CreateCompatibleBitmap function (wingdi.h)

The CreateCompatibleBitmap function creates a bitmap compatible with the device that is associated with the specified device context.

Syntax

HBITMAP CreateCompatibleBitmap(
  [in] HDC hdc,
  [in] int cx,
  [in] int cy
);

Parameters

[in] hdc

A handle to a device context.

[in] cx

The bitmap width, in pixels.

[in] cy

The bitmap height, in pixels.

Return value

If the function succeeds, the return value is a handle to the compatible bitmap (DDB).

If the function fails, the return value is NULL.

Remarks

The color format of the bitmap created by the CreateCompatibleBitmap function matches the color format of the device identified by the hdc parameter. This bitmap can be selected into any memory device context that is compatible with the original device.

Because memory device contexts allow both color and monochrome bitmaps, the format of the bitmap returned by the CreateCompatibleBitmap function differs when the specified device context is a memory device context. However, a compatible bitmap that was created for a nonmemory device context always possesses the same color format and uses the same color palette as the specified device context.

Note: When a memory device context is created, it initially has a 1-by-1 monochrome bitmap selected into it. If this memory device context is used in CreateCompatibleBitmap, the bitmap that is created is a monochrome bitmap. To create a color bitmap, use the HDC that was used to create the memory device context, as shown in the following code:

    HDC memDC = CreateCompatibleDC ( hDC );
    HBITMAP memBM = CreateCompatibleBitmap ( hDC, nWidth, nHeight );
    SelectObject ( memDC, memBM );

If an application sets the nWidth or nHeight parameters to zero, CreateCompatibleBitmap returns the handle to a 1-by-1 pixel, monochrome bitmap.

If a DIB section, which is a bitmap created by the CreateDIBSection function, is selected into the device context identified by the hdc parameter, CreateCompatibleBitmap creates a DIB section.

When you no longer need the bitmap, call the DeleteObject function to delete it.

Examples

For an example, see Scaling an Image.

Requirements

See also

Bitmap Functions

Bitmaps Overview

CreateDIBSection

DeleteObject

SelectObject