Stretchdibits function

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The StretchDIBits function copies the color data for a rectangle of pixels in a DIB, JPEG, or PNG image to the specified destination rectangle. If the destination rectangle is larger than the source rectangle, this function stretches the rows and columns of color data to fit the destination rectangle. If the destination rectangle is smaller than the source rectangle, this function compresses the rows and columns by using the specified raster operation.

translate :

StretchDIBits Function DIB、JPEG、PNG The pixel color data in a rectangular area of the image is copied to the specified target rectangle . If the destination rectangle is larger than the source rectangle , This function stretches the rows and columns to fit the color data of the target rectangle . If the destination rectangle is smaller than the source rectangle , Then this function uses the specified raster operation to compress rows and columns .

grammar ：

int StretchDIBits (HDC hdc,int XDest,YDest,int int nDestWidth,int nDestHeight,int XSrc,int YSrc,int nSrcWidth,int nSrcHeight,const VOID __in * lpBits,__in const BITMAPINFO * lpBitsInfo,__in UINT iUsage,__in dword = dwRop) ;

Parameters ：

hdc [ Enter the reference ]

Handle to the target device context .

XDest [ Enter the reference ]

Corner x coordinate , The upper left corner of the destination rectangle in logical units .

YDest [ Enter the reference ]

Y coordinate , The upper left corner of the target rectangle on the logical unit .

nDestWidth [ Enter the reference ]

Logical unit , The width of the target rectangle .

nDestHeight [ Enter the reference ]

Logical unit , The height of the target rectangle .

XSrc [ Enter the reference ]

Angular x coordinate , In pixels , Source rectangle image .

YSrc [ Enter the reference ]

Y coordinate , In pixels , Source rectangle image .

nSrcWidth [ Enter the reference ]

Width , In pixels , Source rectangle image .

nSrcHeight [ Enter the reference ]

The height is in pixels , Source rectangle image .

lpBits [ Enter the reference ]

Bit of image , Pointer stored as a byte array . For more information , Please refer to the remarks section .

lpBitsInfo [ Enter the reference ]

Directional inclusion DIB Related information BITMAPINFO Pointer to structure .

iUsage [ Enter the reference ]

Specify whether to provide BITMAPINFO Structural bmiColors member , And if so , whether bmiColors Contains explicit red 、 green 、 blue (RGB) Value or index .IUsage The parameter must be one of the following values .

value	remarks
DIB_RGB_COLORS	The color table contains text RGB value .
DIB_PAL_COLORS	This array contains... Into the logical palette of the source device context 16 Bit index .

dwRop [ Enter the reference ]

Combine together in the specified way to form a new image source pixel 、 Current brush and target pixel of the target device context . For more information , Please refer to the remarks section below .

Return value

If the function succeeds , Then the return value is the number of rows scanned and copied . Please note that , This value can be negative image content .

If the function fails , Or no scan line is copied , The return value is 0.

If the driver does not support JPEG or PNG File image is passed to StretchDIBits, This function will fail and return GDI_ERROR. If something goes wrong , Applications must rely on their own JPEG or PNG Support , Decompress the image into bitmap , Then pass the bitmap to StretchDIBits.

remarks

Bottom up DIB The starting position of is the lower left corner ; From top to bottom DIB The starting position of is the upper left corner .

StretchDIBits Create an image of a bitmap mirror , If nSrcWidth and nDestWidth These two parameters or nSrcHeight and nDestHeight The symbols of these two parameters are different .NSrcWidth and nDestWidth Different symbols , Then this function creates an edge x Axis mirrored bitmap image .NSrcHeight and nDestHeight Different symbols , Then the function is created along y Axis mirrored bitmap image .

This function allows JPEG or PNG The image is passed in as the source image . How each parameter is used remains unchanged , Unless ：

• If BITMAPINFOHEADER Of biCompression The members are BI_JPEG or BI_PNG,lpBits Directional inclusion JPEG or PNG Image separate buffer .BITMAPINFOHEADER Structural biSizeImage Member specifies the size of the buffer .IUsage The parameter has to be set to DIB_RGB_COLORS.DwRop The parameter has to be set to SRCCOPY.
• To ensure that there is an appropriate metafile cache pool when printing , Calling StretchDIBits Before , The application must call CHECKJPEGFORMAT or CHECKPNGFORMAT Escape to verify that the printer can recognize JPEG or PNG Images .

ICM： If by using SetICMMode Of iEnableICM Parameter set to ICM_ON The call of enables color management , Then color management will be implemented . If by lpBitsInfo The specified bitmap has a specified gamma and member endpoint member BITMAPV4HEADER Structure or a designation profileData and profileSize Member of or gamma and member end knot member BITMAPV5HEADER Then all pixels of the bitmap will be regarded as expressed in the color space described by these members rather than the source color space of the device context .

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