c# - 使用 ScaleTransform 缩放画布时，ScrollViewer 不显示所有内容

问题描述

我在 ScrollViewer 中有两个 Canvas 面板。一个是主画布，在其背景上绘制了一个网格形状。然后我有两个 ItemsControl。第一个 ItemsControl 将 Stackpanel 作为其具有水平方向的 ItemsPanel。第二个 ItemsControl 将 Canvas 作为其面板。在此画布上，我在 Itemscontrol 的 DataTemplate 中绘制 Line 对象。此画布上有 PreviewMouseWheel 事件。在事件处理程序中，我正在缩放这个正在缩放 Line 对象的画布。此画布的宽度绑定到 ViewModel 属性 CanvasWidth。这也将改变外部画布的宽度，因为它的宽度也绑定到 ViewModel 属性 CanvasWidth。当 PreviewMouseWheel 被触发时，我将在主 Canvas 上添加更多网格线。我有 TextBlock 作为 ItemsSource 的 DataTemplate。在动物园之前，最后一个TextBlock的内容是14260。放大后应该保持14260。但是连续两个TextBlock的步长值应该减小。现在我无法通过 ScrollViewer 查看全部内容。减小了所需的步长，但通过 Scrollviewer 无法看到绘制的新网格线。我知道有内容。但我无法访问它。滚动查看器没有显示它。

    <Grid x:Name="grid1" >
                <Grid.RowDefinitions>
                    <RowDefinition Height="20" /> 
                    <RowDefinition Height="*" /> 
                    <RowDefinition Height="20" /> 
                </Grid.RowDefinitions>

                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="20" /> 
                    <ColumnDefinition Width="Auto" />
                    <ColumnDefinition Width="*"/>   
                    <ColumnDefinition Width="20"/> 
                </Grid.ColumnDefinitions>
         <ScrollViewer Name="scrollViewer" HorizontalScrollBarVisibility="Auto" Grid.Row="1" Grid.Column="3"   Margin="10,10,0,10" >
                        <Canvas Name="back_canvas"  Height="12000"  Width="{Binding CanvasWidth}" Margin="0,0,10,0" >
                            <Canvas.Background>
                                <DrawingBrush TileMode="Tile" Viewport="0,0,40,40"  ViewportUnits="Absolute"> 
                                    <DrawingBrush.Drawing>
                                        <GeometryDrawing>
                                            <GeometryDrawing.Geometry>
                                                <RectangleGeometry Rect="0,0,50,50"/>
                                            </GeometryDrawing.Geometry>
                                            <GeometryDrawing.Pen>
                                                <Pen Brush="Gray" Thickness="1"/>
                                            </GeometryDrawing.Pen>
                                        </GeometryDrawing>
                                    </DrawingBrush.Drawing>
                                </DrawingBrush>
                            </Canvas.Background>


                            <ItemsControl ItemsSource="{Binding TimeAxis}">
                                <ItemsControl.ItemsPanel>
                                    <ItemsPanelTemplate>
                                        <StackPanel Orientation="Horizontal" />
                                    </ItemsPanelTemplate>
                                </ItemsControl.ItemsPanel>
                                <ItemsControl.ItemTemplate>
                                    <DataTemplate>
                                        <TextBlock Text="{Binding}"  Margin="0,0,3,0"    Width="37"  Background="GreenYellow" >
                                        </TextBlock>
                                    </DataTemplate>
                                </ItemsControl.ItemTemplate>
                            </ItemsControl>
                        <ItemsControl ItemsSource="{Binding Lines}">
                            <ItemsControl.ItemsPanel>
                                    <ItemsPanelTemplate>
                                        <Canvas Height="12000" Background="Transparent"  Name="front_canvas" 
                                            PreviewMouseWheel="OnPreviewMouseWheel"
                                              Width="{Binding CanvasWidth, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"/>
                                    </ItemsPanelTemplate>
                                </ItemsControl.ItemsPanel>
                            <ItemsControl.ItemTemplate>
                                    <DataTemplate>
                                        </Line>
                                    </DataTemplate>
                                </ItemsControl.ItemTemplate>
                        </ItemsControl>
         </Canvas>
         </ScrollViewer>
 </Grid>

 private void UpdateGraph(Canvas canvas, double deltaValue)
        {
            List<MarkerView> markers = new List<MarkerView>();
            scaleFactor += deltaValue;

            double tempScale = scaleFactor;

            if (scaleFactor < 1.0)
            {
                scaleFactor = 1.0;
            }
            if (scaleFactor > maximumScale)
            {
                scaleFactor = maximumScale;
            }

            if (tempScale > 0)
            {
                totalSamples = graphVM.maxSignalLength;

                maximumCanvasWidth = totalSamples * maximumDeltaDistance;
                if(scaleFactor<=maximumDeltaDistance)
                {
                ScaleTransform scaleTransform = new ScaleTransform(scaleFactor, 1);
                canvas.RenderTransform = scaleTransform;
                verticalLines.ForEach(x =>
                {
                    x.RenderTransformOrigin = new Point(1, 1);

                    x.RenderTransform = new ScaleTransform(1 / scaleTransform.ScaleX, 1 / scaleTransform.ScaleY);
                });

                if (deltaValue < 0)
                {
                    graphVM.CanvasWidth = graphVM.InitialCanvasWidth * tempScale;
                }
                else
                {
                    if (graphVM.InitialCanvasWidth * scaleFactor > maximumCanvasWidth)
                        graphVM.CanvasWidth = maximumCanvasWidth;
                    else
                    graphVM.CanvasWidth = graphVM.InitialCanvasWidth * scaleFactor;
                }
                    graphVM.ResetLabels();

                   DeltaDistance = canvas.Width / totalSamples;
                MarkerView markerRed =
                UIHelperView.FindChild<MarkerView>(Application.Current.MainWindow, "splitterRed");
                MarkerView markerGreen =
                UIHelperView.FindChild<MarkerView>(Application.Current.MainWindow, "splitterGreen");
                markers.Add(markerRed);
                markers.Add(markerGreen);

                // Move  Markers with  zooming
                foreach (MarkerView marker in markers)
                {
                        marker.Delta = DeltaDistance; // after zooming if you move the marker then this value will be used to get correct position 
                        Canvas.SetLeft(marker, marker.XPosition * DeltaDistance);
                }

                    markers.Clear();

                }
            }

        }

这是输出图片https://imgur.com/a/7WTrBoc 这是放大的输出https://imgur.com/C7SCOSJ

标签： c#wpfcanvasscrollviewerscaletransform

c# - 使用 ScaleTransform 缩放画布时，ScrollViewer 不显示所有内容

问题描述

解决方案

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