如何让鼠标滑动的轨迹显示出来？急！

[alicezc]

我想在窗口中鼠标按下后到鼠标放开前，所移动的轨迹即一个矩形框显示出来，到鼠标放开后，该轨迹就消失，如何实现呢？
非常感谢！

[alicezc]

请问听雨舟，[DllImport("user32.dll")]应该放在C#程序的什么位置？怎么编译也通不过呀？谢谢。

[alicezc]

我试过了，是往窗口上画鼠标移动的轨迹。不是我想要的那种。
我想要的是：从鼠标点击到放开，出现一个虚线框，就象画图里面的选定功能。
有人知道么？能帮帮我么？感谢！

[ekeen]

把line 设为dot line
wangjs720的方法可以

[jackie615]

我知道你要的是类似：
在windows桌面上按下鼠标拖动出现的虚线框

应该不难啊，处理方法跟上面画线的类似，改画框不就是
帮你UP

[Jim3]

刚完成，等一下贴出来

[silverduck]

该程序从鼠标点击到放开，出现一个矩形框,放开时用黑色填充矩形
你可以适当的改这个程序,满足你的要求

//---------------------------------------
// BlockOut.cs ?2001 by Charles Petzold
//---------------------------------------
using System;
using System.Drawing;
using System.Windows.Forms;

class BlockOut: Form
{
bool bBlocking, bValidBox;
Point ptBeg, ptEnd;
Rectangle rectBox;

public static void Main()
{
Application.Run(new BlockOut());
}
public BlockOut()
{
Text = "Blockout Rectangle with Mouse";
BackColor = SystemColors.Window;
ForeColor = SystemColors.WindowText;
}
protected override void OnMouseDown(MouseEventArgs mea)
{
if (mea.Button == MouseButtons.Left)
{
ptBeg = ptEnd = new Point(mea.X, mea.Y);

Graphics grfx = CreateGraphics();
grfx.DrawRectangle(new Pen(ForeColor), Rect(ptBeg, ptEnd));
grfx.Dispose();

bBlocking = true;
}
}
protected override void OnMouseMove(MouseEventArgs mea)
{
if (bBlocking)
{
Graphics grfx = CreateGraphics();
grfx.DrawRectangle(new Pen(BackColor), Rect(ptBeg, ptEnd));
ptEnd = new Point(mea.X, mea.Y);
grfx.DrawRectangle(new Pen(ForeColor), Rect(ptBeg, ptEnd));
grfx.Dispose();
Invalidate();
}
}
protected override void OnMouseUp(MouseEventArgs mea)
{
if (bBlocking && mea.Button == MouseButtons.Left)
{
Graphics grfx = CreateGraphics();
rectBox = Rect(ptBeg, new Point(mea.X, mea.Y));
grfx.DrawRectangle(new Pen(ForeColor), rectBox);
grfx.Dispose();

bBlocking = false;
bValidBox = true;
Invalidate();
}
}
protected override void OnPaint(PaintEventArgs pea)
{
Graphics grfx = pea.Graphics;

if (bValidBox)
grfx.FillRectangle(new SolidBrush(ForeColor), rectBox);

if (bBlocking)
grfx.DrawRectangle(new Pen(ForeColor), Rect(ptBeg, ptEnd));
}
Rectangle Rect(Point ptBeg, Point ptEnd)
{
return new Rectangle(Math.Min(ptBeg.X, ptEnd.X),
Math.Min(ptBeg.Y, ptEnd.Y),
Math.Abs(ptEnd.X - ptBeg.X),
Math.Abs(ptEnd.Y - ptBeg.Y));
}
}

[Jim3]

public class Rubberband
{
protected Control parent;
protected Rectangle rect = Rectangle.Empty;

public Rubberband(Control theParent, Point theStartingPoint)
{
parent = theParent;
parent.Capture = true;
Cursor.Clip = parent.RectangleToScreen(parent.ClientRectangle);
rect = new Rectangle(theStartingPoint.X, theStartingPoint.Y, 0, 0);
}

public void End()
{
Cursor.Clip = Rectangle.Empty;
parent.Capture = false;

// erase the rubberband
Draw();
rect = Rectangle.Empty;
}

public void ResizeTo(Point thePoint)
{
// erase the old rubberband
Draw();

// get the new size of the rubberband
rect.Width = thePoint.X - rect.Left;
rect.Height = thePoint.Y - rect.Top;

// draw the new rubberband
Draw();
}

public Rectangle Bounds()
{
// return a normalized rectangle, i.e. a rect
// where (left <= right) and (top <= bottom)
if ( (rect.Left > rect.Right) || (rect.Top > rect.Bottom) )
{
int left = Math.Min(rect.Left, rect.Right);
int right = Math.Max(rect.Left, rect.Right);
int top = Math.Min(rect.Top, rect.Bottom);
int bottom = Math.Max(rect.Top, rect.Bottom);
return Rectangle.FromLTRB(left, top, right, bottom);
}
return rect;
}

// Reversible drawing method
// Calling theis method the first time draws the rubberband.
// Calling it a second time with the same rect erases the rubberband
protected void Draw()
{
Rectangle r = parent.RectangleToScreen(rect);
ControlPaint.DrawReversibleFrame(r, Color.White, FrameStyle.Dashed);
}
}

[Jim3]

上面的那个类不是我写的，从树上抄的，在窗体的MouseMove，MouseDown，MouseUp加入一下代码即可


private void Form1_MouseMove(object sender, MouseEventArgs e)
{
if (rubberband != null)
rubberband.ResizeTo(new Point(e.X,e.Y));
}


private void Form1_MouseDown(object sender, MouseEventArgs e)
{
this.rubberband = new Rubberband(this,new Point(e.X,e.Y));

}

private void Form1_MouseUp(object sender,MouseEventArgs e)
{
if (rubberband != null)
{

rubberband.End();
rubberband = null;

}

}

[alicezc]

非常感谢，我先看看。

[dahuzizyd]

这个地址：
http://www.c-sharpcorner.com/Code/2002/Mar/RubberBandLinesNShapes.asp
把他的原代码改动一下，就是你要的效果：
在Form1_Paint事件里：
Pen pen = new Pen(Color.Black);
在这一句的后面加上：
float[] dashValues = {1, 1, 1, 1};
pen.DashPattern = dashValues;
ok！

[alicezc]

我试了，的确能实现。非常非常感谢大家。只可惜我设的分值太少了。请多包涵！

[firejie]

mark

[alicezc]

为什么没人回复呢？是不是我没说明白？
我的意思是如果大家在操作系统桌面上点击鼠标，向右下方移动鼠标，就出现一个虚线表示的矩形框，我想在自己的窗口中也做个类似的，如何实现呢？
非常非常感谢！

[alicezc]

没有人知道么？请大帮帮忙！
万分感谢！

[wangjs720]

[DllImport("user32.dll")]
public static extern bool SetCapture(IntPtr hWnd);
[DllImport("user32.dll")]
public static extern bool ReleaseCapture();
[DllImport("gdi32.dll", EntryPoint="SetPixel")]
public static extern int SetPixel (
IntPtr hdc,
int x,
int y,
int crColor
);
[DllImport("user32.dll", EntryPoint="GetDC")]
public static extern IntPtr GetDC (
IntPtr hwnd
);
//-------------------------------------------------------
bool bCapturing = false;


private void Form1_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
{
if(bCapturing)
{
Point pt = PointToScreen(new Point(e.X,e.Y));
IntPtr hDC = GetDC(IntPtr.Zero);
SetPixel(hDC,pt.X,pt.Y,255);
}
}

private void Form1_MouseUp(object sender, System.Windows.Forms.MouseEventArgs e)
{
ReleaseCapture();
bCapturing = false;
}

private void Form1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
SetCapture(this.Handle);
bCapturing = true;
}