PtTree

A tree of items that collapse and expand as requested

Class hierarchy:

PtWidget --> PtBasic --> PtContainer --> PtCompound --> PtGenList --> PtGenTree --> PtTree

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

PhAB icon:

Public header:

<photon/PtTree.h>

Description:

The PtTree widget displays a tree of items that collapse or expand according to the user's selections. PtTree assumes that each tree item contains two images and a string.

The Photon Helpviewer uses a PtTree widget to give you quick access to documentation.

To display items in columns, you can:

• Create a PtDivider widget as a child of the PtTree. Put it at the top of the tree, and create (for example) PtButton widgets as children of the divider, one for each column. The width of each button is the width of the column.

  Or

• Use the inherited Pt_ARG_LIST_COLUMN_POS resource.

With both methods, the Tab character is used in the item strings as a column separator.

Even if you use columns, each line in the tree remains a single item. When you select any part of the line, the entire line is selected - having columns doesn't make the tree into a spreadsheet.

The array of all available images is actually stored within the widget's Pt_ARG_TREE_IMAGES resource, and the items contain only indexes into this array. The item structure, PtTreeItem_t, also contains a "user data" pointer that isn't used by the widget. Note that there are some functions that free items. None of these functions attempts to free the user data.

The items should be allocated using the PtTreeAllocItem() function. This function uses the font and image list stored in the tree widget to determine the item's dimensions. This means that between creating an item and adding it to the widget, you mustn't change the widget's font or images. The tree widget passed to PtTreeAllocItem() must be the same widget that the item will be added to. The PtTree widget will free all its items automatically when it's destroyed.

Use PtTreeAddFirst() and PtTreeAddAfter() to build a tree. For example, suppose you wanted to build the following tree:

Assuming your tree widget is referenced by tree_wgt, use the following code:

PtTreeItem_t *item,*brother;
char *text;

/* Add "Item 1" as first root item */

text = "Item 1";
item = PtTreeAllocItem(tree_wgt,text,-1,-1);
PtTreeAddFirst(tree_wgt,item,NULL);
brother = item;

/* Add "Item 2" as root item after "Item 1" */

text = "Item 2";
item = PtTreeAllocItem(tree_wgt,text,-1,-1);
PtTreeAddAfter(tree_wgt,item,brother);
brother = item;

/* Add "Item 2a" as first child of "Item 2" */

text = "Item 2a";
item = PtTreeAllocItem(tree_wgt,text,-1,-1);
PtTreeAddFirst(tree_wgt,item,brother);

/* Add "Item 3" as root item after "Item 2" */

text = "Item 3";
item = PtTreeAllocItem(tree_wgt,text,-1,-1);
PtTreeAddAfter(tree_wgt,item,brother);

New resources:

Pt_ARG_TREE_BALLOON

A function that inflates a balloon for the item the pointer is on. PtTreeBalloonF_t is a function type:

typedef PtWidget_t *PtTreeBalloonF_t(
    PtWidget_t *widget, PtWidget_t *parent,
    PhArea_t *area, PtListColumn_t *column,
    PtTreeItem_t *item, int coln, 
    const char *font);
      

The parameters are as follows:

widget

A pointer to the PtTree widget.

parent

Its parent window.

area

A PhArea_t structure that covers the item. The area->pos member is relative to the parent window.

column

The position of the column the pointer is on.

item

The item the pointer is on.

coln

The index of the column the pointer is on.

font

The widget's Pt_ARG_LIST_FONT resource.

The default function does this:

return
    PtGenListCreateTextBalloon(
      widget, parent, 
      PtGenListSetColumnBalloon ( area, column ),
      item->string, coln, font);
      

Pt_ARG_TREE_IMAGES

A list of images that can be displayed with tree items. For more information about the image structure, see PhImage_t in the Photon Library Reference.

Set the flags member of the PhImage_t structures to: Ph_RELEASE_IMAGE | Ph_RELEASE_PALETTE | Ph_RELEASE_TRANSPARENCY_MASK | Ph_RELEASE_GHOST_BITMAP before providing the images to the widget. If you do this, the memory used for the images is released when the widget is destroyed or Pt_ARG_TREE_IMAGES is set.

Pt_ARG_TREE_IMGMASK

Defines the mask for selecting an item's image.

When you create an item by calling PtTreeAllocItem(), you specify the images to be used when the item is set or unset. An item is considered set if its flags masked with the tree's Pt_ARG_TREE_IMGMASK resource give a nonzero value. The flags include:

Pt_LIST_ITEM_SELECTED

The item is selected.

Pt_LIST_ITEM_CURRENT

The item is the current item.

Pt_TREE_ITEM_EXPANDABLE

The item can be expanded.

Pt_TREE_ITEM_EXPANDED

The branches of this item are currently displayed.

Pt_CB_TREE_SELECTION

A list of callbacks invoked when an item is selected from the tree.

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

reason

Pt_CB_TREE_SELECTION

reason_subtype

This value depends on the selection mode. One of:

• Pt_LIST_SELECTION_FINAL
• Pt_LIST_SELECTION_BROWSE
• Pt_LIST_SELECTION_CANCEL

event

The event that triggered this callback.

cbdata

This points to a PtTreeCallback_t structure that contains at least the following members:

unsigned sel_mode;

The current selection mode (Pt_ARG_SELECTION_MODE).

PtTreeItem_t *item;

If the selection mode isn't set to Pt_RANGE_MODE, item is the item the user clicked on. If the selection mode is set to Pt_RANGE_MODE, item is the first of the selected items.

unsigned nitems;

This contains the number of selected items, excluding collapsed subtrees.

int click_count;

The number of mouse clicks (0 for keyboard events or if event is NULL).

These callbacks should return Pt_CONTINUE.

If you multi-click on a tree, its Pt_CB_TREE_SELECTION callbacks are invoked once for each click. The callback data includes the click count (1 for the first click, 2 for the second, and so on).

If you want to process only the last of a series of clicks, use a Pt_CB_RAW callback to look for a Ph_EV_BUT_RELEASE event with a subtype of Ph_EV_RELEASE_ENDCLICK. For more information, see PhEvent_t in the Photon Library Reference.

The Ph_EV_BUT_RELEASE event with a subtype of Ph_EV_RELEASE_ENDCLICK occurs approximately half a second after the click, which could be annoying to the user. Most Photon applications don't use multiple clicks because of this.

Pt_CB_TREE_STATE

Defines the state callbacks. Each callback is passed a PtCallbackInfo_t structure that contains at least the following members:

reason

Pt_CB_TREE_STATE

reason_subtype

Pt_TREE_COLLAPSING or Pt_TREE_EXPANDING.

event

The event that triggered this callback.

cbdata

This points to a PtTreeCallback_t structure that contains at least the following members:

unsigned sel_mode;

The current selection mode (Pt_ARG_SELECTION_MODE).

PtTreeItem_t *item;

The item that's being collapsed or expanded.

int expand;

If reason_subtype is Pt_TREE_EXPANDING, this may be assigned a nonzero value to suppress expansion.

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.

Pt_ARG_TREE_FLAGS

In addition to the flags defined by PtGenTree, the following flags are defined:

• Pt_TREE_BALLOON_ON_IMAGE - the balloon is permitted to cover the image and the text
• Pt_TREE_BALLOON_ON_TREE - the balloon is permitted to cover the tree, the image, and the text

By default, neither is set. The width and location of the balloon depend on these flags:

The Pt_ARG_TREE_FLAGS for a PtTree widget.

Convenience functions:

The PtTree widget defines the following convenience functions that make it easier to use the tree once it's been created:

PtTreeAddAfter()

Insert an item after the specified item

PtTreeAddFirst()

Add a root item to the widget, or adds an item as the first child of a specified item

PtTreeAddImages()

Add images to the PtTree widget's image list

PtTreeAllItems()

Fill a buffer with pointers to all items

PtTreeAllocItem()

Allocate a new item

PtTreeClearSelection()

Clear the selection

PtTreeCollapse()

Collapse an expandable item

PtTreeExpand()

Expand an expandable item

PtTreeFreeAllItems()

Unlink and free all items

PtTreeFreeItems()

Free an unlinked item

PtTreeGetCurrent()

Get the current item

PtTreeGetSelIndexes()

Fill a buffer with indexes of selected items

PtTreeGoto()

Set the current item

PtTreeItem_t

PtTree item structure

PtTreeItemIndex()

Calculate the index of the specified item

PtTreeModifyItem()

Change item resources

PtTreeRemoveChildren()

Unlink the children of the specified item

PtTreeRemoveItem()

Unlink an item

PtTreeRemoveList()

Unlink the given item and any siblings that follow

PtTreeRootItem()

Return the first root item of the tree

PtTreeSelect()

Select the specified item

PtTreeSelectedItems()

Fill a buffer with pointers to the selected items

PtTreeSetSelIndexes()

Set the selection indexes

PtTreeShow()

Set the position so that the specified item is visible

PtTreeUnselect()

Unselect the specified item

PtTreeUnselectNonBrothers()

Unselect all items that aren't siblings of the specified item