C++ Win32 在WM_CREATE中加载多个位图不会加载

C++ Win32 loading multiple bitmaps in WM_CREATE won't load

本文关键字：加载 位图 Win32 WM CREATE C++      更新时间：2023-10-16

我正在尝试在启动应用程序时加载一些位图。我正在尝试WM_CREATE加载它们，但只有我加载的最后一个位图会保持加载状态。

我可以在WM_PAINT中加载图片，但我被告知最好将它们加载到WM_CREATE中。

//before switch statement
static HBITMAP bitmap1, bitmap2;
case WM_CREATE: {
HINSTANCE hInstance = GetModuleHandle(NULL);
bitmap1 = (HBITMAP)LoadImage(hInstance, MAKEINTRESOURCE(IDB_BITMAP1),
IMAGE_BITMAP, 0, 0, LR_DEFAULTCOLOR);
bitmap2 = (HBITMAP)LoadImage(hInstance, MAKEINTRESOURCE(IDB_BITMAP2),
IMAGE_BITMAP, 0, 0, LR_DEFAULTCOLOR);
if (!bitmap1 || !bitmap2) MessageBox(NULL, _T("Error while loading images"), _T("Error!"), MB_ICONEXCLAMATION | MB_OK);
case WM_PAINT:{
//Draw bitmap...
}

我希望两个位图都像在WM_PAINT中加载时一样加载

编辑：

问题不是我想的。问题是它画在我制作的填充区域后面。我仍然不知道如何解决。

//Draw bitmap function
bool DrawBitmap(HBITMAP hBitmap, int posX, int posY, int sizeX, int sizeY)
{
BITMAP bmp;
HWND hWnd = FindWindow(windowClassName, NULL);
if (!hWnd) return false;
HDC hdc = GetDC(hWnd);
if (!hdc) return false;
HDC hBitmapDC = CreateCompatibleDC(hdc);
if (!hBitmapDC) return false;
GetObject(hBitmap, sizeof(bmp), &bmp);
SelectObject(hBitmapDC, hBitmap);
BitBlt(hdc, posX, posY, sizeX, sizeY, hBitmapDC, 0, 0, SRCCOPY);
DeleteObject(hBitmap);
ReleaseDC(hWnd, hBitmapDC);
ReleaseDC(hWnd, hdc);
return true;
}
//Before switch
RECT recRect;
STATIC HBITMAP bitmap1;
//case WM_CREATE:
case WM_CREATE: {
HINSTANCE hInstance = GetModuleHandle(NULL);
bitmap1 = (HBITMAP)LoadImage(hInstance, MAKEINTRESOURCE(IDB_BITMAP1),
IMAGE_BITMAP, 0, 0, LR_DEFAULTCOLOR);
if (!bitmap) MessageBox(NULL, _T("Error while loading images"), _T("Error!"), MB_ICONEXCLAMATION | MB_OK);
return 0;
break;
//case WM_PAINT
case WM_PAINT:
DefWindowProc(hwnd, msg, wParam, lParam);
hdc = GetWindowDC(hwnd);
recRect = { -1, -1, 50 + 1, 30 + 1 };
FillRect(hdc, &recRect, (HBRUSH)CreateSolidBrush(RGB(30, 30, 30)));

if (DrawBitmap(bitmap1, 5, 5, 10, 10) == false) MessageBox(NULL, _T("Error while drawing images"), _T("Error!"), MB_ICONEXCLAMATION | MB_OK);
return DefWindowProc(hwnd, msg, wParam, lParam);
return 0;
break;

当我在WM_PAINT中声明位图时不会出现此问题

  1. GetWindowDC返回整个窗口(包括非工作区(的 dc。您通常需要GetDC。

  2. 响应WM_PAINT时始终使用BeginPaint/EndPaint并返回 0。

  3. CreateSolidBrush是 GDI 资源泄漏。创建画笔或其他 GDI 对象后，必须销毁这些对象，否则资源泄漏，程序将在 10,000 次 GDI 泄漏后崩溃。

  4. 在绘制函数中，您有DeleteObject(hBitmap)这将立即销毁位图。但是您可能希望保留位图句柄，并仅在程序完成后销毁它。

建议：

bool DrawBitmap(HDC hdc, HBITMAP hBitmap, int posX, int posY, int sizeX, int sizeY)
{
HDC memdc = CreateCompatibleDC(hdc);
HGDIOBJ oldbmp = SelectObject(memdc, hBitmap);
BitBlt(hdc, posX, posY, sizeX, sizeY, memdc, 0, 0, SRCCOPY);
SelectObject(memdc, oldbmp);
DeleteDC(memdc);
return true;
}
...
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
HBRUSH hbrush = CreateSolidBrush(RGB(255, 0, 0));
FillRect(hdc, &ps.rcPaint, hbrush);
DeleteObject(hbrush); 
BITMAP bm1;
GetObject(bitmap1, sizeof(bm1), &bm1);
DrawBitmap(hdc, bitmap1, 0, 0, bm1.bmWidth, bm1.bmHeight);
int x = bm1.bmWidth;
int y = bm1.bmHeight;
BITMAP bm2;
GetObject(bitmap2, sizeof(bm2), &bm2);
DrawBitmap(hdc, bitmap2, x, y, bm2.bmWidth, bm2.bmHeight);
EndPaint(hwnd, &ps);
return 0;
}
case WM_DESTROY:
DeleteObject(bitmap1);
DeleteObject(bitmap2);
PostQuitMessage(0);
return 0;
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