The CreateCompatibleDC function creates a memory device context (DC) compatible with the specified device.

HDC CreateCompatibleDC(
  HDC hdc   // handle to DC
);

Parameters

hdc

[in] Handle to an existing DC. If this handle is NULL, the function creates a memory DC compatible with the application's current screen.

Return Values

If the function succeeds, the return value is the handle to a memory DC.

If the function fails, the return value is NULL.

Windows NT/2000/XP: To get extended error information, call GetLastError.

Remarks

A memory DC exists only in memory. When the memory DC is created, its display surface is exactly one monochrome pixel wide and one monochrome pixel high. Before an application can use a memory DC for drawing operations, it must select a bitmap of the correct width and height into the DC. To select a bitmap into a DC, use the CreateCompatibleBitmap function, specifying the height, width, and color organization required.

When a memory DC is created, all attributes are set to normal default values. The memory DC can be used as a normal DC. You can set the attributes; obtain the current settings of its attributes; and select pens, brushes, and regions.

The CreateCompatibleDC function can only be used with devices that support raster operations. An application can determine whether a device supports these operations by calling the GetDeviceCaps function.

When you no longer need the memory DC, call the DeleteDC function.

Windows 2000 and later: If hdc is NULL, the thread that calls CreateCompatibleDC owns the HDC that is created. When this thread is destroyed, the HDC is no longer valid. Thus, if you create the HDC andpass it to another thread, then exit the first thread, the second thread will not be able to use the HDC.

ICM: If the DC that is passed to this function is enabled for Image Color Management (ICM), the DC created by the function is ICM-enabled. The source and destination color spaces are specified in the DC.

Example Code

For an example, see Capturing an Image.

Requirements

  Windows NT/2000/XP/Vista: Included in Windows NT 3.1 and later.
  Windows 95/98/Me: Included in Windows 95 and later.
  Header: Declared in Wingdi.h; include Windows.h.
  Library: Use Gdi32.lib.

See Also

Device Contexts Overview, Device Context Functions, CreateCompatibleBitmap, DeleteDC, GetDeviceCaps