坐标转换

基础知识：设备坐标系统属性

其他知识：GDI映射模式

视口与窗口坐标转换公式：

以下代码都需要该代码支持：

 1 //int wmId, wmEvent;
 2     PAINTSTRUCT ps;
 3     HDC hdc;
 4     static int cxClient, cyClient;
 5     static HPEN hPen,oldHPen;
 6     static int cxChar, cxCpas, cyChar;
 7     TEXTMETRIC tm;
 8 
 9     switch (message)
10     {
11     //case WM_COMMAND:
12     //    wmId    = LOWORD(wParam);
13     //    wmEvent = HIWORD(wParam);
14     //    // 分析菜单选择: 
15     //    switch (wmId)
16     //    {
17     //    case IDM_ABOUT:
18     //        DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
19     //        break;
20     //    case IDM_EXIT:
21     //        DestroyWindow(hWnd);
22     //        break;
23     //    default:
24     //        return DefWindowProc(hWnd, message, wParam, lParam);
25     //    }
26     //    break;
27     case WM_CREATE:
28         hPen = CreatePen(PS_DASH, 0, RGB(255, 0, 0));
29         hdc = GetDC(hWnd);
30         GetTextMetrics(hdc, &tm);
31         cxChar = tm.tmAveCharWidth;
32         cxCpas = (tm.tmPitchAndFamily & 1 ? 3 : 2)*cxChar / 2;
33         cyChar = tm.tmHeight + tm.tmExternalLeading;
34         ReleaseDC(hWnd, hdc);
35     case WM_SIZE:
36         cxClient = LOWORD(lParam);
37         cyClient = HIWORD(lParam);
38         return 0;
View Code

原点设置在窗口中间通过更改矩形坐标实现居中

1 //原点设置在窗口中间通过更改矩形坐标实现居中
2         oldHPen = (HPEN)SelectObject(hdc, hPen);
3         MoveToEx(hdc, cxClient / 2, 0, NULL);
4         LineTo(hdc, cxClient / 2, cyClient);
5         MoveToEx(hdc, 0, cyClient / 2,NULL);
6         LineTo(hdc, cxClient, cyClient / 2);
7         SelectObject(hdc, oldHPen);
8         SetViewportOrgEx(hdc, cxClient / 2, cyClient / 2, NULL);
9         Rectangle(hdc, -50, 50, 50, -50);
View Code

通过设置原点使矩形实现居中

1 //通过设置原点使矩形实现居中
2         oldHPen = (HPEN)SelectObject(hdc, hPen);
3         MoveToEx(hdc, cxClient / 2, 0, NULL);
4         LineTo(hdc, cxClient / 2, cyClient);
5         MoveToEx(hdc, 0, cyClient / 2,NULL);
6         LineTo(hdc, cxClient, cyClient / 2);
7         SelectObject(hdc, oldHPen);
8         SetViewportOrgEx(hdc, (cxClient / 2)-150, (cyClient / 2)-150, NULL);
9         Rectangle(hdc, 100, 100, 200, 200);
View Code

通过更改TextOut的y轴实现hello的垂直输出

//通过更改TextOut的y轴实现hello的垂直输出
        oldHPen = (HPEN)SelectObject(hdc, hPen);
        MoveToEx(hdc, cxClient / 2, 0, NULL);
        LineTo(hdc, cxClient / 2, cyClient);
        MoveToEx(hdc, 0, cyClient / 2,NULL);
        LineTo(hdc, cxClient, cyClient / 2);
        SelectObject(hdc, oldHPen);
        for(int t = 0,y; t < 5;++t)
        {
            y = cyChar*t;
            TextOut(hdc, 0, y, TEXT("hello"), 5);
        }
View Code

通过更改视口的原点实现hello的垂直输出

 1 //通过更改视口的原点实现hello的垂直输出
 2         oldHPen = (HPEN) SelectObject(hdc, hPen);
 3         MoveToEx(hdc, cxClient / 2, 0, NULL);
 4         LineTo(hdc, cxClient / 2, cyClient);
 5         MoveToEx(hdc, 0, cyClient / 2, NULL);
 6         LineTo(hdc, cxClient, cyClient / 2);
 7         SelectObject(hdc, oldHPen);
 8         for(int t = 0, y; t < 5; ++t)
 9         {
10             y = cyChar*t;
11             SetViewportOrgEx(hdc, 0, y, NULL);
12             TextOut(hdc, 0, 0, TEXT("hello"), 5);
13         }
View Code

通过更改视口原点的x轴实现hello的横排列输出

 1 //通过更改视口原点的x轴实现hello的横排列输出
 2         oldHPen = (HPEN) SelectObject(hdc, hPen);
 3         MoveToEx(hdc, cxClient / 2, 0, NULL);
 4         LineTo(hdc, cxClient / 2, cyClient);
 5         MoveToEx(hdc, 0, cyClient / 2, NULL);
 6         LineTo(hdc, cxClient, cyClient / 2);
 7         SelectObject(hdc, oldHPen);
 8         for(int t = 0, x; t < 5; ++t)
 9         {
10             x = 50*t;
11             SetViewportOrgEx(hdc, x, 0, NULL);
12             TextOut(hdc, 0, 0, TEXT("hello"), 5);
13         }
View Code

设置窗口原更改Rectanglex轴和y轴实现居中

 1 //设置窗口原更改Rectanglex轴和y轴实现居中
 2         oldHPen = (HPEN)SelectObject(hdc, hPen);
 3         MoveToEx(hdc, cxClient / 2, 0, NULL);
 4         LineTo(hdc, cxClient / 2, cyClient);
 5         MoveToEx(hdc, 0, cyClient / 2,NULL);
 6         LineTo(hdc, cxClient, cyClient / 2);
 7         SelectObject(hdc, oldHPen);
 8         POINT apt;
 9         apt.x = cxClient;
10         apt.y = cyClient;
11         DPtoLP(hdc, &apt, 1);
12         SetWindowOrgEx(hdc, -apt.x / 2, -apt.y / 2, NULL);
13         Rectangle(hdc, -50, 50, 50, -50);
View Code

设置窗口原点实现Rectangle居中

 1 //设置窗口原点实现Rectangle居中
 2         oldHPen = (HPEN) SelectObject(hdc, hPen);
 3         MoveToEx(hdc, cxClient / 2, 0, NULL);
 4         LineTo(hdc, cxClient / 2, cyClient);
 5         MoveToEx(hdc, 0, cyClient / 2, NULL);
 6         LineTo(hdc, cxClient, cyClient / 2);
 7         SelectObject(hdc, oldHPen);
 8         POINT apt;
 9         apt.x = cxClient;
10         apt.y = cyClient;
11         DPtoLP(hdc, &apt, 1);
12         SetWindowOrgEx(hdc, -apt.x / 2+50, -apt.y / 2+50, NULL);
13         Rectangle(hdc, 0, 0, 100, 100);
View Code

非MM_TEXT映射下的坐标转换更改Rectangle坐标轴

 1 //非MM_TEXT映射下的坐标转换更改Rectangle坐标轴
 2         SetMapMode(hdc, MM_LOMETRIC);
 3         oldHPen = (HPEN) SelectObject(hdc, hPen);
 4         POINT pt;
 5         pt.x = cxClient;
 6         pt.y = cyClient;
 7         DPtoLP(hdc, &pt, 1);
 8         MoveToEx(hdc, pt.x/2, 0, NULL);
 9         LineTo(hdc, pt.x / 2, pt.y);
10         MoveToEx(hdc, 0, pt.y / 2, NULL);
11         LineTo(hdc, pt.x, pt.y / 2);
12         SelectObject(hdc, oldHPen);
13         SetWindowOrgEx(hdc, -pt.x / 2, -pt.y / 2, NULL);
14         Rectangle(hdc, -50, 50, 50, -50);
View Code

非MM_TEXT映射下的坐标转换更改原点实现Rectangle居中

 1 //非MM_TEXT映射下的坐标转换更改原点实现Rectangle居中
 2         SetMapMode(hdc, MM_LOMETRIC);
 3         oldHPen = (HPEN) SelectObject(hdc, hPen);
 4         POINT pt;
 5         pt.x = cxClient;
 6         pt.y = cyClient;
 7         DPtoLP(hdc, &pt, 1);
 8         MoveToEx(hdc, pt.x/2, 0, NULL);
 9         LineTo(hdc, pt.x / 2, pt.y);
10         MoveToEx(hdc, 0, pt.y / 2, NULL);
11         LineTo(hdc, pt.x, pt.y / 2);
12         SelectObject(hdc, oldHPen);
13         SetWindowOrgEx(hdc, -pt.x / 2+50, -pt.y / 2+50, NULL);
14         Rectangle(hdc, 0,0, 100, 100);
View Code

等待更新……

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原文地址：https://www.cnblogs.com/2016Study/p/5428850.html