NAME¶
Unidraw - one-of-a-kind object for coordinating and controlling a Unidraw
application
SYNOPSIS¶
#include <Unidraw/unidraw.h>
DESCRIPTION¶
Unidraw applications create a single instance of a Unidraw object, which does
several things. It creates a World, establishing the connection to the
underlying window system. It initializes the catalog and other objects,
manages editor instances, and defines the application main loop. It also
maintains histories of commands that have be executed and reverse-executed for
each component hierarchy being edited. Finally, it cleans up internal state
when it is deleted to ensure orderly program termination.
The Unidraw object must be created before opening any editors but after creating
a catalog. Below is the main program for a typical Unidraw application:
- int main (int argc, char** argv) {
-
AppSpecificCreator creator;
-
Unidraw* unidraw = new Unidraw(
-
new Catalog("appName", &creator),
-
argc, argv, options, properties
-
);
-
unidraw->Open(new AppSpecificEditor);
-
unidraw->Run();
-
delete unidraw;
-
return 0;
- }
PUBLIC OPERATIONS¶
- Unidraw(
- Catalog*, int argc, char** argv,
- OptionDesc* = nil, PropertyData* = nil
- )
- Unidraw(Catalog*, World*)
-
The first constructor form requires a catalog object and command line
argument information. Other arguments include pointers to PropertyData and
OptionDesc arrays. This constructor creates a World instance, passing
whichever of these arguments are supplied (except the catalog). To specify
a World instance explicitly, use the second constructor form.
- virtual void Run()
- virtual void Quit()
- Run initiates the main loop of the program. The call to Run returns when
Quit is called.
- virtual void Update(boolean immedate = false)
- Bring the screen up to date with the state of the application's objects.
By default, this involves moving connectors to their proper positions (by
calling Solve on the global csolver object) and telling editors to update
themselves (by calling their Update functions). Because Update may carry
out potentially lengthy operations, Unidraw batches Update calls by
default. This ensures that multiple consecutive calls do not induce
redundant computations. To force an immediate update, simply call Update(
true).
- virtual void Open(Editor*)
- virtual boolean Opened(Editor*)
- Open inserts an editor into the world, making it visible on the display.
The user positions the editor's window by default. Opened returns whether
an editor has been opened already.
- virtual void Close(Editor*)
- virtual void CloseDependents(Component*)
- virtual void CloseAll()
- Close closes a specified editor, removing it from the user's view and
deleting it. CloseDependents closes those editors that report a
dependence on the given component via their DependsOn operation. CloseAll
closes all open editors. ~Unidraw calls CloseAll.
- void First(Iterator&)
- void Next(Iterator&)
- boolean Done(Iterator)
- Operations for iterating over the Unidraw object's list of open editors.
First initializes an iterator to point to the beginning of the list, Next
increments the iterator to point to the following editor, and Done returns
whether or not the iterator points beyond the first or last editor in the
list.
- Editor* GetEditor(Iterator)
- Return the editor to which an iterator points.
- Editor* Find(Component*)
- Editor* FindAny(Component*)
- Operations for finding an (or the) editor associated with a given
component. Find searches the list of editors for the one whose
GetComponent operation returns the given component. FindAny returns the
first editor in the list whose GetComponent operation returns a component
in the same hierarchy as the the given component.
- Catalog* GetCatalog()
- Return the catalog passed to the constructor.
- World* GetWorld()
- Return the world object, which the Unidraw object creates when it is
instantiated.
- void Log(Command*)
- void Undo(Component*, int i = 1)
- void Redo(Component*, int i = 1)
- The Unidraw object maintains histories of commands associated with a given
component hierarchy. There are two command histories per hierarchy: the
past history and the future history. These histories
normally contain commands that have been executed and unexecuted to
support arbitrary level undo and redo. For example, after a viewer
executes the command that a tool generates by interpreting a manipulator,
it will record that command in a past history for possible undoing in the
future.
The Log operation logs a command, placing it on the past history for the
component hierarchy being edited. Log determines the past that is
approprate from the command's editor, which specifies the component (hence
the hierarchy) that it is editing. Undo reverse-executes the last i
commands that were logged for a given component's hierarchy and moves them
from their past history to the corresponding future history. Redo
re-executes the future i commands and moves them to the past. Note
that calling Redo without a preceding Undo is meaningless; thus calling
Log will clear the future history associated with the affected component
hierarchy.
- void SetHistoryLength(int)
- int GetHistoryLength()
- Assign and retrieve the maximum command history length. No more than this
many commands can be undone and redone. The default length is 20. Older
commands are deleted automatically as new commands are logged.
- void ClearHistory(Component* = nil)
- Clear the past and future for a given component hierarchy, deleting the
corresponding commands. All histories are cleared if no component is
specified.
- void ClearHistory(Editor*)
- Clear the history associated with the given editor's component if no other
editor is editing the same hierarchy. For example, Unidraw::Close calls
this operation to avoid clearing histories when a component hierarchy is
being edited in multiple editors.
PROTECTED OPERATIONS¶
- virtual void Process()
- Process is called once in the main loop defined by the Run operation. It
does nothing by default. Subclasses may redefine Process to carry out any
processing that should be done in each pass through the main loop.
- boolean IsClean(Editor*)
- This convenience function queries the given editor for a ModifStatusVar
instance. If it has one, then it returns its status (modified or
unmodified); otherwise it returns false.
- void Mark(Editor*)
- void Sweep(Editor*)
- These operations support deferred editor deletion, a mechanism to avoid
deleting editors prematurely. For example, if a command to close the
editor is invoked from a pull-down menu, then the command must not delete
the editor, since that will delete the pull-down menu before it has a
chance to close. Thus Close and similar operations do not delete editors
directly; instead, they call Mark to indicate that an editor should be
deleted sometime in the future. Sweep actually deletes the editors that
have been marked. By default, Unidraw::Run calls Sweep each time an event
is handled.
- void DoUpdate()
- A helper function that performs an immediate update independent of the
batching mechanism.
- void GetHistory(Component*, UList*& past, UList*&
future)
- void ClearHistory(UList*, int i = 1)
- Command histories are stored as ULists. These operations provide a
low-level interface to the lists themselves; the corresponding public
operations are built on top. GetHistory returns the past and future lists
for a given component, while ClearHistory deletes the first i
commands on the given list.
- UList* elem(Iterator)
- Command* command(UList*)
- Convenience functions for extracting the list element in an iterator and
the command object from the list element. These are useful in conjunction
with protected history operations described above.
- boolean updated()
- void updated(boolean)
- The first form of this function returns true if there are pending
Update(s) to be performed. The second form sets this value
explicitly.
- boolean alive()
- void alive(boolean)
- The first form of this function returns true if the program is in
the run loop defined by Run. The second form sets this value
explicitly.
SEE ALSO¶
Catalog(3U), Creator(3U), Editor(3U), Interactor(3U), Iterator(3U), Viewer(3I),
UList(3U), World(3I), statevars(3U)