How to Start Resizing Diagram Shape Before Mouse Cursor Enters it

Environment

Product Version 2019.2 826
Product RadDiagram for WPF

Description

How to start resizing a shape (SizeAll cursor shown) before the mouse enters the RadDiagramShape. This behavior can be observed with the Microsoft PowerPoint shapes.

Solution

To introduce a small tolerance between the shape bounds and the mouse position where you can start the resizing operation, create a custom PointerTool and replace the default one in the ToolService.

public class CustomPointerTool : PointerTool 
{ 
    private GroupService groupService; 
    private RadDiagram graph; 
 
    public CustomPointerTool(RadDiagram graph) 
    { 
        this.graph = graph; 
        this.groupService = this.graph.ServiceLocator.GetService<IGroupService>() as GroupService; 
    } 
 
    public override bool MouseMove(PointerArgs e) 
    { 
        var baseResult = base.MouseMove(e); 
        var selectionMode = this.graph.SelectionMode; 
        if (this.HitItem == null && this.ToolService.IsMouseDown && selectionMode != SelectionMode.None) 
        { 
            foreach (var shape in this.graph.Shapes) 
            { 
                var inflatedBounds = shape.ActualBounds.InflateRect(30); 
                if (inflatedBounds.Contains(e.TransformedPoint)) 
                { 
                    if (!shape.IsSelected) 
                    { 
                        bool addToExistingSelection = selectionMode != SelectionMode.Single && (this.ToolService.IsControlDown || selectionMode == SelectionMode.Multiple); 
                        SelectWithGroups(addToExistingSelection, shape); 
                    } 
                    bool isDraggingEnabled = this.SelectionService.SelectedItems.Any(d => d.IsDraggingEnabled == false) ? false : true; 
                    if (isDraggingEnabled) 
                    { 
                        this.ToolService.ActivateTool(DraggingTool.ToolName); 
                        return false; 
                    } 
 
                    return true; 
                } 
            } 
        } 
        return baseResult; 
    } 
 
    private void SelectWithGroups(bool addToExistingSelection, IDiagramItem hitItem) 
    { 
        var itemsToSelect = this.groupService.GetItemSiblings(hitItem, addToExistingSelection).Union(new[] { hitItem }); 
        this.SelectionService.SelectItems(itemsToSelect, addToExistingSelection); 
    } 
} 

public MainWindow() 
{ 
    InitializeComponent(); 
 
    var toolService = this.radDiagram.ServiceLocator.GetService<IToolService>() as ToolService; 
    toolService.ToolList[0] = new CustomPointerTool(this.diagram);             
} 

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