This article shows how to create a Mini Paint Application using a C# Windows Forms application. I will show some basic features of the paint application. Before starting, I hope you have a basic undersanding of GDI+ Graphics. I have added comments to the code so that you can easily understand the code.
Let's understand the Mini Paint Application structure:
Here is the code used in this application:
  1. using System;
  2. using System.Drawing;
  3. using System.Windows.Forms;
  5. namespace MiniPaint
  6. {
  7. public partial class Form1 : Form
  8. {
  9. public Form1()
  10. {
  11. InitializeComponent();
  12. g = pnl_Draw.CreateGraphics();
  13. }
  14. bool startPaint = false;
  15. Graphics g;
  16. //nullable int for storing Null value
  17. int? initX = null;
  18. int? initY = null;
  19. bool drawSquare = false;
  20. bool drawRectangle = false;
  21. bool drawCircle = false;
  22. //Event fired when the mouse pointer is moved over the Panel(pnl_Draw).
  23. private void pnl_Draw_MouseMove(object sender, MouseEventArgs e)
  24. {
  25. if(startPaint)
  26. {
  27. //Setting the Pen BackColor and line Width
  28. Pen p = new Pen(btn_PenColor.BackColor,float.Parse(cmb_PenSize.Text));
  29. //Drawing the line.
  30. g.DrawLine(p, new Point(initX ?? e.X, initY ?? e.Y), new Point(e.X, e.Y));
  31. initX = e.X;
  32. initY = e.Y;
  33. }
  34. }
  35. //Event Fired when the mouse pointer is over Panel and a mouse button is pressed
  36. private void pnl_Draw_MouseDown(object sender, MouseEventArgs e)
  37. {
  38. startPaint = true;
  39. if (drawSquare)
  40. {
  41. //Use Solid Brush for filling the graphic shapes
  42. SolidBrush sb = new SolidBrush(btn_PenColor.BackColor);
  43. //setting the width and height same for creating square.
  44. //Getting the width and Heigt value from Textbox(txt_ShapeSize)
  45. g.FillRectangle(sb, e.X, e.Y, int.Parse(txt_ShapeSize.Text), int.Parse(txt_ShapeSize.Text));
  46. //setting startPaint and drawSquare value to false for creating one graphic on one click.
  47. startPaint = false;
  48. drawSquare = false;
  49. }
  50. if(drawRectangle)
  51. {
  52. SolidBrush sb = new SolidBrush(btn_PenColor.BackColor);
  53. //setting the width twice of the height
  54. g.FillRectangle(sb, e.X, e.Y, 2*int.Parse(txt_ShapeSize.Text), int.Parse(txt_ShapeSize.Text));
  55. startPaint = false;
  56. drawRectangle = false;
  57. }
  58. if(drawCircle)
  59. {
  60. SolidBrush sb = new SolidBrush(btn_PenColor.BackColor);
  61. g.FillEllipse(sb, e.X, e.Y, int.Parse(txt_ShapeSize.Text), int.Parse(txt_ShapeSize.Text));
  62. startPaint = false;
  63. drawCircle = false;
  64. }
  65. }
  66. //Fired when the mouse pointer is over the pnl_Draw and a mouse button is released.
  67. private void pnl_Draw_MouseUp(object sender, MouseEventArgs e)
  68. {
  69. startPaint = false;
  70. initX = null;
  71. initY = null;
  72. }
  73. //Button for Setting pen Color
  74. private void button1_Click(object sender, EventArgs e)
  75. {
  76. //Open Color Dialog and Set BackColor of btn_PenColor if user click on OK
  77. ColorDialog c = new ColorDialog();
  78. if(c.ShowDialog()==DialogResult.OK)
  79. {
  80. btn_PenColor.BackColor = c.Color;
  81. }
  82. }
  83. //New
  84. private void newToolStripMenuItem_Click(object sender, EventArgs e)
  85. {
  86. //Clearing the graphics from the Panel(pnl_Draw)
  87. g.Clear(pnl_Draw.BackColor);
  88. //Setting the BackColor of pnl_draw and btn_CanvasColor to White on Clicking New under File Menu
  89. pnl_Draw.BackColor = Color.White;
  90. btn_CanvasColor.BackColor = Color.White;
  91. }
  92. //Setting the Canvas Color
  93. private void btn_CanvasColor_Click_1(object sender, EventArgs e)
  94. {
  95. ColorDialog c = new ColorDialog();
  96. if(c.ShowDialog()==DialogResult.OK)
  97. {
  98. pnl_Draw.BackColor = c.Color;
  99. btn_CanvasColor.BackColor = c.Color;
  100. }
  101. }
  103. private void btn_Square_Click(object sender, EventArgs e)
  104. {
  105. drawSquare = true;
  106. }
  108. private void btn_Rectangle_Click(object sender, EventArgs e)
  109. {
  110. drawRectangle = true;
  111. }
  113. private void btn_Circle_Click(object sender, EventArgs e)
  114. {
  115. drawCircle = true;
  116. }
  117. //Exit under File Menu
  118. private void exitToolStripMenuItem_Click(object sender, EventArgs e)
  119. {
  120. if(MessageBox.Show("Do you want to Exit?","Exit",MessageBoxButtons.YesNo,MessageBoxIcon.Information)==DialogResult.Yes)
  121. {
  122. Application.Exit();
  123. }
  124. }
  125. //About under Help Menu
  126. private void aboutMiniPaintToolStripMenuItem_Click(object sender, EventArgs e)
  127. {
  128. About a = new About();
  129. a.ShowDialog();
  130. }
  132. }
  133. }
Final preview:
I hope you like it. Thanks.