Drawing Transparent Controls in GDI+
In this article you will learn how you can draw transparent controls.
This article has been
excerpted from book "Graphics Programming with GDI+"
How can I draw transparent controls? This is one of the commonly asked questions
on discussion forums.
Drawing transparent controls involves two steps. First we set a form's style to
enable support for transparent controls. We do this by calling the SetStyle
method of the form, passing ControlStyles.SupportTransparentBackColor as the
first argument, and setting the second argument (which in turn sets the
SupportTransparentBackColor bit) to true. Next we set the Control's BackColor
property to a transparent color. Either we can use Color.Transparent, or we can
create a Color object using an alpha component value less than 255 to provide
Listing 15.4 sets the background color of controls to transparent.
LISTING 15.4: Setting the background color of controls to transparent
/* Code for transparent controls */
button1.BackColor = Color.Transparent;
btnBrowse.BackColor = Color.Transparent;
btnClose.BackColor = Color.Transparent;
panel1.BackColor = Color.FromArgb(70,
0, 0, 255);
The output of Listing 15.4 looks like Figure 15.2
Not all control support transparent color. For example, if you set the BackColor
property of text box to Color.Transparent, you will get an exception.
FIGURE 15.2: Designing transparent controls