CONTROL ADD TEXTBOX statement

Purpose

Add a text box control to a dialog. A text box is very similar to a conventional edit control, and it is used to enter text into an application. Text boxes support single-line and multiple-line input.

Syntax

CONTROL ADD TEXTBOX, hDlg, id&, txt$, x, y, xx, yy [, [style&] [, [exstyle&]]] [[,] CALL callback]

hDlg

Handle of the dialog in which the text box will be created. The dialog will become the parent of the control.

id&

Unique identifier for the control in the range 1 to 65535, frequently specified with numeric equates for clarity of the code. For example, the equate %CustomerName is more informative than a literal value such as 497. Best practice suggests identifiers should start at 100 to avoid conflict with any of the standard predefined identifiers.

txt$

Default text to be displayed in text box. txt$ may be a string, string equate, or string expression. txt$ can be empty if there is no default text.

x, y

Integer expressions, variables, or numeric literal values, specifying the location of the control inside the dialog client area. x is the horizontal position, and y is the vertical position. 0,0 refers to the upper left corner of the dialog box client area. Coordinates are specified in the same terms (pixels or dialog units) as the parent dialog.

Integral expression, variable, or numeric literal value, specifying the width of the control. The width is given in the same terms (pixels or dialog units) as the parent dialog. The most common value used in the Microsoft Dialog Editor and Visual Studio is 100 dialog units.

Integral expression, variable, or numeric literal value, specifying the height of the control. The height is given in the same terms (pixels or dialog units) as the parent dialog. The most common value used in the Microsoft Dialog Editor and Visual Studio is 12 dialog units.

style&

Primary style of the text box control. The default text box style comprises %WS_TABSTOP, %WS_BORDER, %ES_LEFT, and %ES_AUTOHSCROLL. The default style is used if both the primary and extended style parameters are omitted from the statement. For example:

CONTROL ADD TEXTBOX, hDlg, id&, txt$, 100, 100, 150, 200, , , _

CALL EditControlCallback() ' Use default styles

Custom style values replace the default values. That is, they are not additional to the default style values - your code must specify all necessary primary and extended style parameters.

The primary text box style value can be a combination of any values below, combined together with the OR operator to form a bitmask:

%ES_AUTOHSCROLL	Automatically scroll text to the right by 10 characters when the user types a character at the end of the line. When the user presses the ENTER key, scroll all text back to position zero.
%ES_AUTOVSCROLL	Automatically scroll text up one page when the user presses the ENTER key on the last line. This must be combined with the %ES_WANTRETURN and %ES_MULTILINE styles. Also see %WS_VSCROLL.
%ES_CENTER	Center text in a multi-line edit control.
%ES_LEFT	Left-aligns text. (default)
%ES_LOWERCASE	Convert all characters to lowercase as they are typed into the edit control.
%ES_MULTILINE	Allow the control to accept multiple lines of input. By default, the ENTER key activates the default button on the dialog. To use the ENTER key as a carriage return in the text box control, include the %ES_WANTRETURN style. If the %ES_AUTOHSCROLL style is included, the control automatically scrolls horizontally when the caret goes past the right edge of the control. Otherwise, the control automatically wraps words to the beginning of the next line when necessary. The control size determines the position of the word wrap.
%ES_NOHIDESEL	Negate the default behavior for a text box. The default behavior hides the selection when the control loses the input focus, and inverts the selection when the control receives the input focus. If you specify %ES_NOHIDESEL, the selected text is inverted, even if the control does not have the focus.
%ES_NUMBER	Allow only digits ("0123456789") instead of characters. Although Windows does not consider the negation symbol (-) or period symbol (.) to be digits, subclassing a TextBox that does not use %ES_NUMBER and rejecting "unwanted" keystrokes is common practice among advanced programmers.
%ES_OEMCONVERT	Text is converted from the windows character set to OEM, then back to Windows, as it is entered.
%ES_PASSWORD	Display an asterisk (*) for each character typed into the control in order to obscure the password.
%ES_READONLY	Prevent the user from typing or editing text in the control. Text can still be selected and copied from the control to the clipboard with the mouse.
%ES_RIGHT	Right-align text in a multi-line text box.
%ES_UPPERCASE	Convert all characters to uppercase as they are typed into the control.
%ES_WANTRETURN	Allow the ENTER key to insert a carriage return in a multi-line text box. Otherwise, the ENTER key works as the dialog box's default push button. This style has no effect on a single-line text box.
%WS_BORDER	Add a thin line border around the text box control.
%WS_HSCROLL	Add a horizontal scroll bar to the edit control, when used in conjunction to the %ES_AUTOHSCROLL style.
%WS_GROUP	Define the start of a group of controls. The first control in each group should also use %WS_TABSTOP style. The next %WS_GROUP control in the tab order defines the end of this group and the start of a new group.
%WS_TABSTOP	Allow the textbox control to receive keyboard focus when the user presses the TAB and SHIFT+TAB keys. The TAB key shifts keyboard focus to the next control with the %WS_TABSTOP style, and SHIFT+TAB shifts focus to the previous control with %WS_TABSTOP. (default)
%WS_VSCROLL	Add a vertical scroll bar to the edit control. This style should be used in conjunction to the %ES_MULTILINE and %ES_AUTOVSCROLL styles.

exstyle&

Extended style of the text box control. The default extended text box style comprises %WS_EX_CLIENTEDGE with %WS_EX_LEFT. The default extended style is used if both the primary and extended parameters are omitted from the CONTROL ADD TEXTBOX statement, in the same manner as style& above.

The extended text box style value can be a combination of any values below, combined together with the OR operator to form a bitmask:

%WS_EX_CLIENTEDGE	Apply a sunken edge border to the control.
%WS_EX_LEFT	The control has generic "left-aligned" properties. (default)
%WS_EX_RIGHT	The control has generic "right-aligned" properties. This style has an effect only if the shell language is Hebrew, Arabic, or another language that supports reading order alignment; otherwise, the style is ignored.
%WS_EX_STATICEDGE	Apply a three-dimensional border style to the control (intended to be used for items that do not accept user input).
%WS_EX_TRANSPARENT	Controls/windows beneath the control are drawn before the control is drawn. The control is deemed transparent because elements behind the control have already been painted - the control itself is not drawn differently. True transparency is achieved by using Regions - see MSDN for more information.
%WS_EX_WINDOWEDGE	Apply a raised edge border to the control.

callback

Optional name of a Callback Function that receives all %WM_COMMAND and %WM_NOTIFY messages for the control. See the #MESSAGES metastatement to choose which messages will be received. If a callback for the control is not designated, you must create a dialog Callback Function to process messages from your control.

If the Callback Function processes a message, it should return TRUE (non-zero) to prevent the message being passed unnecessarily to the dialog callback (if one exists). The dialog callback should also return TRUE if the notification message is processed by that Callback Function. Otherwise, the DDT engine processes unhandled messages.

Remarks

If you specify the %ES_AUTOHSCROLL style, the control automatically scrolls horizontally when the caret goes past the right edge of the control. To start a new line, the user must press the ENTER key.

If you do not specify %ES_AUTOHSCROLL, the control automatically wraps words to the beginning of the next line when necessary. A new line is also started if the user presses the ENTER key. The control size determines the position of the word wrap.

The following notifications are sent to the Callback Function:

%EN_CHANGE	Sent when the user has taken an action that may have altered text in the text box. Unlike the %EN_UPDATE notification, this message is sent after Windows updates the screen. Programmatically changing the text in a control also triggers this message.
%EN_ERRSPACE	Sent when the text box cannot allocate enough memory to meet a specific request.
%EN_HSCROLL	Sent when the user clicks a multi-line text box's horizontal scroll bar. The callback is notified before the screen is updated.
%EN_KILLFOCUS	Sent when an edit control loses the keyboard focus.
%EN_MAXTEXT	Sent when the current text insertion has exceeded the specified number of characters for the text box. The text insertion is truncated.
%EN_SETFOCUS	Sent when an edit control receives the keyboard focus.
%EN_UPDATE	Sent when a text box is about to display altered text. This notification message is sent after the control has formatted the text, but before it displays the text. Also see %EN_CHANGE.
%EN_VSCROLL	Sent when the user clicks a text box's vertical scroll bar. The callback is notified before the screen is updated.

When a Callback Function receives a %WM_COMMAND message, it should explicitly test the value of CB.CTL and CB.CTLMSG to guarantee it is responding appropriately to the notification message.

Use CONTROL GET TEXT to retrieve the text from a text box control, and use CONTROL SET TEXT to change the text in a text box control. Changing the text in a text box control (in response to a %EN_CHANGE or %EN_UPDATE message) will trigger a second set of %EN_CHANGE and %EN_UPDATE messages. Unless this is compensated for, these notifications can unwittingly cause an endless loop.

For example, the following is potentially fatal:

CALLBACK FUNCTION EditControlCallback()

IF CB.CTL = %ID_EDITBOX1 AND CB.CTLMSG = %EN_CHANGE THEN

CONTROL SET TEXT CB.HNDL, CB.CTL, "New Text"

EXIT FUNCTION

END IF

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As CONTROL SET TEXT is a "blocking" statement (that is, the statement does not complete until the text has been changed), it is a simple matter to block the endless loop effect:

CALLBACK FUNCTION EditControlCallback()

STATIC EditBusy&

IF CB.CTL = %ID_EDITBOX1 AND CB.CTLMSG = %EN_CHANGE THEN

IF EditBusy& THEN EXIT FUNCTION

EditBusy& = -1

CONTROL SET TEXT CB.HNDL, CB.CTL, "New Text"

RESET EditBusy&

EXIT FUNCTION

END IF

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