如何添加多个画布到一个图片框

Question

让我解释一下我的问题:

我有一个图片框，它应该用来绘制列表框的几个元素。我给了画盒一块画布。通过左击和右击，你可以创建一个矩形，它应该预览你想要在图片框的画布上绘制的元素。

现在我的问题是:

这个矩形应该只是一个预览，每次我点击图片框的另一个位置并创建一个新的矩形时，它都应该被擦除。当我点击输入按钮时，它应该只是绘制在画布上。

那么我怎么能预览选定的元素在矩形由左击和右击?

我希望我的问题足够清楚:/

这是我目前所做的:

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;
namespace Interaktive_systeme_sta
{
    public partial class Bildeditor : Form
    {

        void drawRect()
        {
            pbxBild.Refresh();
            using (Graphics g = this.pbxBild.CreateGraphics())
            {
                Pen blackPen = new Pen(Color.Black, 1);
                blackPen.DashPattern = new float[] {2,2};
                int X = Convert.ToInt32(nupX.Value);
                int Y = Convert.ToInt32(nupY.Value);
                int B = Convert.ToInt32(nupBreite.Value);
                int H = Convert.ToInt32(nupHoehe.Value);
                g.DrawRectangle(blackPen, X, Y, B, H);
                g.Dispose();
            }
        }
        public Bildeditor()
        {
            InitializeComponent();
            this.MinimumSize = new Size(630,420);
            this.MaximumSize = new Size(630, 420);
            int canvasWidth = pbxBild.Width;
            int canvasHeight = pbxBild.Height;
            nupBreite.Maximum = canvasWidth;
            nupHoehe.Maximum = canvasHeight;
            nupBreite.Minimum = 0;
            nupHoehe.Minimum = 0;
            nupBreite.Value = canvasWidth;
            nupHoehe.Value = canvasHeight;
            nupX.Maximum = canvasWidth;
            nupY.Maximum = canvasHeight;
            nupX.Minimum = 0;
            nupY.Minimum = 0;
            nupX.Value = 0;
            nupY.Value = 0;
            drawRect();
        }
        private void btnZuruecksetzten_Click(object sender, EventArgs e)
        {
            int canvasWidth = pbxBild.Width;
            int canvasHeight = pbxBild.Height;
            nupX.Value = 0;
            nupY.Value = 0;
            nupBreite.Value = canvasWidth-1;
            nupHoehe.Value = canvasHeight-1;
        }
        private void numericUpDown2_ValueChanged(object sender, EventArgs e)
        {
            drawRect();
        }
        private void pbxBild_MouseUp(object sender, System.Windows.Forms.MouseEventArgs e)
        {
            Point mouseDownLocation = new Point(e.X, e.Y);
            switch (e.Button)
            {
                case MouseButtons.Left:
                    if (e.X < 0)
                    {
                        nupX.Value = 0;
                    }
                    else
                    {
                        nupX.Value = e.X;
                    }
                    if (e.Y < 0)
                    {
                        nupY.Value = 0;
                    }
                    else
                    {
                        nupY.Value = e.Y;
                    }
                    break;
                case MouseButtons.Right:
                    if (e.X - nupX.Value < 1)
                    {
                        nupBreite.Value = 1;
                    }
                    else
                    {
                        nupBreite.Value = e.X - nupX.Value;
                    }
                    if (e.Y - nupY.Value < 1)
                    {
                        nupHoehe.Value = 1;
                    }
                    else
                    {
                        nupHoehe.Value = e.Y - nupY.Value;
                    }
                    break;
            }
            drawRect();
        }
        private void nupY_ValueChanged(object sender, EventArgs e)
        {
            drawRect();
        }
        private void nupBreite_ValueChanged(object sender, EventArgs e)
        {
            drawRect();
        }
        private void nupHoehe_ValueChanged(object sender, EventArgs e)
        {
            drawRect();
        }
        private void btnEinfuegen_Click(object sender, EventArgs e)
        {
            if (lbBildelemente.SelectedIndex == 0)
            {
                zeichneBild();
            }
            else if (lbBildelemente.SelectedIndex == 1)
            {
                zeichneLine();
            }
            else if (lbBildelemente.SelectedIndex == 2)
            {
                zeichneRect();
            }
            else if (lbBildelemente.SelectedIndex == 3)
            {
                zeichneText();
            }
            else if (lbBildelemente.SelectedIndex == 4)
            {
                zeichneKreis();
            }
        }
        private void lbBildelemente_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (lbBildelemente.SelectedIndex == 0) 
            {
                tbFarbe.Enabled = false;
                btnFarbe.Enabled = false;
                nupPen.Enabled = false;
                tbBild.Enabled = true;
                btnBild.Enabled = true;
                tbText.Enabled = false;
                tbSchrift.Enabled = false;
                btnSchrift.Enabled = false;
            }
            else if (lbBildelemente.SelectedIndex == 1 || lbBildelemente.SelectedIndex == 2 || lbBildelemente.SelectedIndex == 4)
            {
                tbFarbe.Enabled = true;
                btnFarbe.Enabled = true;
                nupPen.Enabled = true;
                tbBild.Enabled = false;
                btnBild.Enabled = false;
                tbText.Enabled = false;
                tbSchrift.Enabled = false;
                btnSchrift.Enabled = false;
            }
            else if (lbBildelemente.SelectedIndex == 3)
            {
                tbFarbe.Enabled = true;
                btnFarbe.Enabled = true;
                nupPen.Enabled = true;
                tbBild.Enabled = false;
                btnBild.Enabled = false;
                tbText.Enabled = true;
                tbSchrift.Enabled = true;
                btnSchrift.Enabled = true;
            }
        }
        void zeichneBild()
        {
            Graphics g = pbxBild.CreateGraphics();
            int X = Convert.ToInt32(nupX.Value);
            int Y = Convert.ToInt32(nupY.Value);
            int B = Convert.ToInt32(nupBreite.Value);
            int H = Convert.ToInt32(nupHoehe.Value);
            Bitmap bitmap = new Bitmap(tbBild.Text);
            g.DrawImage(bitmap, X, Y, B, H);
        }
        // Als zusatzfunktion kann man die Pinseldicke auswählen
        void zeichneRect() 
        {
            Graphics g = pbxBild.CreateGraphics();
            Pen Pen = new Pen(tbFarbe.BackColor, Convert.ToInt32(nupPen.Value));
            int X = Convert.ToInt32(nupX.Value);
            int Y = Convert.ToInt32(nupY.Value);
            int B = Convert.ToInt32(nupBreite.Value);
            int H = Convert.ToInt32(nupHoehe.Value);
            g.DrawRectangle(Pen, X, Y, B, H);
        }
        //zusatzfunktion
        void zeichneKreis()
        {
            Graphics g = pbxBild.CreateGraphics();
            Pen Pen = new Pen(tbFarbe.BackColor, Convert.ToInt32(nupPen.Value));
            int X = Convert.ToInt32(nupX.Value);
            int Y = Convert.ToInt32(nupY.Value);
            int B = Convert.ToInt32(nupBreite.Value);
            int H = Convert.ToInt32(nupHoehe.Value);
            g.DrawEllipse(Pen, X, Y, B, H);
        }
        void zeichneLine()
        {
            Graphics g = pbxBild.CreateGraphics();
            Pen Pen = new Pen(tbFarbe.BackColor, Convert.ToInt32(nupPen.Value));
            int X = Convert.ToInt32(nupX.Value);
            int Y = Convert.ToInt32(nupY.Value);
            int B = Convert.ToInt32(nupBreite.Value);
            int H = Convert.ToInt32(nupHoehe.Value);
            g.DrawLine(Pen, X, Y, X+B, Y+H);
        }
        void zeichneText()
        {
            Graphics g = pbxBild.CreateGraphics();
            Brush brush = new SolidBrush(tbFarbe.BackColor);
            int X = Convert.ToInt32(nupX.Value);
            int Y = Convert.ToInt32(nupY.Value);
            g.DrawString(tbText.Text, fontDialog1.Font, brush, X, Y);
        }
        private void btnFarbe_Click(object sender, EventArgs e)
        {
            if (colorDialog1.ShowDialog() == DialogResult.OK)
            {
                tbFarbe.BackColor = colorDialog1.Color;
            }
        }
        private void btnSchrift_Click(object sender, EventArgs e)
        {
            // Show the dialog.
            DialogResult result = fontDialog1.ShowDialog();
            // See if OK was pressed.
            if (result == DialogResult.OK)
            {
                // Get Font.
                Font font = fontDialog1.Font;
                // Set TextBox properties.
                this.tbSchrift.Text = string.Format(font.Name +"; "+ font.Size +"pt");
            }
        }
        private void btnBild_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.Filter = "Joint Photographic Experts Group (*.jpg)|*.jpg|"
                + "EMF Enhanced Metafile Format (*.emf)|*.emf|"
                + "Graphics Interchange Format (*.gif)|*.gif|"
                + "Bitmap (*.bmp)|*.bmp|"
                + "W3C Portable Network Graphics (*.png)|*.png";
            if (openFileDialog.ShowDialog(this) == DialogResult.OK)
            {
                tbBild.Text = openFileDialog.FileName;
            }
        }
        private void bildbereichLöschenToolStripMenuItem_Click(object sender, EventArgs e)
        {
            pbxBild.Refresh();
        }
        private void bildLadenToolStripMenuItem_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.Filter = "Joint Photographic Experts Group (*.jpg)|*.jpg|"
                + "EMF Enhanced Metafile Format (*.emf)|*.emf|"
                + "Graphics Interchange Format (*.gif)|*.gif|"
                + "Bitmap (*.bmp)|*.bmp|"
                + "W3C Portable Network Graphics (*.png)|*.png";
            if (openFileDialog.ShowDialog(this) == DialogResult.OK)
            {
                Graphics g = pbxBild.CreateGraphics();
                int X = 0;
                int Y = 0;
                int B = Convert.ToInt32(pbxBild.Width);
                int H = Convert.ToInt32(pbxBild.Height);
                Bitmap bitmap = new Bitmap(openFileDialog.FileName);
                g.DrawImage(bitmap, X, Y, B, H);
            }
        }
    }
}

Answer 1

我想这就是你需要的

private void Form1_Load(object sender, EventArgs e)
{
    listBox1.SelectedIndexChanged += listBox1_SelectedIndexChanged;
}
private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (listBox1.SelectedItem == "Circle")
    {
        pictureBox1.Image = circle;
    }
}