TGraphObject.md

TGraphObject = class(TPersistent)

This abstract class is the ancestor of all the objects that appear on a graph.

Properties

In addition to the properties of the TPersistent class, the TGraphObject class provides the following properties:

• public BoundsRect: TRect
  Determines the bounding rectangle of the graph object in graph coordinates.

• published Brush: TBrush
  Determines the color and pattern for filling the background of the graph object.

• public Data: Pointer
  Stores a pointer value as part of the graph object.

• public DependentCount: Integer (read-only)
  Determines the number of graph objects whose placement on the graph is dependent on this graph object.

• public Dependents[Index: Integer]: TGraphObject (read-only)
  Contains the list of graph objects whose placement on the graph is dependent on this graph object.

• public Dragging: Boolean (read-only)
  Indicates whether the graph object is being dragged.

• published Font: TFont
  Specifies the font to use when rendering a text on the graph object.

• published HasCustomData: Boolean default false
  Indicates whether the graph object holds some application defined data that should be saved.

  If HasCustomData is set to true, the owner TSimpleGraph control raises an OnObjectWrite event for saving the custom data of the graph object into a stream.

• published Hint: String
  Specifies the text string that appears as the tooltip of the graph object.

• public ID: DWord (read-only)
  Determines the unique identifier of the graph object in the graph.

• public LinkInputCount: Integer
  Determines the number of graph links/edges whose ending point is attached to this graph object.

• public LinkInputs[Index: Integer]: TGraphLink
  Contains the list of graph links/edges whose ending point is attached to this graph object.

  The Target property of all the TGraphLink objects in this list refers to this graph object.

• public LinkOutputCount: Integer
  Determines the number of graph links/edges whose starting point is attached to this graph object.

• public LinkOutputs[Index: Integer]: TGraphLink
  Contains the list of graph links/edges whose starting point is attached to this graph object.

  The Source property of all the TGraphLink objects in this list refers to this graph object.

• published Options: TGraphObjectOptions default [goLinkable, goSelectable, goShowCaption]
TGraphObjectOptions = set of (goLinkable, goSelectable, goShowCaption)
  Specifies the visual and behavioral attributes of the node.

  Value	Description
  goLinkable	A link/edge of the graph can attach to this graph object
  goSelectable	The graph object is selectable
  goShowCaption	The caption of the graph object is visible

• public Owner: TSimpleGraph (read-only)
  Determines the TSimpleGraph control that owns this graph object.

• published ParentFont: Boolean default true
  Determines where the graph object looks for its font information.

  If ParentFont is set to true, the graph object uses the font of its owner TSimpleGraph control.

• published Pen: TPen
  Specifies the kind of pen the graph object uses for drawing lines and outlining shapes.

• public Selected: Boolean
  Indicates whether the graph object is selected.

• public SelectedVisualRect: TRect (read-only)
  Specifies the rectangle area that the graph object occupies on the graph when it is selected.

• public Showing: Boolean (read-only)
  Indicates whether the graph object is showing on the owner TSimpleGraph control.

• public States: TGraphObjectStates
TGraphObjectStates = set of (osCreating, osDestroying, osLoading, osReading, osWriting, osUpdating, osDragging, osDragDisabled, osConverting)
  Describes the current state of the graph object, indicating when a component needs to avoid certain actions.

  Value	Description
  osCreating	The graph object is being created.
  osDestroying	The graph object is about to be destroyed.
  osLoading	The graph object is currently being loaded.
  osReading	The graph object is reading its properties from a stream.
  osWriting	The graph object is writing its properties into a stream.
  osUpdating	The graph object is being updated. This flag is set between BeginUpdate and EndUpdate block.
  osDragging	The graph object is being dragged.
  osDragDisabled	The graph object doesn't accept a drag operation at this moment.
  osConverting	The graph object is currently either source or target of a type conversion operation.

• published Tag: Integer default 0
  Stores an integer value as part of the graph object.

• published Text: String
  Specifies the text string that appears as the caption of the graph object.

• published Visible: Boolean default true
  Determines whether the graph object appears on the owner TSimpleGraph control.

• public VisualRect: TRect
  Specifies the rectangle area that the graph object occupies on the graph when it is not selected.

• public ZOrder: Integer
  Specifies the back-to-front order in which the graph object is displayed relative to other graph objects.

Methods

In addition to the methods of the TPersistent class, the TGraphObject class provides the following methods:

• function ConvertTo(AnotherClass: TGraphObjectClass): TGraphObject;
  Converts the graph object to another graph object type.

  Parameter	Description
  AnotherClass	The new graph object type

  If the graph object is a link, the new class type must be a link, and if the graph object is a node, the new class type must be a node.

• procedure LoadFromStream(Stream: TStream);
  Loads the properties of the graph object from a stream.

  Parameter	Description
  Stream	The input stream

• procedure SaveToStream(Stream: TStream);
  Saves the properties of the graph object into a stream.

  Parameter	Description
  Stream	The output stream

• procedure BeginUpdate;
  Suspends screen repainting of the graph object.

• procedure EndUpdate;
  Resumes screen repainting of the graph object.

• procedure Invalidate;
  Repaints the graph object.

• procedure BringToFront;
  Puts the graph object in front of all other graph objects.

• procedure SendToBack;
  Puts the graph object behind all other graph objects.

• function Delete: Boolean;
  Removes the graph object from the graph

  Returns true if the graph object could be deleted; otherwise, returns false.

  Note:: Any reference to the deleted graph object is invalid and raises an AV exception.

• function CanDelete: Boolean;
  Returns true if the graph object can be deleted; otherwise, returns false.

• function IsLocked: Boolean;
  Returns true if the graph object is being locked by the owner TSimpleGraph control.

  Users cannot interact with a locked graph object using a mouse or keyboard.

• function HitTest(const Pt: TPoint): DWord;
  Determines which part of the graph object is at the specified point specified.

  Parameter	Description
  Pt	The query point in graph coordinates

  Returns the Hit-Test result.

• function ContainsPoint(X, Y: Integer): Boolean;
  Examines whether a given point is inside the graph object.

  Parameter	Description
  X	The x-coordinate of the point
  Y	The x-coordinate of the point

  Returns true if the graph object is visible and the point is inside it; otherwise, returns false.

• function IntersectsWith(const Rect: TRect): Boolean;
  Examines whether a given rectangle has any intersection with the graph object.

  Parameter	Description
  Rect	The rectangle in graph coordinates

  Returns true if the graph object is visible and has intersection with the rectangle; otherwise, returns false.

• function BeginDrag(const Pt: TPoint; HT: DWord = $FFFFFFFF): Boolean;
  Initiates manual dragging of the graph object.

  Parameter	Description
  Rect	The coordinate of the drag origin
  HT	Specifies the part of the graph object that should be dragged (see hit-testing)

  If HT parameter is $FFFFFFFF, the function detects the dragging part of the graph object.

  Returns true if the drag operation is initiated; otherwise, returns false.

  Note: The other selected objects in the graph may follow the drag operation.

• function EndDrag(Accept: Boolean): Boolean;
  Terminates the current drag operation of the graph object.

  Parameter	Description
  Accept	Indicates whether to commit the outcome of the drag operation

  Returns true if the graph object was being dragged; otherwise, returns false.

• function DragTo(const Pt: TPoint; SnapToGrid: Boolean): Boolean;
  Moves the drag origin of the graph object to a given point.

  Parameter	Description
  Pt	The coordinate of the target point
  SnapToGrid	Indicates whether snap the drag origin to the grid

  Returns true if the graph object is being dragged; otherwise, returns false.

• function DragBy(dX, dY: Integer; SnapToGrid: Boolean): Boolean;
  Moves the drag origin of the graph object by a given amount along the x- and y-axis.

  Parameter	Description
  dX	The changes along the x-axis in pixels
  dY	The changes along the y-axis in pixels
  SnapToGrid	Indicates whether snap the drag origin to the grid

  Returns true if the graph object is being dragged; otherwise, returns false.

• class function IsLink: Boolean;
  Returns true if this graph object type representing a link/edge; otherwise, returns false.

• class function IsNode: Boolean;
  Returns true if this graph object type representing a node; otherwise, returns false.