A
Checkbox
is the interface to Java's AWT Checkbox Component.
Yoix programs normally interact with a
Checkbox
using event handlers and by reading or writing the following fields:
| autotrim |
An
int
that is
1
when white space is automatically trimmed from both ends of every string
read from or written to the
text
field, and
0
otherwise.
| | background |
The
Color
that is used to paint the background of the checkbox.
Reading returns a snapshot of the current color.
Writing immediately changes the background to the new color.
Storing
NULL
in
background
is special and means use the background of the nearest component
that contains the checkbox and was assigned a background color other than
NULL;
if no component qualifies the checkbox uses
VM.screen.background.
| | cursor |
An
Object
that should be an
int,
Image,
or
String
that selects the cursor shown when the pointer is over the checkbox.
A
cursor
that is an
int
should be one of the cursors defined in the
yoix.awt.Cursor
dictionary.
A
cursor
that is an
Image
can describe the cursor using its
size
and
hotspot
fields and often draws it using its
paint
function.
A
cursor
that is a
String
should be the name of a cursor that is already defined in
yoix.awt.Cursor
or the name a local a file or URL that contains a GIF or JPEG image
that will be used as the cursor.
Reading returns the current cursor.
Writing immediately changes the checkbox's cursor to the new value.
Storing
STANDARD_CURSOR
(the default) or
NULL
in
cursor
is special and means use the cursor assigned to the nearest component
that contains the checkbox and was assigned a cursor other than
STANDARD_CURSOR;
if no component qualifies the checkbox uses
DEFAULT_CURSOR.
| | enabled |
An
int
that is
1
when the checkbox can respond to user input, and
0
otherwise.
Reading returns the current state.
Writing immediately sets the checkbox's state to the new value.
| | focusable |
An
int
that is non-zero (the default)
when the checkbox can accept the keyboard focus and zero
when it can not.
Reading returns the checkbox's current focusable state.
Writing immediately changes the checkbox's focusable state to the new value,
which means the focus is automatically transferred if the new value is zero
and the checkbox is the current focus owner.
| | focusowner |
A read-only
int
that is non-zero when the checkbox has the focus.
| | font |
The
Font,
or font name if it is a
String,
used to paint the characters stored in the
text
field.
Reading returns a snapshot of the current font.
Writing immediately repaints the text in the new font.
| | foreground |
The
Color
that is used to paint the characters stored in the
text
field.
Reading returns a snapshot of the current color.
Writing immediately repaints the text in the new color.
Storing
NULL
in
foreground
is special and means use the foreground of the nearest component
that contains the checkbox and was assigned a foreground color other than
NULL;
if no component qualifies the checkbox uses
VM.screen.foreground.
| | group |
A
CheckboxGroup
that, when it is not
NULL,
imposes radio button behavior (i.e., at most one checkbox can be selected)
on all the checkboxes in the group.
| | location |
A
Point
that determines the location of the checkbox
in a coordinate system that has its origin at the upper left corner
of the container closest to the checkbox (in the component hierarchy)
that actually contains it, positive x to the right, positive y down,
and a resolution of 72 dots per inch.
Reading returns a snapshot of the current location.
Writing is allowed, but layout managers usually get the final say, so setting
location
should be viewed as a request that may not be honored.
| | popup |
A
PopupMenu
that is associated with the checkbox.
Reading returns the current popup menu.
Writing immediately shows the popup menu at the point in the checkbox's coordinate
system specified by the popup menu's
location
field, assuming of course that the checkbox is showing on the screen.
Storing
TRUE
in the popup menu's
visible
field, which was added in release 1.2.0, is an easy way to show the
popup menu that currently belongs to the checkbox.
| | requestfocus |
An
int
can be used to request or transfer the keyboard focus.
Storing a non-zero value in
requestfocus
tries to get the focus.
Storing
0
tries to transfer the focus.
Reading
requestfocus
does not currently return any useful information.
| | root |
An
Object
that is automatically updated by the interpreter's layout machinery
so it is always the top-level object that contains the checkbox.
For example, put a checkbox in a panel and
root
will be set to that panel;
add the panel to a frame and the checkbox's
root
field will be set to that frame.
A checkbox's event handlers can use
root
when they need to interact with the other components in the container.
| | showing |
A read-only
int
that is non-zero when the checkbox is showing on the screen.
| | size |
A
Dimension
that determines the size of the checkbox
in units of 72 dots per inch.
Reading returns a snapshot of the current size.
Writing is allowed, but layout managers usually get the final say, so setting
size
should be viewed as a request that may not be honored.
| | state |
An
int
that is
1
when the checkbox is selected, and
0
otherwise.
Reading returns the current state.
Writing immediately sets the checkbox's state to the new value.
| | tag |
A
String
used to identify the checkbox that is either supplied when
the checkbox is declared, or automatically generated otherwise.
Add a checkbox to a container, like a
Frame
or
Panel,
and the interpreter's layout machinery updates the
root
field so it points at the top-level container and then adds the checkbox, as
tag,
to the
root.components
dictionary.
| | text |
A
String
of characters that are painted next to the checkbox.
Reading returns the current text.
Writing immediately paints the new text.
| | visible |
An
int
that is
1
when the checkbox is visible, and
0
otherwise.
Reading returns the current visibility.
Writing immediately sets the checkbox's visibility to the new state.
|
Several permanent fields have not been documented and should not be
used in Yoix applications.
Event handlers are functions that must be added to a checkbox when it is
declared.
The handlers that work with checkboxes are listed below;
the names should be familiar if you have done some Java programming.
The
actionPerformed
event handler is only for menus.
| |
| Event Handlers: |
actionPerformed,
componentHidden,
componentMoved,
componentResized,
componentShown,
dragDropEnd,
dragEnter,
dragExit,
dragGestureRecognized,
dragMouseMoved,
dragOver,
drop,
dropActionChanged,
focusGained,
focusLost,
invocationRun,
itemStateChanged,
keyPressed,
keyReleased,
keyTyped,
mouseClicked,
mouseDragged,
mouseEntered,
mouseExited,
mouseMoved,
mousePressed,
mouseReleased,
mouseWheelMoved
| | |
| Example: |
The program,
import yoix.*.*;
CheckboxGroup cbg;
Frame f = {
FlowLayout layoutmanager = {
int hgap = 10;
int vgap = 72;
};
Array layout = {
new Checkbox {
CheckboxGroup group = cbg;
String text = "Right";
int state = 1;
itemStateChanged(e) {
printf("e=%O\n", e);
}
},
new Checkbox {
String text = "Quit";
int state = 0;
itemStateChanged(e) {
if (e.state)
exit(0);
}
},
new Checkbox {
CheckboxGroup group = cbg;
String text = "Left";
int state = 1;
itemStateChanged(e) {
printf("e=%O\n", e);
}
},
};
};
f.visible = TRUE;
adds three checkboxes to a frame,
puts two in the same CheckboxGroup,
prints the event when the left or right checkbox is selected,
and quits when the middle checkbox is selected.
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| See Also: |
Button,
Canvas,
Choice,
Dialog,
FileDialog,
Frame,
Label,
List,
Panel,
postEvent,
ScrollPane,
Scrollbar,
TableColumn,
TableManager,
TextArea,
TextCanvas,
TextField,
TextTerm,
Window
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