text-field% : class?

superclass: object%

extends:  control<%>

A text-field% object is an editable text field with an optional label displayed in front of it. There are two text field styles:

• A single line of text is visible, and a special control event is generated when the user presses Enter (when the text field has the focus) and the event is not handled by the text field’s frame or dialog (see on-traverse-char in top-level-window<%> ).

• Multiple lines of text are visible, and Enter is not handled specially.

Whenever the user changes the content of a text field, its callback procedure is invoked. A callback procedure is provided as an initialization argument when each text field is created.

The text field is implemented using a text% editor (with an inaccessible display). Thus, whereas text-field% provides only get-value and set-value to manipulate the text in a text field, the get-editor returns the field’s editor, which provides a vast collection of methods for more sophisticated operations on the text.

The keymap for the text field’s editor is initialized by calling the current keymap initializer procedure, which is determined by the current-text-keymap-initializer parameter.

(new text-field%   [label label]       [parent parent]      [ [callback callback]       [init-value init-value]       [style style]       [font font]       [enabled enabled]       [vert-margin vert-margin]       [horiz-margin horiz-margin]       [min-width min-width]       [min-height min-height]       [stretchable-width stretchable-width]       [stretchable-height stretchable-height]])

→ (is-a?/c text-field%)

label : (or/c label-string? false/c)

parent   :   (or/c (is-a?/c frame%) (is-a?/c dialog%)       (is-a?/c panel%) (is-a?/c pane%))

callback   :   ((is-a?/c text-field%) (is-a?/c control-event%)  . -> . any)       =   (lambda (t e) (void))

init-value : string? = ""

style   :   (listof (one-of/c 'single 'multiple 'hscroll 'password                   'vertical-label 'horizontal-label                   'deleted))       =   '(single)

font : (is-a?/c font%) = (scheme normal-control-font)

enabled : any/c = #t

vert-margin : (integer-in 0 1000) = 2

horiz-margin : (integer-in 0 1000) = 2

min-width : (integer-in 0 10000) = graphical-minimum-width

min-height : (integer-in 0 10000) = graphical-minimum-height

stretchable-width : any/c = #t

stretchable-height : any/c = (memq 'multiple style)

If label is not #f, it is used as the text field label. Otherwise, the text field does not display its label.

If & occurs in label, it is specially parsed as for button%.

The callback procedure is called when the user changes the text in the text field or presses the Enter key (and Enter is not handled by the text field’s frame or dialog; see on-traverse-char in top-level-window<%>). If the user presses Enter, the type of event passed to the callback is 'text-field-enter, otherwise it is 'text-field.

If init-value is not "", the minimum width of the text item is made wide enough to show init-value. Otherwise, a built-in default width is selected. For a text field in single-line mode, the minimum height is set to show one line and only the control’s width is stretchable. For a multiple-line text field, the minimum height shows three lines of text and is stretchable in both directions.

The style must contain exactly one of 'single or 'multiple; the former specifies a single-line field and the latter specifies a multiple-line field. The 'hscroll style applies only to multiple-line fields; when 'hscroll is specified, the field has a horizontal scrollbar and autowrapping is disabled; otherwise, the field has no horizontal scrollbar and autowrapping is enabled. A multiple-line text field always has a vertical scrollbar. The 'password style indicates that the field should draw each character of its content using a generic symbol instead of the actual character. If style includes 'vertical-label, then the text field is created with a label above the control; if style does not include 'vertical-label (and optionally includes 'horizontal-label), then the label is created to the left of the text field. If style includes 'deleted, then the text field is created as hidden, and it does not affect its parent’s geometry; the text field can be made active later by calling parent’s add-child method..

The font argument determines the font for the control. For information about the enabled argument, see window<%>. For information about the horiz-margin and vert-margin arguments, see subarea<%>. For information about the min-width, min-height, stretchable-width, and stretchable-height arguments, see area<%>.

(send a-text-field get-editor) → (is-a?/c text%)

Returns the editor used to implement the text field.

For a text field, the most useful methods of a text% object are the following:

• (send a-text (method text% get-text)) returns the current text of the editor.

• (send a-text (method text% erase)) deletes all text from the editor.

• (send a-text (method text% insert) str) inserts str into the editor at the current caret position.

(send a-text-field get-value) → string?

Returns the text currently in the text field.

(send a-text-field set-value val) → void?

val : string?

Sets the text currently in the text field. (The control’s callback procedure is not invoked.)

A text field’s value can be changed by the user typing into the control, and such changes do not go through this method; use the controlcallback procedure (provided as an initialization argument) to monitor value changes.