回答編集履歴

- いじっていたら跡形がなくなってしまったのですが、何かの参考になれば。

- > 始点をMouseDownイベント、終点の処理をMouseUpイベント

-

- 線の引き方にこだわりはなさそうなので「ペイント」のようなドラッグ方式です。

-

- Form1.cs

- ```C#

- using System;

- using System.Drawing;

- using System.Drawing.Drawing2D;

- using System.Linq;

- using System.Windows.Forms;

-

- namespace Questions240161

- {

- public partial class Form1 : Form

- {

- private readonly ToolStripButton[] modeButtons;

- private readonly ToolStripButton[] colorButtons;

-

- private Point startPoint;

- private Point endPoint;

-

- private Color penColor = Color.Black;

- private int penSize => (int)toolStripComboBox1.SelectedItem;

-

- private bool isPencilMode => toolStripButton1.Checked;

- private bool isLineMode => toolStripButton2.Checked;

- private bool isLineDragging;

-

- public Form1()

- {

- InitializeComponent();

-

- pictureBox1.Image = new Bitmap(800, 600);

-

- modeButtons = new[] { toolStripButton1, toolStripButton2, };

- modeButtons[0].Checked = true;

-

- toolStripComboBox1.ComboBox.DataSource = Enumerable.Range(1, 10).ToList();

- toolStripComboBox1.SelectedIndex = 2;

-

- colorButtons = new[] { toolStripButton3, toolStripButton4, };

- colorButtons[0].Checked = true;

- }

-

- private void PictureBox1_Paint(object sender, PaintEventArgs e)

- {

- if(!pictureBox1.Capture) return;

- if(!isLineDragging) return;

-

- using(var pen = new Pen(penColor, penSize))

- {

- e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;

- e.Graphics.DrawLine(pen, startPoint, endPoint);

- }

- }

- private void PictureBox1_MouseDown(object sender, MouseEventArgs e)

- {

- startPoint = e.Location;

- if(isLineMode) isLineDragging = true;

- }

- private void PictureBox1_MouseMove(object sender, MouseEventArgs e)

- {

- SetMessage($"Position : {e.X}, {e.Y}");

- if(!pictureBox1.Capture) return;

-

- endPoint = e.Location;

- if(isPencilMode)

- {

- DrawLine(LineCap.Round);

- startPoint = endPoint;

- }

-

- if(isLineMode) pictureBox1.Invalidate();

- }

- private void PictureBox1_MouseUp(object sender, MouseEventArgs e)

- {

- if(!isLineDragging) return;

-

- isLineDragging = false;

- if(isLineMode) DrawLine();

- }

-

- private void DrawLine(LineCap lineCap = LineCap.Flat)

- {

- using(var g = Graphics.FromImage(pictureBox1.Image))

- using(var pen = new Pen(penColor, penSize) { StartCap = lineCap, EndCap = lineCap })

- {

- g.SmoothingMode = SmoothingMode.AntiAlias;

- g.DrawLine(pen, startPoint, endPoint);

- pictureBox1.Image = pictureBox1.Image; // 再割り当てしないと反映されない？？

- }

- }

-

- private void ToolStripModeButton_Click(object sender, EventArgs e)

- {

- foreach(var b in modeButtons) b.Checked = sender == b;

- }

- private void ToolStripColorButton_Click(object sender, EventArgs e)

- {

- foreach(var b in colorButtons) b.Checked = sender == b;

-

- penColor = ((ToolStripButton)sender).ForeColor;

- }

-

- private void SetMessage(string value) => toolStripStatusLabel1.Text = value;

- }

- }

- ```

- Form1.Designer.cs

- ```C#

- namespace Questions240161

- {

- partial class Form1

- {

- private System.ComponentModel.IContainer components = null;

-

- protected override void Dispose(bool disposing)

- {

- if(disposing && (components != null))

- {

- components.Dispose();

- }

- base.Dispose(disposing);

- }

-

- #region Windows フォーム デザイナーで生成されたコード

- private void InitializeComponent()

- {

- this.pictureBox1 = new System.Windows.Forms.PictureBox();

- this.panel1 = new System.Windows.Forms.Panel();

- this.toolStrip1 = new System.Windows.Forms.ToolStrip();

- this.toolStripButton1 = new System.Windows.Forms.ToolStripButton();

- this.toolStripButton2 = new System.Windows.Forms.ToolStripButton();

- this.toolStripComboBox1 = new System.Windows.Forms.ToolStripComboBox();

- this.toolStripButton3 = new System.Windows.Forms.ToolStripButton();

- this.toolStripButton4 = new System.Windows.Forms.ToolStripButton();

- this.statusStrip1 = new System.Windows.Forms.StatusStrip();

- this.toolStripStatusLabel1 = new System.Windows.Forms.ToolStripStatusLabel();

- ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).BeginInit();

- this.panel1.SuspendLayout();

- this.toolStrip1.SuspendLayout();

- this.statusStrip1.SuspendLayout();

- this.SuspendLayout();

-

- this.pictureBox1.BackColor = System.Drawing.Color.White;

- this.pictureBox1.Location = new System.Drawing.Point(0, 0);

- this.pictureBox1.SizeMode = System.Windows.Forms.PictureBoxSizeMode.AutoSize;

- this.pictureBox1.TabStop = false;

- this.pictureBox1.Paint += new System.Windows.Forms.PaintEventHandler(this.PictureBox1_Paint);

- this.pictureBox1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.PictureBox1_MouseDown);

- this.pictureBox1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.PictureBox1_MouseMove);

- this.pictureBox1.MouseUp += new System.Windows.Forms.MouseEventHandler(this.PictureBox1_MouseUp);

-

- this.panel1.AutoScroll = true;

- this.panel1.Controls.Add(this.pictureBox1);

- this.panel1.Dock = System.Windows.Forms.DockStyle.Fill;

-

- this.toolStrip1.Items.AddRange(new System.Windows.Forms.ToolStripItem[] {

- this.toolStripButton1,

- this.toolStripButton2,

- this.toolStripComboBox1,

- this.toolStripButton3,

- this.toolStripButton4});

-

- this.toolStripButton1.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Text;

- this.toolStripButton1.Text = "Pen";

- this.toolStripButton1.Click += new System.EventHandler(this.ToolStripModeButton_Click);

-

- this.toolStripButton2.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Text;

- this.toolStripButton2.Text = "Line";

- this.toolStripButton2.Click += new System.EventHandler(this.ToolStripModeButton_Click);

-

- this.toolStripComboBox1.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;

-

- this.toolStripButton3.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Text;

- this.toolStripButton3.Font = new System.Drawing.Font("メイリオ", 12F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(128)));

- this.toolStripButton3.ForeColor = System.Drawing.Color.Black;

- this.toolStripButton3.Text = "■";

- this.toolStripButton3.Click += new System.EventHandler(this.ToolStripColorButton_Click);

-

- this.toolStripButton4.DisplayStyle = System.Windows.Forms.ToolStripItemDisplayStyle.Text;

- this.toolStripButton4.ForeColor = System.Drawing.Color.Red;

- this.toolStripButton4.Text = "■";

- this.toolStripButton4.Click += new System.EventHandler(this.ToolStripColorButton_Click);

-

- this.statusStrip1.Items.AddRange(new System.Windows.Forms.ToolStripItem[] {

- this.toolStripStatusLabel1});

-

- this.ClientSize = new System.Drawing.Size(800, 450);

- this.Controls.Add(this.panel1);

- this.Controls.Add(this.statusStrip1);

- this.Controls.Add(this.toolStrip1);

- ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).EndInit();

- this.panel1.ResumeLayout(false);

- this.panel1.PerformLayout();

- this.toolStrip1.ResumeLayout(false);

- this.toolStrip1.PerformLayout();

- this.statusStrip1.ResumeLayout(false);

- this.statusStrip1.PerformLayout();

- this.ResumeLayout(false);

- this.PerformLayout();

-

- }

- #endregion

-

- private System.Windows.Forms.PictureBox pictureBox1;

- private System.Windows.Forms.Panel panel1;

- private System.Windows.Forms.ToolStrip toolStrip1;

- private System.Windows.Forms.ToolStripButton toolStripButton1;

- private System.Windows.Forms.ToolStripButton toolStripButton2;

- private System.Windows.Forms.ToolStripComboBox toolStripComboBox1;

- private System.Windows.Forms.ToolStripButton toolStripButton3;

- private System.Windows.Forms.ToolStripButton toolStripButton4;

- private System.Windows.Forms.StatusStrip statusStrip1;

- private System.Windows.Forms.ToolStripStatusLabel toolStripStatusLabel1;

- }

- }