Provided by: libcdk5-dev_5.0.20230201-4_amd64 
NAME
cdk_display - Curses Development Kit Display Capabilities.
SYNOPSIS
Cdk has a number of pre-defined display types. The following are outlined in this manual
page:
• How To Use Colors
• How To Use Different Character Attributes
• How To Justify Strings
• How To Use Special Drawing Characters
• Edit/Display Type Codes (EDisplayType)
DESCRIPTION
Cdk has special formatting commands which can be included in any string which add
highlights, justification, or even colors to a basic string. These attributes, once set,
remain in effect until changed explicitly, or until the end of the string.
This manual page outlines and demonstrates how they work.
How To Use Colors
Cdk has the capability to display colors in almost every string type displayed in a Cdk
widget.
Normally the color pairs are accessed via the COLOR_PAIR macro. You can still do this,
but creating a string with multiple colors is tedious. That is why the color commands
were created. Use initCDKColor to create up to 64 color pairs which you can refer to by
number in strings.
The color settings are stored directly in the string. When the widget is created or
activated, the string is converted to take advantage of any color commands in the string.
• To turn on a color pair insert </XX> into the string; where XX is a numeric value from
0 to the maximum color pair.
Color pair 0 is the standard default color pair for the screen.
If you used initCDKColor, the maximum value for XX is 63 for terminals supporting 8
ANSI colors.
If you created color pairs directly using init_pair, the maximum value for XX is
implementation-dependent, e.g., 63 (for Unix systems) and 255 for ncurses.
If the terminal does not support color, Cdk uses the bold attribute.
• To turn off a color pair use the format command <!XX> where XX is a numeric value from
0 to the maximum color pair.
The following example demonstrates the use of the color commands.
----------------------------------------
#include <cdk/cdk.h>
void main()
{
CDKSCREEN *cdkscreen;
CDKLABEL *demo;
char *mesg[4];
cdkscreen = initCDKScreen (NULL);
/* Start CDK Colors */
initCDKColor();
/* Set the labels up. */
mesg[0] = "</31>This line should have a yellow foreground and a cyan background.<!31>";
mesg[1] = "</05>This line should have a white foreground and a blue background.<!05>";
mesg[2] = "</26>This line should have a yellow foreground and a red background.<!26>";
mesg[3] = "<C>This line should be set to whatever the screen default is.";
/* Declare the labels. */
demo = newCDKLabel (cdkscreen, CENTER, CENTER, mesg, 4, TRUE, TRUE);
/* Draw the label */
drawCDKLabel (demo, TRUE);
waitCDKLabel (demo, ' ');
/* Clean up */
destroyCDKLabel (demo);
destroyCDKScreen (cdkscreen);
endCDK();
exit (0);
}
----------------------------------------
How To Use Different Character Attributes
Cdk also provides attribute commands which allow different character attributes to be
displayed in a Cdk widget. To use a character attribute the format command is </X> where
X is one of several command characters. To turn a attribute off use the command <!X>.
The following table outlines the command characters:
┌────────────────────────────────────────────────────────┐
│Command Character Character Attribute │
├────────────────────────────────────────────────────────┤
│B Bold │
│U Underline │
│K Blink │
│R Reverse │
│S Standout │
│D Dim │
│N Normal │
└────────────────────────────────────────────────────────┘
The following example demonstrates the use of character display attributes.
----------------------------------------
#include <cdk/cdk.h>
void main()
{
CDKSCREEN *cdkscreen;
CDKLABEL *demo;
char *mesg[4];
cdkscreen = initCDKScreen (NULL);
/* Start CDK Colors */
initCDKColor();
/* Set the labels up. */
mesg[0] = "</B/31>Bold text yellow foreground / blue background.<!31>";
mesg[1] = "</U/05>Underlined text white foreground / blue background.<!05>";
mesg[2] = "</K/26>Blinking text yellow foreground / red background.<!26>";
mesg[3] = "<C>This line uses the screen default colors.";
/* Declare the labels. */
demo = newCDKLabel (cdkscreen, CENTER, CENTER, mesg, 4, TRUE, TRUE);
/* Draw the label */
drawCDKLabel (demo, TRUE);
waitCDKLabel (demo, ' ');
/* Clean up */
destroyCDKLabel (demo);
destroyCDKScreen (cdkscreen);
endCDK();
exit (0);
}
----------------------------------------
Note that color commands and format commands can be mixed inside the same format marker.
The above example underlines the label marker, which also sets color pair number 2.
How To Justify Strings
Justification commands can left justify, right justify, or center a string of text. To
use a justification format in a string the command <X> is used. The following table lists
the format commands:
┌─────────────────────────────────────────────────────────┐
│Command Action. │
├─────────────────────────────────────────────────────────┤
│<L> Left Justified. Default if not stated. │
│<C> Centered text. │
│<R> Right justified. │
│<I=X> Indent the line X characters. │
│<B=X> Bullet. X is the bullet string to use. │
│<F=X> Links in a file where X is the │
│ filename. This works only with the │
│ viewer widget. │
└─────────────────────────────────────────────────────────┘
The following example demonstrates how to use the justification commands in a Cdk widget.
----------------------------------------
#include <cdk/cdk.h>
void main()
{
CDKSCREEN *cdkscreen;
CDKLABEL *demo;
char *mesg[5];
cdkscreen = initCDKScreen (NULL);
/* Start CDK Colors */
initCDKColor();
/* Set the labels up. */
mesg[0] = "<R></B/31>This line should have a yellow foreground and a blue background.<!31>";
mesg[1] = "</U/05>This line should have a white foreground and a blue background.<!05>";
mesg[2] = "<B=+>This is a bullet.";
mesg[3] = "<I=10>This is indented 10 characters.";
mesg[4] = "<C>This line should be set to whatever the screen default is.";
/* Declare the labels. */
demo = newCDKLabel (cdkscreen, CENTER, CENTER, mesg, 5, TRUE, TRUE);
/* Draw the label */
drawCDKLabel (demo, TRUE);
waitCDKLabel (demo, ' ');
/* Clean up */
destroyCDKLabel (demo);
destroyCDKScreen (cdkscreen);
endCDK();
exit (0);
}
----------------------------------------
The bullet format command can take either a single character or a string. The bullet in
the above example would look like
+ This is a bullet.
but if we were to use the following command instead
<B=***>This is a bullet.
it would look like
*** This is a bullet.
A format command must be at the beginning of the string.
How To Use Special Drawing Characters
Cdk has a set of special drawing characters which can be inserted into any ASCII file.
These characters are encoded using the format command “<#XX>” where XX is a two-character
name. The char2Chtype and chtype2String functions provide conversion to/from curses
chtype data (see cdk_util(3)).
The following table lists the supported special character commands.
┌────────────────────────────────────────────────────────┐
│Special_Character Character │
├────────────────────────────────────────────────────────┤
│<#UL> Upper Left Corner │
│<#UR> Upper Right Corner │
│<#LL> Lower Left Corner │
│<#LR> Lower Right Corner │
├────────────────────────────────────────────────────────┤
│<#LT> Left Tee │
│<#RT> Right Tee │
│<#TT> Top Tee │
│<#BT> Bottom Tee │
├────────────────────────────────────────────────────────┤
│<#HL> Horizontal Line │
│<#VL> Vertical Line │
├────────────────────────────────────────────────────────┤
│<#PL> Plus Sign │
│<#PM> Plus or Minus Sign │
│<#DG> Degree Sign │
│<#CB> Checker Board │
│<#DI> Diamond │
│<#BU> Bullet │
│<#S1> Scan line 1 │
│<#S9> Scan line 9 │
├────────────────────────────────────────────────────────┤
│<#LA> Left Arrow │
│<#RA> Right Arrow │
│<#TA> Top Arrow │
│<#BA> Bottom Arrow │
└────────────────────────────────────────────────────────┘
The character formats can be repeated using an optional numeric repeat value. To repeat a
character add the repeat count within parentheses to the end of the character format. The
following example draws 10 horizontal-line characters:
<#HL(10)>
The following example draws a box within a label window:
----------------------------------------
#include <cdk/cdk.h>
void main()
{
/* Declare variables. */
CDKSCREEN *cdkscreen;
CDKLABEL *demo;
char *mesg[4];
cdkscreen = initCDKScreen (NULL);
/* Start CDK Colors */
initCDKColor();
/* Set the labels up. */
mesg[0] = "<C><#UL><#HL(26)><#UR>";
mesg[1] = "<C><#VL></R>This text should be boxed.<!R><#VL>";
mesg[2] = "<C><#LL><#HL(26)><#LR>";
mesg[3] = "<C>While this is not.";
/* Declare the labels. */
demo = newCDKLabel (cdkscreen, CENTER, CENTER, mesg, 4, TRUE, TRUE);
/* Is the label NULL??? */
if (demo == (CDKLABEL *)NULL)
{
/* Clean up the memory. */
destroyCDKScreen (cdkscreen);
/* End curses... */
endCDK();
/* Spit out a message. */
printf ("Oops. Can't seem to create the label. Is the window too small?\n");
exit (1);
}
/* Draw the CDK screen. */
refreshCDKScreen (cdkscreen);
waitCDKLabel (demo, ' ');
/* Clean up */
destroyCDKLabel (demo);
destroyCDKScreen (cdkscreen);
endCDK();
exit (0);
}
----------------------------------------
Notice that drawn text can also be justified.
Edit/Display Type Codes (EDisplayType)
┌────────────────────────────────────────────────────────────────┐
│Display_Type Result │
├────────────────────────────────────────────────────────────────┤
│vCHAR Only accepts alphabetic characters. │
│vLCHAR Only accepts alphabetic characters. Maps the │
│ character to lower case when a character has │
│ been accepted. │
│vUCHAR Only accepts alphabetic characters. Maps the │
│ character to upper case when a character has │
│ been accepted. │
│vHCHAR Only accepts alphabetic characters. Displays │
│ a period (.) when a character has been │
│ accepted. │
│vUHCHAR Only accepts alphabetic characters. Displays │
│ a period (.) and maps the character to upper │
│ case when a character has been accepted. │
│vLHCHAR Only accepts alphabetic characters. Displays │
│ a period (.) and maps the character to lower │
│ case when a character has been accepted. │
│vINT Only accepts numeric characters. │
│vHINT Only accepts numeric characters. Displays a │
│ period (.) when a character has been │
│ accepted. │
│vMIXED Accepts any character types. │
│vLMIXED Accepts any character types. Maps the │
│ character to lower case when an alphabetic │
│ character has been accepted. │
│vUMIXED Accepts any character types. Maps the │
│ character to upper case when an alphabetic │
│ character has been accepted. │
│vHMIXED Accepts any character types. Displays a │
│ period (.) when a character has been │
│ accepted. │
│vLHMIXED Accepts any character types. Displays a │
│ period (.) and maps the character to lower │
│ case when a character has been accepted. │
│vUHMIXED Accepts any character types. Displays a │
│ period (.) and maps the character to upper │
│ case when a character has been accepted. │
│vVIEWONLY Uneditable field. │
└────────────────────────────────────────────────────────────────┘
SEE ALSO
cdk(3), cdk_binding(3), cdk_screen(3), cdk_util(3)
cdk_display(3)