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Windows Controls: The Timer |
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A timer is a non-spatial object that uses recurring
lapses of time in a computer or in your application. To work, every lapse of
period, the control sends a message to the operating system. The message is
something to the effect of "I have counted the number of lapses you asked me
to count".
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As opposed to the time that controls your computer, a
timer is partly but greatly under your control. Users do not see nor do they
use a timer as a control. As a programmer, you decide if, why, when, and how
to use this control.
To support timers, the .NET Framework provides the Timer
control from the Toolbox and it is implemented through the Timer
class. To add it to your application at design time, on the Toolbox, click
Timer and click the form.
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 Application:
Introducing the Timer Control
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- Start a new Windows Application named ScreenSaver1
- Change the following properties of the form:
BackColor: Black
FormBorderStyle: None
WindowState: Maximized
- In the Properties window, click the Events button
and double-click MouseMove
- Implement the event as follows:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace ScreenSaver1
{
public partial class Form1 : Form
{
static int MoveCounter = 0;
public Form1()
{
InitializeComponent();
}
private void Form1_MouseMove(object sender, MouseEventArgs e)
{
Cursor.Hide();
if (MoveCounter == 20)
Close();
MoveCounter++;
}
}
}
- Display the form again and, in the Events section of the Properties
window, double-click KeyDown
- Implement its event as follows:
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
// If the user presses Esc, stop the screen saver
if (e.KeyCode == Keys.Escape)
Close();
}
- Execute the application to test it (to close the form, you will just
move the mouse or press Esc)
- Display the form
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Characteristics of a Timer
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A timer is an object used to count lapses of time and
send a message when it has finished counting. Each count is called a tick.
When a tick occurs, the control fires a Tick event. This Tick
event is of type EventArgs, meaning that it doesn't provide more
information than to let you know that a lapse has occurred. Here is an
example of implementing that event:
using System;
using System.Drawing;
using System.Windows.Forms;
public class Exercise : Form
{
Timer tmrFlash;
public Exercise()
{
InitializeComponent();
}
void InitializeComponent()
{
tmrFlash = new Timer ();
tmrFlash.Tick += new EventHandler(btnFlashTick);
Text = "Text Flasher";
Size = new System.Drawing.Size(435, 88);
}
void btnFlashTick(object sender, EventArgs e)
{
}
}
public class Program
{
static int Main()
{
System.Windows.Forms.Application.Run(new Exercise());
return 0;
}
}
The amount of time allocated for counting is called an
interval and it is represented by the Interval property. The
Interval is a very important characteristic of the Timer control because
it measures and controls the total time needed to perform a complete count.
The Interval is measured in milliseconds. Like any counter, the lower
the value, the faster the count, and the higher the value, the longer the
count (if you ask one kid to count from 1 to 10 and you ask another to count
from 1 to 20 at the same time, if you ask them to shout when they finish,
the first kid would finish first and would shout first). The amount of
interval you specify will depend on what you are trying to do. Here is an
example of specifying the interval:
void InitializeComponent()
{
tmrFlash = new Timer ();
tmrFlash.Interval = 500;
tmrFlash.Tick += new EventHandler(btnFlashTick);
}
In order for a timer to count, you must tell it when it
should start counting. In some applications, you may want the control to
work full-time while in some other applications, you may want the control to
work only in response to an intermediate event. The ability to stop and
start a Timer control can be set using the Enabled Boolean property.
Here is an example of enabling a timer:
using System;
using System.Drawing;
using System.Windows.Forms;
public class Exercise : Form
{
Timer tmrFlash;
Label lblFlash;
public Exercise()
{
InitializeComponent();
}
void InitializeComponent()
{
tmrFlash = new Timer();
tmrFlash.Interval = 500;
tmrFlash.Enabled = true;
tmrFlash.Tick += new EventHandler(btnFlashTick);
lblFlash = new Label();
lblFlash.AutoSize = true;
lblFlash.Text = "C# Programming is Fun!!!";
lblFlash.Font = new System.Drawing.Font("Square721 BT", 24F);
lblFlash.ForeColor = System.Drawing.Color.Blue;
lblFlash.Location = new System.Drawing.Point(12, 10);
Text = "Text Flasher";
Size = new System.Drawing.Size(435, 88);
Controls.Add(lblFlash);
}
void btnFlashTick(object sender, EventArgs e)
{
if (lblFlash.Text == "C# Programming is Fun!!!")
lblFlash.Text = "";
else
lblFlash.Text = "C# Programming is Fun!!!";
}
}
public class Program
{
static int Main()
{
System.Windows.Forms.Application.Run(new Exercise());
return 0;
}
}
When, or as soon as, this property is set to true, the
control starts counting. You can also make it start by calling the
Timer.Start() method. Its syntax is:
public void Start();
If, when, or as soon as, the Enabled property is
set to false, the control stops and resets its counter to 0. You can also
stop the timer by calling the Timer.Stop() method. Its syntax is:
public void Stop();
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Application:
Using Timer Controls
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- From the Components section of the Toolbox, click the Timer control
and click the form
- In the Properties window, set the Enabled property to True
and set the Interval to 200
- Under the form, double-click the timer
- In the top section of the file, under the other using System lines,
type using System.Drawing.Drawing2D;
- Scroll down and implement the Tick event as follows:
private void timer1_Tick(object sender, EventArgs e)
{
// Get the Graphics object of the form
Graphics graph = Graphics.FromHwnd(this.Handle);
// Generate a random number
Random rndNumber = new Random(DateTime.Now.Millisecond);
// Create a list of the colors of the .NET Framework
Color[] curColor =
{
Color.AliceBlue, Color.AntiqueWhite, Color.Aqua, Color.Aquamarine,
Color.Azure, Color.Beige, Color.Bisque, Color.Black,
Color.BlanchedAlmond, Color.Blue, Color.BlueViolet, Color.Brown,
Color.BurlyWood, Color.CadetBlue, Color.Chartreuse, Color.Chocolate,
Color.Coral, Color.CornflowerBlue, Color.Cornsilk, Color.Crimson,
Color.Cyan, Color.DarkBlue, Color.DarkCyan, Color.DarkGoldenrod,
Color.DarkGray, Color.DarkGreen, Color.DarkKhaki, Color.DarkMagenta,
Color.DarkOliveGreen, Color.DarkOrange, Color.DarkOrchid,
Color.DarkRed, Color.DarkSalmon, Color.DarkSeaGreen,
Color.DarkSlateBlue, Color.DarkSlateGray, Color.DarkTurquoise,
Color.DarkViolet, Color.DeepPink, Color.DeepSkyBlue, Color.DimGray,
Color.DodgerBlue, Color.Firebrick, Color.FloralWhite, Color.ForestGreen,
Color.Fuchsia, Color.Gainsboro, Color.GhostWhite, Color.Gold,
Color.Goldenrod, Color.Gray, Color.Green, Color.GreenYellow,
Color.Honeydew, Color.HotPink, Color.IndianRed, Color.Indigo,
Color.Ivory, Color.Khaki, Color.Lavender, Color.LavenderBlush,
Color.LawnGreen, Color.LemonChiffon, Color.LightBlue,
Color.LightCoral, Color.LightCyan, Color.LightGoldenrodYellow,
Color.LightGray, Color.LightGreen, Color.LightPink, Color.LightSalmon,
Color.LightSeaGreen, Color.LightSkyBlue, Color.LightSlateGray,
Color.LightSteelBlue, Color.LightYellow, Color.Lime, Color.LimeGreen,
Color.Linen, Color.Magenta, Color.Maroon, Color.MediumAquamarine,
Color.MediumBlue, Color.MediumOrchid, Color.MediumPurple,
Color.MediumSeaGreen, Color.MediumSlateBlue, Color.MediumSpringGreen,
Color.MediumTurquoise, Color.MediumVioletRed, Color.MidnightBlue,
Color.MintCream, Color.MistyRose, Color.Moccasin, Color.NavajoWhite,
Color.Navy, Color.OldLace, Color.Olive, Color.OliveDrab, Color.Orange,
Color.OrangeRed, Color.Orchid, Color.PaleGoldenrod, Color.PaleGreen,
Color.PaleTurquoise, Color.PaleVioletRed, Color.PapayaWhip,
Color.PeachPuff, Color.Peru, Color.Pink, Color.Plum, Color.PowderBlue,
Color.Purple, Color.Red, Color.RosyBrown, Color.RoyalBlue,
Color.SaddleBrown, Color.Salmon, Color.SandyBrown, Color.SeaGreen,
Color.SeaShell, Color.Sienna, Color.Silver, Color.SkyBlue,
Color.SlateBlue, Color.SlateGray, Color.Snow, Color.SpringGreen,
Color.SteelBlue, Color.Tan, Color.Teal, Color.Thistle, Color.Tomato,
Color.Transparent, Color.Turquoise, Color.Violet, Color.Wheat,
Color.White, Color.WhiteSmoke, Color.Yellow, Color.YellowGreen
};
// Create a list of 10 rectangles for each row
Rectangle[] row1 = new Rectangle[10];
Rectangle[] row2 = new Rectangle[10];
Rectangle[] row3 = new Rectangle[10];
Rectangle[] row4 = new Rectangle[10];
Rectangle[] row5 = new Rectangle[10];
Rectangle[] row6 = new Rectangle[10];
Rectangle[] row7 = new Rectangle[10];
Rectangle[] row8 = new Rectangle[10];
// Create the rectangles that will be drawn on the screen
for (int i = 0; i < 9; i++)
{
row1[i] = new Rectangle(i + (i * (Width / 10)), 0,
(Width - 36) / 10, Height / 8);
row2[i] = new Rectangle(i + (i * (Width / 10)), 4 + (Height / 8),
(Width - 36) / 10, Height / 8);
row3[i] = new Rectangle(i + (i * (Width / 10)), 8 + (2 * (Height / 8)),
(Width - 36) / 10, Height / 8);
row4[i] = new Rectangle(i + (i * (Width / 10)), 12 + (3 * (Height / 8)),
(Width - 36) / 10, Height / 8);
row5[i] = new Rectangle(i + (i * (Width / 10)), 16 + (4 * (Height / 8)),
(Width - 36) / 10, Height / 8);
row6[i] = new Rectangle(i + (i * (Width / 10)), 20 + (5 * (Height / 8)),
(Width - 36) / 10, Height / 8);
row7[i] = new Rectangle(i + (i * (Width / 10)), 24 + (6 * (Height / 8)),
(Width - 36) / 10, Height / 8);
row8[i] = new Rectangle(i + (i * (Width / 10)), 28 + (7 * (Height / 8)),
(Width - 36) / 10, Height / 8);
}
// Create the last rectangle of each row
Rectangle row1a = new Rectangle(9 + (9 * (Width / 10)),
0, ((Width - 36) / 10) - 2, Height / 8);
Rectangle row2a = new Rectangle(9 + (9 * (Width / 10)),
4 + (Height / 8), ((Width - 36) / 10) - 2, Height / 8);
Rectangle row3a = new Rectangle(9 + (9 * (Width / 10)),
8 + (2 * (Height / 8)), ((Width - 36) / 10) - 2, Height / 8);
Rectangle row4a = new Rectangle(9 + (9 * (Width / 10)),
12 + (3 * (Height / 8)), ((Width - 36) / 10) - 2, Height / 8);
Rectangle row5a = new Rectangle(9 + (9 * (Width / 10)),
16 + (4 * (Height / 8)), ((Width - 36) / 10) - 2, Height / 8);
Rectangle row6a = new Rectangle(9 + (9 * (Width / 10)),
20 + (5 * (Height / 8)), ((Width - 36) / 10) - 2, Height / 8);
Rectangle row7a = new Rectangle(9 + (9 * (Width / 10)),
24 + (6 * (Height / 8)), ((Width - 36) / 10) - 2, Height / 8);
Rectangle row8a = new Rectangle(9 + (9 * (Width / 10)),
28 + (7 * (Height / 8)), ((Width - 36) / 10) - 2, Height / 8);
// Create a list of the hatch brushes of the .NET Framework using random colors
HatchBrush[] curBrush =
{
new HatchBrush(HatchStyle.BackwardDiagonal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Cross,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DarkDownwardDiagonal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DarkHorizontal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DarkUpwardDiagonal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DarkVertical,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DashedDownwardDiagonal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DashedHorizontal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DashedUpwardDiagonal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DashedVertical,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DashedVertical,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DiagonalBrick,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DiagonalCross,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Divot,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DottedDiamond,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.DottedGrid,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.ForwardDiagonal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Horizontal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.HorizontalBrick,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.LargeCheckerBoard,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.LargeConfetti,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.LargeGrid,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.LightDownwardDiagonal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.LightHorizontal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.LightUpwardDiagonal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.LightVertical,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Max,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Min,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.NarrowHorizontal,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.NarrowVertical,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.OutlinedDiamond,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent05,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent10,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent20,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent25,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent30,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent40,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent50,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent60,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent70,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent75,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent80,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent90,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Plaid,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)]),
new HatchBrush(HatchStyle.Percent05,
curColor[rndNumber.Next(curColor.Length)],
curColor[rndNumber.Next(curColor.Length)])
};
// Draw the rectangles to cover the screen
for (int i = 0; i < 9; i++)
{
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row1[i]);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row1[i]);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row2[i]);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row2[i]);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row3[i]);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row3[i]);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row4[i]);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row4[i]);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row5[i]);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row5[i]);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row6[i]);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row6[i]);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row7[i]);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row7[i]);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row8[i]);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row8[i]);
}
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row1a);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row1a);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row2a);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row2a);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row3a);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row3a);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row4a);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row4a);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row5a);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row5a);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row6a);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row6a);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row7a);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row7a);
graph.FillRectangle(curBrush[rndNumber.Next(curBrush.Length)], row8a);
graph.DrawRectangle(new Pen(curBrush[rndNumber.Next(curBrush.Length)]), row8a);
}
- Execute the application
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