C#畫圖(WinForm)

使用C#在Windows應用程序裏繪圖，可能用到移動圖像、擦掉圖像，調整大小等等。我這裏有一個畫圖的小程序，簡單的實現了這些。。。

 

定義圖像的基類：

 

abstract class DrawBase
...{
    internal Color m_BackColor;
    internal Color m_ForeColor;
    internal static int m_HalfGrab;

    public static int HalfGrab
    ...{
        get ...{ return DrawBase.m_HalfGrab; }
        set ...{ DrawBase.m_HalfGrab = value; }
    }

    public Color BackColor
    ...{
        get ...{ return m_BackColor; }
        set ...{ m_BackColor = value; }
    }

    public Color ForeColor
    ...{
        get ...{ return m_ForeColor; }
        set ...{ m_ForeColor = value; }
    }

    public abstract Rectangle GetBound();
    public abstract void Draw(Graphics g);
    public abstract bool Near(int x, int y);
    public abstract void SetBound(Rectangle bound);
}

定義線：

 

class LineObj:DrawBase
...{
    private Point m_Start;
    private Point m_End;
    public LineObj(Point start, Point end)
    ...{
        this.m_Start = start;
        this.m_End = end;
    }
    public override System.Drawing.Rectangle GetBound()
    ...{
        int x = this.m_Start.X < this.m_End.X ? this.m_Start.X : this.m_End.X;
        int y = this.m_Start.Y < this.m_End.Y ? this.m_Start.Y : this.m_End.Y;
        int r = this.m_Start.X < this.m_End.X ? this.m_End.X : this.m_Start.X;
        int b = this.m_Start.Y < this.m_End.Y ? this.m_End.Y : this.m_Start.Y;
        return Rectangle.FromLTRB(x, y, r, b);
    }

    public override void Draw(System.Drawing.Graphics g)
    ...{
        using (Pen pen = new Pen(this.m_ForeColor))
        ...{
            g.DrawLine(pen, this.m_Start, this.m_End);
        }
    }

    public override bool Near(int x, int y)
    ...{
        //點到直線的距離是否在抓取範圍之內
        float A = this.m_End.Y- this.m_Start.Y;
        float B = this.m_End.X- this.m_Start.X;
        float C = B * this.m_Start.Y - A * this.m_Start.X;
        double D = (A * x - B * y + C) / (Math.Sqrt(A * A + B * B));
        if (D >= -m_HalfGrab && D <= m_HalfGrab)
        ...{
            RectangleF bounds = this.GetBound();
            bounds.Inflate(m_HalfGrab, m_HalfGrab);
            return bounds.Contains(x, y);
        }
        return false;
    }

    public override void SetBound(Rectangle bound)
    ...{
        this.m_Start = new Point(bound.X, bound.Y);
        this.m_End = new Point(bound.Right, bound.Bottom);
    }
}

定義矩形：

 

class RectangleObj:DrawBase
...{
    private Point m_Start;
    private Point m_End;
    private bool m_Solid;
    public RectangleObj(Point start, Point end)
    ...{
        this.m_Start = start;
        this.m_End = end;
    }
    public bool Solid
    ...{
        get ...{ return m_Solid; }
        set ...{ m_Solid = value; }
    }
    public override System.Drawing.Rectangle GetBound()
    ...{
        int x = this.m_Start.X < this.m_End.X ? this.m_Start.X : this.m_End.X;
        int y = this.m_Start.Y < this.m_End.Y ? this.m_Start.Y : this.m_End.Y;
        int r = this.m_Start.X < this.m_End.X ? this.m_End.X : this.m_Start.X;
        int b = this.m_Start.Y < this.m_End.Y ? this.m_End.Y : this.m_Start.Y;
        return Rectangle.FromLTRB(x, y, r, b);
    }

    public override void Draw(Graphics g)
    ...{
        Rectangle bound = this.GetBound();
        if (this.m_Solid)
        ...{
            using (SolidBrush brush = new SolidBrush(this.m_BackColor))
            ...{
                g.FillRectangle(brush, bound);
            }
        }
        using (Pen pen = new Pen(this.m_ForeColor))
        ...{
            g.DrawRectangle(pen, bound);
        }
    }

    public override bool Near(int x, int y)
    ...{
        Rectangle bound = this.GetBound();
        Rectangle inner = bound;
        Rectangle outer = bound;
        inner.Inflate(-m_HalfGrab, -m_HalfGrab);
        outer.Inflate(m_HalfGrab, m_HalfGrab);
        Region reg = new Region(outer);
        reg.Exclude(inner);
        return reg.IsVisible(x, y);
    }

    public override void SetBound(Rectangle bound)
    ...{
        this.m_Start = new Point(bound.X, bound.Y);
        this.m_End = new Point(bound.Right, bound.Bottom);
    }
}

當然也可以繪製Window控件：

 

class ButtonObj:DrawBase
...{
    private Point m_Start;
    private Point m_End;
    private string m_Text;
    public ButtonObj(Point start, Point end)
    ...{
        this.m_Start = start;
        this.m_End = end;
    }
    public string Text
    ...{
        get ...{ return m_Text; }
        set ...{ m_Text = value; }
    }
    public override System.Drawing.Rectangle GetBound()
    ...{
        int x = this.m_Start.X < this.m_End.X ? this.m_Start.X : this.m_End.X;
        int y = this.m_Start.Y < this.m_End.Y ? this.m_Start.Y : this.m_End.Y;
        int r = this.m_Start.X < this.m_End.X ? this.m_End.X : this.m_Start.X;
        int b = this.m_Start.Y < this.m_End.Y ? this.m_End.Y : this.m_Start.Y;
        return Rectangle.FromLTRB(x, y, r, b);
    }

    public override void Draw(Graphics g)
    ...{
        Rectangle bound = this.GetBound();
        using (Pen pen = new Pen(this.m_ForeColor))
        ...{
            ControlPaint.DrawButton(g, bound, ButtonState.Normal);
            using (SolidBrush brush = new SolidBrush(this.m_ForeColor))
            ...{
                using (Font font = new Font("宋體", 10))
                ...{
                    using (StringFormat format = new StringFormat())
                    ...{
                        format.Alignment = StringAlignment.Center;
                        format.LineAlignment = StringAlignment.Center;
                        g.DrawString(this.m_Text, font, brush, bound, format);
                    }
                }
            }
        }
    }

    public override bool Near(int x, int y)
    ...{
        Rectangle bound = this.GetBound();
        Rectangle outer = bound;
        outer.Inflate(m_HalfGrab, m_HalfGrab);
        return outer.Contains(x, y);
    }

    public override void SetBound(Rectangle bound)
    ...{
        this.m_Start = new Point(bound.X, bound.Y);
        this.m_End = new Point(bound.Right, bound.Bottom);
    }
}

定義這些圖像的集合對象：

 

class DrawList:List<DrawBase>
...{
    private Control m_Owner;
    public DrawList(Control owner)
    ...{ 
        this.m_Owner = owner;
    }
    internal DrawBase GetNear(int x, int y)
    ...{
        foreach (DrawBase draw in this)
        ...{
            if (draw.Near(x, y))
            ...{
                return draw;
            }
        }
        return null;
    }

    internal void Draw(Graphics graphics)
    ...{
        foreach (DrawBase draw in this)
        ...{
            draw.Draw(graphics);
        }
    }
}

構建一個Window窗體用來展示圖像操作：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using DrawLines.DrawObjs;

namespace DrawLines
...{
    public partial class Form1 : Form
    ...{
        private DrawList m_drawList;
        private DrawBase m_curDraw;
        private Rectangle m_curBound;
        private Rectangle m_lastBound;
        private Point m_StartPoint;
        public Form1()
        ...{
            InitializeComponent();
            this.SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint, true);

            this.InitObjs();
        }
        /**//// <summary>
        /// 構造對象
        /// </summary>
        private void InitObjs()
        ...{
            this.m_drawList = new DrawList(this);

            DrawBase.HalfGrab = 5;
            LineObj line0 = new LineObj(new Point(10, 10), new Point(100, 100));
            line0.ForeColor = Color.Red;

            LineObj line1 = new LineObj(new Point(16, 67), new Point(100, 180));
            line1.ForeColor = Color.Blue;

            RectangleObj rect = new RectangleObj(new Point(120, 70), new Point(220, 200));
            rect.ForeColor = Color.Green;

            ButtonObj button = new ButtonObj(new Point(20, 20), new Point(90, 45));
            button.ForeColor = Color.Black;
            button.Text = "button1";
            m_drawList.Add(line0);
            m_drawList.Add(line1);
            m_drawList.Add(rect);
            m_drawList.Add(button);
        }
        /**//// <summary>
        /// 繪製對象
        /// </summary>
        /// <param name="e"></param>
        protected override void OnPaint(PaintEventArgs e)
        ...{
            this.m_drawList.Draw(e.Graphics);
            base.OnPaint(e);
        }
        /**//// <summary>
        /// 重寫以移動對象或設置鼠標
        /// </summary>
        /// <param name="e"></param>
        protected override void OnMouseMove(MouseEventArgs e)
        ...{
            base.OnMouseMove(e);
            if (this.Capture)
            ...{
                if (this.m_curDraw != null)
                ...{
                    this.moveObj(e);
                }
                return;
            }
            if (this.m_drawList.GetNear(e.X, e.Y) != null)
            ...{
                this.Cursor = Cursors.SizeAll;
            }
            else
            ...{
                this.Cursor = Cursors.Default;
            }
        }
        /**//// <summary>
        /// 重寫以獲取鼠標下的對象
        /// </summary>
        /// <param name="e"></param>
        protected override void OnMouseDown(MouseEventArgs e)
        ...{
            base.OnMouseDown(e);
            this.getObj(e);
        }
        /**//// <summary>
        /// 重寫以按Delete鍵刪除當前對象
        /// </summary>
        /// <param name="keyData"></param>
        /// <returns></returns>
        protected override bool ProcessDialogKey(Keys keyData)
        ...{
            if (keyData == Keys.Delete)
            ...{
                if (this.m_curDraw != null)
                ...{
                    this.deleteObj();
                }
            }
            return base.ProcessDialogKey(keyData);
        }
        private void btnDelete_Click(object sender, EventArgs e)
        ...{
            if (this.m_curDraw != null)
            ...{
                this.deleteObj();
            }
            else
            ...{
                MessageBox.Show(this, "沒有選中的對象，請使用鼠標點選擇一個！", "提示");
            }
        }
        private void moveObj(MouseEventArgs e)
        ...{
            Rectangle bound = this.m_curBound;

            bound.Offset(e.X - this.m_StartPoint.X, e.Y - this.m_StartPoint.Y);
            this.m_curDraw.SetBound(bound);

            Rectangle _last = this.m_lastBound;
            Rectangle _bound = bound;
            _last.Inflate(2, 2);
            _bound.Inflate(2, 2);

            using (Region invReg = new Region(_last))
            ...{
                invReg.Union(_bound);
                this.Invalidate(invReg);
            }
            this.m_lastBound = bound;
        }
        private void getObj(MouseEventArgs e)
        ...{
            this.m_curDraw = this.m_drawList.GetNear(e.X, e.Y);
            if (this.m_curDraw != null)
            ...{
                this.m_curBound = this.m_curDraw.GetBound();
                this.m_StartPoint = e.Location;
            }
        }
        private void deleteObj()
        ...{
            Rectangle bound = this.m_curDraw.GetBound();
            this.m_drawList.Remove(this.m_curDraw);
            this.m_curDraw = null;
            bound.Inflate(2, 2);
            this.Invalidate(bound);
        }
    }
}