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L_SetBitmapRgnEllipse

#include "l_bitmap.h"

L_LTDIS_API L_INT L_SetBitmapRgnEllipse(pBitmap, pXForm, pRect, uCombineMode)

Creates or updates the bitmap region by adding an elliptical region.

Parameters

pBITMAPHANDLE pBitmap

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

pRGNXFORM pXForm

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

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.

L_RECT * pRect

Pointer to the windows RECT structure that specifies the bounding rectangle of the elliptical region. You specify the structure using device context coordinates, and LEADTOOLS translates the coordinates using the values specified in the pXForm parameter.

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.

Returns

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

Comments

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.

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

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, Linux.

Functions

Topics

Example

For complete sample code, refer to the CHILD.C module of the DEMO example. This example creates an elliptical region and lightens the part of the bitmap that is in the region.

L_INT SetBitmapRgnEllipseExample(L_HWND    hWnd,pBITMAPHANDLE pBitmap) 
{ 
   L_INT nRet; 
   RGNXFORM    XForm;         /* Structure for transforming display coordinates */ 
   HDC         hWindowDC;     /* Device context of the current window */ 
   RECT        rClientArea;   /* Client area of the current window */ 
   RECT        rRgnRect;      /* Rectangle that defines the region */ 
 
   /* Get the device context of the current window */ 
   hWindowDC = GetDC (hWnd); 
   /* Get the client area of the current window */ 
   GetClientRect(hWnd,&rClientArea); 
   /* 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 RGNXFORM fields, assuming that the display rectangle is the same 
   as the client area of the current window */ 
   XForm.uViewPerspective = TOP_LEFT; 
   XForm.nXScalarNum = BITMAPWIDTH(pBitmap); 
   XForm.nXScalarDen = rClientArea.right; 
   XForm.nYScalarNum = BITMAPHEIGHT(pBitmap); 
   XForm.nYScalarDen = rClientArea.bottom; 
   XForm.nXOffset = 0; 
   XForm.nYOffset = 0; 
   /* Specify a rectangle to define the region */ 
   SetRect(&rRgnRect, rClientArea.right/8, rClientArea.bottom/8,  
      rClientArea.right/2, rClientArea.bottom/2); 
   /* Create an elliptical region */ 
   nRet = L_SetBitmapRgnEllipse(pBitmap, &XForm, &rRgnRect, L_RGN_SET); 
   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; 
   /* Free the region */ 
   L_FreeBitmapRgn(pBitmap); 
   return SUCCESS; 
}

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