PtGenList

`PtGenList`

Generic superclass for list and tree widgets

Class hierarchy:

PtWidget --> PtBasic --> PtContainer --> PtCompound --> PtGenList

For more information, see the diagram of the widget hierarchy.

Description:

The PtGenList class is a superclass for creating list widgets. It's discussed in more detail in Building Custom Widgets.

PtGenList handles a vertical, left-aligned list of rectangular items that may have different sizes. You can select one or more items, depending on the selection policy (see Pt_ARG_SELECTION_MODE).

PtGenListItem_t is the data structure used for the items.

A PtGenList widget can have one child, provided it's a PtDivider widget. In this case, PtGenList attaches a callback to the child so that the columns are set automatically to match the children of PtDivider The items are drawn below the PtDivider widget. Some child classes of PtGenList, such as PtList and PtTree, use Tab characters as column separators.

Using scrollbars

The PtGenList widget creates a scroll bar if the list's area isn't large enough to display all the items in the list. By default, the scroll bar is displayed only when necessary. This behavior is controlled by the Pt_LIST_SCROLLBAR_ALWAYS and (the default) Pt_LIST_SCROLLBAR_AS_REQUIRED bits in the Pt_ARG_LIST_FLAGS resource.

Mouse actions

Mouse actions depend on the current selection mode.

Button action	Result
Press	Result depends on the value of Pt_ARG_SELECTION_MODE
Release	Invokes callbacks.

Keyboard actions

Keyboard actions depend on the current selection mode.

Key	Action
Enter	Result depends on value of Pt_ARG_SELECTION_MODE
/\	Previous item
\/	Next item
Pg Up	Previous page
Pg Dn	Next page
Home	First item
End	Last item

New resources:

Resource	C type	Pt type	Default
Pt_ARG_BALLOON_COLOR	`PgColor_t`	Scalar	Pg_BLACK
Pt_ARG_BALLOON_FILL_COLOR	`PgColor_t`	Scalar	See below
Pt_ARG_LIST_COLUMN_ATTR	`PtListColumnAttributes_t *`, `short`	Array	NULL
Pt_ARG_LIST_COLUMN_POS	`PtListColumn_t *`, `short`	Array	NULL
Pt_ARG_LIST_FLAGS	`unsigned short`	Flag	See below
Pt_ARG_LIST_FONT	`char *`	String	`"helv12"`
Pt_ARG_LIST_ITEM_COUNT	`unsigned short`	Scalar	0 (read-only)
Pt_ARG_LIST_SB_RES	`PtArg_t`, `int`	Array
Pt_ARG_LIST_SCROLL_RATE	`short`	Scalar	2
Pt_ARG_LIST_SEL_COUNT	`unsigned short`	Scalar	0 (read-only)
Pt_ARG_LIST_TOTAL_HEIGHT	`unsigned`	Scalar	0 (read-only)
Pt_ARG_SCROLLBAR_WIDTH	`unsigned short`	Scalar	0 (see below)
Pt_ARG_SELECTION_FILL_COLOR	`PgColor_t`	Scalar	Pg_BLUE
Pt_ARG_SELECTION_MODE	`unsigned short`	Scalar	See below
Pt_ARG_SELECTION_TEXT_COLOR	`PgColor_t`	Scalar	Pg_WHITE
Pt_ARG_TOP_ITEM_POS	`unsigned short`	Scalar	1
Pt_ARG_VISIBLE_COUNT	`unsigned short`	Scalar	0 (read-only)
Pt_CB_SCROLL_MOVE	`PtCallback_t *`	Link	NULL

Pt_ARG_BALLOON_COLOR

C type	Pt type	Default
`PgColor_t`	Scalar	Pg_BLACK

The balloon's text color.

Pt_ARG_BALLOON_FILL_COLOR

C type	Pt type	Default
`PgColor_t`	Scalar	Pg_BALLOONCOLOR

The balloon's fill color.

Pt_ARG_LIST_COLUMN_ATTR

C type	Pt type	Default
`PtListColumnAttributes_t *`, `short`	Array	NULL

An array of PtListColumnAttributes_t structures, each containing at least the following:

short flags;

The flags define the alignment of the text. The possible values are:

Pt_LIST_COLUMN_LEFT
Pt_LIST_COLUMN_RIGHT
Pt_LIST_COLUMN_CENTER
Pt_LIST_COLUMN_DAMAGE_ALWAYS

The Pt_LIST_COLUMN_DAMAGE_ALWAYS flag tells the widget to redraw the column when the column's position or size changes, even if it doesn't seem necessary. For example, if a right-aligned column is made narrower but its right edge doesn't move, there's no need to redraw the column. The flag can be set to force a redraw, which needs to be done if the column contains some elements that aren't right-aligned. This flag is usually set by the child class of PtGenList that knows what's drawn in the columns.

Pt_ARG_LIST_COLUMN_POS

C type	Pt type	Default
`PtListColumn_t *`, `short`	Array	NULL

An array of PtListColumn_t column structures. The structure contains at least the following:

short from, to;: They define the positions of the left and right edges of the column (relative to the left edge of widget's canvas).

Pt_ARG_LIST_FLAGS

C type	Pt type	Default
`unsigned short`	Flag	Pt_LIST_BALLOONS_IN_COLUMNS \| Pt_LIST_SCROLLBAR_AS_REQUIRED

Flags that control the appearance and behavior of the list. The possible values are:

Pt_LIST_SHOW_BALLOON: Show list balloons.
Pt_LIST_BALLOON_AS_REQUIRED: Show a balloon if the contents of the list are clipped.
Pt_LIST_BALLOONS_IN_COLUMNS (on by default): Display balloons for individual columns, not the entire row.
Pt_LIST_BOUNDARY_KEY_EVENTS: If this flag is clear (the default), cursor key events (/\, \/, Pg Up, Pg Down, Home, and End) are always consumed by the widget.
If this flag is set, a cursor key event is consumed only if it actually changes the current item. For example, an /\ or Home event won't be consumed if the first item in the list is already the current item.
Pt_LIST_HEADER_AUTORESIZE: When the scrollbar is realized or unrealized, adjust the width of the PtDivider widget (if there is one).
Pt_LIST_INACTIVE: Make the list inactive.
Pt_LIST_NOBLIT: Don't blit when the Pt_ARG_TOP_ITEM_POS resource is changed.
Pt_LIST_NON_SELECT: Make the list read-only.
Pt_LIST_SCROLLBAR_ALWAYS: Always display a scrollbar.
Pt_LIST_SCROLLBAR_AS_REQUIRED (on by default): Display a scrollbar only if required.
Pt_LIST_SCROLLBAR_AUTORESIZE: Resize the scrollbar automatically when the size of the header changes.
Pt_LIST_SCROLLBAR_GETS_FOCUS: Let the scrollbar get focus.
Pt_LIST_SNAP: Make the list snap to fit the number of items. Note that the Pt_LIST_SNAP flag is cleared automatically if the items in the list don't have equal heights.

Pt_ARG_LIST_FONT

C type	Pt type	Default
`char *`	String	`"helv12"`

The font used for the items in the list.

Pt_ARG_LIST_ITEM_COUNT (read-only)

C type	Pt type	Default
`unsigned short`	Scalar	0

The number of items.

Pt_ARG_LIST_SB_RES

C type	Pt type	Default
`PtArg_t`	Array

An array of PtArg_t records that are passed to the scrollbar. Note that only a selected set of resources can be modified: the PtGenList widget won't let you modify resources that might affect the position or size of the scrollbar. The main purpose of this resource is to change the colors of the scrollbar.

To get the Pt_ARG_LIST_SB_RES resource, the application must supply a buffer and pass its address and length to the PtSetArg() macro.

An equivalent of:

PtGetResources( scrollbar, N, args );

would be:

PtArg_t tmp;
PtSetArg( &tmp, Pt_ARG_LIST_SB_RES, args, N );
PtGetResources( list, 1, &tmp );

Pt_ARG_LIST_SCROLL_RATE

C type	Pt type	Default
`short`	Scalar	2

If you drag in a list and move outside the widget, the list scrolls at a rate determined by the number of "button repeats". This resource specifies the number of button repeats that must be received before scrolling occurs. The default value is 2. To make the scrolling faster, set this resource to 1; to make scrolling slower, set this resource to a larger number.

Pt_ARG_LIST_SEL_COUNT (read-only)

C type	Pt type	Default
`unsigned short`	Scalar	0

The number of selected items.

Pt_ARG_LIST_TOTAL_HEIGHT (read-only)

C type	Pt type	Default
`unsigned`	Scalar	0

The total height (in pixels) of all items.

Pt_ARG_SCROLLBAR_WIDTH

C type	Pt type	Default
`unsigned short`	Scalar	0 (see below)

The width of the accompanying scrollbar, if displayed. The minimum width is 6 pixels. If you set this resource to 0, the default width of 15 is used.

Pt_ARG_SELECTION_FILL_COLOR

C type	Pt type	Default
`PgColor_t`	Scalar	Pg_BLUE

The fill color for selected items.

Pt_ARG_SELECTION_MODE

C type	Pt type	Default
`unsigned short`	Scalar	See below

The selection mode. PtGenList supports the selection of items using the mouse or the keyboard. The descriptions below assume the user will be using a mouse. If a mouse isn't available, the /\ and \/ keys on the numeric pad can be used to highlight items in a list. The current selection is accepted by the widget when Enter is pressed.

Pt_BROWSE_MODE (default): To select an item using the mouse, the user either clicks on an item or drags the the pointer down the list and releases the mouse button when the correct item is highlighted. The user can select only one item. If the user drags the mouse, the list can be scrolled.
Pt_MULTIPLE_MODE: To select multiple items using the mouse, the user clicks on more than one item. When the user clicks on a selected item, the item is released.
Pt_EXTENDED_MODE: Click-Shift-click/drag and Ctrl-click combinations are supported to select multiple items. To select all items between and including two items in a list, the user clicks on the first item, presses the Shift key, then clicks on or drags to any other item in the list. To select multiple disjoint items, the user holds down the Ctrl while clicking on selected items.
Pt_SINGLE_MODE: To select an item the user points to the item, then clicks the mouse button. The user can select only one item. If the user selects a second item, the first is released.
Pt_RANGE_MODE: To select a range of items the user points to the first item, drags to the last item in the range, then releases the mouse button. When the user is dragging the mouse, the list can be scrolled.

The PtGenList widget supports several "predefined" selection modes, but you can also set "compose selection modes" using special flag values. To define a compose mode, start with one of the following values, which describe what kind of sets of items can be selected:

Pt_SELECTION_MODE_SINGLE: Select up to one item.
Pt_SELECTION_MODE_NONE: Callback functions will take care of selecting items.
Pt_SELECTION_MODE_MULTIPLE: Each item can be selected independently.
Pt_SELECTION_MODE_RANGE: A range of items can be selected.

You can OR one of these values with zero or more of the following flags, which describe how the mouse and keyboard should work:

Pt_SELECTION_MODE_NOMOVE: Don't move the current item when the user drags the mouse.
Pt_SELECTION_MODE_NOSCROLL: Don't scroll the widget if the user drags the mouse above or below the widget.
Pt_SELECTION_MODE_NOREST: Don't restore the previous state if the mouse is released outside the widget.
Pt_SELECTION_MODE_NOCLEAR: If the user clicks on an item, don't clear the previous selection (use with Pt_SELECTION_MODE_MULTIPLE mode only).
Pt_SELECTION_MODE_AUTO: Keyboard automatically selects the current item (unless Ctrl is used).
Pt_SELECTION_MODE_NOFOCUS: If the Pt_SELECTION_MODE_AUTO flag is set, don't select the current item automatically when the widget gets focus.
Pt_SELECTION_MODE_TOGGLE: Item can be deselected by clicking on it (Pt_SELECTION_MODE_SINGLE and Pt_SELECTION_MODE_MULTIPLE modes only).

Note that zero isn't a valid value for the selection mode, neither is a mixture of predefined and compose values.

The "predefined" selection modes are equivalent to the following compose modes:

For Pt_BROWSE_MODE:: Pt_SELECTION_MODE_SINGLE | Pt_SELECTION_MODE_AUTO
For Pt_MULTIPLE_MODE:: Pt_SELECTION_MODE_MULTIPLE | Pt_SELECTION_MODE_NOMOVE | Pt_SELECTION_MODE_NOCLEAR | Pt_SELECTION_MODE_TOGGLE | Pt_SELECTION_MODE_NOSCROLL
For Pt_EXTENDED_MODE:: Pt_SELECTION_MODE_MULTIPLE | Pt_SELECTION_MODE_AUTO | Pt_SELECTION_MODE_NOMOVE | Pt_SELECTION_MODE_NOFOCUS
For Pt_SINGLE_MODE:: Pt_SELECTION_MODE_SINGLE | Pt_SELECTION_MODE_NOCLEAR
For Pt_RANGE_MODE:: Pt_SELECTION_MODE_RANGE | Pt_SELECTION_MODE_AUTO | Pt_SELECTION_MODE_NOFOCUS

Pt_ARG_SELECTION_TEXT_COLOR

C type	Pt type	Default
`PgColor_t`	Scalar	Pg_WHITE

The text color for selected items.

Pt_ARG_TOP_ITEM_POS

C type	Pt type	Default
`unsigned short`	Scalar	1

The item index that appears at the top of the list. (The first item is 1.) Note that unless the widget has been held (using PtContainerHold()), setting the Pt_ARG_TOP_ITEM_POS resource will cause the widget to draw if damaged and possibly blit afterwards. The widget doesn't blit when its fill color is set to Pg_TRANSPARENT.

Pt_ARG_VISIBLE_COUNT (read-only)

C type	Pt type	Default
`unsigned short`	Scalar	0

The number of items currently visible.

Pt_CB_SCROLL_MOVE

C type	Pt type	Default
`PtCallback_t *`	Link	NULL

The list of callbacks that the widget invokes when the top item position changes.

If the widget has the Pt_CALLBACKS_ACTIVE bit set in its Pt_ARG_FLAGS resource, this callback is also invoked when the top item position (Pt_ARG_TOP_ITEM_POS) is changed by a call to PtSetResources().

Each callback is passed a PtCallbackInfo_t structure that contains at least the following members:

reason

The name of the callback resource (Pt_CB_SCROLL_MOVE) that caused this callback to be invoked.

reason_subtype

Defines the source of the position change:

Pt_LIST_SCROLL_SCROLLBAR: The scrollbar was used.
Pt_LIST_SCROLL_LIST: The list was used directly.

cbdata

A pointer to a PtScrollbarCallback_t structure that contains at least the following members:

unsigned action;: A value indicating what happened - see below.
int position;: A value corresponding to the handle's location.

The action field can be one of the following:

Pt_SCROLL_DECREMENT: The scrollbar handle position has been decreased by one increment.
Pt_SCROLL_INCREMENT: The handle position has been increased by one increment.
Pt_SCROLL_PAGE_INCREMENT: The handle position has been increased by one page.
Pt_SCROLL_PAGE_DECREMENT: The handle position has been decreased by one page.
Pt_SCROLL_TO_MAX: The handle has been moved to the maximum value.
Pt_SCROLL_TO_MIN: The handle has been moved to the minimum value.
Pt_SCROLL_DRAGGED: The handle is being dragged.
Pt_SCROLL_RELEASED: The handle has been released after having been dragged.
Pt_SCROLL_SET: The change of position is the result of a call to PtSetResources() and the widget has the Pt_CALLBACKS_ACTIVE bit set in its Pt_ARG_FLAGS resource.

These callbacks should return Pt_CONTINUE.

Inherited resources:

If the widget modifies an inherited resource, the "Default override" column indicates the new value. This modification affects any subclasses of the widget.

Resource	Inherited from	Default override
Pt_ARG_ANCHOR_FLAGS	`PtContainer`
Pt_ARG_ANCHOR_OFFSETS	`PtContainer`
Pt_ARG_AREA	`PtWidget`
Pt_ARG_BANDWIDTH_THRESHOLD	`PtBasic`	Not used by this class.
Pt_ARG_BITMAP_CURSOR	`PtWidget`
Pt_ARG_BORDER_WIDTH	`PtWidget`	2
Pt_ARG_BOT_BORDER_COLOR	`PtBasic`
Pt_ARG_COLOR	`PtBasic`
Pt_ARG_CONTAINER_FLAGS	`PtContainer`
Pt_ARG_CURSOR_COLOR	`PtWidget`
Pt_ARG_CURSOR_TYPE	`PtWidget`
Pt_ARG_DATA	`PtWidget`
Pt_ARG_DIM	`PtWidget`
Pt_ARG_EFLAGS	`PtWidget`	Pt_CONSUME_EVENTS
Pt_ARG_FILL_COLOR	`PtBasic`
Pt_ARG_FILL_PATTERN	`PtBasic`
Pt_ARG_FLAGS	`PtWidget`	\|= Pt_HIGHLIGHTED \| Pt_ETCH_HIGHLIGHT \| Pt_SET \| Pt_GETS_FOCUS \| Pt_FOCUS_RENDER
Pt_ARG_HELP_TOPIC	`PtWidget`
Pt_ARG_HIGHLIGHT_ROUNDNESS	`PtBasic`
Pt_ARG_MARGIN_HEIGHT	`PtBasic`	0
Pt_ARG_MARGIN_WIDTH	`PtBasic`	0
Pt_ARG_POS	`PtWidget`
Pt_ARG_RESIZE_FLAGS	`PtWidget`	0
Pt_ARG_TOP_BORDER_COLOR	`PtBasic`
Pt_ARG_TRANS_PATTERN	`PtBasic`
Pt_ARG_USER_DATA	`PtWidget`
Pt_CB_ACTIVATE	`PtBasic`
Pt_CB_ARM	`PtBasic`
Pt_CB_BALLOONS	`PtContainer`
Pt_CB_BLOCKED	`PtWidget`
Pt_CB_DESTROYED	`PtWidget`
Pt_CB_DISARM	`PtBasic`
Pt_CB_FILTER	`PtContainer`
Pt_CB_GOT_FOCUS	`PtBasic`
Pt_CB_HOTKEY	`PtWidget`
Pt_CB_LOST_FOCUS	`PtBasic`
Pt_CB_MENU	`PtBasic`
Pt_CB_RAW	`PtWidget`
Pt_CB_REALIZED	`PtWidget`
Pt_CB_REPEAT	`PtBasic`
Pt_CB_RESIZE	`PtContainer`
Pt_CB_UNREALIZED	`PtWidget`

Convenience functions:

Most of PtGenList's convenience functions are useful only if you're creating a custom list widget; they're described in the Creating a List Widget chapter of the Building Custom Widget manual.

The following convenience functions and data structure are useful when working with descendants of PtGenList:

PtGenListCreateTextBalloon(): Create a popup balloon for an item in the list.
PtGenListItem_t: PtGenList item structure
PtGenListSetColumnBalloon(): Adjust the balloon text to correspond to a given column.

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