Question

我正在尝试保存由图形工具修改的图像，例如可以绘制到图像上的笔和形状。我使用带有背景图像的面板并尝试设置一个位图来保存此面板中的更改，这样做了：

    private void saveToolStripButton_Click(object sender, EventArgs e)
    {
        //sets panel1 contents as bit map to be saved at set locations
        int width = panel1.Size.Width;
        int height = panel1.Size.Height;

        using (Bitmap bmp = new Bitmap(width, height))
        {
            panel1.DrawToBitmap(bmp, new Rectangle(0, 0, width, height));
            bmp.Save(@"C:\Users\Me\Pics\testBitmap.jpeg", ImageFormat.Jpeg);
        }
        MessageBox.Show("Your image has been saved");
     }

单击保存按钮后，图像会保存，但使用图形工具所做的更改不会显示。有人可以提出解决方案吗？

以下是我在面板中设置的图形工具的一些代码：

    {
        InitializeComponent();
        //Create graphics object in panel1
        g = panel1.CreateGraphics();
    }

    private void btnExit2_Click(object sender, EventArgs e)
    {
        this.Close();
    }
    Graphics g;
    //set a drawing boolean
    bool draw = false;
    private void panel1_MouseDown(object sender, MouseEventArgs e)
    {
        draw = true;
        if (drawSq)
        {
            SolidBrush brush = new SolidBrush(Color.FromArgb(128, 255, 0, 0));
            if (toolStripTextBox1.Text != "")
            {
                g.FillRectangle(brush, e.X, e.Y, Convert.ToInt32(toolStripTextBox1.Text), Convert.ToInt32(toolStripTextBox1.Text));
            }
            else if (toolStripTextBox1.Text == "")
            {
               MessageBox.Show("Please enter a shape size");
            }

            draw = false;
            drawSq = false; 
        }
    }

以及更多：

      private void panel1_MouseUp(object sender, MouseEventArgs e)
    {
        draw = false;
        mouseX = null;
        mouseY = null;
    }
    //null values allow freehand style drawing
    int? mouseX = null;
    int? mouseY = null;
    private void panel1_MouseMove(object sender, MouseEventArgs e)
    {
        //creates a pen tool and sets properties by mouse location
        if (draw)
        {
            Pen pen = new Pen(btnColor.ForeColor, float.Parse(txtBox1.Text));
            g.DrawLine(pen, new Point(mouseX ?? e.X, mouseY ?? e.Y), new Point(e.X, e.Y));
            mouseX = e.X;
            mouseY = e.Y;
        }
    }

Answer 1

让我们试着解决这个问题。

首先创建图片：

Bitmap bmp;

protected override void OnLoad(EventArgs e) {
  base.OnLoad(e); 
  bmp = new Bitmap(panel1.ClientSize.Width, panel1.ClientSize.Height);
}

现在当你想要画画时：

void panel1_MouseMove(object sender, MouseEventArgs e) {
  if (e.Button == MouseButtons.Left) {
    using (Graphics g = Graphics.FromImage(bmp)) {
      g.FillEllipse(Brushes.Red, new Rectangle(e.X - 4, e.Y - 4, 8, 8));
    }
    panel1.Invalidate();
  }
}

显示结果：

void panel1_Paint(object sender, PaintEventArgs e) {
  e.Graphics.DrawImage(bmp, Point.Empty);
}

要保存，只需使用您的位图：

bmp.Save(@"c:\filename.png", ImageFormat.Png);

使用Double buffering with Panel避免闪烁。

Answer 2

这样可以。我测试了它并且效果很好........

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

namespace drawing
{
    public partial class Form2 : Form
    {
        Graphics g;
        bool startPaint = false;
        int? initX = null;
        int? initY = null;

        bool drawSquare = false;
        bool drawRectangle = false;
        bool drawCircle = false;
        public Form2()
        {
            InitializeComponent();

            bmp = new Bitmap(panel1.ClientSize.Width, panel1.ClientSize.Height);

        }
        Bitmap bmp;

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);

        }
        void panel1_MouseMove(object sender, MouseEventArgs e)
        {
            if (startPaint)
            {
                using ( g = Graphics.FromImage(bmp))
                {
                  //  g.FillEllipse(Brushes.Black, new Rectangle(e.X, e.Y , 5, 5));

                    Pen p = new Pen(btn_PenColor.BackColor, float.Parse(cmb_PenSize.Text));
                    g.DrawLine(p, new Point(initX ?? e.X, initY ?? e.Y), new Point(e.X, e.Y));
                    initX = e.X;
                    initY = e.Y;
                    //g.DrawImage(bmp, new Rectangle(e.X - 4, e.Y - 4, 8, 8));
                }
                panel1.Invalidate();
            }
        }
        private void pnl_Draw_MouseDown(object sender, MouseEventArgs e)
        {
            startPaint = true;
             if (drawSquare)
             {
                 //Use Solid Brush for filling the graphic shapes
                 SolidBrush sb = new SolidBrush(btn_PenColor.BackColor);
                 //setting the width and height same for creating square.
                 //Getting the width and Heigt value from Textbox(txt_ShapeSize)
                 g.FillRectangle(sb, e.X, e.Y, int.Parse(txt_ShapeSize.Text), int.Parse(txt_ShapeSize.Text));
                 //setting startPaint and drawSquare value to false for creating one graphic on one click.
                 startPaint = false;
                 drawSquare = false;
             }
             if (drawRectangle)
             {
                 SolidBrush sb = new SolidBrush(btn_PenColor.BackColor);
                 //setting the width twice of the height
                 g.FillRectangle(sb, e.X, e.Y, 2 * int.Parse(txt_ShapeSize.Text), int.Parse(txt_ShapeSize.Text));
                 startPaint = false;
                 drawRectangle = false;
             }
             if (drawCircle)
             {
                 SolidBrush sb = new SolidBrush(btn_PenColor.BackColor);
                 g.FillEllipse(sb, e.X, e.Y, int.Parse(txt_ShapeSize.Text), int.Parse(txt_ShapeSize.Text));
                 startPaint = false;
                 drawCircle = false;
             }
        }
         private void pnl_Draw_MouseUp(object sender, MouseEventArgs e)
        {
            startPaint = false;
            initX = null;
            initY = null;
        }
        void panel1_Paint(object sender, PaintEventArgs e)
        {
            e.Graphics.DrawImage(bmp, Point.Empty);
        }


        private void button1_Click(object sender, EventArgs e)
        {
            bmp.Save("D://filename.jpg", ImageFormat.Png);
        }


    }
}

C＃在面板中保存修改后的图像

2 个答案: