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Documentation of class 'AbstractHierarchicalItem':

Class: AbstractHierarchicalItem

Inheritance
Description
Related information
Class protocol
Instance protocol

Inheritance:

   Object
   |
   +--AbstractHierarchicalItem
      |
      +--CompactHierarchicalItem
      |
      +--HierarchicalItem

Package:: stx:libwidg2

Category:: Views-Support

Version:: rev: 1.20 date: 2018/04/29 15:08:12; user: cg; file: AbstractHierarchicalItem.st directory: libwidg2; module: stx stc-classLibrary: libwidg2

Author:: Claus Atzkern; Claus Gittinger (redesign and refactoring)

Description:

Hierarchical Items are mostly like Models, but the list of
dependencies are kept by its HierarchicalList.
The class is used to build up hierarchical trees.

2015 update:
    the original HierarchicalItem has been refactored into this abstract class,
    which provides all the mechanisms, but leaves the concrete representation
    of some slots open.
    These are:
        - if and how the geometry information (width + height) are cached,
        - if and how the expanded-state is remembered.
        - if and how the underlying model is fetched

    The old class used private slots for the first three (width-height-isExpanded),
    but did not keep a reference to the model. This leads to a very poor performance,
    as many algorithms degenerated to O(n log(n)) or even O(n^2) time behavior,
    as the model was fetched by walking along the parent chain - sometimes for every item
    in a long list.

    The old class is still around and may be used for small trees,
    but we recommend rewriting applications to use the new CompactHierarchicalItem
    class, which behaves the same on the outside, but uses clever tricks to be both more
    space efficient (saving 2 slots) and time efficient (caching the model).
    For this, make sure that the subclass does not access the instvars isExpanded, width and height
    directly, but uses the getters isExpanded, width and height and the setters setExpanded:, width: and height:

[Instance variables:]
    parent      <Item, List or nil>         parent or my HierarchicalList.
    children    <Collection or nil>         list of children

Related information:

    HierarchicalItem
    (the
    old
    item
    class)
    HierarchicalList
    (typical
    model)
    HierarchicalListView
    (typical
    user
    of
    me)

Class protocol:

instance creation

new
parent: aParent

protocol

doResetExtentOnChange: true: the extent of the item is reset if a change
notification is raised from the item. the default is true

queries

isAbstract: Return if this class is an abstract class.
True is returned here for myself only; false for subclasses.
Abstract subclasses must redefine this again.

Instance protocol:

accessing

getChildren: returns the children as they are present (or not); not going to the model...
level: returns the level starting with 0 for the root
parent: returns the parent or nil
parent: aParent: set the parent (or the model if the item is the root item)
rootItem: returns the root item

accessing-children

at: anIndex: return the child at anIndex if valid;
if the index is invalid, nil is returned
at: anIndex ifAbsent: exceptionBlock: return the child at anIndex if valid; if the index is
invalid, the result of evaluating the exceptionBlock is returned.
at: anIndex put: anItem: replace a child by a new item. return anItem (sigh)
children: aListOfChildren: set a new list of children
first: returns the first child
last: returns the last child
second: returns the second child

accessing-hierarchy

collapse: hide all my subitems
enforcedExpand: expand children - even if there are no children,
the item is initially expanded (but this might be undone later,
when we know that no children are there
expand: expand children - but only if there are children
(i.e. this cannot be used before the childInfo is valid;
aka not before the updateTask came along this item)
expand: enforced: expand children
expandLevels: numLevels: expand children numLevels down
expandLevels: numLevels max: maxNumExpandedHolder: expand children numLevels down
labelPath: return my label-path as an ordered collection of individual labels
makeVisible: expand all my parents
recursiveCollapse: collapse all item and sub items
**** must be expanded
recursiveExpand: expand children and sub-children
**** must be collapsed
recursiveToggleExpand: if the item is collapsed, the item and all its sub-items
are expanded otherwise collapsed
toggleExpand: if the item is collapsed, the item is expanded otherwise collapsed

accessing-mvc

application: returns the responsible application or nil
applicationsDo: aOneArgBlock: evaluate the block for each dependent application
model: returns the hierachicalList model or nil.
This is a stupid implementation here, in that the top-item's parent is assumed to
be the model of the tree, and that is returned.
This saves a slot in every node, but makes some algorithms O(n*log n) or even O(n^2).
So be aware of the performance penalty

adding & removing

add: aChildItem: add a child at end
add: aChildItem after: aChild: add an item after an existing item
add: aChildItem afterIndex: anIndex: add an item after an index
add: aChildItem before: aChild: add an item before an existing item
add: aChildItem beforeIndex: anIndex: add an item before an index
add: aChild sortBlock: aBlock: add a child sorted
addAll: aList: add children at the end
addAll: aList before: aChild: add an item before an existing item
addAll: aList beforeIndex: anIndex: add children before an index
addAll: aList sortBlock: aBlock: add children sorted
addAllFirst: aCollectionOfItems: add children at the beginning
addAllLast: aCollectionOfItems: add children at the end
addFirst: aChildItem: add a child at the beginning
addLast: anItem: add a child at the end
remove: remove the item
remove: aChild: remove a child
removeAll: remove all children
removeAll: aList: remove all children in the collection
removeAllIdentical: aList: remove all children in the collection
removeFromIndex: startIndex: remove the children from startIndex up to end of children
removeFromIndex: startIndex toIndex: stopIndex: remove the children from startIndex up to and including
the child under stopIndex.
Returns the receiver.
removeIndex: anIndex: remove the child at an index

basic adding & removing

basicAdd: aChild sortBlock: aBlock: add a child sorted
basicAddAll: aList beforeIndex: anIndex: add children before an index
basicRemoveFromIndex: startIndex toIndex: stopIndex: remove the children from startIndex up to and including
the child under stopIndex.

change & update

changed: what with: anArgument: the item changed; raise change notification
#icon icon is modified; height and width are unchanged
#hierarchy collapsed/expanded; height and width are unchanged
#redraw redraw but height and width are unchanged
....... all others: the height and width are reset
childrenOrderChanged: called if the order of the children changed by a user
operation. Update the model and raise a change notification for
each item which has changed its position
triggered by the user operation !
fontChanged: called if the font has changed.
Clear the precomputed width and height
hierarchyChanged: hierarchy changed; optimize redrawing
iconChanged: icon changed; optimize redrawing
labelChanged: called if the label has changed.
Clear the precomputed width and height

enumerating

allExpandedItemsDo: aBlock: recursively enumerate all expanded nodes
(depth first; parent before children)
collect: aBlock: for each child in the receiver (non recursive), evaluate the argument, aBlock
and return a new collection with the results
contains: aBlock: evaluate aOneArgBlock for each of the receiver's children (non recursive).
Return true and skip remaining elements, if aBlock ever returns true,
otherwise return false
do: aOneArgBlock: evaluate a block for each child (non recursive)
from: startIndex do: aOneArgBlock: evaluate a block on each child starting with the
child at startIndex to the end.
from: startIndex reverseDo: aOneArgBlock: evaluate a block on each child (non recursive) starting at end to the startIndex
from: startIndex to: endIndex do: aOneArgBlock: evaluate a block on each child (non recursive),
starting with the child at startIndex to the endIndex.
from: startIndex to: endIndex reverseDo: aOneArgBlock: evaluate a block on each child (non recursive),
starting with the child at endIndex to the startIndex.
keysAndValuesDo: aTwoArgBlock: evaluate the argument, aBlock for every child (non recursive),
passing both index and element as arguments.
keysAndValuesReverseDo: aTwoArgBlock: evaluate the argument, aBlock in reverse order for every child (non recursive),
passing both index and element as arguments.
recursiveCollect: aBlock: for each child in the receiver, evaluate the argument, aBlock
and return a new collection with the results.
Warning: this only enumerates already visible child elements
i.e. any collapsed items are not visited.
recursiveDo: aOneArgBlock: evaluate a block on each item and all the sub-items.
Warning: this only enumerates already visible child elements
i.e. any collapsed items are not visited.
recursiveReverseDo: aOneArgBlock: evaluate a block on each item and all the sub-items;
proccesing children in reverse direction.
Warning: this only enumerates already visible child elements
i.e. any collapsed items are not visited.
recursiveSelect: aBlock: return a new collection with all children and subChildren from the receiver,
for which the argument aBlock evaluates to true.
Warning: this only enumerates already visible child elements
i.e. any collapsed items are not visited.
reverseDo: aOneArgBlock: evaluate a block on each child (non recursive) in reverse direction
select: aBlock: return a new collection with all items from the receiver (non recursive),
for which the argument aBlock evaluates to true.
withAllDo: aOneArgBlock: recursively evaluate aOneArgBlock on each item and subitem including self

enumerating parents

allParents: return a collection of all parents (in parent, grandparent, ... order)
parentsDetect: aBlock: find the first parent, for which evaluation of the block returns
true; if none does so, report an error
parentsDetect: aBlock ifNone: anExceptionBlock: find the first parent, for which evaluation of the block returns
true; if none does so, return the evaluation of anExceptionBlock
parentsDo: aBlock: evaluate a block for each parent

initialization

initialize

private

addVisibleChildrenTo: aList: add all visible children and sub-children to the list
clearExpandedWhenLastChildWasRemoved: https://expeccoalm.exept.de/D227397
Do not set #isExpanded to false just because #children is empty (may children appear 'again' later).
Do modify #isExpanded ONLY when a user presses the expand/collapse toggle, otherwise #isExpanded should be persistent.

The user's preference if the item is expanded or collapsed should be kept,
regardless if there are chilren or not (even regardless anything else).
All other related things, like the drawing in case for #isExpanded is true and children is empty,
has to be solved within the drawing (or within any feature requesting this information)
criticalDo: aBlock
listIndex: returns the visible index or nil; for a non-visible root, 0 is returned
numberOfVisibleChildren: returns number of all visible children including subchildren
parentOrModel: returns the parent without checking for item or model

private-displaying

displayLabel: aLabel h: lH on: aGC x: x y: y h: h: display the label at x@y

** This is an obsolete interface - do not use it (it may vanish in future versions) **
displayLabel: aLabel h: lH on: aGC x: x y: y h: h isHighlightedAsSelected: isHighlightedAsSelected: display the label at x@y
heightOf: aLabel on: aGC: returns the height of the label or 0
widthOf: aLabel on: aGC: returns the height of the label or 0

private-enumerating

nonCriticalDo: aOneArgBlock: evaluate a block noncritical for each child.
nonCriticalFrom: startIndex to: endIndex do: aOneArgBlock: evaluate a block noncritical for each child starting with the
child at startIndex to the endIndex (if nil to end of list).
nonCriticalFrom: startIndex to: endIndex reverseDo: aOneArgBlock: evaluate a block non critical for each child starting with the
child at endIndex (if nil to end of list) to startIndex.
nonCriticalKeysAndValuesReverseDo: aOneArgBlock: evaluate the argument, aBlock in reverse order for every
child, passing both index and element as arguments.
nonCriticalRecursiveDo: aOneArgBlock: evaluate the block non critical for each item and all the sub-items
nonCriticalRecursiveReverseDo: aOneArgBlock: evaluate the block non critical for each item and all the sub-items;
proccesing children in reverse direction
nonCriticalRecursiveSort: aSortBlock: evaluate a block noncritical for each child.

private-hierarchy

recursiveSetCollapsed: collapse all children and sub-children without notifications
recursiveSetCollapsedHelper: private helper.
collapse all children and sub-children without notifications.
Helper only - does not lock
recursiveSetExpandedAndAddToList: aList: expand all children and sub-children without notifications;
add children to list
recursiveSetExpandedAndAddToListHelper: aList: private helper.
expand all children and sub-children without notifications; adds children to aList
Helper only - does not lock

private-to be redefined

fetchChildren
heightOn: aGC: return the height of the receiver, if it is to be displayed on aGC

** This method raises an error - it must be redefined in concrete classes **
isExpanded: returns true if the item is expanded

** This method raises an error - it must be redefined in concrete classes **
makeWidthAndHeightUnknown: invalidate any cached with/height information

** This method raises an error - it must be redefined in concrete classes **
setExpanded: aBoolean: set expanded flag without any computation or notification.
It is left to the subclasses responsibility, where this expanded state is stored;
could be in the model (as a list of expanded items), in the item itself (as boolean flag),
or somewhere else.
For huge trees, it may make sense to not store the expanded flag in a slot
(in order to save space). See CompactHierarchicalItem as a clever example of how it can be
stored without ANY additional space requirements.

** This method raises an error - it must be redefined in concrete classes **
widthOn: aGC: return the width of the receiver, if it is to be displayed on aGC

** This method raises an error - it must be redefined in concrete classes **

protocol-accessing

children: returns a list of children. When first asked, the list is fetched, if it was
built lazily.
*** to optimize: either redefine this or fetchChildren by subClass
icon: returns the icon or nil;
*** to optimize:redefine by subClass
label: returns the label displayed on aGC;
*** to optimize:redefine by subClass
middleButtonMenu: returns the items middleButtonMenu or nil if no menu is defined.
If nil is returned, the view is asked for a menu.
recursiveSortChildren: aSortBlock
sortChildren: aSortBlock: sort the children inplace using the 2-arg block sortBlock for comparison

** This is an obsolete interface - do not use it (it may vanish in future versions) **

protocol-displaying

displayIcon: anIcon atX: x y: y on: aGC: called to draw the icon - can be redefined to manipulate the icon
displayOn: aGC x: x y: y h: h: draw the receiver in the graphicsContext, aGC

** This is an obsolete interface - do not use it (it may vanish in future versions) **
displayOn: aGC x: x y: y h: h isHighlightedAsSelected: isHighlightedAsSelected: draw the receiver in the graphicsContext, aGC

protocol-event processing

processButtonPress: button visibleX: visX visibleY: visY on: view: A mouse button was pressed on myself. The visX/visY coordinates
are relative to the viewOrigin.

If this method returns TRUE, the other method
#processButtonPress:x:y:on: IS NOT CALLED !!!
processButtonPress: button x: x y: y: a mouse button was pressed in my label.
Return true, if the event is eaten (ignored by the gc).
By default, false is returned (should be handled by the gc).
processButtonPress: button x: x y: y on: aGC: a mouse button was pressed in my label.
Return true, if the event is eaten (ignored by the gc).
By default, false is returned (should be handled by the gc).
processButtonPressOnIcon: button on: aGC: a mouse button was pressed in my icon.
Return true, if the event is eaten (ignored by the gc).
By default, false is returned (should be handled by the gc).

protocol-monitoring

monitoringCycle: called every 'n' seconds by the model, if the monitoring
cycle is enabled. The item can perform some checks, ..
**** can be redefined by subclass to perform some actions

protocol-queries

canCollapse: called before collapsing the item; can be redefined
by subclass to omit the collapse operation
canExpand: called before expanding the item; can be redefined
by subclass to omit the expand operation
canRecursiveCollapse: called before collapsing the item; can be redefined
by subclass to omit the collapse operation
canRecursiveExpand: called before expanding the item; can be redefined
by subclass to omit the collapse operation
drawHorizontalLineUpToText: draw the horizizontal line for the selected item up to the text
or on default to the start of the the vertical line; only used by
the hierarchical view
hasChildren: checks whether the item has children;
the list needs not to be loaded yet( example. FileDirectory ).
*** to optimize: redefine in subClass
hasIndicator: on default the indicator is drawn if the item has children
isSelectable: returns true if the item is selectable. Can be redefined in subclasses
string: access the printable string used for stepping through a list
searching for an entry starting with a character.
*** to optimize:redefine by subClass

queries

isChildOf: anItem: returns true if the item is a child of anItem
isCollapsed: returns true if the item is collapsed
isDirectoryItem
isHierarchicalItem: used to decide if the parent is a hierarchical item or the model
isRealChildOf: anItem: returns true if the item is a child of anItem
isRootItem: returns true if the item is the root item
size: return the number of children

searching

detect: aOneArgBlock: find the first child (not recursive), for which evaluation of the block returns
true; if none does so, report an error
detect: aOneArgBlock ifNone: exceptionValue: find the first child (not recursive), for which evaluation of the block returns
true; if none does so, return the value of anExceptionValue
detectLast: aOneArgBlock: find the last child (not recursive), for which evaluation of the block returns
true; if none does so, an exception is raised
detectLast: aOneArgBlock ifNone: anExceptionValue: find the last child (not recursive), for which evaluation of the block returns
true; if none does so, return the value of anExceptionValue
findChildByLabelPath: aLabelPath: recursivly find the child by its label path.
A label path is an ordered collection (or array) of strings,
which are the labels of items (i.e. as retrived by labelPath).
findFirst: aOneArgBlock: find the first child (not recursive), for which evaluation of the argument, aOneArgBlock
returns true; return its index or 0 if none detected.
findLast: aOneArgBlock: find the last child (not recursive), for which evaluation of the argument, aOneArgBlock
returns true; return its index or 0 if none detected.
identityIndexOf: aChild: return the index of aChild or 0 if not found. Compare using ==
identityIndexOf: aChild startingAt: startIndex: return the index of aChild, starting search at startIndex.
Compare using ==; return 0 if not found
recursiveDetect: aOneArgBlock: recursive find the first child, for which evaluation
of the block returns true; if none, nil is returned.
Warning: this only searches in already visible child elements
i.e. any collapsed items are not searched.
recursiveDetectLast: aBlock: recursive find the last child, for which evaluation of the block returns true;
if none does so, nil is returned.
Warning: this only searches in already visible child elements
i.e. any collapsed items are not searched.
withAllDetect: aOneArgBlock: recursive find the first item including self,
for which evaluation of the block returns true; if none nil is returned.
Warning: this only searches in already visible child elements
i.e. any collapsed items are not searched.

sorting & reordering

recursiveSort: aSortBlock: recursive sort the children inplace using the 2-arg block sortBlock for comparison
sort: aSortBlock: sort the children inplace using the 2-arg block sortBlock for comparison

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