WM_DWMSENDICONICLIVEPREVIEWBITMAP message
Instructs a window to provide a static bitmap to use as a live preview (also known as a Peek preview) of that window.
Parameters
-
wParam
-
Not used.
-
lParam
-
Not used.
Return value
If an application processes this message, it should return zero.
Remarks
A live preview (also known as a Peek preview) of a window appears when a user moves the mouse pointer over the window's thumbnail in the taskbar or gives the thumbnail focus in the ALT+TAB window. This view is a full-sized preview of the window and can be a live snapshot or an iconic representation.
Desktop Window Manager (DWM) sends this message to a window if all of the following situations are true:
- Live preview has been invoked on the window.
- The DWMWA_HAS_ICONIC_BITMAP attribute is set on the window.
- An iconic representation is the only one that exists for this window.
The window that receives this message should respond by generating a full-scale bitmap. The window then calls the DwmSetIconicLivePreviewBitmap function to set the live preview. If the window does not set a bitmap in a given amount of time, DWM uses its own default iconic representation for the window.
Examples
The following example demonstrates a response to the WM_DWMSENDICONICLIVEPREVIEWBITMAP message. The example calls the DwmSetIconicLivePreviewBitmap function with a handle to a customized, device-independent bitmap to use as the window's representation.
case WM_DWMSENDICONICLIVEPREVIEWBITMAP:
{
// This window is being asked to provide a bitmap to show in Peek preview.
// This indicates the thumbnail in the taskbar is being previewed.
RECT rectWindow = {0, 0, 0, 0};
if (GetClientRect(hwnd, &rectWindow))
{
nWidth = rectWindow.right - rectWindow.left;
nHeight = rectWindow.bottom - rectWindow.top;
}
hbm = CreateDIB(nWidth, nHeight);
if (hbm)
{
hr = DwmSetIconicLivePreviewBitmap(hwnd, hbm, NULL, DWM_SIT_DISPLAYFRAME);
DeleteObject(hbm);
}
}
break;
For the complete code, see the Customize an Iconic Thumbnail and a Live Preview Bitmap sample.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client |
Windows 7 [desktop apps only] |
| Minimum supported server |
Windows Server 2008 R2 [desktop apps only] |
| Header |
|