        TOleServices.EnsureThreadState();
+
+        HRESULT result;
+        int retryCount = retryTimes;
+
+        while ((result = TOleServices.OleFlushClipboard()).Failed)
+        {
+            if (--retryCount < 0)
+            {
+                break;
+            }
+
+            Thread.Sleep(millisecondsTimeout: retryDelay);
+        }
+
+        return result;
+    }
+
     /// <summary>
     ///  Attempts to set the specified data on the Clipboard.
     /// </summary>
@@ -104,7 +130,8 @@ internal static HRESULT SetData(
     /// <param name="proxyDataObject">The proxy data object retrieved from the Clipboard.</param>
     /// <param name="originalObject">The original object retrieved from the Clipboard, if available.</param>
     /// <returns>An <see cref="HRESULT"/> indicating the success or failure of the operation.</returns>
-    public static HRESULT TryGetData(
+    /// <inheritdoc cref="SetData(IComVisibleDataObject, bool, int, int)"/>
+    internal static HRESULT TryGetData(
         out ComScope<IDataObject> proxyDataObject,
         out object? originalObject,
         int retryTimes = OleRetryCount,
@@ -146,6 +173,38 @@ public static HRESULT TryGetData(
         return result;
     }
 
+    /// <summary>
+    ///  Returns true if the given <paramref name="object"/> is currently on the Clipboard.
+    /// </summary>
+    /// <remarks>
+    ///  <para>This is meant to emulate the OleIsCurrentClipboard API.</para>
+    /// </remarks>
+    /// <param name="object">The object to check.</param>
+    /// <returns>'true' if <paramref name="object"/> is currently on the Clipboard.</returns>
+    /// <inheritdoc cref="SetData(IComVisibleDataObject, bool, int, int)"/>
+    internal static bool IsObjectOnClipboard(
+        object @object,
+        int retryTimes = OleRetryCount,
+        int retryDelay = OleRetryDelay)
+    {
+        if (@object is null)
+        {
+            return false;
+        }
+
+        HRESULT result = TryGetData(
+            out ComScope<IDataObject> proxyDataObject,
+            out object? originalObject,
+            retryTimes,
+            retryDelay);
+
+        // Need to ensure we release the ref count on the proxy object.
+        using (proxyDataObject)
+        {
+            return result.Succeeded && @object == originalObject;
+        }
+    }
+
     /// <summary>
     ///  Returns the data that is currently on the clipboard as the platform specified <typeparamref name="TIDataObject"/>.
     /// </summary>

src/System.Windows.Forms/src/System/Windows/Forms/OLE/WinFormsOleServices.cs

@@ -85,24 +85,26 @@ static unsafe bool TryGetBitmapData(Com.IDataObject* dataObject, [NotNullWhen(tr
                 tymed = (uint)TYMED.TYMED_GDI
             };
 
-            STGMEDIUM medium = default;
-
-            if (dataObject->QueryGetData(formatEtc).Succeeded)
+            HRESULT result = dataObject->QueryGetData(formatEtc);
+            if (result.Failed)
             {
-                HRESULT hr = dataObject->GetData(formatEtc, out medium);
-
-                // One of the ways this can happen is when we attempt to put binary formatted data onto the
-                // clipboard, which will succeed as Windows ignores all errors when putting data on the clipboard.
-                // The data state, however, is not good, and this error will be returned by Windows when asking to
-                // get the data out.
-                Debug.WriteLineIf(hr == HRESULT.CLIPBRD_E_BAD_DATA, "CLIPBRD_E_BAD_DATA returned when trying to get clipboard data.");
+                return false;
             }
 
+            result = dataObject->GetData(formatEtc, out STGMEDIUM medium);
+
+            // One of the ways this can happen is when we attempt to put binary formatted data onto the
+            // clipboard, which will succeed as Windows ignores all errors when putting data on the clipboard.
+            // The data state, however, is not good, and this error will be returned by Windows when asking to
+            // get the data out.
+            Debug.WriteLineIf(result == HRESULT.CLIPBRD_E_BAD_DATA, "CLIPBRD_E_BAD_DATA returned when trying to get clipboard data.");
+
             try
             {
                 // GDI+ doesn't own this HBITMAP, but we can't delete it while the object is still around. So we
                 // have to do the really expensive thing of cloning the image so we can release the HBITMAP.
-                if ((uint)medium.tymed == (uint)TYMED.TYMED_GDI
+                if (result.Succeeded
+                    && (uint)medium.tymed == (uint)TYMED.TYMED_GDI
                     && !medium.hGlobal.IsNull
                     && Image.FromHbitmap(medium.hGlobal) is Bitmap clipboardBitmap)
                 {