Java Reference
In-Depth Information
A
true
argument to the method will allow the toolbar to float, so you can switch this on and off in your
program as you wish. You can also test whether the toolbar can float by calling the
isFloatable()
method for the
JToolBar
object. This will return
true
if the toolbar is floatable, and
false
otherwise. If you recompile
SketchFrame
and run Sketcher again you will see that the gray bit at the
left hand end of the toolbar is no longer there, and you cannot drag the toolbar around.
The button that has been created uses the name from the
Action
object as its label by default. We
really want toolbar buttons with icons, so that's got to be the next step.
Adding Icons
A reference to an icon is generally stored in a variable of type
Icon
.
Icon
is an interface that declares
methods to obtain the height and width of an icon in pixels - these are the
getHeight()
and
getWidth()
methods respectively, and to paint the icon image on a component - the
paint()
method. One class that implements the
Icon
interface is
ImageIcon
and it is this class that
you use to create an icon object in your program from a file containing the icon image. The class
provides several constructors that create an
ImageIcon
object and the one we will use accepts a
String
argument that specifies the file where the icon image is to be found. The
String
object can be
just a file name, in which case the file should be in the current directory - the one that contains the
.class
files for the application or applet. You can also supply a string that specifies the path and file
name where the file containing the image is to be found. The
ImageIcon
constructors accept icon files
in
PNG
(Portable Network Graphics format, which have
.png
extensions),
GIF
(
G
raphics
I
nterchange
F
ormat, or
.gif
files), or
JPEG
(
J
oint
P
hotographic
E
xperts
G
roup format,
.jpg
files) formats, but we
will assume GIF files in our code.
We will put the icons for Sketcher in a subdirectory of the Sketcher directory called
Images
, so create a
subdirectory to your Sketcher application directory with this name. To create an icon for the
openAction
object from an image in a file
open.gif
in the
Images
directory, we could write:
openAction.putValue(Action.SMALL
_
ICON, new ImageIcon ("Images/open.gif"));
This stores the
ImageIcon
object in our
Action
object associated with the
SMALL
_
ICON
key. The
add()
method for the toolbar object will then look for the icon for the toolbar button it creates using
this key. Let's see if it works.
You will need to create the GIF files containing the icons. Any graphics editor that can save files in
the GIF format will do, Paint Shop Pro, Microsoft Paint, or gimp, for instance. I created my icons
as 16x16 pixels since it is a fairly standard size for toolbar buttons. Make sure the file for the
openAction
object is called
open.gif
, and stored in the
Images
subdirectory. We will need
GIF files for other buttons too, and they will each have a file name that is the same as the label on
the corresponding menu item.
If you want to put them together in one go, for the file menu toolbar button you will need
save.gif
,
new.gif
and
print.gif
, for the element types you will need
line.gif
,
rectangle.gif
,
circle.gif
, and
curve.gif
, and for the colors you will need
red.gif
,
yellow.gif
,
green.gif
and
blue.gif
. GIF files for all these icons are
available along with the Sketcher source code at the Wrox web site:
http://www.wrox.com/Consumer/Store/Download.asp .
