在按钮上绘制对象单击WINAPI32

Question

我是 winapi 和 c ++ 的新手，所以我试图尝试制作绘图项目。我用3个单选按钮创建了GUI来选择颜色，4个用于获取尺寸的文本字段和一个用于绘制任何对象的按钮（ex.Rectangle）。但是我无法找到一种在点击按钮后绘制的方法，只有当我把代码放到 ＆＃34; WM_PAINT＆＃34; <时才能绘制。 /强>

案例WM_CREATE：

    label1 = CreateWindow(L"STATIC", L"Title",
        WS_VISIBLE | WS_CHILD ,
        200, 10, 60, 20,
        hwnd, NULL, NULL, NULL);
    //X,Y,WIDHT,HIGHT
    label2 = CreateWindow(L"STATIC", L"Select color",
        WS_VISIBLE | WS_CHILD,
        190, 40, 60, 20,
        hwnd, NULL, NULL, NULL);

    HWND radiobutton1, radiobutton2, radiobutton3;
    radiobutton1 = CreateWindow(L"BUTTON", L"Red",
        WS_CHILD | WS_VISIBLE | BS_AUTORADIOBUTTON,
        50, 70, 100, 50,
        hwnd, (HMENU)801,
        GetModuleHandle(NULL), 0);

    radiobutton2 = CreateWindow(L"BUTTON", L"Blue",
        WS_CHILD | WS_VISIBLE | BS_AUTORADIOBUTTON,
        150, 70, 100, 50,
        hwnd, (HMENU)802,
        GetModuleHandle(NULL), 0);

    radiobutton3 = CreateWindow(L"BUTTON", L"Green",
        WS_CHILD | WS_VISIBLE | BS_AUTORADIOBUTTON,
        250, 70, 100, 50,
        hwnd, (HMENU)803,
        GetModuleHandle(NULL), 0);


    textbox1 = CreateWindow(L"EDIT",
        L"X0", WS_BORDER | WS_CHILD | WS_VISIBLE,
        50, 120, 50, 20,
        hwnd, NULL, NULL, NULL);
    textbox2 = CreateWindow(L"EDIT",
        L"Y0", WS_BORDER | WS_CHILD | WS_VISIBLE,
        110, 120, 50, 20,
        hwnd, NULL, NULL, NULL);
    textbox3 = CreateWindow(L"EDIT",
        L"X", WS_BORDER | WS_CHILD | WS_VISIBLE,
        170, 120, 50, 20,
        hwnd, NULL, NULL, NULL);
    textbox4 = CreateWindow(L"EDIT",
        L"Y", WS_BORDER | WS_CHILD | WS_VISIBLE,
        230, 120, 50, 20,
        hwnd, NULL, NULL, NULL);
    CreateWindowExA(0, "Button", "Random text", WS_CHILD | WS_VISIBLE |
        WS_CLIPSIBLINGS | BS_AUTOCHECKBOX | BS_TEXT | WS_GROUP |
        WS_TABSTOP, 100, 300, 300, 48, hwnd, (HMENU)811, NULL, 0);
    button = CreateWindow(L"Button",
        L"Print", WS_VISIBLE | WS_CHILD | WS_BORDER,
        150, 480, 100, 30, hwnd, (HMENU)111, NULL, NULL);

    AddMenus(hwnd);

    break;

我试着这样做：

案例WM_COMMAND：

    wmId = LOWORD(wParam);
    wmEvent = HIWORD(wParam);
    PAINTSTRUCT ps;
    HDC hdc;
    hdc = BeginPaint(hwnd, &ps);
    if (wmId == 801)
    {
        if (wmEvent == BN_CLICKED)
        {
            LRESULT chkState = SendMessage((HWND)lParam, BM_GETCHECK, 0, 0);
            if (chkState == BST_CHECKED)
                qEllipseColor = RGB(255, 0, 0);
        }
        break;
    };
    if (wmId == 802)
    {
        if (wmEvent == BN_CLICKED)
        {
            LRESULT chkState = SendMessage((HWND)lParam, BM_GETCHECK, 0, 0);
            if (chkState == BST_CHECKED)
                qEllipseColor = RGB(0, 0, 255);
        }
        break;
    };
    if (wmId == 803)
    {
        if (wmEvent == BN_CLICKED)
        {
            LRESULT chkState = SendMessage((HWND)lParam, BM_GETCHECK, 0, 0);
            if (chkState == BST_CHECKED)
                qEllipseColor = RGB(0, 255, 0);
        }
        break;
    };

    switch (LOWORD(wParam)) {


    case 111:{


        HPEN hEllipsePen;
        hEllipsePen = CreatePen(PS_SOLID, 3, qEllipseColor);// qEllipseColor is global which gets its RGB value from radio buttons
        hPenOld = (HPEN)SelectObject(hdc, hEllipsePen);

        Arc(hdc, 100, 100, 500, 250, 0, 0, 0, 0);

        SelectObject(hdc, hPenOld);
        DeleteObject(hEllipsePen);



    }break;