Question

我有一个简单的GUI，当我在某个标签上时，它应该显示图像。我在选项卡过程中有WM_PAINT消息，如下所示

case WM_PAINT:
    {
            PAINTSTRUCT psLOGO;
            RECT rcLOGO;
            HDC hdcLOGO;
            //Prepares for painting window
            hdcLOGO = BeginPaint(hwndMonitor, &psLOGO);
            //Retrieves the coordinates of the windows client area
            GetClientRect(hwndMonitor, &rcLOGO);
            //creates a copy of the memory device context 
            HDC hdcDoubleLOGO = CreateCompatibleDC(hdcLOGO);
            HBITMAP Logo = LoadBitmap(GetModuleHandle(NULL), MAKEINTRESOURCE(IDB_BITMAP1));         //Get a bitmap of the picture to be updated
            HBITMAP bmOldLOGO = (HBITMAP)SelectObject(hdcDoubleLOGO, Logo);                                 //Get a handle to the image being replaced
            BitBlt(hdcLOGO, 0, 0, rcLOGO.right, rcLOGO.bottom, hdcDoubleLOGO, 0, 0, SRCCOPY);   //Bit block transfer of the bitmap color data

            SelectObject(hdcDoubleLOGO, bmOldLOGO);
            DeleteDC(hdcDoubleLOGO);
            EndPaint(hwndMonitor, &psLOGO);
            DeleteObject(Logo);
        break;
    }

hwndMonitor是该特定标签页的句柄

当我打开选项卡时图像显示，但如果我调整窗口大小，或者如果我最小化并重新打开GUI，图像将消失

我必须转到另一个标签并返回该标签以获取图像

我在WM_PAINT消息中做错了吗？

Answer 1

您还必须对WM_SIZE消息做出反应。调整窗口大小不会释放绘制消息。

在WM_SIZE上只需调用：

InvalidateRect(hwnd,&rect,TRUE);
UpdateWindow(hwnd);

rect是一个具有当前窗口大小的矩形。 Invalidate标记重绘的矩形，UpdateWindow确保它立即重新绘制。

调整窗口大小时位图消失

1 个答案: