Volume 7A: XView Programming Manual

This call to xv_get() returns TRUE if row i is selected. To return the first selected row, use

PANEL_LIST_FIRST_SELECTED as follows:

int first_selected;

first_selected = (int)xv_get(list_item, PANEL_LIST_FIRST_SELECTED);

PANEL_LIST_NEXT_SELECTED

returns the next selected row after a specified row. This attri-

bute takes a single integer argument representing the row to start from. If no row is selected

following the specified row, PANEL_LIST_NEXT_SELECTED returns -1.

7.11.4 List Notification

The procedure specified via the attribute PANEL_NOTIFY_PROC is called when a row is se-

lected, de-selected, added, or deleted. List notify procedures are passed the following: the

list item, the string indicating the label of the item being acted upon, any client data associat-

ed with the list entry, a parameter indicating the action being taken, the event which caused

notification, and the row number of the row being operated on. The form of the procedure is:

int

list_notify_proc(item, string, client_data, op, event, row)

Panel_item item; /* panel list item */

char *string;

Xv_opaque client_data;

Panel_list_op op;

Event *event;

int row; /* row number */

item is the panel list item that contains the row that was acted upon. The string parame-

ter is the label of the row. If there is no string associated with the row, the parameter is NULL.

If the row contains both a string and an image, then the string is passed as the parameter.

op is one of the following:

PANEL_LIST_OP_SELECT

PANEL_LIST_OP_DESELECT

PANEL_LIST_OP_VALIDATE

PANEL_LIST_OP_DELETE

If the user selects a row that is not currently selected, the notify procedure is called twice.

The first time it is called with the previously selected row, the op is

PANEL_LIST_OP_DESELECT. The next time the function is called, the op is

PANEL_LIST_OP_SELECT. If the user selects an item that is already selected, the function is

called once, passing the row selected (op is PANEL_LIST_OP_SELECT). Validate is called

when the user inserts a new row (op is set to

PANEL_LIST_OP_VALIDATE). The notify

procedure should return XV_OK to accept the row, or XV_ERROR to reject the row. Delete is

called when the user deletes a row (op is set to PANEL_LIST_OP_DELETE).

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7.11.4.1 List item client data

The client_data parameter is set to whatever client data is associated with the row.

list_glyphs.c uses the attribute PANEL_LIST_CLIENT_DATAS to assign a set of values to the

list items. Each value could have been assigned to the rows one by one using the attribute

PANEL_LIST_CLIENT_DATA. This attribute takes two values: the first is the number of the

row to assign the data to, and the second is the data itself.

xv_create(panel, PANEL_LIST,

...

PANEL_LIST_CLIENT_DATA, 0, "one",

PANEL_LIST_CLIENT_DATA, 1, "two",

PANEL_LIST_CLIENT_DATA, 2, "three",

...

NULL);

You can still assign client data to the panel list item itself using XV_KEY_DATA as with any

other XView object. However, this data can only be retrieved using xv_get() from the

panel list item itself, the first parameter in the callback function.

7.11.5 The Scrolling List Menu

PANEL_ITEM_MENU sets or gets the scrolling list’s read menu if the Scrolling List is in read

mode or the edit menu if the Scrolling List is in edit mode. The mode of the scrolling list is

set with the attribute PANEL_LIST_MODE. PANEL_LIST_MODE takes one of two values:

PANEL_LIST_READ and PANEL_LIST_EDIT. The attribute PANEL_VALUE_

STORED_LENGTH

controls the amount of text that may be edited when in edit mode.

7.12 Message Items

Message items display a text or image message within a panel. The only visible component

of a message item is the label itself. Message items are useful for annotations of all kinds, in-

cluding titles, comments, descriptions, pictures and dynamic status messages. The message is

often used to identify elements on the panel. A message has no value.

You may set or change the label for a message item via PANEL_LABEL_STRING or

PANEL_LABEL_IMAGE. Message items can have notify procedures which are called when

SELECT_UP occurs over the message item. Panel message items are the only panel items

whose font can be set to boldface. The boldness of message items is controlled using the at-

tribute

PANEL_LABEL_BOLD.

Since messages cannot be selected, their primary use is for display purposes only. In

Example 7-4, two message items display normal pipeline pressure, and a warning for high

pipeline pressure.

184 XView Programming Manual

Example 7-4. The message_item.c program

#include <xview/xview.h>

#include <xview/panel.h>

Frame frame;

Panel_item message;

Panel panel;

Panel_item slider;

void

slider_notify_proc(item, value, event)

Panel_item item;

int value;

Event *event;

{

xv_set(message,

PANEL_LABEL_STRING,

value > 500 ? "** HIGH PIPELINE PRESSURE **" : "Okay",

0);

}

main(argc, argv)

int argc;

char **argv;

{

xv_init(XV_INIT_ARGS, argc, argv, 0);

frame = xv_create(NULL, FRAME,

FRAME_LABEL, "Message Item",

0);

panel = xv_create(frame, PANEL,

PANEL_LAYOUT, PANEL_VERTICAL,

0);

slider = xv_create(panel, PANEL_SLIDER,

PANEL_LABEL_STRING, "Pipeline pressure (psi):",

PANEL_MIN_VALUE, 0,

PANEL_MAX_VALUE, 1000,

PANEL_NOTIFY_PROC, slider_notify_proc,

PANEL_SHOW_RANGE, TRUE,

PANEL_VALUE, 100,

0);

message = xv_create(panel, PANEL_MESSAGE,

PANEL_LABEL_STRING, "Okay",

0);

window_fit(panel);

window_fit(frame);

xv_main_loop(frame);

exit(0);

}

Messages produced by this program are shown in Figure 7-15 and Figure 7-16.

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Figure 7-15. Sample panel with message item

Figure 7-16. Sample panel with message item

–

High Pressure

7.13 Slider Items

Slider items allow the graphical representation and selection of a value within a range. Slid-

ers are appropriate for situations where it is desired to make fine adjustments over a continu-

ous range of values. The user selects the slider bar and drags it to the value that he wishes. A

slider has the following displayable components: the label, the current value, the slider bar

and the minimum and maximum allowable integral values (the range), end boxes, tick marks,

tick mark minimum and maximum tick strings, as well as minimum and maximum value text

strings.

Sliders may be horizontal or vertical depending on the value of PANEL_DIRECTION. This at-

tribute defaults to PANEL_HORIZONTAL, but may be set to a vertical orientation by using the

value PANEL_VERTICAL. The attribute PANEL_SLIDER_END_BOXES sets whether the boxes

at the endpoints of the slider are visible. This attribute defaults to FALSE. The PANEL_TICKS

attribute takes a numeric value that indicates how many evenly spaced “tick-marks” are

drawn next to the item. When PANEL_SHOW_VALUE is TRUE, the current value is shown after

the label in an editable text field. The minimum and maximum allowable values are set with

PANEL_MIN_VALUE and PANEL_MAX_VALUE. The width of the slider bar can be adjusted us-

ing the

PANEL_SLIDER_WIDTH

attribute. When PANEL_SHOW_RANGE is TRUE, the minimum

value of the slider PANEL_MIN_VALUE is shown to the left of the slider bar and the maximum

value PANEL_MAX_VALUE is shown to the right of the slider bar.* The attributes

PANEL_MIN_TICK_STRING and PANEL_MAX_TICK_STRING specify text labels for the mini-

mum and maximum tick values. On horizontal sliders, these strings appear

underneath the maximum and minimum tick marks. If the attribute PANEL_SHOW_RANGE

does not adequately describe the slider values, PANEL_MIN_VALUE_STRING and

*The top and bottom of the slider is used when the orientation is vertical.

186 XView Programming Manual

PANEL_MAX_VALUE_STRING can specify string value labels for the minimum and maximum

slider values. On horizontal sliders, these strings appear to the left/right of the mini-

mum/maximum end boxes.

7.13.1 Slider Selection

Only the slider bar of a slider may be selected. When the SELECT button is pressed within

the slider drag box, the black area of the bar will advance or retreat with the position of the

cursor. The slider value can also be changed via the numeric text field by clicking in the sli-

der bar to the left (horizontal sliders) or below (vertical sliders) the drag box to decrement the

value, or by clicking in the slider bar to the right (horizontal sliders) or above (vertical sli-

ders) to increment the value.

7.13.2 Slider Notification

Slider notify procedures are passed the item, the item’s value at time of notification, and the

event which caused notification:

void

slider_notify_proc(item, value, event)

Panel_item item;

int value;

Event *event;

The notification behavior of a slider is controlled by the value of

PANEL_NOTIFY_LEVEL. It

can be set to one of two values:

PANEL_DONE The default. The notify procedure is called only when the SELECT button

is released within the panel or when the user types in a new value for the

slider’s numeric text field.

PANEL_ALL The notify procedure is called whenever the value of the slider is changed;

this includes when the user selects, drags or releases the SELECT button in

a slider. For each movement of the mouse while dragging the slider drag

box, the slider’s notify procedure is called.

7.13.3 Slider Value

The value of a slider is an integer in the range

PANEL_MIN_VALUE to PANEL_MAX_VALUE.

You can retrieve or set a slider’s value with the attribute PANEL_VALUE and the functions

xv_set() or xv_get().

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