Introduction:
This article describes a generic application framework
that may be of some use in projects that would need an interface similar to
Visual Studio. The application demonstrates approaches to providing a toolbox,
a workspace, an object treeview, and an object editor.
The application framework will allow the user to create
objects in the workspace by dragging items out of the toolbox and onto the work
surface, the user may drag the objects around within the workspace to reposition
them, and the user may select objects in the workspace and use the property
editor to change the object's properties. Changes made in the property editor
will immediately be reflected in the appearance of the object and in the
treeview. The treeview shows all of the workspace objects as well as child
objects. The user may also select objects from the treeview to push them into
the property editor or to delete them from the project. The user may save the
workspace as a custom file type and use the application's file open command to
restore the custom file back into the workspace for subsequent views and edits.
The application is not of any value in and of itself,
it is just intended to demonstrate an approach to building a useful application
that needs to incorporate these types of features. The application is intended
to serve only as a demonstration of one approach to building this sort
interface; it is not the only way to do it but it is a representative of a
simple way to build a fairly powerful interface that will be familiar to many
users through the use of similar products.
The application is not complete in as much as a lot of
typical functions are not described and mechanized in the project; for example,
I have not addressed things like printing or object alignment and distribution.
It is intended to serve as the basis for a more complex application but it is
not itself a complete or complex application. You can alter the approach as I
have described in any number of different ways and still achieve the same sort
of resulting interface. For example, I will demonstrate using buttons as the
objects in the toolbox but in reality any object that works with drag and drop
can be used in place of the buttons.
This application and article will attempt to
demonstrate the following concepts:
- Drag and Drop to support an application toolbox
interface
- Panel drag and drop to support moving existing
objects at run time
- Treeview control used to provide a map to all
existing parent and child objects
- Treeview control used to allow object selection
- Treeview control used to delete project objects
and child objects through simple recursion
- The property grid control used to edit object
properties
- Serialization used to store files containing all
of the necessary data needed to reconstruct the file between uses
(collective object persistence through a custom file type)
- Deserialization used to recover stored, serialized
objects to support a file open function and subsequently used to restore a
stored workspace to the active application
- Processing command line arguments to open a file
immediately upon initialization
- Creation of a custom file type through the setup
and deployment package
Getting Started:
In order to get started, unzip the attachment and load
the solution into Visual Studio 2005. Examine the solution explorer and note
the files contained in the project:
![DesktopAppFramework1.gif]()
Figure 1: The Solution Explorer Showing the Project
Files
Beneath the solution title node, observe that there are
two added folders, one containing graphics, and one containing classes. The
classes folder contains four classes; three are user controls and one is a
standard class file. These classes are used for demonstration purposes only and
form the basis for the objects and object data used within the application. The
three user controls are: Animal.vb, Person.vb, and Place.vb. The remaining
class (ObjectNote.vb) is the standard class.
The graphics folder contains a collection of icons and
images used within the application.
In the solution root, note that there are two files:
FileSerialize.vb which is a module used to handle serialization and
deserialization within the application. The remaining class is the frmMain.vb;
this class is the main application and it contains most of the code used to
drive the application.
The main form (frmMain.vb) of the application has a
layout consisting of a left side panel containing a tabbed panel; the tabbed
panel has two tabs: Toolbox and Properties. The toolbox panel contains three
user controls represented by buttons; these buttons can be dragged onto the form
and whenever a control is dragged onto the form a control of the associated type
is added to the workspace panel controls control collection as well as to a
sorted list containing references to those objects added to the panel. The
properties tab is used to expose a treeview control and a property grid
control. The treeview control shows all objects contained within the current
project; the property grid shows the properties for any object selected from
either the workspace (panel control) or the treeview control. The user may edit
any property exposed but the application is only configured to persist the
custom properties defined in the class; this could be modified to support
persisting any or all of the values associated with the object but in an effort
to keep the code small and readable, I opted only to support a few properties in
serialization and deserialization.
Take a look at figures 2 and 3 to see an example of the
demonstration application running; figure 2 shows the application with the
toolbox tab selected; the objects in the toolbox panel may be dragged and
dropped onto the panel in the right; in this example you can see several objects
that have been dropped onto the panel. Figure 3 shows the property tab selected
in the application, the treeview at the top shows all of the objects currently
in the workspace. The property grid control is set to allow edits to be made to
the last selected object. Each time a new object is selected from the treeview
or the panel, the property grid will update to show the properties for that
selected object.
![DesktopAppFramework2.gif]()
Figure 2: Application Running with Toolbox Tab
Selected
![DesktopAppFramework3.gif]()
Figure 3: Application Running with Properties Tab
Selected
The Code: User Controls.
There are three user controls contained in the class
folder in the solution. They all are basically constructed the same way so I
will only describe one of them and you can examine the others if you so desire;
the user controls are arbitrary to this discussion; the application framework
can be used to edit the properties of any object; the controls I have included
are only useful for this demonstration.
Open up the Animal.vb class file. This is user
control; user controls can't be easily serialized so there is a little extra
work involved to persist them and to bring them back to life between uses.
Each of the user controls starts out with a few
imports; these imports are used to add design support for the controls when in
use. The class starts with the following code:
Imports
System.ComponentModel
Imports
System.ComponentModel.EditorAttribute
Imports
System.ComponentModel.Design.DesignerCollection
Public
Class Animal
After the class declaration, a region called
declarations is defined and populated with private member variables and
enumerations. I have included the enumerations to demonstrate how the property
grid displays options based upon an enumeration (they are exposed in a combo box
within the property editor); the declaration region content is as follows:
#Region
"Declarations"
Private mUniqueID As
Guid
Private mDisplayName
As String
Private mSpecies As
String
Private mType As
AnimalType
Private mHabitat As
HabitatType
Private mColor As
System.Drawing.Color
Private mLocation As
Point
Public Enum
AnimalType
Mammal
Amphibeon
Fish
Bird
Reptile
End Enum
Public Enum
HabitatType
Water
Desert
Forest
Arid
Mountain
Plain
Coastal
End Enum
#End
Region
Following the declarations region, the "New" subroutine
is overloaded; one version of the subroutine is used to create new instances of
the control whilst the other is used to recreate the controls following
deserialization:
' Default
Constructor
Public
Sub New()
InitializeComponent()
Dim newGuid As
Guid = Guid.NewGuid
Me.mUniqueID = newGuid
Habitat =
HabitatType.Arid
Type =
AnimalType.Mammal
DisplayName =
"myAnimal"
End
Sub
This is the default constructor used to create new
instances of the control; it sets a unique ID for the control which is used in
managing relationships within the treeview and it sets a few default properties
for the control. Next is the alternate constructor:
' Alternate
constructor
Public
Sub New(ByVal
theId As Guid, _
ByVal theDisplayName
As String, _
ByVal theSpecies As
String, _
ByVal theType As
String, _
ByVal theHabitat As
String, _
ByVal theColor As
System.Drawing.Color, _
ByVal theLocation As
Point)
InitializeComponent()
' when restoring from data after deserialization, set
the UID to
' the stored value and the recovered properties for
the control
' including its location are stored into a new
instance of the
' user control
mUniqueID = theId
DisplayName =
theDisplayName
Species = theSpecies
Type = theType
Habitat = theHabitat
MajorColor = theColor
Me.Location = theLocation
End
Sub
This is the alternate constructor used to restore a
control following deserialization; the values supplied to the constructor will
be supplied by a structure populated from the original control's properties at
serialization. Additional properties could easily be added however in effort to
keep things simple I opted to only support a few of the available properties and
only one from the user control class (location). If you wanted to add in other
properties such as a border style or background color, you could capture those
values at serialization and post them back to the control whenever it is
reconstructed through this alternate constructor.
The rest of the Animal class contains the properties
used by the control. When looking at the properties, examine each of the
attributes assigned to the properties that may be edited within the property
editor control. That region is as follows:
#Region
"Properties"
Public ReadOnly
Property ID() As
Guid
Get
Return mUniqueID
End Get
End Property
Public Property
MyLocation() As Point
Get
Return mLocation
End Get
Set(ByVal
value As Point)
mLocation =
value
End Set
End Property
<CategoryAttribute("Animal
Information"), _
Browsable(True),
_
BindableAttribute(False),
_
DescriptionAttribute("The
display name of this animal object.")>_
Public Property
DisplayName() As
String
Get
Return mDisplayName
End Get
Set(ByVal
value As String)
mDisplayName =
value
txtTitle.Text =
"ANIMAL: " & mDisplayName
End Set
End Property
<CategoryAttribute("Animal
Information"), _
Browsable(True),
_
BindableAttribute(False),
_
DescriptionAttribute("The
species of this animal object.")>_
Public Property
Species() As String
Get
Return mSpecies
End Get
Set(ByVal
value As String)
mSpecies =
value
lblSpecies.Text
= "Species: " & mSpecies
End Set
End Property
<CategoryAttribute("Animal
Information"), _
Browsable(True),
_
BindableAttribute(False),
_
DescriptionAttribute("The
type of this animal object.")>_
Public Property
Type() As AnimalType
Get
Return mType
End Get
Set(ByVal
value As AnimalType)
mType = value
lblType.Text =
"Type: " & mType.ToString()
End Set
End Property
<CategoryAttribute("Animal
Information"), _
Browsable(True),
_
BindableAttribute(False),
_
DescriptionAttribute("The
habitat used by this animal object.")>_
Public Property
Habitat() As HabitatType
Get
Return mHabitat
End Get
Set(ByVal
value As HabitatType)
mHabitat = value
lblHabitat.Text = "Habitat: " &
mHabitat.ToString()
End
Set
End Property
<CategoryAttribute("Animal
Information"), _
Browsable(True),
_
BindableAttribute(False),
_
DescriptionAttribute("The
primary color of this animal object.")>_
Public Property
MajorColor() As System.Drawing.Color
Get
Return mColor
End Get
Set(ByVal
value As System.Drawing.Color)
mColor = value
lblColor.Text =
"Color: " & mColor.ToString()
End Set
End Property
#End
Region
As far
as the attributes go, the Category Attribute is used to group properties within
the property editor. If three properties have a common Category Attribute, they
will appear grouped together during edit. The Browsable attribute determines
whether or not the property will appear in the property editor. The Description
Attribute provides the text string that appears at the bottom of the editor;
this is generally used to provide instructions to the user or to describe the
property.
![DesktopAppFramework4.gif]()
Figure
4: Property Grid in Use
That pretty much wraps up the content of the user
controls; again all three are basically built the same and therefore I have
described only one of the three user controls.
The Code: Serializable Class.
The class folder contains one other class; it is called
ObjectNote.vb and it is a simple, serializable class. It is included in the
demonstration for two reasons. The first is that everything in a serializable
class can be serialized (you probably guessed that was coming) and therefore you
will not need to do anything extra to serialize, deserialize, or to reconstruct
objects between uses. The other reason I have included it in the demonstration
is because I use it to show adding and removing child nodes from the treeview
control.
The class is very simple and it only contains three
properties worthy of note: Its unique ID, its parent's unique ID, and string
used to hold the note itself. At runtime, if the user right clicks on an object
in the treeview or in the panel, the application will reveal a context menu and
one of the two menu options is to add a note to the object. This is the
container class that holds that note.
The code starts with a few imports and a class
declaration. Note that the class is marked serializable:
Imports
System.ComponentModel
Imports
System.ComponentModel.EditorAttribute
Imports
System.ComponentModel.Design.DesignerCollection
Imports
System.Runtime.Serialization
<Serializable()>_
Public
Class ObjectNote
Following the imports and class declaration,
a default constructor is defined as follows:
' Default Constructor
Public Sub
New(ByVal
parent As Guid)
' In order to keep track of who this note belongs to
when displayed
' in the treeview control, we need to know the
identity of the parent
object (node)
' Here we give the new object a new guid and set its
parent property
to
the value passed to the constructor.
Dim newGuid As
Guid = Guid.NewGuid
Me.mUniqueID = newGuid
Me.mParentID = parent
End Sub
As per the comments in the code, the constructor is
passed in its parents unique ID (a guid) and its unique ID and parent ID
properties are set. The parent ID is used to do two things: Maintain the
relationship between objects stored in the treeview, and to allow child objects
to be found and deleted if the primary node is deleted by the user.
Following the constructor, a few declarations are made
within a region; that section is as follows:
#Region
"Declarations"
Private mUniqueID As
Guid
Private mParentID As
Guid
Private mDisplayName
As String
Private mNote As
String
#End
Region
These private member variables are set either when the
control is created or by the properties which are added next:
#Region
"Properties"
Public ReadOnly
Property ID() As
Guid
Get
Return mUniqueID
End Get
End Property
Public Property
MyParent() As Guid
Get
Return mParentID
End Get
Set(ByVal
value As Guid)
mParentID =
value
End Set
End Property
<CategoryAttribute("Object
Note"), _
Browsable(True),
_
BindableAttribute(False),
_
DescriptionAttribute("Enter
text to describe the associated object.")>_
Public Property
Note() As String
Get
Return mNote
End Get
Set(ByVal
value As String)
mNote = value
End Set
End Property
<CategoryAttribute("Object
Note"), _
Browsable(True),
_
BindableAttribute(False),
_
DescriptionAttribute("The
display name of this note object.")>_
Public Property
DisplayName() As
String
Get
Return mDisplayName
End Get
Set(ByVal
value As String)
mDisplayName =
value
End Set
End Property
#End
Region
Of the properties shown, the unique and parent IDs have
already been mentioned. The display name is the name of the note as it is
displayed at run time and the Note property is the note assigned to the parent
node.
That wraps up the controls used by the application.
Again, these classes were only defined to allow the demonstration of the
approach defined within this demonstration; aside from the demonstration they
don't serve any useful purpose (well, unless you have some unusual requirements
and just so happen to need controls to monitor people, animals, and places).
The Code: Main Form.
Main Form Layout.
The main form contains a menu at the top of the form, a
tabbed control is docked to the left and has two panels, one is used as a
toolbox and the other to show the treeview and properties. The tabbed panel has
a vertical splitter on its right side; within the property tab, that panel is
split horizontally with the treeview docked to the top, the horizontal splitter
under the treeview, and the property grid control set to dock full under the
horizontal splitter. On the right side of the splitter, a toolbar is docked to
the top and a panel is set to dock full beneath the toolbar. The panel is set
to have a background color of white and it is used as the container for the
objects.
Given the panel control is going to be the target for
objects dragged from the toolbar, the Allow Drop property of the panel has to be
set to true.
Each of the three user controls is represented by a
button placed into the toolbox. Each button has an image and a text label
describing it.
The toolbar has two buttons added to it; one is called
select and one is called drag or move. If the user is in select mode, the
clicking on an item in the panel will select it and make the control active for
edit in the property grid; if the user is in drag mode, the mouse may be used to
drag the objects around on the panel to reposition them.
In addition to the visual elements, the form also
contains a file open dialog, a save file dialog, a context menu containing two
options: Delete Selected Element and Add Note To Selected Element. There is
also a tooltip and the main menu strip.
The main menu has a file menu with options to create a
new file, open an existing file, save a file, and to exit the application.
The Main Form Code.
The main form's code is divided into several regions;
these regions are as follows: Declarations, Drag and Drop - Mouse Down
Handlers, Drag and Drop - Drop Handlers, and Methods.
The declarations region contains a few member variables
used within the application, that section is as follows:
#Region
"Declarations"
' Private member variable declarations
Private mCurrentObjectName
As String
Private mCurrentObject
As Object
Private mObjectCollection
As New
SortedList
Private mObjectNotes
As New SortedList
Private mObjectFileBundle
As New
SortedList
Private mSelect As
Boolean = False
' Data Containers for Serialization --
' This example uses three user controls for the basis
of the
' objects needed to demonstrate the concept; these
are not
' serializable and in order to persist them, you need
to capture
' the user control's properties into a serializable
construct and
' store that instead of the control itself. The
following
' three structs are used to contain the user control
data.
' if you wish to persist other data from the control
such as the
' background color, font, etc., you would need to add
additional
' items to these data container structs and populate
and recover
' those values at runtime during the save and open
file operations
<Serializable()> _
Private Structure
AnimalData
Public theId As
Guid
Public theDisplayName
As String
Public theSpecies As
String
Public theType As
String
Public theHabitat As
String
Public theColor As
System.Drawing.Color
Public theLocation As
Point
End Structure
<Serializable()> _
Private Structure
PersonData
Public theId As
Guid
Public theDisplayName
As String
Public thePersonName
As String
Public theBirthPlace
As String
Public theDateOfBirth
As Date
Public theOccupation
As String
Public theLocation As
Point
End Structure
<Serializable()> _
Private Structure
PlaceData
Public theId As
Guid
Public theDisplayName
As String
Public thePlaceName
As String
Public theCity As
String
Public theState As
String
Public theCountry As
String
Public theLocation As
Point
End Structure
#End
Region
The private member variables are used to keep track of
the currently selected object and the name of that object, there are two other
collections (sorted lists) used to contain all of the user controls and all of
the notes, an additional sorted list is used to pack up all of the object data
and notes for serialization into a single file with a custom extension.
After the member variables have been declared, three
serializable structures are defined: one for each of the three user controls.
Since we are not going to try to serialize everything in the user control, we
are just adding in a few key properties. As was mentioned earlier, it would be
easy to add additional properties from the user control and to serialize and
deserialize those properties between uses.
In the Drag and Drop - Mouse Down region, each of the
three buttons is set up to support the drag and drop operation. A handler was
written for each button but since they are all basically the same, I will only
show one here:
Private
Sub Button1_MouseDown(ByVal
sender As Object,
ByVal e As
System.Windows.Forms.MouseEventArgs) Handles
Button1.MouseDown
' When the user clicks down on the button, we assume
we are going to
drag
one to the panel so we instance an animal, set its default
properties and make the DoDragDrop call. The control is not yet
added
to the panel's control collection
' and is not yet included in any data that will be
serialized; the
user
has to complete the drop onto the panel for this transaction
to
complete.
Dim myAnimal As
New Animal
mCurrentObjectName =
"Animal"
mCurrentObject =
myAnimal
myAnimal.DisplayName
= "myAnimal"
Button1.DoDragDrop(myAnimal, DragDropEffects.All)
End
Sub
The mouse down event is used to instance the associated
class, set a couple of properties on the object, and evoke the button's Do Drag
Drop method whilst passing it the new object and setting the Drag Drop Effect to
all. That sets up the drag side of the house, now we need to handle the drop
side. Looking at the drop handlers region, you will see two subroutines defined
to prepare the panel control to receive the dropped items: Panel1_DragDrop, and
Panel1_DragEnter; they are written as follows:
Private
Sub Panel1_DragDrop1(ByVal
sender As Object,
ByVal e As
System.Windows.Forms.DragEventArgs) Handles
Panel1.DragDrop
' Get the current mouse position and define a point,
then
' convert the point to work on the panel control
(within its
coordinates)
Dim dropX As
Single = e.X
Dim dropY As
Single = e.Y
Dim dropLocation =
New Point(dropX, dropY)
Dim dropPoint As
New Point()
dropPoint =
Panel1.PointToClient(dropLocation)
' Create new objects based upon what has been dropped
onto the panel
' and set the user control's handlers to work with
the dropped
object.
Select Case
mCurrentObjectName.ToString()
Case "Animal"
Dim myAnimal As
New Animal
myAnimal =
CType(Me.mCurrentObject,
Animal)
Panel1.Controls.Add(myAnimal)
myAnimal.Location = dropPoint
myAnimal.ContextMenuStrip = ContextMenuStrip1
mObjectCollection.Add(myAnimal.ID, myAnimal)
AddHandler myAnimal.MouseClick,
AddressOf Object_MouseClick
AddHandler myAnimal.MouseDown,
AddressOf Object_MouseDown
Case "Person"
Dim myPerson As
New Person
myPerson =
CType(Me.mCurrentObject,
Person)
Panel1.Controls.Add(myPerson)
myPerson.Location = dropPoint
myPerson.ContextMenuStrip = ContextMenuStrip1
mObjectCollection.Add(myPerson.ID, myPerson)
AddHandler myPerson.MouseClick,
AddressOf Object_MouseClick
AddHandler myPerson.MouseDown,
AddressOf Object_MouseDown
Case "Place"
Dim myPlace As
New Place
myPlace =
CType(Me.mCurrentObject,
Place)
Panel1.Controls.Add(myPlace)
myPlace.Location = dropPoint
myPlace.ContextMenuStrip = ContextMenuStrip1
mObjectCollection.Add(myPlace.ID, myPlace)
AddHandler
myPlace.MouseClick, AddressOf Object_MouseClick
AddHandler myPlace.MouseDown,
AddressOf Object_MouseDown
Case Else
mCurrentObject.Location = dropPoint
End Select
' With a new item dropped into the panel, update the
treeview to
' reflect the latest addition to the node collection
UpdateTreeview()
End Sub
The first part of this handler gets the current mouse
position at the time of the drop and converts it into a value usable by the
panel control. This will make sure that the dropped item's upper left hand
corner will be located at the exact position indicated by the mouse when the
drop was made. Following the location conversion, the subroutine evaluates the
current object's name (set when the button received its mouse down command)
within a select case statement; depending upon the current object, the
subroutine then creates an instance of the appropriate object type sets it to be
the current object, adds the control to the panel, sets its location to be at
the drop point, and then adds a context menu and mouse click and mouse down
event handlers to the control .
Once the object has been placed and added to the panel,
the treeview control is updated to show the newly added object. The Drag Enter
event handler is set up to handle whether or not the drag drop will be used to
move a control or add a new one.
Private
Sub Panel1_DragEnter1(ByVal
sender As Object,
ByVal e As
System.Windows.Forms.DragEventArgs) Handles
Panel1.DragEnter
' Setup to either copy or move the dragged control.
If (e.Data.GetDataPresent(DataFormats.Text))
Then
e.Effect =
DragDropEffects.Copy
Else
e.Effect =
DragDropEffects.Move
End If
End
Sub
The last section of code to describe is contained in
the Methods region; within this region, fifteen separate subroutines are
defined. Some of these subroutines are very simple and are barely worth
mentioning, others will require some explanation.
The first two subroutines in the methods region are two
generic handlers: a mouse down handler, and an mouse click handler.
Private
Sub Object_MouseClick(ByVal
sender As Object,
ByVal e As
System.Windows.Forms.MouseEventArgs)
' A generic mouse click handler used for dynamically
added user
control
objects. This sets the current object, current object
name,
and object associated with the property grid in response to a
click
Try
Me.mCurrentObject = sender
Me.mCurrentObjectName =
sender.DisplayName.ToString()
Me.PropertyGrid1.SelectedObject = sender
Catch ex As
Exception
End Try
End
Sub
Private
Sub Object_MouseDown(ByVal
sender As Object,
ByVal e As
System.Windows.Forms.MouseEventArgs)
' A generic mouse down handler used for dynamically
added user
control
objects.
' This works such that if the user to swap between
selecting a
control
to load
' it into the property grid control, or to allow the
user to drag a
control
to a new location on the form panel.
Try
If mSelect = True
Then
mCurrentObject
= sender
mCurrentObjectName = sender.DisplayName.ToString()
mCurrentObject.DoDragDrop(mCurrentObject,
DragDropEffects.All)
Me.PropertyGrid1.SelectedObject = sender
End
If
Catch ex As
Exception
End
Try
End
Sub
The comments provided within each of these two
subroutines defines the purpose of the handler. In general, these handlers are
added to new instances of any controls added to the panel control at run time.
The next two subroutines are used to set a Boolean
value used to allow the application to determine whether or not it is in select
or drag mode. This code is the click event handler for the two toolbar
controls. That code is as follows:
Private
Sub tbnSelect_Click_1(ByVal
sender As System.Object,
ByVal e As
System.EventArgs)
Handles tbnSelect.Click
' Select mode is used allow the user to click on an
object without
dragging
mSelect =
False
End
Sub
Private
Sub tbnDrag_Click_1(ByVal
sender As System.Object,
ByVal e As
System.EventArgs)
Handles tbnDrag.Click
' With select mode disabled the user can drag objects
around to move
them
mSelect =
True
End
Sub
Moving right along, the next thing up is the call that
updates the treeview. This call is made whenever a property grid item is edited
or an item is added or deleted from the current workspace. That code looks like
this:
Private
Sub UpdateTreeview()
' Clears and reloads all of the nodes in the treeview
' based upon object data stored in the objects sorted
list
' This first loads the objects, and then checks for
and loads
' any notes associated with the current object.
TreeView1.Nodes.Clear()
Dim de As
DictionaryEntry
For Each de
In mObjectCollection
Dim nd As
New TreeNode
nd.Name =
de.Value.displayname.ToString()
nd.Text =
de.Value.displayname.ToString()
nd.Tag =
de.Value.ID.ToString()
Me.TreeView1.Nodes.Add(nd)
' add any notes
Dim de2 As
DictionaryEntry
For Each de2
In mObjectNotes
If de2.Value.MyParent.ToString() =
nd.Tag.ToString() Then
Dim newNoteNode As
New TreeNode
newNoteNode.Text = "Note"
newNoteNode.Tag = de2.Value.ID.ToString()
nd.Nodes.Add(newNoteNode)
End If
Next
Next
' The treeview will normally collapse all nodes in
response to a
change,
this call forces all nodes to open.
TreeView1.ExpandAll()
End
Sub
This code is pretty simple; it clears all of the items
out of the current treeview and then loops through the object collection to
restore the treeview. As items are added and removed from the object
collection, the treeview will reflect only the current status of the workspace.
Equally simple is the handler for the property grid's
property event changed handler which just calls for the treeview to update:
Private
Sub PropertyGrid1_PropertyValueChanged(ByVal
s As Object,
ByVal e
As
System.Windows.Forms.PropertyValueChangedEventArgs)
Handles
PropertyGrid1.PropertyValueChanged
' Whenever the user updates a property in the
property editor, the
object
will update
' automatically but the treeview will not; this call
will update the
treeview
in response
' to dynamic edits to the property grid control.
UpdateTreeview()
End
Sub
Whenever the user selects an item from the treeview
control, the property grid control needs to be updated to display the selected
item's associated object for edit; this code accomplishes that:
Private
Sub TreeView1_AfterSelect(ByVal
sender As Object,
ByVal e As
System.Windows.Forms.
TreeViewEventArgs)
Handles TreeView1.AfterSelect
' Whenever the user clicks on a treeview node, this
subroutine will
' select the object associated with the treeview node
into the
property
' grid and make it available for edits.
' The first check is for user control objects
Dim de As
DictionaryEntry
For Each de
In mObjectCollection
If de.Key.ToString = e.Node.Tag.ToString()
Then
Me.mCurrentObject = de.Value
Me.mCurrentObjectName =
de.Value.DisplayName.ToString()
PropertyGrid1.SelectedObject = de.Value
End If
Next
' The second check is for notes
Dim de2 As
DictionaryEntry
For Each de2
In mObjectNotes
If de2.Key.ToString = e.Node.Tag.ToString()
Then
Me.mCurrentObject
= de2.Value
Me.mCurrentObjectName
= de2.Value.DisplayName.ToString()
PropertyGrid1.SelectedObject = de2.Value
End If
Next
End
Sub
As you can see, after the user selects an item from the
treeview control, the application will loop through the collection of objects
and the collection of notes looking for a match. When the match is made, the
control is updated to show the selected object's properties.
The call to delete a selected item works in a similar
manner:
Private
Sub DelectCurrentObjectToolStripMenuItem_Click(ByVal
sender As System.Object,
ByVal e As
System.EventArgs) Handles
DelectCurrentObjectToolStripMenuItem.Click
' This function will delete the selected object and
treeview node
' in response to a user request to delete the
object. The option to
delete an object is presented in the context menu.
Dim de As
DictionaryEntry
For Each de
In mObjectCollection
If de.Value.ID.ToString =
mCurrentObject.ID.ToString() Then
mObjectCollection.Remove(de.Key)
DeleteOrphanNotes(de.Key)
Exit For
End If
Next
UpdateTreeview()
Me.Panel1.Controls.Remove(mCurrentObject)
End
Sub
In this code, when the user selects the Delete Current
Object from the context menu (after right clicking on either the treeview or one
of the panel control's objects), the object collection is looped through
searching for a match to the selected (current) object. When a match is found,
two things happen, first the collection is updated to remove the current object,
and second, the unique ID for the object just deleted is passed to function
called DeleteOrphanNotes. Delete orphan notes is used to track down any and all
notes assigned to the deleted object and remove them from the object note
collection. After the change is made, the treeview control is updated and the
panel's control collection is updated to remove the current object from that
collection as well.
The next bit of code to examine is used to add a new
note the current selected object. When this code is executed, a new note object
will be created and its parent ID will be set to the current object's unique
ID. After the note is added, the treeview is updated to show the new child node
appended to its parent node. That code is as follows:
Private
Sub AddNoteToolStripMenuItem_Click(ByVal
sender As System.Object,
ByVal e As
System.EventArgs) Handles
AddNoteToolStripMenuItem.Click
' The option to add a note to a selected object
(either from the
treeview or panel)
' is supported here; the control option appears in
the context menu.
Dim newNote As
New ObjectNote(mCurrentObject.ID)
newNote.DisplayName
= "Note"
Me.mObjectNotes.Add(newNote.ID, newNote)
UpdateTreeview()
End
Sub
Next up is the Delete Orphan Notes subroutine, this
function will continue to search for child notes until no more are found. In
response to finding a node, the function will again call itself to look for
notes with a parent ID that matches the argument passed to the function. The
process will continue to operate recursively until the search term is not
found. That code looks like this:
Public
Sub DeleteOrphanNotes(ByVal
parentID As Guid)
' Recursively deletes all child note objects
associated with
' a parent that has been deleted. The code continues
to look
' for notes with a matching parent ID until no more
are found; at
' that point the search will cease.
Dim blnFound As
Boolean = False
Dim de As
DictionaryEntry
For Each de
In Me.mObjectNotes
If
de.Value.MyParent = parentID Then
mObjectNotes.Remove(de.Key)
blnFound =
True
Exit
For
End
If
Next
If blnFound = False
Then
Exit
Sub
Else
DeleteOrphanNotes(parentID)
End If
End
Sub
Next up is a main menu item click event handler. This
code is used to handle a request for a new project and all it does is call
another subroutine called Clear All. That code and the code for Clear All are
as follows:
Private
Sub NewToolStripMenuItem_Click(ByVal
sender As System.Object,
ByVal e As
System.EventArgs) Handles
NewToolStripMenuItem.Click
' Reset all collections and controls to a default
' empty state
ClearAll()
End
Sub
Private
Sub ClearAll()
' This just clears and empties everything out of the
project
mCurrentObjectName =
""
mCurrentObject =
New Object()
mObjectCollection.Clear()
mObjectNotes.Clear()
mObjectFileBundle.Clear()
mSelect =
False
Panel1.Controls.Clear()
TreeView1.Nodes.Clear()
PropertyGrid1.SelectedObject = Nothing
End
Sub
If you take a look at the Clear All subroutine, you
will note that it empties all of the object collections, object selections, and
the panel control's control collection. It also empties the treeview control and
sets the property grid control's selected object to nothing. This code was
placed in a separate subroutine since it is called both in response the "New"
menu option select as well as when file is opened from the file system.
Moving on the next menu option, "Open", this bit of
code is used to open a file from the file system and load its content into the
application. The Open menu item select's code looks like this:
Private
Sub OpenToolStripMenuItem_Click(ByVal
sender As System.Object,
ByVal e As
System.EventArgs) Handles
OpenToolStripMenuItem.Click
' Configure the appearance and file association used
by the
' openfiledialog box; limit the files that may be
opened to the
' custom file type extension. BXS is arbitrary, you
can make up
' any file extension (well, don't use something like
.doc, .txt, or
.bmp)
OpenFileDialog1.Title =
"Open BXS Document"
OpenFileDialog1.Filter
= "BXS Documents (*.bxs)|*.bxs"
' if the user cancels, close out the dialog and
return to the form
If OpenFileDialog1.ShowDialog =
Windows.Forms.DialogResult.Cancel
Then
Exit Sub
End If
' Exit if no BXS document is selected
Dim sFilePath As
String
sFilePath =
OpenFileDialog1.FileName
If sFilePath = ""
Then Exit
Sub
' Verify that the requested file is in place and
' exit the subroutine if the file does not exist.
If System.IO.File.Exists(sFilePath) =
False Then
Exit Sub
End If
' Since we have a valid source file, clear all is
called
' to empty the applications sorted lists and to clear
the
' panel of controls
ClearAll()
mObjectFileBundle =
New SortedList
mObjectFileBundle =
FileSerializer.Deserialize(sFilePath)
Dim ObjectData As
New SortedList
' Recover the object collections to populate the
local
' sortedlists used to hold the objects.
Dim de As
DictionaryEntry
For Each de
In mObjectFileBundle
If de.Key.ToString() =
"TheObjects" Then
ObjectData =
de.Value
ElseIf de.Key.ToString() =
"TheNotes" Then
mObjectNotes.Clear()
mObjectNotes =
de.Value
End If
Next
' Add the objects back into the panel by recovering
the stored
' object data and creating a new set of controls with
the properties
' set to the object data gathered from the original
object during
' file save and serialization
Dim de2 As
DictionaryEntry
For Each de2
In ObjectData
Select
Case de2.Value.GetType.ToString()
Case
"ObjectManager.frmMain+AnimalData"
Dim
ast As New
AnimalData
ast =
de2.Value
Dim
animl As New
Animal(ast.theId, _
ast.theDisplayName, _
ast.theSpecies, _
ast.theType, _
ast.theHabitat, _
ast.theColor, _
ast.theLocation)
animl.ContextMenuStrip = ContextMenuStrip1
mObjectCollection.Add(animl.ID, animl)
AddHandler animl.MouseClick,
AddressOf Object_MouseClick
AddHandler animl.MouseDown,
AddressOf Object_MouseDown
Panel1.Controls.Add(animl)
Case
"ObjectManager.frmMain+PersonData"
Dim pst As
New PersonData
pst =
de2.Value
Dim pers As
New Person(pst.theId, _
pst.theDisplayName, _
pst.thePersonName, _
pst.theBirthPlace, _
pst.theDateOfBirth, _
pst.theOccupation, _
pst.theLocation)
pers.ContextMenuStrip = ContextMenuStrip1
mObjectCollection.Add(pers.ID, pers)
AddHandler pers.MouseClick,
AddressOf Object_MouseClick
AddHandler pers.MouseDown,
AddressOf Object_MouseDown
Panel1.Controls.Add(pers)
Case
"ObjectManager.frmMain+PlaceData"
Dim pls As
New PlaceData
pls =
de2.Value
Dim plc As
New Place(pls.theId,
_
pls.theDisplayName, _
pls.thePlaceName, _
pls.theCity, _
pls.theState, _
pls.theCountry, _
pls.theLocation)
plc.ContextMenuStrip = ContextMenuStrip1
mObjectCollection.Add(plc.ID, plc)
AddHandler
plc.MouseClick, AddressOf Object_MouseClick
AddHandler plc.MouseDown,
AddressOf Object_MouseDown
Panel1.Controls.Add(plc)
Case Else
' do nothing
End Select
Next
' update the treeview to show the objects loaded from
a file
UpdateTreeview()
End
Sub
This code is annotated well enough to follow but in
general, the option is used to open an Open File Dialog; the dialog is
configured to show files that match the custom file extension we are using
(.bxs). When the user selects a valid file, the path the that file is captured
as a string and passed to the deserialization handler code; this code recovers
the local file bundle object from the serialized bundle (the bundle is a sorted
list that contains two other sorted lists, one for the control object data, and
one for the note objects.
The bundled sorted list is examined and the serialized
object sorted list and the object note sorted list are used to populate the
local object list and object note list. The objects contained in the control
object sorted list are evaluated and new controls are instanced, their
properties are set to match the stored property values, and the appropriate
event handlers are associated with the new control. Once all of the new
controls have been defined and added to the panel control, the treeview is
updated. Note that the object notes sorted list did not require any processing
other than to write it over directly to the current object notes sorted list.
This is because the entire class and all of its properties was directly
serializable.
The next bit of code accomplishes the save function
called form the main menu:
Private
Sub SaveToolStripMenuItem_Click(ByVal
sender As System.Object,
ByVal e As
System.EventArgs) Handles
SaveToolStripMenuItem.Click
Try
' Open a file dialog for saving BXS documents
SaveFileDialog1.Title = "Save BXS Document"
SaveFileDialog1.Filter = "BXS Documents
(*.bxs)|*.bxs"
If SaveFileDialog1.ShowDialog() =
Windows.Forms.DialogResult.Cancel Then
Exit Sub
End If
Catch ex As
Exception
Exit Sub
End Try
' Exit if no BXS document is selected
Dim sFilePath As
String
sFilePath =
SaveFileDialog1.FileName
If sFilePath = ""
Then Exit
Sub
' Create a new sorted list to hold the data contain
in the
' user controls for subsequent serialization
Dim ObjectData As
New SortedList
' Move the notes and object collections into the file
bundle
' for subsequetn serialization
Dim de As
DictionaryEntry
For Each de
In mObjectCollection
Select Case
de.Value.GetType.ToString()
Case
"ObjectManager.Animal"
Dim ad As
New AnimalData
ad.theId =
de.Key
ad.theColor
= de.Value.MajorColor
ad.theDisplayName = de.Value.DisplayName
ad.theHabitat = de.Value.Habitat
ad.theSpecies = de.Value.Species
ad.theLocation = de.Value.Location
ObjectData.Add(ad.theId, ad)
Case
"ObjectManager.Person"
Dim ps As
New PersonData
ps.theId =
de.Key
ps.theBirthPlace = de.Value.BirthPlace
ps.theDateOfBirth = de.Value.DateOfBirth
ps.theDisplayName = de.Value.DisplayName
ps.theLocation = de.Value.Location
ps.theOccupation = de.Value.Occupation
ps.thePersonName = de.Value.PersonName
ObjectData.Add(ps.theId, ps)
Case
"ObjectManager.Place"
Dim pls As
New PlaceData
pls.theId =
de.Key
pls.theDisplayName = de.Value.DisplayName
pls.thePlaceName = de.Value.PlaceName
pls.theCity
= de.Value.City
pls.theState = de.Value.State
pls.theCountry = de.Value.Country
pls.theLocation = de.Value.Location
ObjectData.Add(pls.theId, pls)
Case Else
'do nothing
End Select
Next
' Place the object data and notes into a sorted list
' for subsequent serialization to a file location
mObjectFileBundle =
New SortedList
mObjectFileBundle.Add("TheObjects",
ObjectData)
mObjectFileBundle.Add("TheNotes",
mObjectNotes)
' Once the values have been set, serialize the
content into the
' file path established using the save file dialog
FileSerializer.Serialize(sFilePath, mObjectFileBundle)
End
Sub
This code works in a manner similar to the Open File menu
option, although it is operating in reverse. Here, the user is presented with a
File Save dialog box; the dialog box is used to collect a valid path to be used
to store the serialized application data as a custom (.bxs) file. Once a valid
path is selected or created, the subroutine collects the control object data
from the control object collection and moves it into a separate, serializable
collection. The structures defined for each control type are used to contain
individual copies of each control objects properties; not all of the properties
but those that we have decided to keep.
Once the control data has been gathered into the object data collection, both
the object note and object data sorted lists are added to the Object File Bundle
sorted list (so that all data is now stored in a single sorted list). The
object file bundle is then serialized to the file path specified.
The next two sections of code are used to handle
opening the application by double clicking on an associated file of the custom
file type from an explorer window. The first subroutine configures form load to
look for file path strings passed to the application on load, and if any are
passed in, it passes the path to the second subroutine which loads it into the
application on start up.
That code looks like this:
Private
Sub frmMain_Load(ByVal
sender As Object,
ByVal e As
System.EventArgs)
Handles Me.Load
'check each parameter to get the file name (there is
only one though)
For Each param
As String
In My.Application.CommandLineArgs
Try
' pass the file path if it exists
OpenFromPath(param)
Catch
'do nothing, just open the application with no file
End Try
Next param
End
Sub
Private
Sub OpenFromPath(ByVal
sFilePath As String)
mObjectFileBundle =
New SortedList
mObjectFileBundle =
FileSerializer.Deserialize(sFilePath)
Dim ObjectData As
New SortedList
' Recover the object collections to populate the
local
' sortedlists used to hold the objects.
Dim de As
DictionaryEntry
For Each de
In mObjectFileBundle
If de.Key.ToString() =
"TheObjects" Then
ObjectData =
de.Value
ElseIf de.Key.ToString() =
"TheNotes" Then
mObjectNotes.Clear()
mObjectNotes =
de.Value
End If
Next
' Add the objects back into the panel by recovering
the stored
' object data and creating a new set of controls with
the properties
' set to the object data gathered from the original
object during
' file save and serialization
Dim de2 As
DictionaryEntry
For Each de2
In ObjectData
Select Case
de2.Value.GetType.ToString()
Case
"ObjectManager.frmMain+AnimalData"
Dim ast As
New AnimalData
ast =
de2.Value
Dim animl As
New Animal(ast.theId, _
ast.theDisplayName, _
ast.theSpecies, _
ast.theType, _
ast.theHabitat, _
ast.theColor, _
ast.theLocation)
animl.ContextMenuStrip = ContextMenuStrip1
mObjectCollection.Add(animl.ID, animl)
AddHandler animl.MouseClick,
AddressOf Object_MouseClick
AddHandler
animl.MouseDown, AddressOf Object_MouseDown
Panel1.Controls.Add(animl)
Case
"ObjectManager.frmMain+PersonData"
Dim pst As
New PersonData
pst =
de2.Value
Dim pers As
New Person(pst.theId, _
pst.theDisplayName, _
pst.thePersonName, _
pst.theBirthPlace, _
pst.theDateOfBirth, _
pst.theOccupation, _
pst.theLocation)
pers.ContextMenuStrip = ContextMenuStrip1
mObjectCollection.Add(pers.ID, pers)
AddHandler pers.MouseClick,
AddressOf Object_MouseClick
AddHandler pers.MouseDown,
AddressOf Object_MouseDown
Panel1.Controls.Add(pers)
Case
"ObjectManager.frmMain+PlaceData"
Dim pls As
New PlaceData
pls =
de2.Value
Dim plc As
New Place(pls.theId,
_
pls.theDisplayName, _
pls.thePlaceName, _
pls.theCity, _
pls.theState, _
pls.theCountry, _
pls.theLocation)
plc.ContextMenuStrip = ContextMenuStrip1
mObjectCollection.Add(plc.ID, plc)
AddHandler plc.MouseClick,
AddressOf Object_MouseClick
AddHandler plc.MouseDown,
AddressOf Object_MouseDown
Panel1.Controls.Add(plc)
Case Else
' do nothing
End Select
Next
' update the treeview to show the objects loaded from
a file
UpdateTreeview()
End
Sub
The code for the Open From File subroutine is identical
to a portion of the code used in the File Open menu click event handler except
for the fact that is works with a file path passed into the function directly
rather than through a value collected from an open file dialog. This function
could be called directly from the File Open menu event handler with no impact on
the application.
The last subroutine in the application is merely used
to close the application in response to the user's selection of the exit
function from the main menu:
Private
Sub ExitToolStripMenuItem_Click(ByVal
sender As System.Object,
ByVal e As
System.EventArgs) Handles
ExitToolStripMenuItem.Click
Application.Exit()
End
Sub
That concludes the description of the code contained
within the main form's code and for all of the application code in general.
The Code: File Serializer Module
The code module contains two methods; one to serialize
data and one to deserialize data. Both methods use a binary formatter to handle
the serialization and deserialization process. Take a look at the module and
note how each was construction.
The Serializer subroutine appears as follows:
Sub
Serialize(ByVal strPath
As String,
ByVal myFile As
SortedList)
' Create a filestream to allow saving the file after
it has
' been serialized in this method
Dim fs As
New FileStream(strPath, FileMode.OpenOrCreate)
' Create a new instance of the binary formatter
Dim formatter As
New BinaryFormatter
'Dim
formatter As New SoapFormatter
Try
' save the serialized data to the file path specified
formatter.Serialize(fs, myFile)
fs.Close()
Catch ex As
SerializationException
MessageBox.Show(ex.Message & ": " &
ex.StackTrace, "Error",
MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
End
Sub
The subroutine is quite simple; it opens a file stream
pointed to the file path string passed in the argument list; the file mode is
set to open or create. Following the creation of the file stream, a new
instance of the BinaryFormatter is created. The try catch block is then set up;
the try section is used to evoke the formatters serialize method; this method
accepts two arguments: One to identify the file stream to write to, and one to
accept the file which in this case is the sorted list containing references to
both the application objects and the note objects. Once the serializer
completes writing to the file stream, the file stream is closed.
The other method in the File Serializer class is used
to deserialize the contents of the stored file back into the application's file
bundle sorted list. Once reconstructed from a file, the sorted list is used to
recreate the work space objects. That code looks like this:
Public
Function Deserialize(ByVal
strPath As String)
As SortedList
' Create filestream allowing the user to open an
existing file
Dim fs As
New FileStream(strPath, FileMode.Open)
' Create a new instance of the Personal Data class
Dim myFile As
SortedList
myfile =
New SortedList
Try
' Create a binary formatter
Dim formatter As
New BinaryFormatter
'Dim formatter As New SoapFormatter
' Deserialize the data stored in the specified file
and
' use that data to populate the new instance of the
personal data
class.
myfile =
formatter.Deserialize(fs)
fs.Close()
' Return the deserialized data back to the calling
application
Return myFile
Catch ex As
SerializationException
MessageBox.Show(ex.StackTrace, ex.Message, MessageBoxButtons.OK,
MessageBoxIcon.Error)
Return myFile
End Try
End
Function
This code works much like the serializer subroutine in
that it opens a file stream and returns the contents of the file (the file
bundle sorted list) which is passed to a new sorted list call "myFile". The
deserializer function returns the reconstructed sorted list to the calling
method. The calling method in this case is the file open command in the main
form; the file open command then reconstructs the objects and notes sorted lists
from the file bundle sorted list.
Custom File Association.
If you want to create a custom file association such
that when a user double clicks on a file of the custom type's extension in a
windows explorer window, the application will open it up directly, you will need
to set that association up in the setup and deployment package, and you will
need to modify the main entry point of the application to allow it to process a
file passed to it immediately upon initialization.
The process of creating a file type association through
the use of the Visual Studio 2005 setup and deployment project is far easier to
manage than it once was; you can manually code the necessary information into
the application, and depending upon the installation package you are using, you
may need to do that. If you are interested in that approach, take a look at
this link,
http://www.vbcity.com/forums/faq.asp?fid=15&cat=Registry#TID72502,
[see File Associations the hard way].
First off, in the main form of the application, you
will need to modify the form load event handler to respond to the receipt of a
command line argument (the file name), this is now a trivial bit of code and it
should look something like this:
Private
Sub frmMain_Load(ByVal
sender As System.Object,
ByVal e As
System.EventArgs)
Handles MyBase.Load
'check each parameter to get the file name (there is
only one though)
For Each param
As String
In My.Application.CommandLineArgs
Try
' pass the file path if it exists
OpenFromPath(param)
Catch
'do nothing, just open the application with no file
End Try
Next param
End
Sub
In this example, when the form loads, it will examine
the contents of My.Application.CommandLineArgs to see if it contains a file
name; since that is all we are going pass in, it will either be empty or will
contain a file path. If a file path is present, it will passed to a subroutine
called, "OpenFromPath" which captures the data from the file and then
reconstructs the file's objects.
In order to pass the file path to the command line
arguments, you need to set up a couple of things in the Setup and Deployment
project. To begin, add a setup and deployment project to the existing solution
and configure it to suit your requirements. Once the project has been added,
click on the setup project's name in the solution explorer, click on the "View"
and then click on the "File Types" option. This will bring up a File Types
Designer in the main window of Visual Studio.
Once the file type designer has been displayed, right
click on "File Types on Target Machine" and the click on the "Add File Type"
option. This will add an empty file type to the tree view, select the new file
type's node and look in the property editor:
![DesktopAppFramework5.gif]()
Figure 5: File Type Property Editor
In the property editor, set the name to match the name
of the custom type, set the command to point to the application (as the Primary
output from the application), key in a description, set the extension to the
custom file type's extension, and set an icon for the file type. Having set
those values, click on the Open node.
![DesktopAppFramework6.gif]()
Figure 6: The Open node under the custom file type
Once you have clicked on the open node, the property
editor will show these properties:
![DesktopAppFramework7.gif]()
Figure 7: Property Editor Set to the Open Node
These default properties are correct in that the
default process is set to "open" and the "%1" is set to pass the file name of a
selected file to the application's command line arguments on startup. After a
user installs the application, when they double click on a file of the custom
file type, it will pass the file path to the application and open it. Also, if
the user right clicks on the custom file type icon, they will be able to select
the "open with" option and be presented with a link to your application as
indicated in the following figure:
![DesktopAppFramework8.gif]()
Figure 8: Open With option in Windows Explorer context
menu
Summary.
The purpose of this article has been to demonstrate an
easy approach to providing a complete framework for an application that is
centered upon creating and editing objects at run time. In order to achieve
that goal, the application demonstrates the following key elements:
- Drag and Drop to support an application toolbox
interface.
- Panel drag and drop to support moving existing
objects at run time.
- Treeview control used to provide a map to all
existing parent and child objects.
- Treeview control used to allow object selection.
- Treeview control used to delete project objects
and child objects through simple recursion.
- The property grid control used to edit object
properties.
- Serialization used to store files containing all
of the necessary data needed to reconstruct the file between uses
(collective object persistence through a custom file type).
- Deserialization used to recover stored, serialized
objects to support a file open function and subsequently used to restore a
stored workspace to the active application.
- Processing command line arguments to open a file
immediately upon initialization.
- Creation of a custom file type through the setup
and deployment package.