Volume 7A: XView Programming Manual

25.11.6 The Wizzy Set Method

The code for the set method is as follows:

Pkg_private Xv_opaque

wizzy_set_avlist(item, avlist)

Panel_item item; /* this object */

Attr_avlist avlist; /* attribute list */

{

Wizzy_private *dp = WIZZY_PRIVATE(item);

Xv_opaque result;

Rect value_rect;

Attr_attribute *attrs;

/* Parse panel item generic attributes before parsing Wizzy

* specific attributes and prevent panel_redisplay_item() from

* being called in item_set_avlist()

*/

if (*avlist != XV_END_CREATE) {

xv_set( dp->panel, PANEL_NO_REDISPLAY_ITEM, TRUE, NULL);

result = xv_super_avlist( item, &xv_wizzy_panel_pkg, avlist);

xv_set( dp->panel, PANEL_NO_REDISPLAY_ITEM, FALSE, NULL);

if (result != XV_OK)

return (result);

}

for ( attrs = avlist; *avlist; attrs = attr_next(attrs)) {

switch ( (int)attrs[0 ] ) {

case WIZZY_OFFSET:

dp->offset = attrs[1];

break;

case WIZZY_FLAG:

dp->flag = attrs[1];

break;

case XV_END_CREATE:

value_rect = *(Rect *)xv_get(item, PANEL_ITEM_VALUE_RECT);

rect_construct(&dp->block,

value_rect.r_left + dp->offset,

value_rect.r_top,

BLOCK_WIDTH, BLOCK_HEIGHT);

value_rect = rect_bounding(&value_rect, &dp->block);

/* Note: setting the value rect will cause the item

* item rect to be recalculated as the enclosing rect

* containing both the label and value rects.

*/

xv_set( item, PANEL_ITEM_VALUE_RECT, &value_rect,

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NULL);

break;

default:

break;

}

}

return XV_OK; /* return XV_ERROR if something went very wrong */

}

The purpose of the set method is to set any of the attributes defined in the public header file

by storing the corresponding value in the private data structure. In the case of the Wizzy

package, WIZZY_OFFSET and WIZZY_FLAG are the only attributes and they correspond to

offset and flag, respectively.

However, before parsing attributes specific to the Wizzy object, it is necessary to parse any

attributes generic to Panel. This is done by a call to xv_super_avlist(). It is also nec-

essary to prevent the parent panel from redisplaying while these attributes are being set. This

is taken care of by setting the attribute PANEL_NO_REDISPLAY_ITEM to TRUE for the parent

panel and then resetting it to FALSE.

After all attributes are handled, the value rectangle value_rect is constructed and the

item rectangle is recalculated since it encloses both the label and value rectangles.

25.11.7 The Wizzy Get Method

The get routine for the Wizzy package provides the ability to return values for

WIZZY_OFFSET and WIZZY_FLAG.

Pkg_private Xv_opaque

wizzy_get_attr(item, status, which_attr, avlist)

Panel_item item;

int *status;

Attr_attribute which_attr;

va_list avlist;

{

Wizzy_private *dp = WIZZY_PRIVATE(item);

switch ( (int)which_attr ) {

case WIZZY_OFFSET:

return (Xv_opaque)dp->offset;

break;

case WIZZY_FLAG:

return (Xv_opaque)dp->flag;

break;

default:

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*status = xv_check_bad_attr(WIZZY, attr);

return (Xv_opaque)XV_OK;

}

}

25.11.8 The Wizzy Destroy Method

When an instance of the Wizzy class is destroyed, the destroy procedure is called. The first

parameter to the destroy function is a handle to the panel item being destroyed. The second

parameter is the destroy status (see Chapter 20, The Notifier, for more information on des-

troy_status). The task of the destroy function for the Wizzy package is to remove the

item from the list of items attached to the panel object and free it. Once the object has been

freed, all references to the object become invalid.

Pkg_private int

wizzy_destroy(item, status)

Panel_item item;

Destroy_status status;

{

Wizzy_private *dp = WIZZY_PRIVATE(item);

if ( (status==DESTROY_CHECKING) || (status==DESTROY_YOURSELF) )

return XV_OK;

#ifdef WIZZY_CAN_ACCEPT_KBD_FOCUS

wizzy_remove(item);

#endif WIZZY_CAN_ACCEPT_KBD_FOCUS

free(dp);

return XV_OK;

}

25.11.9 Panel Item Handler Procedures

25.11.9.1 The handle event function

The handle event function allows the application writer to specify a notify procedure for the

panel item.

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25.11.9.2 The begin preview function

The begin preview function is called when SELECT-down has been detected. Highlight the

item to show active feedback but don’t actually take any action yet. Private data may be ac-

cessed as necessary. The function has the form:

static void

wizzy_begin_preview (item, event)

Panel_item item;

Event *event;

25.11.9.3 The update preview function

The update preview function is called when the pointer has been dragged within the item af-

ter begin preview was detected. Adjust highlighting to reflect the new position of the pointer

and update the appropriate private data. The function has the form:

static void

wizzy_update_preview (item, event)

Panel_item item;

Event *event;

25.11.9.4 The cancel preview function

The cancel preview function is called when the pointer has been dragged out of the item after

begin preview was detected. Remove the active feedback (i.e., de-highlight) and clean up any

private data. The function has the form:

static void

wizzy_cancel_preview (item, event)

Panel_item item;

Event *event;

25.11.9.5 The accept preview function

The accept preview function is called when the SELECT button has been released over the

item. Remove the active feedback (i.e., de-highlight), paint the busy feedback, perform the

action associated with the item, and then remove the busy feedback. Also update any private

data as necessary. The function has the form:

static void

wizzy_accept_preview (item, event)

Panel_item item;

Event *event;

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25.11.9.6 The accept menu function

The accept menu function is called when the MENU button has been pressed over the item.

Show the menu item attached to the item, if any. The function has the form:

static void

wizzy_accept_menu (item, event)

Panel_item item;

Event *event;

25.11.9.7 The accept key function

The accept key function is called when a keyboard event has been detected. Process the key

and update the data and/or display as necessary. The function has the form:

static void

wizzy_accept_key (item, event)

Panel_item item;

Event *event;

25.11.9.8 The clear function

The clear function is called whenever the item’s rectangle needs to be cleared. Clear the

item rectangle and update any private data as needed. An example of this function would be:

static void

wizzy_clear (item, event)

Panel_item item;

Event *event;

{

panel_default_clear_item(item);

}

25.11.9.9 The paint function

The paint function is called when the panel needs to be repainted. Do everything necessary

to paint the entire item but do not go outside of the rectangle describing the boundaries of the

item. An example of this function would be:

static void

wizzy_paint(item)

Panel_item item;

Display *display;

Wizzy_info *dp = WIZZY_PRIVATE(item);

Panel_paint_window *ppw; /* ptr to Panel_paint_window structure */

Xv_Window pw; /* paint window */

XID xid;

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