| Choice |
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typedict |
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A
Choice
is the interface to Java's AWT Choice Component.
Yoix programs normally interact with a
Choice
using event handlers and by reading or writing the following fields:
| background |
The
Color
that is used to paint the background of the choice.
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 choice and was assigned a background color other than
NULL;
if no component qualifies the choice uses white on the Windows
operating system and
VM.screen.background
everywhere else.
| | cursor |
An
Object
that should be an
int,
Image,
or
String
that selects the cursor shown when the pointer is over the choice.
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 choice'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 choice and was assigned a cursor other than
STANDARD_CURSOR;
if no component qualifies the choice uses
DEFAULT_CURSOR.
| | enabled |
An
int
that is
1
when the choice can respond to user input, and
0
otherwise.
Reading returns the current state.
Writing immediately sets the choice's state to the new value.
| | focusowner |
A read-only
int
that is non-zero when the choice has the focus.
| | font |
The
Font,
or font name if it is a
String,
used to paint the text strings displayed by the choice.
Reading returns a snapshot of the current font.
Writing immediately repaints the text strings displayed by the choice
in the new font.
| | foreground |
The
Color
that is used to paint text strings displayed by the choice.
Reading returns a snapshot of the current color.
Writing immediately repaints the text strings displayed by the choice
in the new color.
Storing
NULL
in
foreground
is special and means use the foreground of the nearest component
that contains the choice and was assigned a foreground color other than
NULL;
if no component qualifies the choice uses
VM.screen.foreground.
| | items |
An
Array
of strings, organized in pairs, that determines what is loaded
in the choice (i.e., what users see) and what is returned by
the choice when reading the
selected
field.
Strings at even indices in
items
are loaded in the choice;
strings at odd indices are return values.
A
NULL
at an odd index means the return value is the string at the
corresponding even index
(i.e., the one that was loaded in the choice).
Setting this field to
NULL
clears the choice completely.
Reading this value will always return an
Array
of at least size 0.
This field affects the values of the
labels
and
mappings
fields (and vice versa).
| | labels |
An
Array
of strings that determines what is loaded
in the choice and what is returned by
the choice when reading the
selected
field.
All the strings are loaded into the choice and the same values are returned
in the
selected
field.
The result is equivalent to using the
items
field with alternating
NULL
values.
Setting this field to
NULL
clears the choice completely.
Reading this value will always return an
Array
of at least size 0.
This field affects the values of the
items
and
mappings
fields.
| | location |
A
Point
that determines the location of the choice
in a coordinate system that has its origin at the upper left corner
of the container closest to the choice (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.
| | mappings |
An
Array
of strings that determines what is returned by
the choice when reading the
selected
field.
This field must be set after the
labels
or
items
field is set and the length of the
Array
must match the length of the
Array
returned by the
labels
field.
The strings are assigned to be the return values for corresponding element,
positionally, in the labels
Array.
This field can be used to replace existing mappings, even those set by the
items
field.
Setting this field to
NULL
removes is equivalent to using the
items
field with alternating
NULL
values or the
labels
field alone.
Reading this value will always return an
Array
of at least size 0.
| | popup |
A
PopupMenu
that is associated with the choice.
Reading returns the current popup menu.
Writing immediately shows the popup menu at the point in the choice's coordinate
system specified by the popup menu's
location
field, assuming of course that the choice 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 choice.
| | requestfocus |
An
int
that 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 choice.
For example, put a choice in a panel and
root
will be set to that panel;
add the panel to a frame and the choice's
root
field will be set to that frame.
A choice's event handlers can use
root
when they need to interact with the other components in the container.
| | selected |
A
String
or
int
that refers to the item that is currently selected by the choice.
Reading always returns the string that corresponds to the currently
selected item.
Storing an integer in
selected
picks the item at that index.
Storing a string in
selected
picks the item that has that string as its return value,
or if there is no match, the item that has that string as its label value,
if any, is selected.
If there is no match, the current selection is unchanged.
| | showing |
A read-only
int
that is non-zero when the choice is showing on the screen.
| | size |
A
Dimension
that determines the size of the choice
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.
| | tag |
A
String
used to identify the choice that is either supplied when
the choice is declared, or automatically generated otherwise.
Add a choice 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 choice, as
tag,
to the
root.components
dictionary.
| | visible |
An
int
that is
1
when the choice is visible, and
0
otherwise.
Reading returns the current visibility.
Writing immediately sets the choice's visibility to the new state.
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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 choice when it is
declared.
The handlers that work with choices are listed below;
the names should be familiar if you have done some Java programming.
The
actionPerformed
event handler is only for menus.
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| 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
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| Example: |
The program,
import yoix.*.*;
Frame f = {
FlowLayout layoutmanager = {
int hgap = 10;
int vgap = 72;
};
Array layout = {
new Choice {
Array items = {"one", "1", "two", NULL, "three", "3"};
itemStateChanged(e) {
printf("selected=%O\n", selected);
}
},
new Choice {
Array items = {" ", NULL, "Continue", NULL, "Quit", NULL};
int selected = 1;
itemStateChanged(e) {
printf("selected=%O\n", selected);
if (strcmp(selected, "Quit") == 0)
exit(0);
}
},
};
};
f.visible = TRUE;
adds two choices to a frame,
prints the selected value when either one is changed,
and quits when the last item in the right choice is
selected.
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| See Also: |
Button,
Canvas,
Checkbox,
Dialog,
FileDialog,
Frame,
Label,
List,
Panel,
postEvent,
ScrollPane,
Scrollbar,
TableColumn,
TableManager,
TextArea,
TextCanvas,
TextField,
TextTerm,
Window
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Yoix is a registered trademark of AT&T Intellectual Property.
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