C# 绘图问题

linxinru1976 2009-04-26 02:48:01

使用C# GDI+绘图中，如何实现以下效果？随着鼠标的移动画矩形线（及时删除原来的矩形框），松开鼠标时显示最后状态下的矩形框

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优途科技 2009-04-27

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完全可以，类似橡皮线。

null1 2009-04-27

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http://blog.csdn.net/null1/archive/2008/10/22/3124630.aspx

a260881071 2009-04-27

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顶

热学沸腾56 2009-04-27

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lz如果是这样移动一个图中的部分的话，建立lz最好不要这么搞...会出现闪烁...效果很差...
我以前也用GDI+做过流程图..

冰凝瞬间1986 2009-04-27

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GDI+

gomoku 2009-04-27

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这是个DrawReversibleFrame的例子:



public partial class Form1 : Form

{

    Point startPoint = new Point(-1, -1);

    Rectangle lastRect = Rectangle.Empty;

    List<Rectangle> rectangles = new List<Rectangle>();



    public Form1()

    {

        InitializeComponent();

    }



    protected override void OnMouseDown(MouseEventArgs e)

    {

        this.startPoint = this.PointToScreen(e.Location);

    }



    protected override void OnMouseMove(MouseEventArgs e)

    {

        if (this.startPoint.X >= 0)

        {

            Point current = this.PointToScreen(e.Location);

            Size size = new Size(current.X - startPoint.X, current.Y - startPoint.Y);



            ControlPaint.DrawReversibleFrame(lastRect, this.BackColor, FrameStyle.Dashed);  //擦旧

            lastRect = new Rectangle(startPoint, size);

            ControlPaint.DrawReversibleFrame(lastRect, this.BackColor, FrameStyle.Dashed);  //画新

        }

    }



    protected override void OnMouseUp(MouseEventArgs e)

    {

        if (this.startPoint.X >= 0)

        {

            ControlPaint.DrawReversibleFrame(lastRect, this.BackColor, FrameStyle.Dashed);  //擦

            this.startPoint.X = -1;



            this.rectangles.Add(Normalize(this.RectangleToClient(lastRect)));

            this.lastRect = Rectangle.Empty;

            this.Invalidate();

        }

    }



    protected override void OnPaint(PaintEventArgs e)

    {

        foreach (Rectangle rect in this.rectangles)

        {

            e.Graphics.DrawRectangle(Pens.Black, rect);

        }

    }



    private Rectangle Normalize(Rectangle rect)

    {

        if (rect.Width < 0) { rect.X += rect.Width; rect.Width = -rect.Width; }

        if (rect.Height < 0) { rect.Y += rect.Height; rect.Height = -rect.Height; }

        return rect;

    }

}

aimeast 2009-04-26

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用gdi的异或原理画图吧，这样容易擦除。
注意，不是gdi++

LemIST 2009-04-26

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up
先用背景色重画原来的矩形,可以清除原来的.
然后再画现在的矩形.

zcandyly20211 2009-04-26

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友情up！

yeaicc 2009-04-26

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处理鼠标的单击事件

footprint2008 2009-04-26

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[Quote=引用楼主 linxinru1976 的帖子:]
使用C# GDI+绘图中，如何实现以下效果？随着鼠标的移动画矩形线（及时删除原来的矩形框），松开鼠标时显示最后状态下的矩形框
[/Quote]

ding^^^^^^^^^^^

yangqidong 2009-04-26

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把以前做的一个东西裁剪了一下，供参考
public partial class Form1 : Form
{
private bool isDrawing = false;
Rectangle currentShape;
private BufferedGraphics bg;
public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
this.BackColor = Color.White;
bg = BufferedGraphicsManager.Current.Allocate(this.CreateGraphics(), this.ClientRectangle);

}
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
if (!isDrawing)
{
isDrawing = true;
currentShape = new Rectangle(e.Location, 0, 0);
}
}

private void Form1_MouseUp(object sender, MouseEventArgs e)
{
if (isDrawing)
{
isDrawing = false;
currentShape = null;
}
}

private void Form1_MouseMove(object sender, MouseEventArgs e)
{
if (isDrawing)
{
Rectangle rectangle = (Rectangle)currentShape;
rectangle.RectangleWidth = e.X - rectangle.Location.X;
rectangle.RectangleHight = e.Y - rectangle.Location.Y;
bg.Graphics.Clear(Color.White);
rectangle.Draw(bg.Graphics);
bg.Render();
}

}
}

class Rectangle
{

private Point location;
public Point Location
{
get { return location; }
set { location = value; }
}

private int rectangleHeight;

public int RectangleHight
{
get { return rectangleHeight; }
set { rectangleHeight = value; }
}
private int rectangleWidth;

public int RectangleWidth
{
get { return rectangleWidth; }
set { rectangleWidth = value; }
}

public Rectangle(Point location, int rectangleWidth, int rectangleHeight)
{
this.location = location;
this.rectangleWidth = rectangleWidth;
this.rectangleHeight = rectangleHeight;
}

public void Draw(Graphics gfx)
{
Point actualLocation = new Point(
location.X + (rectangleWidth >= 0 ? 0 : rectangleWidth),
location.Y + (rectangleHeight >= 0 ? 0 : rectangleHeight)
);
int actualWidth = (rectangleWidth >= 0 ? rectangleWidth : -rectangleWidth);
int actualHeight = (rectangleHeight >= 0 ? rectangleHeight : -rectangleHeight);
gfx.DrawRectangle(Pens.Red, actualLocation.X, actualLocation.Y, actualWidth, actualHeight);
}
}