The
ImageList is a control that enables you to store
graphic images in an application. Other controls can then use the
ImageList as a central repository for the images that they will use. Both
bitmaps (*.bmp files) and icons (*.ico files) can be stored in the
ImageList control. At runtime the
ImageList
is invisible, just like a Timer or a
CommonDialog control,
so you can place it anywhere on a form without interfering with the user interface.
After an ImageList control has been
added to a form, images can be added to the control at design time through the
Custom Properties dialog box. The first tab of the dialog box, as shown in Figure
4.2, enables you to change general properties of the ImageList.
On this tab, you can select the style and size of a graphic that will be included
in the ImageList. Three of the resolutions, 16´16,
32´32, and 48´48, refer to the resolution of icon files. The Custom
option lets you include bitmap images in the ImageList
as well as icon images. You do not need to choose a resolution, height, and width
for the ImageList. As soon as you add an image to the
control, Visual Basic automatically determines the properties for you. After you
have placed an image in the ImageList, you cannot change
the resolution property. It is locked for as long as there is an image in the
ImageList control.
FIGURE 4.2 The General tab of the Property Pages dialog box for the ImageList
control.
The list of images contained in the ImageList
control can be managed through the Images tab of the Property Pages dialog
box, as shown in Figure 4.3. This tab enables you to add and remove images from
the control as well as set additional information about each image. The Index
of each image is assigned by Visual Basic. The Index starts at 1 for the first
image and increments by 1 for each additional image.
FIGURE 4.3 The Images tab of the Property Pages dialog box for the ImageList
control.
You can use the Key property to refer to an image in the
ImageList's collection of images. The Key property is a string value that
you can use in place of the Index property to refer to an image in the list.
The easiest way to add images to the ImageList
is to use the Images tab at design time. Just click on the Insert Picture
button, and you can browse for the *.ico and *.bmp files that you want to add
to the control.
After you have added images to the ImageList
control, they are available for your application to use in other controls.
You can load images into PictureBoxes and Image controls
from the ImageList. The images can also be used by
the other controls discussed later in this chapter, such as the ToolBar and
ListView controls.
Although you can add all the images you may need in your application
to the ImageList at design time, there are times when
you will have to manipulate these images at runtime. This can be done through
the ListImages Collection of the
ImageList control. The ListImages Collection
contains ListImage objects.
See Also
<< Previous | Contents
| Next >>
