如何在不清除原始图像的情况下从pictureBox1中清除所有绘制的图形？

Question

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using System.Windows.Forms; 
using System.Drawing.Imaging; 
using System.Runtime.InteropServices; 

namespace mws 
{ 
    public partial class ColorClouds : Form 
    { 
     private Bitmap _bmpBU = null; 
     private Rectangle mRect; 

     public ColorClouds() 
     { 
      InitializeComponent(); 

      this.DoubleBuffered = true; 
      _bmpBU = new Bitmap(@"D:\MyWeatherStation-Images-And-Icons\radar090.PNG"); 
     } 

     private void ColorClouds_Load(object sender, EventArgs e) 
     { 
      this.pictureBox1.Image = (Bitmap)_bmpBU.Clone(); 
      this.pictureBox2.Image = (Bitmap)_bmpBU.Clone(); 
     } 

     private void button1_Click(object sender, EventArgs e) 
     { 
      if (pictureBox1.Image != null) 
      { 
       ScanBmpFast((Bitmap)this.pictureBox1.Image, true, new Rectangle(40, 10, 20, 50)); 
       this.pictureBox1.Refresh(); 
      } 
     } 

     private unsafe void ScanBmpFast(Bitmap bmp, bool setToOpaqueYellow, Rectangle rect) 
     { 
      BitmapData b1 = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb); 

      int stride = b1.Stride; 
      int nWidth = bmp.Width; 
      int nHeight = bmp.Height; 

      System.IntPtr Scan0 = b1.Scan0; 

      byte* p = (byte*)(void*)Scan0; 

      int sX = Math.Min(Math.Max(rect.X, 0), bmp.Width); 
      int sY = Math.Min(Math.Max(rect.Y, 0), bmp.Height); 
      int w = Math.Min(rect.Width, bmp.Width - sX); 
      int h = Math.Min(rect.Height, bmp.Height - sY); 

      for (int y = sY; y < sY + h; y++) 
      { 
       p = (byte*)(void*)Scan0; 
       p += (y * stride + sX * 4); 

       for (int x = sX; x < sX + w; x++) 
       { 
        if (p[0] != 0 || p[1] != 0 || p[2] != 0) 
        { 
         p[1] = p[2] = (byte)255; 

         if (setToOpaqueYellow) 
         { 
          p[0] = (byte)0; 
          p[3] = (byte)255; 
         } 
        } 

        p += 4; 
       } 
      } 

      bmp.UnlockBits(b1); 
     } 

     private void button2_Click(object sender, EventArgs e) 
     { 
      if (pictureBox2.Image != null) 
      { 
       ScanBmp((Bitmap)this.pictureBox2.Image, true, new Rectangle(400, 100, 200, 500)); 
       this.pictureBox2.Refresh(); 
      } 
     } 

     private void ScanBmp(Bitmap bmp, bool setToOpaqueYellow, Rectangle rect) 
     { 
      BitmapData b1 = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb); 

      int stride = b1.Stride; 
      int nWidth = bmp.Width; 
      int nHeight = bmp.Height; 

      System.IntPtr Scan0 = b1.Scan0; 
      IntPtr p = b1.Scan0; 

      int sX = Math.Min(Math.Max(rect.X, 0), bmp.Width); 
      int sY = Math.Min(Math.Max(rect.Y, 0), bmp.Height); 
      int w = Math.Min(rect.Width, bmp.Width - sX); 
      int h = Math.Min(rect.Height, bmp.Height - sY); 

      for (int y = sY; y < sY + h; y++) 
      { 
       p = Scan0; 
       p += y * stride + sX * 4; 

       for (int x = sX; x < sX + w; x++) 
       { 

        if (Marshal.ReadByte(p) != 0 || Marshal.ReadByte(p + 1) != 0 || Marshal.ReadByte(p + 2) != 0) 
        { 
         byte res = (byte)255; 
         Marshal.WriteByte(p + 1, res); 
         Marshal.WriteByte(p + 2, res); 

         if (setToOpaqueYellow) 
         { 
          Marshal.WriteByte(p, (byte)0); 
          Marshal.WriteByte(p + 2, (byte)255); 
         } 
        } 

        p += 4; 
       } 
      } 

      bmp.UnlockBits(b1); 
     } 

     private void button3_Click(object sender, EventArgs e) 
     { 
      Image iOLd = this.pictureBox1.Image; 
      this.pictureBox1.Image = (Bitmap)_bmpBU.Clone(); 
      if (iOLd != null) 
       iOLd.Dispose(); 
     } 

     private void button4_Click(object sender, EventArgs e) 
     { 
      Image iOLd = this.pictureBox2.Image; 
      this.pictureBox2.Image = _bmpBU; 
      if (iOLd != null) 
       iOLd.Dispose(); 
     } 

     private void ColorClouds_FormClosing(object sender, FormClosingEventArgs e) 
     { 
      Image iOLd = this.pictureBox1.Image; 
      this.pictureBox1.Image = (Bitmap)_bmpBU.Clone(); 
      if (iOLd != null) 
       iOLd.Dispose(); 
      iOLd = this.pictureBox2.Image; 
      this.pictureBox2.Image = _bmpBU; 
      if (iOLd != null) 
       iOLd.Dispose(); 

      if (_bmpBU != null) 
       _bmpBU.Dispose(); 
     } 

     private void pictureBox1_Paint(object sender, PaintEventArgs e) 
     { 
      using (Pen pen = new Pen(Color.Red, 2)) 
      { 
       e.Graphics.DrawRectangle(pen, mRect); 
      } 
     } 

     private void pictureBox1_MouseMove(object sender, MouseEventArgs e) 
     { 
      if (e.Button == MouseButtons.Left) 
      { 
       mRect = new Rectangle(mRect.Left, mRect.Top, e.X - mRect.Left, e.Y - mRect.Top); 
       pictureBox1.Invalidate(); 
      } 
     } 

     private void pictureBox1_MouseDown(object sender, MouseEventArgs e) 
     { 
      mRect = new Rectangle(e.X, e.Y, 0, 0); 
     } 

     private void pictureBox1_MouseUp(object sender, MouseEventArgs e) 
     { 
      if (pictureBox1.Image != null) 
      { 
       ScanBmpFast((Bitmap)this.pictureBox1.Image, true, mRect); 
       this.pictureBox1.Refresh(); 
      } 
     } 
    } 
} 

我这样做了，我可以在picturebox1上绘制矩形，并用矩形填充矩形。 当我点击pictureBox1再次绘制矩形框架是清楚的，但绘制它自己内部矩形不是。

ScanBmpFast只是填充我用某种颜色绘制的矩形。 这种颜色没有清除。只有矩形框架。 我想清除一切，只保留原始图像。

Answer 1

感叹。如果您没有画出Paint（直接或在其可能传递的e.Graphics）事件，则事件将不会持续。

因此，所有你需要做的，摆脱那些非持久性的像素是调用

pictureBox1.Invalidate(); 

这当然会导致的问题，你在画什么和你为什么不这样做的权利？在Paint事件外画什么，不仅被删除由Invalidate()打电话给你的代码，但也受到许多外界活动，如最小化Form等。

持久绘制（除非你拉入Image）将需要创建数据持有什么样的细节结构画在哪里以及如何，即Points, Rectangles, Brushes, Pens等。

，并删除此类持续拉你清楚这些数据..

所以，如果你不想做Rectangle要绘制在Paint事件中，不要这样做！只要你有代码，它总是会重新出现。