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L_CombineBitmapWarp

Summary

Combines image data from the source bitmap (the slave) and the destination bitmap (the master), using a perspective warp.

Syntax

#include "l_bitmap.h"

L_LTKRN_API L_INT L_CombineBitmapWarp(pBitmapDst, ptDstArray, pBitmapSrc, ptSrc, nSrcWidth, nSrcHeight, uFlags)

Parameters

pBITMAPHANDLE pBitmapDst

Pointer to the bitmap handle referencing the destination bitmap. This is the master bitmap and is the bitmap that the function updates.

L_POINT ptDstArray

An array of POINT structures that contain the four points that define the warp area in the destination bitmap.

pBITMAPHANDLE pBitmapSrc

Pointer to the bitmap handle referencing the source bitmap. This is the slave bitmap, which is combined with the destination bitmap.

POINT structure that contains the point of origin of the source bitmap. This is the upper left corner. This point, along with nSrcWidth and nSrcHeight define the area of the source bitmap to be warped.

L_INT nSrcWidth

The width of the area in the source bitmap to be warped to the destination bitmap. This value, along with ptSrc and nSrcHeight define the area of the source bitmap to be warped.

L_INT nSrcHeight

The height of the area in the source bitmap to be warped to the destination bitmap. This value, along with ptSrc and nSrcWidth define the area of the source bitmap to be warped.

L_UINT uFlags

Flags that indicate the type of interpolation to use, if interpolation is used. Possible values are:

Value	Meaning
0	No interpolation
CBW_BILINEAR	Bilinear interpolation. This value is only valid if the bits per pixel of the image is 1-bit, 8-bit grayscale, 12-bit without a lookup table, 16-bit without a lookup table, 24, 32, 48, or 64.

Returns

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

Comments

You can warp the entire source bitmap, or a portion of the source bitmap. To warp a portion of the source bitmap, set ptSrc, nSrcWidth and nSrcHeight accordingly. To warp the entire source bitmap, set the following:

ptSrc.x = 0;   
ptSrc.y = 0;   
nSrcWidth = pBitmapSrc.BitmapWidth;   
nSrcHeight = pBitmapSrc.BitmapHeight;

The warp area in the destination bitmap is specified in ptDstArray. The polygon specified in ptDstArray must:

be concave.
fit entirely on the destination bitmap.

If either of these conditions is FALSE, this function will return an error.

The ordering of the points in ptDstArray can affect the resulting warp. For example, if the source bitmap is the following:

$image\WarpEx1.gif$

then ordering the points in ptDstArray as shown below results in the following warp:

$image\WarpEx2.gif$

while ordering the points in ptDstArray as shown below, results in the following warp:

$image\WarpEx3.gif$

Required DLLs and Libraries

LTKRN
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.

Example

L_INT CombineBitmapWarpExample(L_VOID) 
{ 
   L_INT nRet; 
   BITMAPHANDLE   Master; 
   BITMAPHANDLE   Slave; 
   POINT          ptSrc = {0,0}; 
   POINT          aptsDest[4]= { 
                                 {50,50}, 
                                 {100,75}, 
                                 {100,150}, 
                                 {50,100} 
                               }; 
 
   //load images as 24-bit, so we don't have to worry about palettes 
   nRet = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("master.jpg")), &Master, sizeof(BITMAPHANDLE), 24, ORDER_BGR, NULL, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
   nRet = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("cannon.jpg")), &Slave, sizeof(BITMAPHANDLE), 24, ORDER_BGR, NULL, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   nRet = L_CombineBitmapWarp(&Master, 
                              aptsDest, 
                              &Slave, 
                              ptSrc, 
                              Slave.Width, Slave.Height, 
                              CBW_BILINEAR); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.jpg")), &Master, FILE_JPEG, 0, 2, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
   if(Master.Flags.Allocated) 
      L_FreeBitmap(&Master); 
   if(Slave.Flags.Allocated) 
   L_FreeBitmap(&Slave); 
   return SUCCESS; 
}