C++ WinAPI位图内存泄漏？

Question

所以，我对WinAPI非常陌生，我成功地加载了一个精灵，我可以用箭头键移动它。我的老师告诉我要非常小心的‘内存泄漏’，我不知道如何释放内存的正确方式，因为C++已经为我做了当我做控制台编程。我运行了这个程序，在移动角色一段时间后，它冻结了我的电脑一分钟，所以我想我做错了什么。你能告诉我如何正确释放内存(如果我做错了)，如果我的位图方法有什么坏的地方需要优化？谢谢!这是密码。

void LoadAndBlitBitmap(LPCSTR szFileName, HWND hwnd, HDC winDC, int xPos, int yPos)
{
//DEFINITIONS

/*TransparentBlt(destDC, destXpos, destYpos, sizeX, sizeY, srcDC, 0, 0, sizeX, sizeY, RGB(a, b, c)) = TRANSPARENT BITMAP BLIT. Ex. RGB(255, 255, 255) if background is white*/
/*BitBlt(destDC, destXpos, destYpos, sizeX, sizeY, srcDC, 0, 0, SRCCOPY);                           = SOLID BITMAP BLIT WITH NO TRANSPARENCY*/ 

//END DEFINITIONS

//-----Get the size of the window---------
RECT rect;
int win_width   = 0;
int win_height  = 0;
if(GetWindowRect(hwnd, &rect))
{
    win_width   = rect.right - rect.left;   //Subtracting the right coordinate with the left gives the width
    win_height  = rect.bottom - rect.top;   //Subtracting the bottom coordinate with the top gives the height
}
//----------------------------------------

HDC     hdcMem  = CreateCompatibleDC(winDC);                                //Create the DC that will hold the off-screen printing. (Double Buffering "Anti-Flicker" Method)
HBITMAP hbmMem  = CreateCompatibleBitmap(winDC, win_width, win_height);     //Create the bitmap with the size of the window
HANDLE  hOld    = SelectObject(hdcMem, hbmMem);                             //Set the paintable bitmap to the off-screen DC


//Draw to the off-screen DC
HBITMAP bitmap = (HBITMAP)LoadImage(NULL, szFileName, IMAGE_BITMAP, 69, 69, LR_LOADFROMFILE);       //Load the .bmp from a file
HDC blockDC = CreateCompatibleDC(NULL);                                                             //Create a DC to hold the .bmp
SelectObject(blockDC, bitmap);                                                                      //Select the .bmp to the DC
TransparentBlt(hdcMem, xPos, yPos, 69, 69, blockDC, 0, 0, 69, 69, RGB(255, 255, 255));              //Blit the .bmp to the DC*/


//Transfer off-screen DC to the screen
BitBlt(winDC, 0, 0, win_width, win_height, hdcMem, 0, 0, SRCCOPY);

// Uninitialize and deallocate resources
SelectObject(hdcMem, hOld);
DeleteDC(hdcMem);
SelectObject(blockDC, hOld);
DeleteDC(blockDC);
DeleteObject(bitmap);
}

Answer 1

有两件事是错误的：

SelectObject(blockDC, hOld);

hOld不是来自blockDC，而是来自hdcMem。您甚至没有从blockDC中保存旧的位图。改为：

HBITMAP hOld2 = SelectObject(blockDC, bitmap);
// and
SelectObject(blockDC, hOld2);

其次，您不能在任何地方删除hbmMem。在底部加上：

DeleteObject(hbmMem);

实际上，第三件事也是错误的--您没有检查您所做的任何API调用是否失败。您应该检查CreateCompatibleDC是否返回NULL，如果返回，则中止和清除。