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CreateCompatibleDC function

Applies to: desktop apps only

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

Syntax

Copy

HDC CreateCompatibleDC(
  __in  HDC hdc
);

Parameters

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

Return value

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

If the function fails, the return value is NULL.

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. We recommend that you call DeleteDC to delete the DC. However, you can also call DeleteObject with the HDC to delete the DC.

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 When this thread is destroyed, the HDC is no longer valid.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.

Examples

For an example, see Capturing an Image.

Requirements

Minimum supported client	Windows 2000 Professional
Minimum supported server	Windows 2000 Server
Header	Wingdi.h (include Windows.h)
Library	Gdi32.lib
DLL	Gdi32.dll

[tfl - 15 08 10] Hi - and thanks for your post. You should post questions like this to the MSDN Forums at http://forums.microsoft.com/msdn or the MSDN Newsgroups at http://www.microsoft.com/communities/newsgroups/en-us/. You are much more likely get a quicker response using the forums than through the Community Content. For specific help about:
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History

7/22/2010
cotaque

8/15/2010
Thomas Lee

what why will this function fail

why will this function fail, when will this function fail and why does getlasterror return 0. this function works well for a time then returns null but there is no info on why what's going wrong????

[tfl - 15 08 10] Hi - and thanks for your post. You should post questions like this to the MSDN Forums at http://forums.microsoft.com/msdn or the MSDN Newsgroups at http://www.microsoft.com/communities/newsgroups/en-us/. You are much more likely get a quicker response using the forums than through the Community Content. For specific help about:
Visual Studio  : http://groups.google.com/groups/dir?sel=usenet%3Dmicrosoft.public.vstudio%2C&
SQL Server     : http://groups.google.com/groups/dir?sel=usenet%3Dmicrosoft.public.sqlserver%2C&
.NET Framework : http://groups.google.com/groups/dir?sel=usenet%3Dmicrosoft.public.dotnet.framework
PowerShell     : http://groups.google.com/group/microsoft.public.windows.powershell/topics?pli=1
All Public     : http://groups.google.com/groups/dir?sel=usenet%3Dmicrosoft.public%2C&