Scrollviewer, canvas et apparition des scrollbar

Bonjour,

J'ai un canvas dans un scroll viewer :
Code:

1 2 3 4 5 6 <ScrollViewer Name="theScrollViewer" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Hidden" Grid.Row="1" CanContentScroll="True"> <DockPanel> <Canvas Name="theStack" ClipToBounds="True"/> </DockPanel> </ScrollViewer>
Je remplis le canvas via code, mais malheureusement la scrollbar du canvas n'apparait pas automatiquement comme pour les autres conteneurs.

Merci.

Ca doit être parce que ton Canvas n'a ni hauteur, ni largeur. Si tu crées un Canvas de 50x50 par exemple, tu peux dessiner en dehors, sans que ça ne pose problème, le Canvas ne sera pas agrandit pour autant (du coup là ça pose problème...).

Tu peux faire des tests en mettant une couleur de fond sur ton Canvas.

canvas avec scrollbar et zoom

bonjour
ca depend si tu as personnalise ta classe canvas en surchargeant la methode MeasureOverride qui doit faire une espece de mise à l'echelle.

ici code behind de la classe canvas perso :

Code:

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Imports System
Imports System.Windows
Imports System.Windows.Controls
Public Class CanvasScrollable
    Inherits Canvas
    Public Sub New()
        'This OverrideMetadata call tells the system that this element wants to provide a style that is different than its base class.
        'This style is defined in Themes\Generic.xaml
        DefaultStyleKeyProperty.OverrideMetadata(GetType(CanvasScrollable), New FrameworkPropertyMetadata(GetType(CanvasScrollable)))
    End Sub
    'Surcharge overrides  MeasureOverride
    Protected Overrides Function MeasureOverride(ByVal constraint As System.Windows.Size) As System.Windows.Size
        'Return MyBase.MeasureOverride(constraint)
        Dim bottomMost As Double = 0.0
        Dim rightMost As Double = 0.0
 
        'Boucle sur tous les elements enfanst et 
        'recherche plus grande valeur de  Top and Left parmi eux.   
        For Each obj As Object In Me.Children
            Dim x_child As FrameworkElement = TryCast(obj, FrameworkElement)
            If (x_child IsNot Nothing) Then
                x_child.Measure(constraint)
                bottomMost = Math.Max( _
                bottomMost, GetTop(x_child) + x_child.DesiredSize.Height)
                rightMost = Math.Max( _
                rightMost, GetLeft(x_child) + x_child.DesiredSize.Width)
            End If
        Next
        If (Double.IsNaN(bottomMost) Or Double.IsInfinity(bottomMost)) Then
            bottomMost = 0.0
        End If
        If (Double.IsNaN(rightMost) Or Double.IsInfinity(rightMost)) Then
            rightMost = 0.0
        End If
        'Renvoi nouvelle taille
        Return New Size(rightMost, bottomMost)
    End Function
 
End Class

ici code de la forme qui utilise ce canvas personnalise scrollable:

Code:

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<Window x:Class="Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:TestCanvas"
Title="WPF Scrollable Canvas" Height="Auto" Width="Auto" SizeToContent="Manual" >
 
    <DockPanel >
        <ScrollViewer   
                    VerticalScrollBarVisibility="Auto"
                    HorizontalScrollBarVisibility="Auto" >
            <local:CanvasScrollable
 
                    HorizontalAlignment="Stretch" 
                    VerticalAlignment="Stretch" 
                    Background="Beige" >
 
                <Rectangle
                            Canvas.Top="0"
                            Canvas.Left="0"
                            StrokeThickness="2"
                            Stroke="DarkRed"
                            Width="50"
                            Height="50"
                        />
                <Rectangle
                            Canvas.Top="150"
                            Canvas.Left="150"
                            StrokeThickness="2"
                            Stroke="Blue"
                            Width="150"
                            Height="150"
                        />
                <Rectangle
                            Canvas.Top="200"
                            Canvas.Left="200"
                            StrokeThickness="2"
                            Stroke="Green"
                            Width="200"
                            Height="200"
                        />
            </local:CanvasScrollable>
        </ScrollViewer>
    </DockPanel>
 
</Window>

ici code d'une 2eme forme qui utilise la -meme-classe canvas personnalise sans modif- et on a rajoute simplement un slider dans Window2 pour faire le zoom:

Code:

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<Window x:Class="Window2"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:TestCanvas"
    Title="WPF Scrollable et Zoomable Canvas" Height="Auto" Width="Auto" SizeToContent="Manual" >
    <DockPanel >
        <Slider
                DockPanel.Dock="Bottom"
                x:Name="zoomSlider"
                Minimum="0.1"
                Maximum="5"
                Value="1" Background="CadetBlue" />
 
        <ScrollViewer   
                    VerticalScrollBarVisibility="Auto"
                    HorizontalScrollBarVisibility="Auto" >
            <local:CanvasScrollable
 
                    HorizontalAlignment="Stretch" 
                    VerticalAlignment="Stretch" 
                    Background="Beige" >
                <Canvas.LayoutTransform>
                    <ScaleTransform
                        ScaleX="{Binding Path=Value, ElementName=zoomSlider}"
                        ScaleY="{Binding Path=Value, ElementName=zoomSlider}"
                        />
                </Canvas.LayoutTransform>
                <Rectangle
                            Canvas.Top="0"
                            Canvas.Left="0"
                            StrokeThickness="2"
                            Stroke="Red"
                            Fill="Blue"
                            Width="50"
                            Height="50"
                        />
                <Rectangle
                            Canvas.Top="150"
                            Canvas.Left="150"
                            StrokeThickness="2"
                            Stroke="Blue"
                            Fill="LimeGreen"
                            Width="150"
                            Height="150"
                        />
                <Rectangle
                            Canvas.Top="200"
                            Canvas.Left="200"
                            StrokeThickness="2"
                            Stroke="Green"
                            Width="200"
                            Height="200"
                        />
            </local:CanvasScrollable>
        </ScrollViewer>
    </DockPanel>
 
</Window>

bon code.....................

Ok merci beaucoup pour l'aide.