C# 画国标五星红旗

时间：2010-10-05 来源：Jeffery You

INationFlag 1 public interface INationFlag
2 {
3     float WidthProportion { get; }
4     float HeightProportion { get; }
5     SizeF Size { get; set; }
6
7     void AdjustFlagSizeF(int width);
8     Image GetFlagImage();
9 }

ChinaFlag   1 class ChinaFlag : INationFlag
  2 {
  3     #region -  INationFlag Members  -
  4
  5     public float WidthProportion { get { return 3F; } }
  6     public float HeightProportion { get { return 2F; } }
  7
  8     SizeF size = SizeF.Empty;
  9
10     public SizeF Size
11     {
12         get { return size; }
13         set { if (size != value) size = value; }
14     }
15
16     public void AdjustFlagSizeF(int w)
17     {
18         int width = w + w % (int)WidthProportion;
19         int height = (int)(HeightProportion * width / WidthProportion);
20
21         Size = new SizeF(width, height);
22     }
23
24     public Image GetFlagImage()
25     {
26         Bitmap flag = new Bitmap((int)size.Width, (int)size.Height);
27         float piece = size.Width / 30;
28
29         int bigStarRadius = (int)(piece * 3);
30         int smlStarRadius = (int)piece;
31
32         using (Graphics g = Graphics.FromImage(flag))
33         {
34             g.SmoothingMode = SmoothingMode.AntiAlias;
35             g.FillRectangle(Brushes.Red, 0, 0, size.Width, size.Height);
36
37             g.DrawImage(GetStarImage(bigStarRadius), piece * 2, piece * 2);
38             g.DrawImage(GetStarImage(smlStarRadius, -(int)(Math.Atan(3.0 / 5.0) * 180.0 / Math.PI) - 18), piece * 9, piece);
39             g.DrawImage(GetStarImage(smlStarRadius, -(int)(Math.Atan(1.0 / 7.0) * 180.0 / Math.PI) - 18), piece * 11, piece * 3);
40             g.DrawImage(GetStarImage(smlStarRadius, 0), piece * 11, piece * 6);
41             g.DrawImage(GetStarImage(smlStarRadius, (int)(Math.Atan(4.0 / 5.0) * 180.0 / Math.PI) - 18), piece * 9, piece * 8);
42         }
43
44         return flag;
45     }
46
47     #endregion
48
49     #region -  Private Members  -
50
51     public Image GetStarImage(int radius)
52     {
53         Bitmap bigStar = new Bitmap(radius * 2, radius * 2);
54
55         using (Graphics g = Graphics.FromImage(bigStar))
56         {
57             g.SmoothingMode = SmoothingMode.AntiAlias;
58             Point pc = new Point(radius, radius);
59
60             PointF p0 = new PointF(pc.X, pc.Y - radius);
61             PointF p1 = new PointF((float)(pc.X + radius * Math.Sin(72 * Math.PI / 180)), (float)(pc.Y - radius * Math.Cos(72 * Math.PI / 180)));
62             PointF p2 = new PointF((float)(pc.X + radius * Math.Sin(36 * Math.PI / 180)), (float)(pc.Y + radius * Math.Cos(36 * Math.PI / 180)));
63             PointF p3 = new PointF((float)(pc.X - radius * Math.Sin(36 * Math.PI / 180)), (float)(pc.Y + radius * Math.Cos(36 * Math.PI / 180)));
64             PointF p4 = new PointF((float)(pc.X - radius * Math.Sin(72 * Math.PI / 180)), (float)(pc.Y - radius * Math.Cos(72 * Math.PI / 180)));
65
66             using (GraphicsPath path = new GraphicsPath(FillMode.Winding))
67             {
68                 path.AddLine(p0, p2);
69                 path.AddLine(p2, p4);
70                 path.AddLine(p4, p1);
71                 path.AddLine(p1, p3);
72                 path.AddLine(p3, p0);
73                 path.CloseFigure();
74                 g.FillPath(Brushes.Yellow, path);
75             }
76         }
77         return bigStar;
78     }
79
80     public Image GetStarImage(int radius, int angle)
81     {
82         return RotateImage(GetStarImage(radius), angle);
83     }
84     public Image RotateImage(Image b, int angle)
85     {
86         angle = angle % 360;
87         // 弧度转换
88          double radian = angle * Math.PI / 180.0;
89         double cos = Math.Cos(radian);
90         double sin = Math.Sin(radian);
91         // 原图的宽和高
92         int w = b.Width;
93         int h = b.Height;
94         int W = (int)(Math.Max(Math.Abs(w * cos - h * sin), Math.Abs(w * cos + h * sin)));
95         int H = (int)(Math.Max(Math.Abs(w * sin - h * cos), Math.Abs(w * sin + h * cos)));
96         // 目标位图
97         Bitmap dsImage = new Bitmap(W, H);
98         using (Graphics g = Graphics.FromImage(dsImage))
99         {
100             g.InterpolationMode = InterpolationMode.Bilinear;
101             g.SmoothingMode = SmoothingMode.AntiAlias;
102             // 计算偏移量
103               Point Offset = new Point((W - w) / 2, (H - h) / 2);
104             // 构造图像显示区域：让图像的中心与窗口的中心点一致
105             Rectangle rect = new Rectangle(Offset.X, Offset.Y, w, h);
106             Point center = new Point(rect.X + rect.Width / 2, rect.Y + rect.Height / 2);
107             g.TranslateTransform(center.X, center.Y);
108             g.RotateTransform(angle - 360);
109             // 恢复图像在水平和垂直方向的平移
110             g.TranslateTransform(-center.X, -center.Y);
111             g.DrawImage(b, rect);
112             // 重至绘图的所有变换
113             g.ResetTransform();
114             g.Save();
115
116         }
117         return dsImage.Clone(new Rectangle((W - w) / 2, (H - h) / 2, w, h), PixelFormat.DontCare);
118     }
119
120     #endregion
121
122     #region -  Constructor  -
123
124     public ChinaFlag(int w)
125     {
126         AdjustFlagSizeF(w);
127     }
128
129     #endregion
130 }
131

FrmMain 1 public partial class FrmMain : Form
2 {
3     public FrmMain()
4     {
5         InitializeComponent();
6     }
7     private void pbxCanvas_Paint(object sender, PaintEventArgs e)
8     {
9         INationFlag chinaFlag = new ChinaFlag(pbxCanvas.Width);
10         e.Graphics.DrawImage(chinaFlag.GetFlagImage(), 0, 0);
11     }
12     private void pbxCanvas_Resize(object sender, EventArgs e)
13     {
14         pbxCanvas.Invalidate();
15     }
16 }

本来是放在自己 QQ 博客里面的，因为《偷窥门事件》，最近不太想用 QQ 了，把一些东西陆陆续续地搬过来。