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.

PhAB icon:

None - not normally instantiated.

Public header:

<photon/PtGenList.h>

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.

Keyboard actions

Keyboard actions depend on the current selection mode.

New resources:

Pt_ARG_BALLOON_COLOR

The balloon's text color.

Pt_ARG_BALLOON_FILL_COLOR

The balloon's fill color.

Pt_ARG_LIST_COLUMN_ATTR

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

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

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

The font used for the items in the list.

Pt_ARG_LIST_ITEM_COUNT (read-only)

The number of items.

Pt_ARG_LIST_SB_RES

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

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)

The number of selected items.

Pt_ARG_LIST_TOTAL_HEIGHT (read-only)

The total height (in pixels) of all items.

Pt_ARG_SCROLLBAR_WIDTH

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

The fill color for selected items.

Pt_ARG_SELECTION_MODE

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

The text color for selected items.

Pt_ARG_TOP_ITEM_POS

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)

The number of items currently visible.

Pt_CB_SCROLL_MOVE

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.

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.