Working with Icons in GDI+

This article has been excerpted from book "Graphics Programming with GDI+".

The Icon class represents a Windows icon, which is a small transparent bitmap. Just like the Bitmap class, this class is inherited from the Image class.

An application can create an Icon object from a stream, string, icon, icon file, or type by using the Icon class constructors with the size of the icon as an optional parameter. The Icon provides four read-only properties-Handle, Height, Size, and Width-which return a window handle to the icon, height, size, and width of an icon, respectively.

Listing 7.21 creates an Icon object from an icon file and sets the icon of a form using the Form class's Icon property.

LISTING 7.21: Creating an icon and setting a form's Icon property

private void Form1_Paint(object sender, PaintEventArgs e)

{

//Create an icon

Icon curIcon = new Icon("D:/VB.NET Basic Practice Projects/WindowsApplication8/Images/ico-32bit/wi0126-48.ico");

//Set form's icon

this.Icon = curIcon;

//Get icon properties

float h = curIcon.Height;

float w = curIcon.Width;

Size sz = curIcon.Size;

}

The FromHandle method of the Icon class creates an Icon object from a window handle to an icon (HICON). The Save method saves an Icon object to a stream, and the ToBitmap method converts an Icon object to a Bitmap object. Listing 7.22 creates a Bitmap object from an Icon object using ToBitmap and draws the bitmap using DrawImage.

LISTING 7.22: Creating a bitmap from an icon and displaying it

private void Form1_Paint(object sender, PaintEventArgs e)

{

//Create and icon

Icon curIcon = new Icon("D:/VB.NET Basic Practice Projects/WindowsApplication8/Images/ico-32bit/wi0126-48.ico");

//Create a bitmap from an icon

Bitmap bmp = curIcon.ToBitmap();

//Draw bitmap

Graphics g = e.Graphics;

g.Clear(this.BackColor);

g.DrawImage(bmp, 10, 10);

g.Dispose();

}

Figure 7.35 shows the output from Listing 7.21 and 7.22.

FIGURE 7.35: Viewing icons

Sometimes you will need to convert a Bitmap object into an Icon object.

The following code snipped shows how to do this:

Icon curIcon;

curIcon = Icon.FromHandle(bmp.GetHicon());

Conclusion

Hope the article would have helped you in understanding working with Icons in GDI+. Read other articles on GDI+ on the website.

This book teaches .NET developers how to work with GDI+ as they develop applications that include graphics, or that interact with monitors or printers. It begins by explaining the difference between GDI and GDI+, and covering the basic concepts of graphics programming in Windows.

This article has been excerpted from book "Graphics Programming with GDI+".

The Icon class represents a Windows icon, which is a small transparent bitmap. Just like the Bitmap class, this class is inherited from the Image class.

Listing 7.21 creates an Icon object from an icon file and sets the icon of a form using the Form class's Icon property.

LISTING 7.21: Creating an icon and setting a form's Icon property

private void Form1_Paint(object sender, PaintEventArgs e)

{

//Create an icon

Icon curIcon = new Icon("D:/VB.NET Basic Practice Projects/WindowsApplication8/Images/ico-32bit/wi0126-48.ico");

//Set form's icon

this.Icon = curIcon;

//Get icon properties

float h = curIcon.Height;

float w = curIcon.Width;

Size sz = curIcon.Size;

}

LISTING 7.22: Creating a bitmap from an icon and displaying it