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3.9. Create a Windows Explorer-like Split Window
.NET 1.0 gave developers the tools they
needed to create split windows of the kind seen in Windows Explorer
with the Splitter control. Unfortunately, creating
these windows wasn't always easy, because it
commonly required a combination of a Splitter and
three Panel controls, all of which needed to be
docked in the correct order. If you needed to split a window in more
than one way, the task became even more awkward. Thankfully, .NET 2.0
streamlines the process with a SplitContainer
control.
Note: Split windows are easier than ever now that the
SplitContainer control replaces the bare-bones Splitter.
3.9.1. How do I do that?
Essentially, the SplitContainer control represents
two panels separated by a splitter bar. The user can drag the bar to
one side or another to change the relative amount of space given to
each section. To help signal the availability of this functionality,
the mouse pointer switches from a single- to a double-headed arrow
icon when the user mouses over the splitter bar.
Note: A SplitContainer control is often used when the content in
the two panels is related. When the user makes a selection in the
first panel, the content in the second is refreshed.
To create a simple interface with the
SplitContainer, you should first decide how much
screen real estate the SplitContainer will occupy.
For example, if you need to reserve some space below the
SplitContainer, start by docking a
Panel to the bottom of the form. When you add the
SplitContainer, its Dock property will
automatically be set to DockStyle.Fill so that it
fills whatever space is left over.The SplitContainer always consists of two panels.
If you set the Orientation property
to Orientation.Vertical (the default), the
splitter runs from top to bottom, creating left and right panels. The
other option is Orientation.Horizontal, which
creates top and bottom panels with a splitter bar running from left
to right between them.Once you've set the appropriate orientation, the
next step is to add controls to each side of the
SplitContainer. If you want a single control on
each side, you simply need to drag the control to the appropriate
panel in the SplitContainer and set the
Dock property of the control to
DockStyle.Fill, so that it fills all the available
space between the splitter bar and the edges of the
SplitContainer.If you need to add more than one control in the same region of the
SplitContainer, start by adding a
Panel and setting the Dock
property to DockStyle.Fill. Then, you can anchor
other controls inside the Panel.Once you've set up the
SplitContainer, you don't need to
write any code to manage the control resizing or user interaction.
Figure 3-9 shows an example. (The complete
SplitWindow project is available with the downloadable samples.)
Figure 3-9. A vertically split window
Note: You can also nest a SplitContainer inside another
SplitContainer. This is most useful if you are using different
orientations (for example, dividing a window into left and right
regions and then dividing the region on the right into top and bottom
compartments).
3.9.2. What about...
...restricting how a SplitContainer can be
resized? The SplitContainer provides several
properties tailored for this purpose. For example, you can set the
Panel1MinSize and
Panel2MinSize
properties with the minimum pixel width of the appropriate panels.
Once you set these properties, the user won't be
able to move the splitter bar to a position that shrinks the panel to
less than its minimum allowed size. You can also stop resizing
altogether by setting the IsSplitterFixed
property to False (in which case you can still
adjust the position of the splitter bar by programmatically modifying
the SplitterDistance property).Additionally, you can configure how the
SplitContainer behaves when the whole form is
resized. By default, the panels are sized proportionately. However,
you can designate one of the panels as a fixed
panel by setting the FixedPanel property.
In this case, that panel won't be modified when the
form is resized. (For example, in Windows Explorer the directory tree
is in a fixed panel, and it doesn't change size when
you expand or shrink the window.) Finally, you can even hide a panel
temporarily by setting the Panel1Collapsed or
Panel2Collapsed
property to true.
3.9.3. Where can I learn more?
For more details on the SplitContainer and some
how-to tips, look up "SplitContainer
Overview" in the index of the MSDN help
reference.
