#include "l_bitmap.h"

L_LTDIS_API L_INT L_SetBitmapRgnHandle(pBitmap, pXForm, hRgn, uCombineMode)

Creates or updates the bitmap region by adding a region that is specified by a Windows region handle.



Pointer to the bitmap handle referencing the bitmap where the region is to be created or updated.


Pointer to an RGNXFORM structure that LEADTOOLS uses to translate between display coordinates and bitmap coordinates.

You should create this structure when the Windows region is created. Otherwise the device context values may not be available when you are ready to add the Windows region to the bitmap region.

If you specify NULL in this parameter, the scalar fields default to 1, the offsets default to 0, and the view perspective defaults to the bitmap's view perspective.


Handle to the Windows region.

L_UINT uCombineMode

The action to take regarding the existing bitmap region, if one is defined. For descriptions of the possible values, refer to Creating a Bitmap Region.


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


Before calling this function, you must declare an RGNXFORM structure and set its values, which LEADTOOLS uses to translate between device context coordinates and bitmap coordinates. For details about how the structure works refer to the RGNXFORM structure description. For a description of common usage, refer to Translating Coordinates for a Bitmap Region.

The device coordinates are the ones that were in effect at the time the Windows region was created.

If you want to assign a region from one bitmap to another, you must use the L_GetBitmapRgnHandle function to get region from the first bitmap; then use the L_SetBitmapRgnHandle function to assign the region to the second bitmap.

To update an existing region, you specify how the new region is to be combined with the existing one. For descriptions of the possibilities, refer to Creating a Bitmap Region.

Required DLLs and Libraries


Win32, x64, Linux.

See Also




For complete sample code, refer to the DRAW
This example creates and saves one elliptical region. It then creates a second
elliptical region and adds the saved region to it. Finally, it lightens the part of
the bitmap that is in the resulting region.

L_INT SetBitmapRgnHandleExample(L_HWND           hWnd,pBITMAPHANDLE  pBitmap) 
   L_INT nRet; 
   RGNXFORM XFormToBitmap;    /* Structure for transforming display coordinates */ 
   RGNXFORM XFormFromBitmap;  /* Structure for transforming bitmap coordinates */ 
   HDC      hWindowDC;        /* Device context of the current window */ 
   RECT     rClientArea;      /* Client area of the current window */ 
   RECT     rRgnRect;         /* Rectangle that defines the region */ 
   HRGN     SavedRegion;      /* Windows region handle used to save a region */ 
   /* Get the device context of the current window */ 
   hWindowDC = GetDC (hWnd); 
   /* Get the client area of the current window */ 
   /* Load a bitmap */ 
   nRet = L_LoadBitmap (MAKE_IMAGE_PATH(TEXT("ImageProcessingDemo\\Image3.cmp")), pBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Set XFormToBitmap fields, assuming that the display rectangle is the same 
   as the client area of the current window */ 
   XFormToBitmap.uViewPerspective = TOP_LEFT; 
   XFormToBitmap.nXScalarNum = BITMAPWIDTH(pBitmap); 
   XFormToBitmap.nXScalarDen = rClientArea.right; 
   XFormToBitmap.nYScalarNum = BITMAPHEIGHT(pBitmap); 
   XFormToBitmap.nYScalarDen = rClientArea.bottom; 
   XFormToBitmap.nXOffset = 0; 
   XFormToBitmap.nYOffset = 0; 
   /* Set XFormFromBitmap fields, assuming that the display rectangle is the same 
   as the client area of the current window */ 
   XFormFromBitmap.uViewPerspective = TOP_LEFT; 
   XFormFromBitmap.nXScalarNum = rClientArea.right; 
   XFormFromBitmap.nXScalarDen = BITMAPWIDTH(pBitmap); 
   XFormFromBitmap.nYScalarNum = rClientArea.bottom; 
   XFormFromBitmap.nYScalarDen = BITMAPHEIGHT(pBitmap); 
   XFormFromBitmap.nXOffset = 0; 
   XFormFromBitmap.nYOffset = 0; 
   /* Specify a rectangle to define the first elliptical region */ 
   SetRect(&rRgnRect, 0, rClientArea.bottom/8,  
      rClientArea.right/4, rClientArea.bottom/2); 
   /* Create the first elliptical region */ 
   nRet = L_SetBitmapRgnEllipse(pBitmap, &XFormToBitmap, &rRgnRect, L_RGN_SET); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Save the first elliptical region */ 
   nRet = L_GetBitmapRgnHandle(pBitmap, &XFormFromBitmap, &SavedRegion); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Free the region */ 
   /* Specify a rectangle to define the second elliptical region */ 
   SetRect(&rRgnRect, rClientArea.right/4, rClientArea.bottom/8,  
      rClientArea.right/2, rClientArea.bottom/2); 
   /* Create the second elliptical region */ 
   nRet = L_SetBitmapRgnEllipse(pBitmap, &XFormToBitmap, &rRgnRect, L_RGN_SET); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Add the saved region to the new one, resulting in side-by-side elliptical shapes */ 
   nRet = L_SetBitmapRgnHandle(pBitmap, &XFormToBitmap, SavedRegion, L_RGN_OR); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Lighten the region so that we will see it */ 
   nRet = L_ChangeBitmapIntensity(pBitmap,500, 0); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Delete the HRGN object */ 
   return SUCCESS; 

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