L_SetBitmapDataPointer (original) (raw)

Summary

Sets the data pointer for the specified bitmap to the specified data pointer pData.

Syntax

#include "l_bitmap.h"

L_LTKRN_API L_INT L_SetBitmapDataPointer(pBitmap, pData, dwSize)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle that references the bitmap whose data pointer will be set.

L_UCHAR *pData

Data pointer used to set the specified bitmaps data pointer.

L_SIZE_T dwSize

Size of the data buffer pointed to by pData.

Returns

Comments

This function can be used to change the data pointer of a bitmap that was created by L_CreateBitmap, or allocated by L_AllocateBitmap, with memory type TYPE_USER. The data pointer to of the bitmap is set to the data pointer passed in through pData.

You are responsible for managing the image data. L_FreeBitmap will not free pData.

The memory buffer pointed to by pData must be valid when the bitmap is being used. If you free a memory buffer that is referenced by a bitmap, you will get access violations when you try to use that bitmap.

If you pass NULL for pData, the bitmap has no bitmap data. You should not try to use a bitmap that has no data pointer.

Note: To calculate the correct size for a single row of image data:

• Windows: (((Width * BitsPerPixel) + 31) >> 3)) &~3
• Linux: (((Width * BitsPerPixel) + 7) / 8)

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.

See Also

Functions

• L_AllocateBitmap
• L_CreateBitmap

Topics

• Raster Image Functions: Creating and Deleting Images

Example

Please note that you need to free the memory allocated for the bitmap
and the bitmap data using the following:

L_INT SetBitmapDataPointerExample(pBITMAPHANDLE pBitmap) { // allocate a buffer large enough to hold two copies of the image L_UCHAR* pBuffer = (L_UCHAR*)GlobalAllocPtr(GMEM_MOVEABLE, pBitmap->Size * 2); L_INT i; L_INT nRet; // lock the bitmap L_AccessBitmap(pBitmap); // loop and get the flipped and normal versions of the image into pBuffer for(i = 0; i < pBitmap->Height; i++) { nRet =(L_INT) L_GetBitmapRow(pBitmap, pBuffer + i * pBitmap->BytesPerLine, pBitmap->ViewPerspective == TOP_LEFT ? pBitmap->Height - i - 1 : i, pBitmap->BytesPerLine); if(nRet < 1) return nRet; memcpy( pBuffer + pBitmap->Size + (pBitmap->Height - i - 1) * pBitmap->BytesPerLine, pBuffer + i * pBitmap->BytesPerLine, pBitmap->BytesPerLine); } //unlock the bitmap L_ReleaseBitmap(pBitmap); // free the original image. Note that it is assumed that the image was 24 bit // for simplicity, so that it is not necessary to pass an array of palette entries to L_CreateBitmap // For color images, you would have to get the palette entries and pass them instead of NULL L_FreeBitmap(pBitmap); // this sets the image to be the flipped version if((nRet = L_CreateBitmap(pBitmap, sizeof(BITMAPHANDLE), TYPE_USER, pBitmap->Width, pBitmap->Height, pBitmap->BitsPerPixel, pBitmap->Order, NULL, TOP_LEFT, pBuffer, pBitmap->Size)) == SUCCESS) { MessageBox( NULL, TEXT("The image is flipped"), TEXT(""), MB_OK); // this sets the image to be the non-flipped version return L_SetBitmapDataPointer(pBitmap, pBuffer + pBitmap->Size, pBitmap->Size); } return nRet; }