#include "l_bitmap.h"
L_LTDIS_API L_INT L_DoubleBufferEnd(hDoubleBufferHandle, hDC)
L_HANDLE hDoubleBufferHandle; |
/* double buffering handle */ |
L_HDC hDC; |
/* handle to the target device context */ |
Displays the double buffered paint operations.
Parameter |
Description |
hDoubleBufferHandle |
Handle that identifies the double buffering process. |
hDC |
Handle to the original target device context. |
Returns
SUCCESS |
The function was successful. |
< 1 |
An error occurred. Refer to Return Codes. |
Comments
Use L_DoubleBufferEnd when ready to paint all that has been double-buffered to the target hDC. All double buffered paint operations should be wrapped in L_DoubleBufferBegin and L_DoubleBufferEnd calls.
The hDC argument is the device context that you want to double buffer, which in this case should be the same as the hDC argument that was passed to L_DoubleBufferBegin.
Note that you must create a double buffer handle with L_DoubleBufferCreateHandle before calling this function.
For more information, see the topic Minimizing Flicker With Double Buffering.
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_DoubleBufferEnable, L_DoubleBufferCreateHandle, L_DoubleBufferDestroyHandle, L_DoubleBufferBegin |
Topics: |
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Example
To see how double buffering can be used in an application, see the source code for the API annotation demo. This sample illustrates double buffering by bouncing a ball around a window that contains an image For simplicity, we assume both the window the hDC are 24 bit Run the example twice -- * once with bDoubleBuffer set to FALSE * once with bDoubleBuffer set to TRUE to see the difference hWnd -- window to paint image and bounce ball pszFile -- file name of image to load bDoubleBuffer - flag saying whether or not to double buffer the paints
#define BALL_RADIUS 30 L_INT DoubleBufferEndExample(L_HWND hWnd, L_TCHAR* pszFile, L_BOOL bDoubleBuffer) { HBRUSH hBrush; BITMAPHANDLE Bitmap; L_HANDLE hDoubleBufferHandle; L_INT cx, cy; HDC hDC, hMemDC; RECT rcClient; RECT rcBitmap; RECT rcBall; L_INT dx, dy; L_INT i; L_INT nRet; nRet = L_LoadBitmap(pszFile, &Bitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGRORGRAY, NULL, NULL); if (nRet != SUCCESS) { MessageBox(hWnd, TEXT("Failed to load image"), TEXT("Error"), MB_OK); return nRet; } hBrush = CreateSolidBrush( RGB(100,100,100)); nRet = L_DoubleBufferCreateHandle(&hDoubleBufferHandle); if(nRet != SUCCESS) return nRet; nRet = L_DoubleBufferEnable(hDoubleBufferHandle, bDoubleBuffer); if(nRet != SUCCESS) return nRet; GetClientRect(hWnd, &rcClient); cx = rcClient.right - rcClient.left; cy = rcClient.bottom - rcClient.top; hDC = GetDC(hWnd); rcBitmap.left = 0; rcBitmap.top = 0; rcBitmap.right = BITMAPWIDTH(&Bitmap); rcBitmap.bottom = BITMAPWIDTH(&Bitmap); SetRect(&rcBall, 0, 0, BALL_RADIUS, BALL_RADIUS); dx = dy = 1; for (i=0; i<2000; i++) { // Double buffer painting the image and the moving ball hMemDC = L_DoubleBufferBegin(hDoubleBufferHandle, hDC, cx, cy); FillRect(hMemDC, &rcClient, hBrush); nRet = L_PaintDC(hMemDC, &Bitmap, NULL, NULL, &rcBitmap, NULL, SRCCOPY); if(nRet != SUCCESS) return nRet; Ellipse(hMemDC, rcBall.left, rcBall.top, rcBall.right, rcBall.bottom); nRet = L_DoubleBufferEnd(hDoubleBufferHandle, hDC); if(nRet != SUCCESS) return nRet; if ((rcBall.bottom) > rcClient.bottom) dy = -1; if (rcBall.top < 0) dy = 1; if (rcBall.left < 0) dx = 1; if ((rcBall.right) > rcClient.right) dx = -1; OffsetRect(&rcBall, dx, dy); } // Cleanup L_FreeBitmap(&Bitmap); L_DoubleBufferDestroyHandle(hDoubleBufferHandle); DeleteObject(hBrush); return SUCCESS; }