请问在winform里,怎样在一个图片上面绘制一个区域

[Navymk]

想让用户自己在图片上划一个区域做裁切.该区域应可以移动和改变大小等,类似ps中的crop功能.
谢谢!

[Navymk]

补充一句:仅画出区域就可以了,不必裁切.

[财富实验室]

gdi+

[SuperTyro]

你可以看看 有关GDI+编程的部分

他对于动态的图片处理 和类似画板功能的实现 都很有帮助的



我是小菜鸟！ 说的不好清见谅， 希望能够帮到你！

[Navymk]

具体说说思路可否?

[SuperTyro]

在GID+ 中 有画笔类

可以使用画笔来画 当然 这需要使用画笔的一些方法

这样 我给你一个例子吧

一个画椭圆的例子
protected override void OnPaint(PaintEventArgs e)
{
//创建对象
Graphics g=e.Graphics;
//创建一支宽度为8象素的实践笔
Pen solidPen=new Pen(Color.Black,8);
//创建一支虚线笔
Pen dashPen=new Pen(Color.Red);

dashPen.DashStyle=System.Drawing.Drawing2D.DashStyle.Dash;

//绘制一个椭圆:边框的宽度为80,高度为40,左上角位于(100,50)
g.DrawEllipse(solidPen,100,50,80,40);

//再来个绘制弧线的 我正好复习下代码 ^_^
g.DrawArc(dashPen,100,50,140,70,30,180);

//释放画笔
solidPen.Dispose();
dashPen.Dispose();
}

希望对你有帮助

我是小菜鸟！ 说的不好清见谅， 希望能够帮到你！

[Navymk]

谢谢.
gdi的绘制已经了解了.
我现在需要的是一个可以拖动并改变大小的半透明的层.gdi绘制的这个矩形可以实现吗?

[wzuomin]

给你看看这个
http://blog.csdn.net/wzuomin/archive/2006/12/13/1441007.aspx

[Navymk]

晕,刚才我也是用picturebox模拟了这种效果...呵呵,我用c#,vb代码看得好累...但是透明还没实现...感觉gdi绘图似乎不是我想要的效果

[wzuomin]

lz想要的这种效果其实可以通过显示一个Form（设置该Form的透明度）来实现。
但是这个Form需要设置无边框，并可以拖动及改变大小才行。
下面这个是我用过的方法，不妨试一下吧。呵呵

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Text;
using System.Windows.Forms;

namespace BrowserPlugins
{
    public partial class FormCatcher : Form
    {
        public FormCatcher()
        {
            InitializeComponent();
        }

        public int x = 0;
        public int y = 0;
        public Rectangle r; 
               
        private void FormCatcher_Paint(object sender, PaintEventArgs e)
        {
            using (Graphics g = e.Graphics)
            {
                Rectangle rect = new Rectangle(0, 0, this.ClientRectangle.Width - 1, this.ClientRectangle.Height - 1);
                g.DrawRectangle(Pens.Red, rect);
            }
        }

        private void FormCatcher_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                this.x = e.X;
                this.y = e.Y;
                r = this.Bounds;
            }
        }

        private void FormCatcher_MouseMove(object sender, MouseEventArgs e)
        {          
            if (e.Button == MouseButtons.Left)
            {
                int dx = e.X - x;
                int dy = e.Y - y;
                this.Location = new Point(this.Location.X + dx, this.Location.Y + dy);   
            }                                         
        }

        private void FormCatcher_DoubleClick(object sender, EventArgs e)
        {
            Bitmap bmpCatched = new Bitmap(this.Width, this.Height);
            Graphics g = Graphics.FromImage(bmpCatched);
            g.CopyFromScreen(this.Location, new Point(0, 0), this.ClientRectangle.Size);
            Clipboard.SetImage(bmpCatched);
            MessageBox.Show("截图已经复制到剪切板！","info", MessageBoxButtons.OK, MessageBoxIcon.Information);
            this.Close();
        }

        #region ReSize
        private void FormCatcher_Resize(object sender, EventArgs e)
        {
            btn0.SetBounds(0,0,8,8);
            btn1.SetBounds((this.Width-8)/2,0,8,8 );
            btn2.SetBounds(this .Width -8,0,8,8);
            btn3.SetBounds(0,(this .Height -8)/2,8,8);
            btn4.SetBounds(this .Width -8,(this.Height -8)/2,8,8);
            btn5.SetBounds(0,this.Height -8,8,8);
            btn6.SetBounds((this .Width -8)/2,this .Height -8,8,8);
            btn7.SetBounds(this .Width -8,this .Height -8,8,8);
        }
       
        int x0, y0;
        private void btn0_MouseDown(object sender, MouseEventArgs e)
        {
            x0 = e.X; y0 = e.Y;
        }

        private void btn0_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                int dx = e.X - x0; int dy = e.Y - y0;
                this.SetBounds(this.Location.X + dx, this.Location.Y + dy, this.Width - dx, this.Height - dy);
            }
        }

        int x1, y1;
        private void btn1_MouseDown(object sender, MouseEventArgs e)
        {
            x1 = e.X; y1 = e.Y;
        }

        private void btn1_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                int dx = e.X - x1; int dy = e.Y - y1;
                this.SetBounds(this .Location .X,this .Location .Y +dy,this.Width ,this.Height -dy);
            }
        }

        int x2, y2;
        private void btn2_MouseDown(object sender, MouseEventArgs e)
        {
            x2 = e.X; y2 = e.Y;
        }

        private void btn2_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                int dx = e.X - x2; int dy = e.Y - y2;
                this.SetBounds(this .Location .X ,this .Location .Y+dy ,this .Width +dx,this .Height -dy);
            }
        }

        int x3, y3;
        private void btn3_MouseDown(object sender, MouseEventArgs e)
        {
            x3 = e.X; y3 = e.Y;
        }

        private void btn3_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                int dx = e.X - x3; int dy = e.Y - y3;
                this.SetBounds(this .Location .X+dx ,this .Location .Y,this .Width -dx,this .Height  );
            }
        }

        int x4, y4;
        private void btn4_MouseDown(object sender, MouseEventArgs e)
        {
            x4 = e.X; y4 = e.Y;
        }

        private void btn4_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                int dx = e.X - x4; int dy = e.Y - y4;
                this.SetBounds(this .Location .X,this .Location .Y ,this .Width+dx,this .Height );
            }
        }

        int x5, y5;
        private void btn5_MouseDown(object sender, MouseEventArgs e)
        {
            x5 = e.X; y5 = e.Y;
        }

        private void btn5_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                int dx = e.X - x5; int dy = e.Y - y5;
                this.SetBounds(this .Location .X +dx,this .Location .Y ,this.Width -dx,this .Height +dy);
            }
        }

        int x6, y6;
        private void btn6_MouseDown(object sender, MouseEventArgs e)
        {
            x6 = e.X; y6 = e.Y;
        }

        private void btn6_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                int dx = e.X - x6; int dy = e.Y - y6;
                this.SetBounds(this .Location .X ,this .Location .Y ,this .Width,this .Height +dy);
            }
        }

        int x7, y7;
        private void btn7_MouseDown(object sender, MouseEventArgs e)
        {
            x7 = e.X; y7 = e.Y;
        }

        private void btn7_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                int dx = e.X - x7; int dy = e.Y - y7;
                this.SetBounds(this .Location .X ,this.Location .Y ,this .Width +dx,this .Height +dy);
            }
        }
        #endregion
                
    }
}

[Navymk]

谢谢了.
我需要对层做拖拽移动/改变大小等多次修改,恐怕gdi绘制的矩形并不能满足要求.

[Navymk]

代码收藏了,谢谢.

已经解决,还是使用的picturebox.

透明的问题绕开了.

大致的思路是这样.

picturebox1原始图
picturebox2做区域划分,visiable为false

自定义一个cutimage方法,返回一个Image对象.

在picturebox1中的mousedown事件中,确定p2的位置,将picturebox2的visiable设置为true,置于p1的上方.
根据鼠标位置,确定对p1的Image的裁切位置,使用cutimage将切好的图片赋给p2,让p2的裁切图与下面的p1完全吻合模拟透明效果.
picturebox1的mousemove实现对p2拖拽大小.

...笨就笨点吧...总归实现了...还是用的自己的那几个老类...

感谢关注,感谢wzuomin,来者有分...总归也没几个人...

[yatobiaf]

可以用GDI来实现的。画一个矩形，然后用一把刷子填充这个矩形。这个刷子的颜色是RGBA格式的，最后一个A是alpha值，表示不透明值，你把这个值设成128（也就255的一半）就可以了。

//这是一个半透明蓝色的刷子，用这个刷子来刷矩形
Brush brush = new SolidBrush(Color.FromArgb(128, Color.Blue));

[yatobiaf]

都结贴了阿……我刚才到项目中试了一下，回来就结贴了……什么世道阿，早知道不去试了……