Como: Selecionar Tinta de um Controle Personalizado

Ao adicionar um IncrementalLassoHitTester ao seu controle personalizado, você pode habilitar seu controle para que um usuário possa selecionar tinta com uma ferramenta de laço, semelhante à maneira como o InkCanvas seleciona tinta com um laço.

Este exemplo pressupõe que você esteja familiarizado com a criação de um controle personalizado com suporte a tinta. Para criar um controle personalizado que aceita entrada de tinta, consulte Criando um controle de entrada de tinta.

Exemplo

Quando o usuário desenha um laço, o IncrementalLassoHitTester prevê quais traços estarão dentro dos limites do caminho do laço depois que o usuário concluir o laço. Traços que são determinados como estando dentro dos limites do caminho do laço podem ser considerados selecionados. Traços selecionados também podem se tornar não selecionados. Por exemplo, se o usuário inverter a direção ao desenhar o laço, o IncrementalLassoHitTester poderá desmarcar alguns traços.

O IncrementalLassoHitTester gera o evento SelectionChanged, que permite que seu controle personalizado responda enquanto o usuário está desenhando o laço. Por exemplo, você pode alterar a aparência dos traços enquanto o usuário os seleciona e os deseleciona.

Gerenciando o modo de tinta

Será útil para o usuário se o laço aparecer de forma diferente da tinta em seu controle. Para fazer isso, seu controle personalizado deve acompanhar se o usuário está gravando ou selecionando tinta. A maneira mais fácil de fazer isso é declarar uma enumeração com dois valores: um para indicar que o usuário está escrevendo tinta e outro para indicar que o usuário está selecionando tinta.

// Enum that keeps track of whether StrokeCollectionDemo is in ink mode
// or select mode.
public enum InkMode
{
    Ink, Select
}

' Enum that keeps track of whether StrokeCollectionDemo is in ink mode 
' or select mode.
Public Enum InkMode
    Ink
    [Select]
End Enum 'InkMode

Em seguida, adicione duas DrawingAttributes à classe: uma para usar quando o usuário gravar tinta, uma a ser usada quando o usuário selecionar tinta. No construtor, inicialize o DrawingAttributes e anexe os dois eventos AttributeChanged ao mesmo manipulador de eventos. Em seguida, defina a propriedade DrawingAttributes do DynamicRenderer para a tinta DrawingAttributes.

DrawingAttributes inkDA;
DrawingAttributes selectDA;

Private inkDA As DrawingAttributes
Private selectDA As DrawingAttributes

// In the constructor.
// Selection drawing attributes use dark gray ink.
selectDA = new DrawingAttributes();
selectDA.Color = Colors.DarkGray;

// ink drawing attributes use default attributes
inkDA = new DrawingAttributes();
inkDA.Width = 5;
inkDA.Height = 5;

inkDA.AttributeChanged += new PropertyDataChangedEventHandler(DrawingAttributesChanged);
selectDA.AttributeChanged += new PropertyDataChangedEventHandler(DrawingAttributesChanged);

' In the constructor.
' Selection drawing attributes use dark gray ink.
selectDA = New DrawingAttributes()
selectDA.Color = Colors.DarkGray

' ink drawing attributes use default attributes
inkDA = New DrawingAttributes()
inkDA.Width = 5
inkDA.Height = 5

AddHandler inkDA.AttributeChanged, _
           AddressOf DrawingAttributesChanged

AddHandler selectDA.AttributeChanged, _
           AddressOf DrawingAttributesChanged

Adicione uma propriedade que expõe o modo de seleção. Quando o usuário alterar o modo de seleção, defina a propriedade DrawingAttributes do DynamicRenderer para o objeto DrawingAttributes apropriado e, em seguida, reanexe a Propriedade RootVisual ao InkPresenter.

// Property to indicate whether the user is inputting or
// selecting ink.
public InkMode Mode
{
    get
    {
        return mode;
    }

    set
    {
        mode = value;

        // Set the DrawingAttributes of the DynamicRenderer
        if (mode == InkMode.Ink)
        {
            renderer.DrawingAttributes = inkDA;
        }
        else
        {
            renderer.DrawingAttributes = selectDA;
        }

        // Reattach the visual of the DynamicRenderer to the InkPresenter.
        presenter.DetachVisuals(renderer.RootVisual);
        presenter.AttachVisuals(renderer.RootVisual, renderer.DrawingAttributes);
    }
}

' Property to indicate whether the user is inputting or
' selecting ink.  
Public Property Mode() As InkMode
    Get
        Return Mode
    End Get

    Set(ByVal value As InkMode)
        modeState = value

        ' Set the DrawingAttributes of the DynamicRenderer
        If modeState = InkMode.Ink Then
            renderer.DrawingAttributes = inkDA
        Else
            renderer.DrawingAttributes = selectDA
        End If

        ' Reattach the visual of the DynamicRenderer to the InkPresenter.
        presenter.DetachVisuals(renderer.RootVisual)
        presenter.AttachVisuals(renderer.RootVisual, renderer.DrawingAttributes)
    End Set
End Property

Exponha o DrawingAttributes como propriedades para que os aplicativos possam determinar a aparência dos traços de tinta e traços de seleção.

// Property to allow the user to change the pen's DrawingAttributes.
public DrawingAttributes InkDrawingAttributes
{
    get
    {
        return inkDA;
    }
}

// Property to allow the user to change the Selector'newStroke DrawingAttributes.
public DrawingAttributes SelectDrawingAttributes
{
    get
    {
        return selectDA;
    }
}

' Property to allow the user to change the pen's DrawingAttributes.
Public ReadOnly Property InkDrawingAttributes() As DrawingAttributes
    Get
        Return inkDA
    End Get
End Property

' Property to allow the user to change the Selector'newStroke DrawingAttributes.
Public ReadOnly Property SelectDrawingAttributes() As DrawingAttributes
    Get
        Return selectDA
    End Get
End Property

Quando uma propriedade de um objeto DrawingAttributes é alterada, o RootVisual deve ser anexado novamente ao InkPresenter. No manipulador de eventos do evento AttributeChanged, reanexe o RootVisual ao InkPresenter.

void DrawingAttributesChanged(object sender, PropertyDataChangedEventArgs e)
{
    // Reattach the visual of the DynamicRenderer to the InkPresenter
    // whenever the DrawingAttributes change.
    presenter.DetachVisuals(renderer.RootVisual);
    presenter.AttachVisuals(renderer.RootVisual, renderer.DrawingAttributes);
}

Private Sub DrawingAttributesChanged(ByVal sender As Object, _
                             ByVal e As PropertyDataChangedEventArgs)

    ' Reattach the visual of the DynamicRenderer to the InkPresenter 
    ' whenever the DrawingAttributes change.
    presenter.DetachVisuals(renderer.RootVisual)
    presenter.AttachVisuals(renderer.RootVisual, _
                            renderer.DrawingAttributes)

End Sub

Usando o IncrementalLassoHitTester

Crie e inicialize um StrokeCollection que contenha os traços selecionados.

// StylusPointCollection that collects the stylus points from the stylus events.
StylusPointCollection stylusPoints;

' StylusPointCollection that collects the stylus points from the stylus events.
Private stylusPoints As StylusPointCollection

Quando o usuário começa a desenhar um traço, tinta ou laço, desmarque os traços selecionados. Em seguida, se o usuário estiver desenhando um laço, crie um IncrementalLassoHitTester chamando GetIncrementalLassoHitTester, assine o evento SelectionChanged e chame AddPoints. Esse código pode ser um método separado e chamado a partir dos métodos OnStylusDown e OnMouseDown.

private void InitializeHitTester(StylusPointCollection collectedPoints)
{
    // Deselect any selected strokes.
    foreach (Stroke selectedStroke in selectedStrokes)
    {
        selectedStroke.DrawingAttributes.Color = inkDA.Color;
    }
    selectedStrokes.Clear();

    if (mode == InkMode.Select)
    {
        // Remove the previously drawn lasso, if it exists.
        if (lassoPath != null)
        {
            presenter.Strokes.Remove(lassoPath);
            lassoPath = null;
        }

        selectionTester =
            presenter.Strokes.GetIncrementalLassoHitTester(80);
        selectionTester.SelectionChanged +=
            new LassoSelectionChangedEventHandler(selectionTester_SelectionChanged);
        selectionTester.AddPoints(collectedPoints);
    }
}

Private Sub InitializeHitTester(ByVal collectedPoints As StylusPointCollection)

    ' Deselect any selected strokes.
    Dim selectedStroke As Stroke
    For Each selectedStroke In selectedStrokes
        selectedStroke.DrawingAttributes.Color = inkDA.Color
    Next selectedStroke
    selectedStrokes.Clear()

    If modeState = InkMode.Select Then
        ' Remove the previously drawn lasso, if it exists.
        If Not (lassoPath Is Nothing) Then
            presenter.Strokes.Remove(lassoPath)
            lassoPath = Nothing
        End If

        selectionTester = presenter.Strokes.GetIncrementalLassoHitTester(80)
        AddHandler selectionTester.SelectionChanged, AddressOf selectionTester_SelectionChanged
        selectionTester.AddPoints(collectedPoints)
    End If

End Sub

Adicione os pontos de caneta à IncrementalLassoHitTester enquanto o usuário desenha o laço. Chame o seguinte método a partir dos métodos OnStylusMove, OnStylusUp, OnMouseMovee OnMouseLeftButtonUp.

private void AddPointsToHitTester(StylusPointCollection collectedPoints)
{

    if (mode == InkMode.Select &&
        selectionTester != null &&
        selectionTester.IsValid)
    {
        // When the control is selecting strokes, add the
        // stylus packetList to selectionTester.
        selectionTester.AddPoints(collectedPoints);
    }
}

Private Sub AddPointsToHitTester(ByVal collectedPoints As StylusPointCollection)

    If modeState = InkMode.Select AndAlso _
       Not selectionTester Is Nothing AndAlso _
       selectionTester.IsValid Then

        ' When the control is selecting strokes, add the
        ' stylus packetList to selectionTester.
        selectionTester.AddPoints(collectedPoints)
    End If

End Sub

Manipule o evento IncrementalLassoHitTester.SelectionChanged para responder quando o usuário seleciona e deseleciona traços. A classe LassoSelectionChangedEventArgs tem as propriedades SelectedStrokes e DeselectedStrokes que obtêm os traços selecionados e não selecionados, respectivamente.

void selectionTester_SelectionChanged(object sender,
    LassoSelectionChangedEventArgs args)
{
    // Change the color of all selected strokes to red.
    foreach (Stroke selectedStroke in args.SelectedStrokes)
    {
        selectedStroke.DrawingAttributes.Color = Colors.Red;
        selectedStrokes.Add(selectedStroke);
    }

    // Change the color of all unselected strokes to
    // their original color.
    foreach (Stroke unselectedStroke in args.DeselectedStrokes)
    {
        unselectedStroke.DrawingAttributes.Color = inkDA.Color;
        selectedStrokes.Remove(unselectedStroke);
    }
}

Private Sub selectionTester_SelectionChanged(ByVal sender As Object, _
                                     ByVal args As LassoSelectionChangedEventArgs)

    ' Change the color of all selected strokes to red.
    Dim selectedStroke As Stroke
    For Each selectedStroke In args.SelectedStrokes
        selectedStroke.DrawingAttributes.Color = Colors.Red
        selectedStrokes.Add(selectedStroke)
    Next selectedStroke

    ' Change the color of all unselected strokes to 
    ' their original color.
    Dim unselectedStroke As Stroke
    For Each unselectedStroke In args.DeselectedStrokes
        unselectedStroke.DrawingAttributes.Color = inkDA.Color
        selectedStrokes.Remove(unselectedStroke)
    Next unselectedStroke

End Sub

Quando o usuário terminar de desenhar o laço, cancele a assinatura do evento SelectionChanged e chame EndHitTesting.

if (mode == InkMode.Select && lassoPath == null)
{
    // Add the lasso to the InkPresenter and add the packetList
    // to selectionTester.
    lassoPath = newStroke;
    lassoPath.DrawingAttributes = selectDA.Clone();
    presenter.Strokes.Add(lassoPath);
    selectionTester.SelectionChanged -= new LassoSelectionChangedEventHandler
                    (selectionTester_SelectionChanged);
    selectionTester.EndHitTesting();
}

If modeState = InkMode.Select AndAlso lassoPath Is Nothing Then
    ' Add the lasso to the InkPresenter and add the packetList
    ' to selectionTester.
    lassoPath = newStroke
    lassoPath.DrawingAttributes = selectDA.Clone()
    presenter.Strokes.Add(lassoPath)
    RemoveHandler selectionTester.SelectionChanged, _
                  AddressOf selectionTester_SelectionChanged
    selectionTester.EndHitTesting()
End If

Juntando Tudo

O exemplo a seguir é um controle personalizado que permite que um usuário selecione tinta com um laço.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Input;
using System.Windows.Input.StylusPlugIns;
using System.Windows.Ink;

// Enum that keeps track of whether StrokeCollectionDemo is in ink mode
// or select mode.
public enum InkMode
{
    Ink, Select
}

// This control allows the user to input and select ink.  When the
// user selects ink, the lasso remains visible until they erase, or clip
// the selected strokes, or clear the selection.  When the control is
// in selection mode, strokes that are selected turn red.
public class InkSelector : Label
{
    InkMode mode;

    DrawingAttributes inkDA;
    DrawingAttributes selectDA;

    InkPresenter presenter;
    IncrementalLassoHitTester selectionTester;
    StrokeCollection selectedStrokes = new StrokeCollection();

    // StylusPointCollection that collects the stylus points from the stylus events.
    StylusPointCollection stylusPoints;
    // Stroke that represents the lasso.
    Stroke lassoPath;

    DynamicRenderer renderer;

    public InkSelector()
    {
        mode = InkMode.Ink;

        // Use an InkPresenter to display the strokes on the custom control.
        presenter = new InkPresenter();
        this.Content = presenter;

        // In the constructor.
        // Selection drawing attributes use dark gray ink.
        selectDA = new DrawingAttributes();
        selectDA.Color = Colors.DarkGray;

        // ink drawing attributes use default attributes
        inkDA = new DrawingAttributes();
        inkDA.Width = 5;
        inkDA.Height = 5;

        inkDA.AttributeChanged += new PropertyDataChangedEventHandler(DrawingAttributesChanged);
        selectDA.AttributeChanged += new PropertyDataChangedEventHandler(DrawingAttributesChanged);

        // Add a DynmaicRenderer to the control so ink appears
        // to "flow" from the tablet pen.
        renderer = new DynamicRenderer();
        renderer.DrawingAttributes = inkDA;
        this.StylusPlugIns.Add(renderer);
        presenter.AttachVisuals(renderer.RootVisual,
            renderer.DrawingAttributes);
    }

    static InkSelector()
    {
        // Allow ink to be drawn only within the bounds of the control.
        Type owner = typeof(InkSelector);
        ClipToBoundsProperty.OverrideMetadata(owner,
            new FrameworkPropertyMetadata(true));
    }

    // Prepare to collect stylus packets. If Mode is set to Select,
    // get the IncrementalHitTester from the InkPresenter'newStroke
    // StrokeCollection and subscribe to its StrokeHitChanged event.
    protected override void OnStylusDown(StylusDownEventArgs e)
    {
        base.OnStylusDown(e);

        Stylus.Capture(this);

        // Create a new StylusPointCollection using the StylusPointDescription
        // from the stylus points in the StylusDownEventArgs.
        stylusPoints = new StylusPointCollection();
        StylusPointCollection eventPoints = e.GetStylusPoints(this, stylusPoints.Description);

        stylusPoints.Add(eventPoints);

        InitializeHitTester(eventPoints);
    }

    protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
    {
        base.OnMouseLeftButtonDown(e);

        Mouse.Capture(this);

        if (e.StylusDevice != null)
        {
            return;
        }

        Point pt = e.GetPosition(this);

        StylusPointCollection collectedPoints = new StylusPointCollection(new Point[] { pt });

        stylusPoints = new StylusPointCollection();

        stylusPoints.Add(collectedPoints);

        InitializeHitTester(collectedPoints);
    }
    private void InitializeHitTester(StylusPointCollection collectedPoints)
    {
        // Deselect any selected strokes.
        foreach (Stroke selectedStroke in selectedStrokes)
        {
            selectedStroke.DrawingAttributes.Color = inkDA.Color;
        }
        selectedStrokes.Clear();

        if (mode == InkMode.Select)
        {
            // Remove the previously drawn lasso, if it exists.
            if (lassoPath != null)
            {
                presenter.Strokes.Remove(lassoPath);
                lassoPath = null;
            }

            selectionTester =
                presenter.Strokes.GetIncrementalLassoHitTester(80);
            selectionTester.SelectionChanged +=
                new LassoSelectionChangedEventHandler(selectionTester_SelectionChanged);
            selectionTester.AddPoints(collectedPoints);
        }
    }

    // Collect the stylus packets as the stylus moves.
    protected override void OnStylusMove(StylusEventArgs e)
    {
        if (stylusPoints == null)
        {
            return;
        }

        StylusPointCollection collectedPoints = e.GetStylusPoints(this, stylusPoints.Description);
        stylusPoints.Add(collectedPoints);
        AddPointsToHitTester(collectedPoints);
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {

        base.OnMouseMove(e);

        if (e.StylusDevice != null)
        {
            return;
        }

        if (e.LeftButton == MouseButtonState.Released)
        {
            return;
        }

        stylusPoints ??= new StylusPointCollection();

        Point pt = e.GetPosition(this);

        StylusPointCollection collectedPoints = new StylusPointCollection(new Point[] { pt });

        stylusPoints.Add(collectedPoints);

        AddPointsToHitTester(collectedPoints);
    }

    private void AddPointsToHitTester(StylusPointCollection collectedPoints)
    {

        if (mode == InkMode.Select &&
            selectionTester != null &&
            selectionTester.IsValid)
        {
            // When the control is selecting strokes, add the
            // stylus packetList to selectionTester.
            selectionTester.AddPoints(collectedPoints);
        }
    }

    // When the user lifts the stylus, create a Stroke from the
    // collected stylus points and add it to the InkPresenter.
    // When the control is selecting strokes, add the
    // point data to the IncrementalHitTester.
    protected override void OnStylusUp(StylusEventArgs e)
    {
        stylusPoints ??= new StylusPointCollection();
        StylusPointCollection collectedPoints =
            e.GetStylusPoints(this, stylusPoints.Description);

        stylusPoints.Add(collectedPoints);
        AddPointsToHitTester(collectedPoints);
        AddStrokeToPresenter();
        stylusPoints = null;

        Stylus.Capture(null);
    }

    protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
    {

        base.OnMouseLeftButtonUp(e);

        if (e.StylusDevice != null) return;

        if (stylusPoints == null) stylusPoints = new StylusPointCollection();

        Point pt = e.GetPosition(this);

        StylusPointCollection collectedPoints = new StylusPointCollection(new Point[] { pt });

        stylusPoints.Add(collectedPoints);
        AddPointsToHitTester(collectedPoints);
        AddStrokeToPresenter();

        stylusPoints = null;

        Mouse.Capture(null);
    }

    private void AddStrokeToPresenter()
    {
        Stroke newStroke = new Stroke(stylusPoints);

        if (mode == InkMode.Ink)
        {
            // Add the stroke to the InkPresenter.
            newStroke.DrawingAttributes = inkDA.Clone();
            presenter.Strokes.Add(newStroke);
        }

        if (mode == InkMode.Select && lassoPath == null)
        {
            // Add the lasso to the InkPresenter and add the packetList
            // to selectionTester.
            lassoPath = newStroke;
            lassoPath.DrawingAttributes = selectDA.Clone();
            presenter.Strokes.Add(lassoPath);
            selectionTester.SelectionChanged -= new LassoSelectionChangedEventHandler
                            (selectionTester_SelectionChanged);
            selectionTester.EndHitTesting();
        }
    }

    void selectionTester_SelectionChanged(object sender,
        LassoSelectionChangedEventArgs args)
    {
        // Change the color of all selected strokes to red.
        foreach (Stroke selectedStroke in args.SelectedStrokes)
        {
            selectedStroke.DrawingAttributes.Color = Colors.Red;
            selectedStrokes.Add(selectedStroke);
        }

        // Change the color of all unselected strokes to
        // their original color.
        foreach (Stroke unselectedStroke in args.DeselectedStrokes)
        {
            unselectedStroke.DrawingAttributes.Color = inkDA.Color;
            selectedStrokes.Remove(unselectedStroke);
        }
    }

    // Property to indicate whether the user is inputting or
    // selecting ink.
    public InkMode Mode
    {
        get
        {
            return mode;
        }

        set
        {
            mode = value;

            // Set the DrawingAttributes of the DynamicRenderer
            if (mode == InkMode.Ink)
            {
                renderer.DrawingAttributes = inkDA;
            }
            else
            {
                renderer.DrawingAttributes = selectDA;
            }

            // Reattach the visual of the DynamicRenderer to the InkPresenter.
            presenter.DetachVisuals(renderer.RootVisual);
            presenter.AttachVisuals(renderer.RootVisual, renderer.DrawingAttributes);
        }
    }
    void DrawingAttributesChanged(object sender, PropertyDataChangedEventArgs e)
    {
        // Reattach the visual of the DynamicRenderer to the InkPresenter
        // whenever the DrawingAttributes change.
        presenter.DetachVisuals(renderer.RootVisual);
        presenter.AttachVisuals(renderer.RootVisual, renderer.DrawingAttributes);
    }

    // Property to allow the user to change the pen's DrawingAttributes.
    public DrawingAttributes InkDrawingAttributes
    {
        get
        {
            return inkDA;
        }
    }

    // Property to allow the user to change the Selector'newStroke DrawingAttributes.
    public DrawingAttributes SelectDrawingAttributes
    {
        get
        {
            return selectDA;
        }
    }
}

Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media
Imports System.Windows.Input
Imports System.Windows.Input.StylusPlugIns
Imports System.Windows.Ink


' Enum that keeps track of whether StrokeCollectionDemo is in ink mode 
' or select mode.
Public Enum InkMode
    Ink
    [Select]
End Enum 'InkMode

' This control allows the user to input and select ink.  When the
' user selects ink, the lasso remains visible until they erase, or clip
' the selected strokes, or clear the selection.  When the control is
' in selection mode, strokes that are selected turn red.
Public Class InkSelector
    Inherits Label

    Private modeState As InkMode

    Private inkDA As DrawingAttributes
    Private selectDA As DrawingAttributes

    Private presenter As InkPresenter
    Private selectionTester As IncrementalLassoHitTester
    Private selectedStrokes As New StrokeCollection()

    ' StylusPointCollection that collects the stylus points from the stylus events.
    Private stylusPoints As StylusPointCollection

    ' Stroke that represents the lasso.
    Private lassoPath As Stroke

    Private renderer As DynamicRenderer


    Public Sub New()
        modeState = InkMode.Ink

        ' Use an InkPresenter to display the strokes on the custom control.
        presenter = New InkPresenter()
        Me.Content = presenter

        ' In the constructor.
        ' Selection drawing attributes use dark gray ink.
        selectDA = New DrawingAttributes()
        selectDA.Color = Colors.DarkGray

        ' ink drawing attributes use default attributes
        inkDA = New DrawingAttributes()
        inkDA.Width = 5
        inkDA.Height = 5

        AddHandler inkDA.AttributeChanged, _
                   AddressOf DrawingAttributesChanged

        AddHandler selectDA.AttributeChanged, _
                   AddressOf DrawingAttributesChanged

        ' Add a DynmaicRenderer to the control so ink appears
        ' to "flow" from the tablet pen.
        renderer = New DynamicRenderer()
        renderer.DrawingAttributes = inkDA
        Me.StylusPlugIns.Add(renderer)
        presenter.AttachVisuals(renderer.RootVisual, _
            renderer.DrawingAttributes)

    End Sub


    Shared Sub New()
        ' Allow ink to be drawn only within the bounds of the control.
        Dim owner As Type = GetType(InkSelector)
        ClipToBoundsProperty.OverrideMetadata(owner, _
            New FrameworkPropertyMetadata(True))

    End Sub

    ' Prepare to collect stylus packets. If Mode is set to Select,  
    ' get the IncrementalHitTester from the InkPresenter'newStroke 
    ' StrokeCollection and subscribe to its StrokeHitChanged event.
    Protected Overrides Sub OnStylusDown(ByVal e As StylusDownEventArgs)
        MyBase.OnStylusDown(e)

        Stylus.Capture(Me)

        ' Create a new StylusPointCollection using the StylusPointDescription
        ' from the stylus points in the StylusDownEventArgs.
        stylusPoints = New StylusPointCollection()
        Dim eventPoints As StylusPointCollection = e.GetStylusPoints(Me, stylusPoints.Description)

        stylusPoints.Add(eventPoints)

        InitializeHitTester(eventPoints)

    End Sub


    Protected Overrides Sub OnMouseLeftButtonDown(ByVal e As MouseButtonEventArgs)
        MyBase.OnMouseLeftButtonDown(e)

        Mouse.Capture(Me)

        If Not (e.StylusDevice Is Nothing) Then
            Return
        End If

        Dim pt As Point = e.GetPosition(Me)

        Dim collectedPoints As New StylusPointCollection(New Point() {pt})

        stylusPoints = New StylusPointCollection()

        stylusPoints.Add(collectedPoints)

        InitializeHitTester(collectedPoints)

    End Sub


    Private Sub InitializeHitTester(ByVal collectedPoints As StylusPointCollection)

        ' Deselect any selected strokes.
        Dim selectedStroke As Stroke
        For Each selectedStroke In selectedStrokes
            selectedStroke.DrawingAttributes.Color = inkDA.Color
        Next selectedStroke
        selectedStrokes.Clear()

        If modeState = InkMode.Select Then
            ' Remove the previously drawn lasso, if it exists.
            If Not (lassoPath Is Nothing) Then
                presenter.Strokes.Remove(lassoPath)
                lassoPath = Nothing
            End If

            selectionTester = presenter.Strokes.GetIncrementalLassoHitTester(80)
            AddHandler selectionTester.SelectionChanged, AddressOf selectionTester_SelectionChanged
            selectionTester.AddPoints(collectedPoints)
        End If

    End Sub

    ' Collect the stylus packets as the stylus moves.
    Protected Overrides Sub OnStylusMove(ByVal e As StylusEventArgs)

        If stylusPoints Is Nothing Then
            Return
        End If

        Dim collectedPoints As StylusPointCollection = e.GetStylusPoints(Me, stylusPoints.Description)
        stylusPoints.Add(collectedPoints)
        AddPointsToHitTester(collectedPoints)

    End Sub


    Protected Overrides Sub OnMouseMove(ByVal e As MouseEventArgs)

        MyBase.OnMouseMove(e)

        If Not (e.StylusDevice Is Nothing) Then
            Return
        End If

        If e.LeftButton = MouseButtonState.Released Then
            Return
        End If

        If stylusPoints Is Nothing Then
            stylusPoints = New StylusPointCollection()
        End If

        Dim pt As Point = e.GetPosition(Me)

        Dim collectedPoints As New StylusPointCollection(New Point() {pt})

        stylusPoints.Add(collectedPoints)

        AddPointsToHitTester(collectedPoints)

    End Sub


    Private Sub AddPointsToHitTester(ByVal collectedPoints As StylusPointCollection)

        If modeState = InkMode.Select AndAlso _
           Not selectionTester Is Nothing AndAlso _
           selectionTester.IsValid Then

            ' When the control is selecting strokes, add the
            ' stylus packetList to selectionTester.
            selectionTester.AddPoints(collectedPoints)
        End If

    End Sub

    ' When the user lifts the stylus, create a Stroke from the
    ' collected stylus points and add it to the InkPresenter.
    ' When the control is selecting strokes, add the
    ' point data to the IncrementalHitTester.
    Protected Overrides Sub OnStylusUp(ByVal e As StylusEventArgs)

        If stylusPoints Is Nothing Then
            stylusPoints = New StylusPointCollection()
        End If

        Dim collectedPoints As StylusPointCollection = _
            e.GetStylusPoints(Me, stylusPoints.Description)

        stylusPoints.Add(collectedPoints)
        AddPointsToHitTester(collectedPoints)
        AddStrokeToPresenter()

        stylusPoints = Nothing

        Stylus.Capture(Nothing)

    End Sub


    Protected Overrides Sub OnMouseLeftButtonUp(ByVal e As MouseButtonEventArgs)

        MyBase.OnMouseLeftButtonUp(e)

        If Not (e.StylusDevice Is Nothing) Then
            Return
        End If
        If stylusPoints Is Nothing Then
            stylusPoints = New StylusPointCollection()
        End If
        Dim pt As Point = e.GetPosition(Me)

        Dim collectedPoints As New StylusPointCollection(New Point() {pt})

        stylusPoints.Add(collectedPoints)
        AddPointsToHitTester(collectedPoints)
        AddStrokeToPresenter()

        stylusPoints = Nothing

        Mouse.Capture(Nothing)

    End Sub


    Private Sub AddStrokeToPresenter()
        Dim newStroke As New Stroke(stylusPoints)

        If modeState = InkMode.Ink Then
            ' Add the stroke to the InkPresenter.
            newStroke.DrawingAttributes = inkDA.Clone()
            presenter.Strokes.Add(newStroke)
        End If

        If modeState = InkMode.Select AndAlso lassoPath Is Nothing Then
            ' Add the lasso to the InkPresenter and add the packetList
            ' to selectionTester.
            lassoPath = newStroke
            lassoPath.DrawingAttributes = selectDA.Clone()
            presenter.Strokes.Add(lassoPath)
            RemoveHandler selectionTester.SelectionChanged, _
                          AddressOf selectionTester_SelectionChanged
            selectionTester.EndHitTesting()
        End If

    End Sub

    Private Sub selectionTester_SelectionChanged(ByVal sender As Object, _
                                         ByVal args As LassoSelectionChangedEventArgs)

        ' Change the color of all selected strokes to red.
        Dim selectedStroke As Stroke
        For Each selectedStroke In args.SelectedStrokes
            selectedStroke.DrawingAttributes.Color = Colors.Red
            selectedStrokes.Add(selectedStroke)
        Next selectedStroke

        ' Change the color of all unselected strokes to 
        ' their original color.
        Dim unselectedStroke As Stroke
        For Each unselectedStroke In args.DeselectedStrokes
            unselectedStroke.DrawingAttributes.Color = inkDA.Color
            selectedStrokes.Remove(unselectedStroke)
        Next unselectedStroke

    End Sub

    ' Property to indicate whether the user is inputting or
    ' selecting ink.  
    Public Property Mode() As InkMode
        Get
            Return Mode
        End Get

        Set(ByVal value As InkMode)
            modeState = value

            ' Set the DrawingAttributes of the DynamicRenderer
            If modeState = InkMode.Ink Then
                renderer.DrawingAttributes = inkDA
            Else
                renderer.DrawingAttributes = selectDA
            End If

            ' Reattach the visual of the DynamicRenderer to the InkPresenter.
            presenter.DetachVisuals(renderer.RootVisual)
            presenter.AttachVisuals(renderer.RootVisual, renderer.DrawingAttributes)
        End Set
    End Property
    Private Sub DrawingAttributesChanged(ByVal sender As Object, _
                                 ByVal e As PropertyDataChangedEventArgs)

        ' Reattach the visual of the DynamicRenderer to the InkPresenter 
        ' whenever the DrawingAttributes change.
        presenter.DetachVisuals(renderer.RootVisual)
        presenter.AttachVisuals(renderer.RootVisual, _
                                renderer.DrawingAttributes)

    End Sub

    ' Property to allow the user to change the pen's DrawingAttributes.
    Public ReadOnly Property InkDrawingAttributes() As DrawingAttributes
        Get
            Return inkDA
        End Get
    End Property

    ' Property to allow the user to change the Selector'newStroke DrawingAttributes.
    Public ReadOnly Property SelectDrawingAttributes() As DrawingAttributes
        Get
            Return selectDA
        End Get
    End Property

End Class

Consulte também

• IncrementalLassoHitTester
• StrokeCollection
• StylusPointCollection
• Criando um Controle de Entrada de Tinta