Re-render Canvas

Question

Hi, there.

I working in a kind of a paint program which can zoom in and out and has a pan option too.

I have implemented the code in a Canvas object.

Now, how can I re-render the canvas and replace it to fit the outside border?

Thanks,

Tiago.

<Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="50" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Name="MenuColumn" Width="250" />
        </Grid.ColumnDefinitions>

        <StackPanel Grid.Row="0" Grid.ColumnSpan="2" Orientation="Horizontal" HorizontalAlignment="Center">
            <Button Name="PreviousButton">Previous</Button>
            <Button Name="ForwardButton">Forward</Button>
        </StackPanel>

        
        <!--<Border Grid.Row="1" Grid.Column="0" Name="MeshBorder" BorderBrush="red" BorderThickness="2">-->
        <Viewbox Grid.Row="1" Grid.Column="0" Stretch="UniformToFill">
            <Canvas Name="MeshCanvas" Background="Gray">
                <Canvas.RenderTransform>
                    <TransformGroup>
                        <ScaleTransform x:Name="st" />
                        <TranslateTransform x:Name="tt" />
                    </TransformGroup>
                </Canvas.RenderTransform>
                <Ellipse Canvas.Left="58" Canvas.Top="71" Height="65" Name="ellipse1" Stroke="Black" Width="84" />
            </Canvas>
        <!--</Border>-->
        </Viewbox>

        <Grid Grid.Row="1" Grid.Column="1" Height="500" Width="250">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="50" />
                <ColumnDefinition Width="*" />
            </Grid.ColumnDefinitions>
            <ItemsControl Grid.Column="0" ItemsSource="Menu" HorizontalAlignment="Center" />
            <StackPanel Grid.Column="1">
                <Button HorizontalAlignment="Right">Pin</Button>
                <Button>Test Button</Button>
            </StackPanel>
        </Grid>
    </Grid>

Private Sub MeshCanvas_MouseWheel(ByVal sender As System.Object, ByVal e As System.Windows.Input.MouseWheelEventArgs) Handles MeshCanvas.MouseWheel

        Dim zoom As Double = 0
        If e.Delta > 0 Then
            zoom = 0.2
        Else
            zoom = -0.2
        End If
        Dim center As Point = e.GetPosition(MeshCanvas)
        st.ScaleX = st.ScaleX * (1 + zoom)
        st.ScaleY = st.ScaleY * (1 + zoom)
        st.CenterX = center.X
        st.CenterY = center.Y
        
    End Sub

    Dim start As Point
    Private Sub MeshCanvas_MouseLeftButtonDown(ByVal sender As System.Object, ByVal e As System.Windows.Input.MouseButtonEventArgs) Handles MeshCanvas.MouseLeftButtonDown

        MeshCanvas.CaptureMouse()
        start = e.GetPosition(MeshCanvas)

    End Sub

    Private Sub MeshCanvas_MouseMove(ByVal sender As System.Object, ByVal e As System.Windows.Input.MouseEventArgs) Handles MeshCanvas.MouseMove

        Dim currentPoint As Point = e.GetPosition(MeshCanvas)
        If MeshCanvas.IsMouseCaptured Then
            tt.X = tt.X + (currentPoint.X - start.X)
            tt.Y = tt.Y + (currentPoint.Y - start.Y)
        End If

    End Sub

    Private Sub MeshCanvas_MouseLeftButtonUp(ByVal sender As System.Object, ByVal e As System.Windows.Input.MouseButtonEventArgs) Handles MeshCanvas.MouseLeftButtonUp
        MeshCanvas.ReleaseMouseCapture()
    End Sub

Answer 1

Hi,

i think you can re-render you can by accessing e.Source property as follows

(e.Source as Canvas).LayoutTransform=st

---

Thanks & Regards dhampall

Answer 2

Hi Lion's Claw,

I think the simply method is remove your canvas from parent control, and then add it again, it will re-render.

Best regards,

---

Sheldon _Xiao[MSFT]
MSDN Community Support | Feedback to us
Microsoft
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

Answer 3

Hi Lion's Claw,
 
I am marking your issue as "Answered", if you have new findings about your issue, please let me know.

Best regards,

---

Sheldon _Xiao[MSFT]
MSDN Community Support | Feedback to us
Microsoft
Please remember to mark the replies as answers if they help and unmark them if they provide no help.