Set Screen Brightness/Contrast in C#

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I loaded Microsoft Windows Vista Business operating System on my old Toshiba Tecra A4 laptop and then realized that my Fn key is no longer working. The software and drivers that came with my laptop were not compatible with Vista. Alas, the one thing that I missed the most was setting up the brightness using Fn+F6 key. Usually when Windows starts, my LCD screen is just so bright that I have to adjust the brightness every time I start my laptop. Now, that leisure was gone. So I thought why not give it a try in C#. Found an API on MSDN and used it here in C# to make it work for me. It's not that great a program but a stupid slider to just reduce the Gamma component to give you a feeling that brightness is reduced. Actually the contrast is reduced. See the full code here. You can just copy and paste the full code in a Form class in a new Windows project and hit F5. If one of you is interested in just the executable, let me know via your comment here so I can send you the exe if you so desire.

1 // No copyrights (c). Use it as you wish!!

2

3 using System;

4 using System.Runtime.InteropServices;

5 using System.Windows.Forms;

6

7 namespace Yours.Truly

8 {

9 // *************************************************************************

10 /// <summary>

11 /// A form class to demnstrate the brightness adjustment for computer

12 /// monitors.

13 /// </summary>

14 /// <remarks>

15 /// <para>

16 /// It uses the Interop <see cref="SetDeviceGammaRamp"/> call to set the

17 /// Gamma component to adjust the screen contrast.

18 /// </para>

19 /// <para>

20 /// The <see cref="SetDeviceGammaRamp"/> function sets the gamma ramp on

21 /// direct color display boards having drivers that support downloadable

22 /// gamma ramps in hardware.

23 /// </para>

24 /// <para>

25 /// Direct color display modes do not use color lookup tables and are

26 /// usually 16, 24, or 32 bit. Not all direct color video boards support

27 /// loadable gamma ramps. SetDeviceGammaRamp succeeds only for devices with

28 /// drivers that support downloadable gamma ramps in hardware.

29 /// </para>

30 /// </remarks>

31 public class SetBrightness : Form

32 {

33 // *********************************************************************

34 /// <summary>

35 /// A structure of gamma corrections.

36 /// </summary>

37 [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi)]

38 private struct RAMP

39 {

40 [ MarshalAs(UnmanagedType.ByValArray, SizeConst=256)]

41 public UInt16[] Red;

42 [ MarshalAs(UnmanagedType.ByValArray, SizeConst=256)]

43 public UInt16[] Green;

44 [ MarshalAs(UnmanagedType.ByValArray, SizeConst=256)]

45 public UInt16[] Blue;

46 }

47

48 [DllImport("gdi32.dll")]

49 private static extern bool SetDeviceGammaRamp(IntPtr hDC, ref RAMP lpRamp);

50

51 [DllImport("user32.dll")]

52 static extern IntPtr GetDC(IntPtr hWnd);

53

54 /// <summary> Required designer variable.</summary>

55 private System.ComponentModel.IContainer components = null;

56 private TrackBar m_trackBar;

57

58 private static RAMP s_ramp = new RAMP();

59

60 // *********************************************************************

61 /// <summary>

62 /// Initializes a new instance of <see cref="SetBrightness"/> class.

63 /// </summary>

64 public SetBrightness ()

65 {

66 InitializeComponent();

67 }

68

69 // *********************************************************************

70 /// <summary>

71 /// Clean up any resources being used.

72 /// </summary>

73 /// <param name="disposing">true if managed resources should be

74 /// disposed; otherwise, false.</param>

75 protected override void Dispose (bool disposing)

76 {

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

78 {

79 components.Dispose();

80 }

81 base.Dispose(disposing);

82 }

83

84 // *********************************************************************

85 /// <summary>

86 /// Handles the <see cref="TrackBar.ValueChanged"/> event for the TrackBar

87 /// control. The value of the track bar control sets the Gamma value for

88 /// the device.

89 /// </summary>

90 /// <param name="sender">The object that initiated the event.</param>

91 /// <param name="e">An <see cref="EventArgs"/> object containing event

92 /// data</param>

93 private void HandleValueChanged (object sender, EventArgs e)

94 {

95 SetGamma(m_trackBar.Value);

96 }

97

98 // *********************************************************************

99 /// <summary>

100 /// Main entry point for the application.

101 /// </summary>

102 /// <param name="args">An array of optional arguments.</param>

103 static void Main (string[] args)

104 {

105 SetBrightness mainForm = new SetBrightness();

106 Application.Run(mainForm);

107 }

108

109 // *********************************************************************

110 /// <summary>

111 /// Sets the Gamma corection at the specified <paramref name="gamma"/>

112 /// value.

113 /// </summary>

114 /// <param name="gamma">New Gamma value to be set.</param>

115 private static void SetGamma(int gamma)

116 {

117 s_ramp.Red = new ushort[256];

118 s_ramp.Green = new ushort[256];

119 s_ramp.Blue = new ushort[256];

120

121 for( int i=1; i<256; i++ )

122 {

123 // gamma is a value between 3 and 44

124 s_ramp.Red[i] = s_ramp.Green[i] = s_ramp.Blue[i] =

125 (ushort)(Math.Min(65535,

126 Math.Max(0, Math.Pow((i+1) / 256.0, gamma*0.1) * 65535 + 0.5)));

127 }

128 // Now set the value.

129 SetDeviceGammaRamp(GetDC(IntPtr.Zero), ref s_ramp);

130 }

131

132 #region Windows Form Designer generated code

133

134 /// <summary>

135 /// Required method for Designer support - do not modify

136 /// the contents of this method with the code editor.

137 /// </summary>

138 private void InitializeComponent ()

139 {

140 this.m_trackBar = new System.Windows.Forms.TrackBar();

141 ((System.ComponentModel.ISupportInitialize)(this.m_trackBar)).BeginInit();

142 this.SuspendLayout();

143 //

144 // m_trackBar

145 //

146 this.m_trackBar.Dock = System.Windows.Forms.DockStyle.Fill;

147 this.m_trackBar.Location = new System.Drawing.Point(0,0);

148 this.m_trackBar.Maximum = 44;

149 this.m_trackBar.Minimum = 3;

150 this.m_trackBar.Name = "m_trackBar";

151 this.m_trackBar.RightToLeft = System.Windows.Forms.RightToLeft.Yes;

152 this.m_trackBar.RightToLeftLayout = true;

153 this.m_trackBar.Size = new System.Drawing.Size(277,42);

154 this.m_trackBar.TabIndex = 0;

155 this.m_trackBar.Value = 18;

156 this.m_trackBar.ValueChanged += new System.EventHandler(this.HandleValueChanged);

157 //

158 // SetBrightness

159 //

160 this.AutoScaleDimensions = new System.Drawing.SizeF(6F,13F);

161 this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;

162 this.ClientSize = new System.Drawing.Size(277,42);

163 this.Controls.Add(this.m_trackBar);

164 this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;

165 this.MaximizeBox = false;

166 this.MinimizeBox = false;

167 this.Name = "SetBrightness";

168 this.Opacity = 0.8;

169 this.ShowIcon = false;

170 this.SizeGripStyle = System.Windows.Forms.SizeGripStyle.Hide;

171 this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;

172 this.Text = "SetBrightness";

173 this.TopMost = true;

174 ((System.ComponentModel.ISupportInitialize)(this.m_trackBar)).EndInit();

175 this.ResumeLayout(false);

176 this.PerformLayout();

177

178 }

179

180 #endregion

181

182 } // end class SetBrightness

183 } // end namespace Yours.Truly