Constraints in Blazor Diagram Component

12 Nov 202424 minutes to read

Constraints are used to enable or disable certain behaviors of the diagram, nodes, and connectors. Constraints are provided as flagged enumerations, so that multiple behaviors can be enabled or disabled using the Bitwise operators (&, |, ~, <<, etc.).

To know more about Bitwise operators, refer to the Bitwise Operations.

Diagram constraints

DiagramConstraints allow you to enable or disable the following behaviors.

• PageEditable
• Bridging
• Zoom
• UndoRedo
• UserInteraction
• Tooltip

Constraints	Description
None	Disable all diagram functionalities.
Bridging	Enables or disables Bridging support for connector in diagram.
Undo/redo	Enables or disables the Undo/Redo support for the diagram.
UserInteraction	Enables or disables user interaction support for the diagram.
ApiUpdate	Enables or disables update API support for the diagram.
PageEditable	Enables or disables Page Editable support for the diagram.
Zoom	Enables or disables Zoom support for the diagram.
PanX	Enables or disables Panning X coordinate support for the diagram.
PanY	Enables or disables Panning Y coordinate support for the diagram.
Pan	Enables or disables panning both X and Y coordinates support for the diagram.
ZoomTextEdit	Enables or disables zooming the text box while editing the text.
Tooltip	Enables or disables the tooltip for the diagram elements(Nodes and connectors).
Default	Enables or disables all constraints in diagram.

The following example shows how to disable PageEditable constraint from default diagram constraints.

@using Syncfusion.Blazor.Diagram

@* Initialize the diagram with constraints *@
<SfDiagramComponent Height="600px" Nodes="@nodes" 
Constraints="@DiagramConstraints" />

@code
{
    //Sets the Diagram constraints.
    DiagramConstraints DiagramConstraints = DiagramConstraints.Default & ~DiagramConstraints.PageEditable;
    //Initialize the Nodes Collection.
    DiagramObjectCollection<Node> nodes;

    protected override void OnInitialized()
    {
        nodes = new DiagramObjectCollection<Node>();
        Node node = new Node()
        {
            ID = "node1",
            Height = 100,
            Width = 100,
            OffsetX = 100,
            OffsetY = 100,
        };
        nodes.Add(node);
    }
}

The following example shows how to add Bridging constraint to the default constraints of diagram.

DiagramConstraints DiagramConstraints = DiagramConstraints.Default | DiagramConstraints.Bridging;

The diagram constraints are provided as flagged enumerations, so that multiple behaviors can be added or removed from the default constraints using the Bitwise Operations in the diagram.

//Removing multiple constraints from default.
DiagramConstraints DiagramConstraints = DiagramConstraints.Default & ~(DiagramConstraints.PageEditable|DiagramConstraints.Zoom);

For more information about diagram constraints, refer to the Diagram constraints.

NOTE

By default, the following constraints are enabled in the diagram,

* ApiUpdate

* PanX

* PanY

* Pan

* ZoomTextEdit

* Default

* None

* Tooltip

Node constraints

The Constraints property of the Node allows you to enable or disable the following behaviors.

• Select
• Drag
• Resize
• Rotate
• Delete
• InConnect
• OutConnect
• Tooltip

Constraints	Description
None	Disable all node Constraints
Select	Enables or disables the node to be selected.
Drag	Enables or disables the node to be dragged.
Rotate	Enables or disables the node to be rotated.
Shadow	Enables or disables the node to display shadow.
PointerEvents	Enables or disables the node to provide pointer option.
Delete	Enables or disables node to be deleted.
InConnect	Enables or disables node to provide in connect option.
OutConnect	Enables or disables node to provide out connect option.
AllowDrop	Enables node to provide allow to drop option.
ResizeNorthEast	Enable or disable to resize NorthEast side of the node.
ResizeEast	Enable or disable to resize East side of the node.
ResizeSouthEast	Enable or disable to resize SouthEast side of the node.
ResizeSouth	Enable or disable to resize South side of the node.
ResizeSouthWest	Enable or disable to resize SouthWest side of the node.
ResizeWest	Enable or disable to resize West side of the node.
ResizeNorthWest	Enable or disable to resize NorthWest side of the node.
ResizeNorth	Enable or disable to resize North side of the node.
AspectRatio	Enables the Aspect ratio of the node.
ReadOnly	Enables the ReadOnly support for annotation in the node.
HideThumbs	Enable to hide all resize thumbs for the node.
Tooltip	Enables or disables tooltip for the Nodes.
InheritTooltip	Enables or disables inherit tooltip option from the parent object.
Resize	Enables or Disables the expansion or compression of a node.
Inherit	Enables the node to inherit the interaction option from the parent object.
Default	Enables all default constraints for the node.

The following example shows how to disable rotate constraint from the default node constraints.

@using Syncfusion.Blazor.Diagram

@* Initialize the diagram with NodeCollection *@
<SfDiagramComponent Height="600px" Nodes="@nodes" />

@code
{
    DiagramObjectCollection<Node> nodes;

    protected override void OnInitialized()
    {
        nodes = new DiagramObjectCollection<Node>();
        Node node = new Node()
        {
            ID = "node1",
            Height = 100,
            Width = 100,
            OffsetX = 100,
            OffsetY = 100,
            Style = new ShapeStyle() { Fill = "#6495ED", StrokeColor = "White" },
            //Sets the NodeConstraints constraints.
            Constraints = NodeConstraints.Default & ~NodeConstraints.Rotate
        };
        nodes.Add(node);
    }
}

You can download a complete working sample from GitHub

The following example shows how to add Shadow constraint to the default constraints of node.

NodeConstraints NodeConstraints = NodeConstraints.Default | NodeConstraints.Shadow;

The node constraints are provided as flagged enumerations, so that multiple behaviors can be added or removed from the default constraints using the Bitwise Operations.

 //Removing multiple constraints from default.
NodeConstraints NodeConstraints = NodeConstraints.Default & ~ (NodeConstraints.Select | NodeConstraints.Drag);

The following code example shows how the tooltip can be enabled for the node.

//Enabled the tooltip constraints for the node.
node.Constraints = NodeConstraints.Default | NodeConstraints.Tooltip;

For more information about node constraints, refer to the NodeConstraints.

NOTE

By default, the following constraints are enabled for the node,

* Shadow

* PointerEvents

* AllowDrop

* ResizeNorthEast

* ResizeEast

* ResizeSouthEast

* ResizeSouth

* ResizeSouthWest

* ResizeWest

* ResizeNorthWest

* ResizeNorth

* AspectRatio

* ReadOnly

* HideThumbs

* Inherit

* Default

Connector constraints

The Constraints property of the Connector allows you to enable or disable the following behaviors of connectors.

• Select
• Drag
• DragSourceEnd
• DragTargetEnd
• Delete
• InheritBridging
• PointerEvents
• Tooltip

Constraints	Description
None	Disable all connector Constraints.
Select	Enables or disables connector to be selected.
Delete	Enables or disables connector to be deleted.
Drag	Enables or disables connector to be dragged.
DragSourceEnd	Enables connectors source end to be selected.
DragTargetEnd	Enables connectors target end to be selected.
DragSegmentThumb	Enables control point and end point of every segment in a connector for editing.
Interaction	Enables or disables Interaction for the connector.
AllowDrop	Enables allow drop support to the connector.
Bridging	Enables bridging to the connector.
InheritBridging	Enables to inherit bridging option from the parent object.
PointerEvents	Enables to set the pointer events.
ConnectToNearByNode	Enables to connect to the nearest node.
ConnectToNearByPort	Enables to connect to the nearest port.
Tooltip	Enables or disables tooltip for the connectors.
InheritTooltip	Enables or disables inherit tooltip option from the parent object
ConnectToNearByElement	Enables to connect to the nearest elements.
ReadOnly	Enables or disables readonly for the connector.
Default	Enables all constraints for the connector.

The following code shows how to disable select constraint from the default constraints of connector.

@using Syncfusion.Blazor.Diagram

@* Initialize the diagram with connectors *@
<SfDiagramComponent Height="600px" Connectors="@connectors" />

@code
{
    DiagramObjectCollection<Connector> connectors;

    protected override void OnInitialized()
    {
        connectors = new DiagramObjectCollection<Connector>();
        Connector connector = new Connector()
        {
            ID = "connector1",
            Type = ConnectorSegmentType.Straight,
            SourcePoint = new DiagramPoint() { X = 100, Y = 100 },
            TargetPoint = new DiagramPoint() { X = 200, Y = 200 },
            //Sets the ConnectorConstraints.
            Constraints = ConnectorConstraints.Default & ~ConnectorConstraints.Select
        };
        connectors.Add(connector);
    }
}

You can download a complete working sample from GitHub

The following example shows how to add Bridging constraint to the default constraints of a connector.

ConnectorConstraints ConnectorConstraints = ConnectorConstraints.Default | ConnectorConstraints.Bridging;

The connector constraints are provided as flagged enumerations, so that multiple behaviors can be added or removed from the default constraints using the Bitwise Operations.

//Removing multiple constraints from default.
ConnectorConstraints ConnectorConstraints = ConnectorConstraints.Default & ~ (ConnectorConstraints.Select | ConnectorConstraints.Drag);

The following code example shows how the tooltip can be enabled for the connector.

//Enabled the tooltip constraints for the connector.
connector.Constraints = ConnectorConstraints.Default | ConnectorConstraints.Tooltip;

For more information about connector constraints, refer to the ConnectorConstraints.

NOTE

By default, the following constraints are enabled for the connector,

* DragSegmentThumb

* Interaction

* AllowDrop

* Bridging

* InheritBridging

* ConnectToNearByNode

* ConnectToNearByPort

* ConnectToNearByElement

* ReadOnly

* Default

Port constraints

The Constraints property of the Port allows you to enable or disable the following behaviors of port.

• InConnect
• OutConnect

Constraints	Description
None	Disable all port Constraints.
Draw	Enables to create the connection when mouse hover on the port.
InConnect	Enables or disables to connect only the target end of connector.
OutConnect	Enables or disables to connect only the source end of connector.
Default	Enables all constraints for the port.

The following code shows how to disable creating connections with a port.

@using Syncfusion.Blazor.Diagram

@* Initialize the diagram with NodeCollection *@
<SfDiagramComponent Height="600px" Nodes="@nodes" />

@code
{
    DiagramObjectCollection<Node> nodes;

    protected override void OnInitialized()
    {
        // Initialize the NodeCollection.
        nodes = new DiagramObjectCollection<Node>();
        Node node = new Node()
        {
            ID = "node1",
            Height = 100,
            Width = 100,
            OffsetX = 100,
            OffsetY = 100,
        };
        node.Ports = new DiagramObjectCollection<PointPort>()
        {
            new PointPort()
            {
                ID="port1",
                Offset=new DiagramPoint(){X=0,Y=0.5},
                Shape=PortShapes.Circle,
                Visibility=PortVisibility.Visible,
                // Sets the PortConstraints.
                Constraints=PortConstraints.None
            }
        };
        nodes.Add(node);
    }
}

You can download a complete working sample from GitHub

The following code example shows how to modify the port constraints to accept target connection alone.

//Enable to create target connection alone.
port.Constraints = PortConstraints.InConnect;

The port constraints are provided as flagged enumerations, so that multiple behaviors can be added or removed from the default constraints using the Bitwise Operations.

//Enable to create target connection alone.
port.Constraints = PortConstraints.Default | PortConstraints.Draw;

For more information about port constraints, refer to the PortConstraints.

NOTE

By default, the following constraints are enabled for the port,

* Draw

* Default

Annotation constraints

The Constraints property of the Annotations allows you to enable or disable read-only mode for the annotations by using the annotation constraints.

Constraints	Description
ReadOnly	Enables or disables the ReadOnly Constraints,
InheritReadOnly	Enables or disables to inherit the ReadOnly option from the parent object.
None	Disables all constraints for the annotation.

The following code shows how to enable read-only mode for the annotations.

@using Syncfusion.Blazor.Diagram

@* Initialize the diagram with NodeCollection *@
<SfDiagramComponent Height="600px" Nodes="@nodes" />

@code
{
    DiagramObjectCollection<Node> nodes;

    protected override void OnInitialized()
    {
        //Initialize the NodeCollection.
        nodes = new DiagramObjectCollection<Node>();
        Node node = new Node()
        {
            ID = "node1",
            Height = 100,
            Width = 100,
            OffsetX = 100,
            OffsetY = 100,
        };
        node.Annotations = new DiagramObjectCollection<ShapeAnnotation>()
        {
            new ShapeAnnotation()
            {
                ID="annotation1",
                Content="Annotation Text Wrapping",
                // Sets the Constraints for Annotation.
                Constraints=AnnotationConstraints.ReadOnly,
                Style= new TextStyle()
                {
                    Color="#000000",
                    Fill="Transparent",
                    FontFamily="TimesNewRoman",
                    FontSize=12,
                    Bold=true,
                    Italic=true
                },
            }
        };
        nodes.Add(node);
    }
}

You can download a complete working sample from GitHub

For more details about annotation constraints, refer to the AnnotationConstraints.

Selector constraints

Selector visually represents the selected elements with certain editable thumbs. The visibility of the thumbs can be controlled with selector constraints. The part of selector is categorized as follows:

• ResizeAll
• UserHandle
• Rotate
• Tooltip

Constraints	Description
None	Hides all the selector elements.
ConnectorSourceThumb	Shows or hides the source thumb of the connector.
ConnectorTargetThumb	Shows or hides the target thumb of the connector.
ResizeSouthEast	Shows or hides the bottom right resize handle of the selector.
ResizeSouthWest	Shows or hides the bottom left resize handle of the selector.
ResizeNorthEast	Shows or hides the top right resize handle of the selector.
ResizeNorthWest	Shows or hides the top left resize handle of the selector.
ResizeEast	Shows or hides the middle right resize handle of the selector.
ResizeWest	Shows or hides the middle left resize handle of the selector.
ResizeSouth	Shows or hides the bottom center resize handle of the selector.
ResizeNorth	Shows or hides the top center resize handle of the selector.
Rotate	Shows or hides the rotate handle of the selector.
UserHandle	Shows or hides the user handles of the selector.
Tooltip	Shows or hides the tooltip for the drag, resize, and rotate operation of nodes and connectors.
ResizeAll	Shows or hides all resize handles of the selector.
All	Shows all handles of the selector.

The following code shows how to hide rotator.

@using Syncfusion.Blazor.Diagram

<SfDiagramComponent Height="600px" Nodes="@nodes" SelectionSettings="@selectionSettings"/>

@code
{
    DiagramObjectCollection<Node> nodes;
    public DiagramSelectionSettings selectionSettings = new DiagramSelectionSettings() 
    { 
        Constraints = SelectorConstraints.All & ~SelectorConstraints.Rotate 
    };

    protected override void OnInitialized()
    {
        //Initialize the NodeCollection.
        nodes = new DiagramObjectCollection<Node>();
        Node node = new Node()
        {
            ID = "node1",
            Height = 100,
            Width = 100,
            OffsetX = 100,
            OffsetY = 100,
        };
        nodes.Add(node);
    }
}

You can download a complete working sample from GitHub

The following code illustrates how to show or hide the tooltip for the drag, resize and rotate operation of the nodes.

@using Syncfusion.Blazor.Diagram
@using Syncfusion.Blazor.Popups
<p>Selector Constraints</p>
 <input type="checkbox" value="Tooltip" @onchange="@constraintschange"checked="@check5" />Tooltip
<SfDiagramComponent Width="1000px" Height="500px" Nodes="@nodes" />
@code
{
    DiagramObjectCollection<Node> nodes;
    bool selector=true;
    protected override void OnInitialized()
    {
        nodes = new DiagramObjectCollection<Node>();
        Node node = new Node()
        {
            ID = "node1",
            OffsetX = 250,
            OffsetY = 250,
            Width = 100,
            Height = 100,
            Style = new ShapeStyle() 
            { 
                Fill = "#6495ED", 
                StrokeColor = "white" 
            },
            Tooltip = new DiagramTooltip(){Content="NodeTooltip"},
            Constraints = NodeConstraints.Default|NodeConstraints.Tooltip,
        };
        nodes.Add(node);
    }
     private void constraintschange(object value)
    {
        var obj = value as ChangeEventArgs;

        if ((bool)obj.Value)
        {
             selection.Constraints |= SelectorConstraints.Tooltip;
              selector = true;
        }
        else
        {
              selection.Constraints &= ~SelectorConstraints.Tooltip;
              selector = false;
        }

    }
}

You can download a complete working sample from GitHub

NOTE

Element should be in a selected state, then only Rotator, UserHandle and Resizer thumbs will be visible.

The following code example shows how to disable the userhandle functionality for the selected item.

//Enable userhandle constraint for the selected item.
selectedItems.Constraints = SelectorConstraints.All &~ SelectorConstraints.UserHandle;

For more information about selector constraints, refer to the SelectorConstraints.

NOTE

By default, the following constraints are enabled for the selected items,

* ConnectorSourceThumb

* ConnectorTargetThumb

* ResizeSouthEast

* ResizeSouthWest

* ResizeEast

* ResizeWest

* ResizeSouth

* ResizeNorth

* All

* Tooltip

Snap constraints

The Constraints property of the SnapConstraints control the visibility of gridlines and enable or disable snapping. Snap constraints allow to set the following behaviors.

• Show only horizontal or vertical gridlines.
• Show both horizontal and vertical gridlines.
• Snap to either horizontal or vertical gridlines.
• Snap to both horizontal and vertical gridlines.

The following list of snapping constraints are used to enable or disable certain features of snapping.

Constraints	Description
None	Disable snapping the nodes/connectors in diagram.
ShowHorizontalLines	Displays only the horizontal gridlines in diagram.
ShowVerticalLines	Displays only the Vertical gridlines in diagram.
ShowLines	Display both Horizontal and Vertical gridlines.
SnapToHorizontalLines	Enables the object to snap only with horizontal gridlines.
SnapToVerticalLines	Enables the object to snap only with Vertical gridlines.
SnapToLines	Enables the object to snap with both horizontal and Vertical gridlines.
SnapToObject	Enables the object to snap with the other objects in the diagram.
All	Shows gridlines and enables snapping.

The following code shows how to show only horizontal gridlines.

@using Syncfusion.Blazor.Diagram

<SfDiagramComponent Height="600px" Nodes="@nodes">
    @* Initialize the snapsettings with constraints *@
    <SnapSettings Constraints="SnapConstraints.ShowHorizontalLines" />
</SfDiagramComponent>

@code
{
    DiagramObjectCollection<Node> nodes;

    protected override void OnInitialized()
    {
        //Initialize the NodeCollection.
        nodes = new DiagramObjectCollection<Node>();
        Node node = new Node()
        {
            ID = "node1",
            Height = 100,
            Width = 100,
            OffsetX = 100,
            OffsetY = 100,
        };
        nodes.Add(node);
    }
}

You can download a complete working sample from GitHub

The snap constraints are provided as flagged enumerations, so that multiple behaviors can be added or removed from the default constraints using the Bitwise Operations.

snapconstraints = SnapConstraints.ShowHorizontalLines | SnapConstraints.ShowVerticalLines | SnapConstraints.ShowLines;

For more information about snap constraints, refer to the SnapConstraints.

NOTE

By default, the following constraints are enabled for the snap functionality in the diagram,

* ShowLines

* ShowVerticalLines

* ShowHorizontalLines

* SnapToHorizontalLines

* SnapToObject

* All

Boundary constraints

Boundary constraints defines a boundary for the diagram inside that the interaction should be done. Boundary constraints allow to set the following behaviors.

• Infinity
• Diagram
• Page

The following list of constraints are used to enable or disable certain features of boundary interactions of the diagram.

Constraints	Description
Infinity	Allow the interactions to take place at the infinite height and width.
Diagram	Allow the interactions to take place around the diagram height and width.
Page	Allow the interactions to take place around the page height and width.

The following code shows how to limit the interaction done inside a diagram within a page.

@using Syncfusion.Blazor.Diagram

<SfDiagramComponent Height="600px" Nodes="@nodes">
    @* Initialize the pagesettings with boundary constraints *@
    <PageSettings Width="600" Height="500" BoundaryConstraints="BoundaryConstraints.Page"/>
</SfDiagramComponent>

@code
{
    DiagramObjectCollection<Node> nodes;

    protected override void OnInitialized()
    {
        //Initialize the NodeCollection.
        nodes = new DiagramObjectCollection<Node>();
        Node node = new Node()
        {
            ID = "node1",
            Height = 100,
            Width = 100,
            OffsetX = 100,
            OffsetY = 100,
        };
        nodes.Add(node);
    }
}

You can download a complete working sample from GitHub

For more information about selector constraints, refer to the BoundaryConstraints.

NOTE

By default, the following boundary constraints are enabled for the snap functionality in the diagram,

* Diagram

Inherit behaviors

Some of the behaviors can be defined through both the specific object (node or connector) and diagram. When the behaviors are contradictorily defined through both, the actual behavior is set through inherit options.

The following code example shows how to inherit the line bridging behavior from the diagram.

@using Syncfusion.Blazor.Diagram

@* Initialize the diagram with constraints *@
<SfDiagramComponent Height="600px"
                    Connectors="@connectors"
                    Constraints="@diagramConstraints">
</SfDiagramComponent>

@code
{
    //Sets the diagram constraints.
    DiagramConstraints diagramConstraints = DiagramConstraints.Default | DiagramConstraints.Bridging;
    DiagramObjectCollection<Connector> connectors;

    protected override void OnInitialized()
    {
        connectors = new DiagramObjectCollection<Connector>();
        Connector connector = new Connector()
        {
            ID = "connector1",
            SourcePoint = new DiagramPoint() { X = 100, Y = 100 },
            TargetPoint = new DiagramPoint() { X = 200, Y = 200 },
            //Sets the ConnectorConstraints.
            Constraints = ConnectorConstraints.Default | ConnectorConstraints.InheritBridging
        };
        Connector connector1 = new Connector()
        {
            ID = "connector2",
            SourcePoint = new DiagramPoint() { X = 200, Y = 100 },
            TargetPoint = new DiagramPoint() { X = 100, Y = 200 },
        };
        connectors.Add(connector);
        connectors.Add(connector1);
    }
}

You can download a complete working sample from GitHub

Bitwise operations

Bitwise operations are used to manipulate the flagged enumerations enum. In this section, Bitwise operations are shown by using the node constraints. The same is applicable when working with node constraints, connector constraints, or port constraints.

Add operation

You can add or enable multiple values at a time by using the Bitwise | (OR) operator.

The following code shows how to add bridging constraints into the default diagram constraints to enable bridging functionality in the diagram.

@using Syncfusion.Blazor.Diagram

<SfDiagramComponent Height="600px" Constraints="@diagramConstraint"/>

@code
{
    //To add line routing constraint with default contraints.
    DiagramConstraints diagramConstraint = DiagramConstraints.Default | DiagramConstraints.Bridging;
}

Remove operation

You can remove or disable values by using the Bitwise ‘&~’ (XOR) operator.

The following code shows to remove zoom and pan constraints from the default constraints to disable zoom and panning functionality in the diagram.

@using Syncfusion.Blazor.Diagram

<SfDiagramComponent Height="600px" Constraints="@diagramConstraint"/>

@code
{
    //To remove zoom and panning constraints from the default constraints.
    //It has disabled zoom and panning functionality for the diagram.
    DiagramConstraints diagramConstraint = DiagramConstraints.Default &~ (DiagramConstraints.Zoom | DiagramConstraints.Pan);
}

Check operation

You can check any value by using the Bitwise ‘&’ (AND) operator.

if ((node.constraints & (NodeConstraints.Rotate)) == (NodeConstraints.Rotate));

In the previous example, check whether the rotate constraints are enabled in a node. When node constraints have rotated constraints, the expression returns a rotate constraint.