L_PaintRgnDCBufferCallback

#include "l_bitmap.h"

L_LTDIS_API L_INT L_PaintRgnDCBufferCallback (pCallbackData, pBitmap, pSrc, pClipSrc, pDst, pClipDst, uROP3, pBuffer, nRow, nCount)

pPAINTCALLBACKDATA pCallbackData;	/* pointer to the callback data structure */
pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_RECT * pSrc;	/* pointer to the display source rectangle */
L_RECT * pClipSrc;	/* pointer to the display source clipping rectangle */
L_RECT * pDst;	/* pointer to the display destination rectangle */
L_RECT * pClipDst;	/* pointer to the display destination clipping rectangle */
L_UINT32 uROP3;	/* windows ROP code for display */
L_UCHAR * pBuffer;	/* pointer to the source buffer */
L_INT nRow;	/* first row to paint */
L_INT nCount;	/* number of rows to paint */

Paints image data from a buffer using paint callbacks. This function works the same as L_PaintDCBufferCallback, except that only the bitmap region is painted.

Parameter	Description
pCallbackData	Pointer to a structure containing the device context (DC) and the paint callbacks. The mapping mode of the device context must be MM_TEXT.
pBitmap	Pointer to the bitmap handle referencing the bitmap that has the region to paint.
pSrc	Pointer to the Windows RECT structure that specifies the part of the bitmap to use as the display source.
	The coordinates in the RECT structure are relative to the bitmap. You can pass NULL to use the default, which matches the bitmap.
pClipSrc	Pointer to the Windows RECT structure that specifies the portion of the display source to paint. Generally, this is used for updating the display when part of the source bitmap has changed.
	The coordinates in the RECT structure are relative to the bitmap. You can pass NULL to use the default, which matches the bitmap.
pDst	Pointer to the Windows RECT structure that determines how the source rectangle is scaled and how the image is positioned in the device context.
	The coordinates in the RECT structure are relative to the device context. There is no default for this parameter. You must specify the RECT structure.
pClipDst	Pointer to the Windows RECT structure that specifies the portion of the display rectangle to paint. Generally, this is used for updating changes in the display surface, such as when a user moves another window, uncovering a part of the image that had been covered up.
	The coordinates in the RECT structure are relative to the device context. You can pass NULL to use the default, which matches the device context. In most cases, however, you should use the rectangle returned by the Windows WM_PAINT message.
uROP3	The Windows ROP code that determines how the destination rectangle is updated. This parameter takes the same codes as the Windows BitBlt function. For ordinary painting, use SRCCOPY.
pBuffer	Pointer to the buffer that contains the image data to paint.
nRow	The first row to paint. The painted portion of any row may be limited by the RECT parameters.
nCount	The number of rows to paint. The painted portion of any row may be limited by the RECT parameters.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

The HDC you are painting to should stored in the PAINTCALLBACKDATA structure. Please refer to its documentation for details on which GDI functions you can override.

The bitmap must be allocated before you can create a region for it. Therefore, if you use this function in a paint-while-load routine, you must use your callback function to create the region after the bitmap is allocated.

Required DLLs and Libraries

LTDIS

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Win32, x64.

See Also

Functions:	L_FrameBitmapRgn, L_PaintRgnDC, L_PaintRgnDCCallback, L_PaintDCBuffer, L_PaintDCBufferCallback, L_PaintRgnDCEffect, L_WindowLevel, L_RectToBitmap, L_RectFromBitmap
Structures:	PAINTCALLBACKDATA
Topics:	Raster Image Functions: Displaying Images
	Paint Using Custom Callbacks
	Raster Image Functions: Palettes
	Defining and Using a Bitmap Region
	Handling Palette Changes
	Raster Image Functions: Using Custom Paint

Example

Creates a region in the image, then gets the data one line at a time and paints it.

L_INT PaintRgnDCBufferCallbackExample(L_HWND hWnd, pBITMAPHANDLE pBitmap)
{
   L_INT    nRet=SUCCESS;
   HDC      hdc;                    /* Device context for the current window */
   RECT     rcDest;                 /* Destination rectangle for painting */
   HPALETTE hSavedPalette = NULL;   /* Temporary copy of the current system palette */
   HPALETTE hOurPalette = NULL;     /* The palette that we will use to paint */
   RECT     rcRgn;
   L_INT    x;
   PAINTCALLBACKDATA PaintCallbackData;

   SetRect(&rcRgn, BITMAPWIDTH(pBitmap)*1/4, BITMAPHEIGHT(pBitmap)*1/4,
                   BITMAPWIDTH(pBitmap)*3/4, BITMAPHEIGHT(pBitmap)*3/4);
   L_SetBitmapRgnEllipse(pBitmap, NULL, &rcRgn, L_RGN_SET);

   /* Get the device context */
   hdc = GetDC (hWnd);
   /* Set the destination rectangle to be the same as the bitmap.
   Other painting rectangles can take defaults. */
   GetClientRect(hWnd, &rcDest);
   /* Create the palette that we will use to paint */
   hOurPalette = L_CreatePaintPalette (hdc, pBitmap);
   /* Select our palette and save the old one */
   hSavedPalette = SelectPalette (hdc, hOurPalette, FALSE);
   /* Realize our palette */
   RealizePalette (hdc); 

   /* Initialize the paint callback data structure */
   memset(&PaintCallbackData, 0, sizeof(PaintCallbackData));
   PaintCallbackData.uStructSize = sizeof(PAINTCALLBACKDATA);
   PaintCallbackData.pDisplay = hdc;

   /* set the paint callbacks for the GDI functions you are overriding here

        PaintCallbackData.pIsCompatibleDC = MyIsCompatibleDC;
        PaintCallbackData.pStretchDIBits = MyStretchDIBits;
        etc
   */

   /* Paint the image */
   L_AccessBitmap(pBitmap);
   for(x=0; x<pBitmap->Height; x++)
   {
      L_UCHAR *pBuf = (L_UCHAR*)malloc(pBitmap->BytesPerLine);
      L_GetBitmapRow(pBitmap, pBuf, x, pBitmap->BytesPerLine);
      nRet = L_PaintRgnDCBufferCallback(&PaintCallbackData, pBitmap, NULL, NULL, &rcDest, NULL, SRCCOPY, pBuf, x, 1);
   }
   L_ReleaseBitmap(pBitmap);

   /* Restore the old palette */
   SelectPalette (hdc, hSavedPalette, FALSE);

   /* Delete the newly created palette */
   DeleteObject (hOurPalette);

   /* Release the device context */
   ReleaseDC(hWnd, hdc);
   return nRet;
}