Device Objects: An Icon



An icon is used to display graphics on window objects. While a picture can have any dimension, the size of an icon is limited. This is because icons assume different roles on an application.

Icons are used to represent folders in Windows Explorer and My Computer:

Windows Explorer or My Computer

Creating Icons

To create an icon, you can use any application that has the capability. Normally, you can use Microsoft Visual Studio 2005 to create or design an icon. To do this, on the main menu, you can click Project -> Add New Item... In the Templates list, you can click Icon, give it a name, and click Add. You would then receive a platform to design an icon.

When you start designing an icon, you would be presented with a drawing area whose dimensions are 32 x 32 pixels. This is the size of the icon that displays as Large Icon. Here is an example from the New File dialog box of Microsoft Visual Studio 2005 in the Templates list:

In some cases, you may allow the user to display smaller icons, which are 16x16 pixels:

To make this possible, you can associate a second icon to the 32x32 one. The application you use to design your icon should make it simple for you to add this second icon. To do this in Microsoft Visual Studio 2005, while the icon is displaying:

  • On the main menu, you can click Image -> New Image Type...
  • You can right-click an empty area in the icon window and click New Image Type...

When the New Icon Image Type dialog box comes up, you can click 16x16, 16 colors and click OK. Whether you create only one or both versions of the icon, both are stored in a single file whose extension is .ico

Practical LearningPractical Learning: Introducing GDI+ Resources

  1. Start Microsoft Visual C# and create a new Windows Application named Resources1
  2. On the main menu, click Project -> Add New Item...
  3. In the Templates list, click Icon File
  4. Set the name to diamond and click Add
  5. On the main menu, click File -> Save diamond.ico As...
  6. Locate and display the bin sub-folder of your project
  7. Double-click Debug to select that folder
  8. Click Save
  9. If the Colors window is not displaying, on the main menu, click Image -> Show Colors Window.
    On the Colors window, click the small green monitor
  10. On the Image Editor toolbar, click the Erase Tool and wipe the whole drawing area
  11. On the Image Editor toolbar, click the Line button Line
  12. In the Colors Palette, click the blue color
  13. In the empty drawing area, count 15 small boxes from the top left to the right. In the 16th box, click and drag right and down for an angle of 45˚ for 7 boxes. Release the mouse
  14. Click the next small box on the right side of the top blue box then drag left and down at 45˚ for 7 boxes:
    Icon Design
  15. Using the tools of Image Editor toolbar, complete the design as follows:
  16. To design the 16x16 pixel version of the icon, right-click a white area in the drawing section and click New Image Type
  17. In the New Icon Image Type dialog box, click 16x16, 16 Colors if necessary and click OK
    New Icon Type
  18. Design the icon as follows:
    Icon Design: Diamond
  19. Save the file

Using an Icon

To support icons, the GDI+ library provides the Icon class, which is defined in the System.Drawing namespace. To use an icon in your application, you can first declare a variable of type Icon using one of the class' constructors. If the icon is stored in a file, the simplest constructor to use has the following syntax:

public Icon(string filename);

With this constructor, the name of, or the path to, the icon file is passed as argument.

After creating the icon, if you want to use only one size version, you can use one the following constructors to declare the variable:

public Icon(Icon original, Size size);
public Icon(Icon original, int width, int height);

After initializing an Icon variable, if you want to get its dimensions, you can access its Width and its Height properties, or its Size property.

As mentioned already, there are various ways an icon can be used. For example, you can display it in a control by drawing it. To do this, you can call the Graphics.DrawIcon() method which is overloaded with two versions whose syntaxes are:

public void DrawIcon(Icon icon, Rectangle targetRect);
public void DrawIcon(Icon icon, int x, int y);

The first version allows you to specify the location and dimensions of the icon. Here is an example of calling it:

private void btnGrapher_Click(object sender, EventArgs e)
            System.Drawing.Icon ico = new Icon("sample.ico");
            Graphics graph = CreateGraphics();
            graph.DrawIcon(ico, new Rectangle(10, 10, 42, 42));

The second version allows you to specify only the location of the icon.

Practical Learning Practical Learning: Using an Icon

  1. Display the form and double-click the middle of its body
  2. To display the icon in the title bar, implement the event as follows:
    private void Form1_Load(object sender, EventArgs e)
        System.Drawing.Icon icoMain = new System.Drawing.Icon("diamond.ico");
        Icon = icoMain;
  3. Execute the application
  4. Close the form and return to your programming environment

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