WPF 图像平移、缩放和滚动 Canvas 上的图层

Question

我希望有人可以在这里帮助我。我正在构建一个 WPF 成像应用程序，该应用程序从相机获取实时图像，允许用户查看图像，然后突出显示该图像上的感兴趣区域 (ROI)。然后将有关 ROI 的信息(宽度、高度、相对于图像上某个点的位置等)发送回相机，实际上是告诉/训练相机固件在哪里寻找条形码、文本、液位、转弯等信息图像上的螺钉等)。所需的功能是能够平移和缩放图像及其 ROI，以及在图像缩放到大于查看区域时进行滚动。 ROI 的 StrokeThickness 和 FontSize 需要保持原始比例，但 ROI 内形状的宽度和高度需要随图像缩放(这对于捕获精确的像素位置以传输到相机至关重要)。除了滚动和其他一些问题外，我已经解决了大部分问题。我关心的两个方面是:

当我引入 ScrollViewer 时，我没有得到任何滚动行为。据我了解，我需要引入一个 LayoutTransform 以获得正确的 ScrollViewer 行为。但是，当我这样做时，其他区域开始崩溃(例如，ROI 没有在图像上保持正确的位置，或者鼠标指针在平移时开始远离图像上的选定点，或者我的图像的左角弹跳到 MouseDown 上的当前鼠标位置。)

我不能完全按照我需要的方式来扩展我的投资返回率。我有这个工作，但它并不理想。我所拥有的没有保留确切的笔画粗细，而且我没有考虑忽略文本 block 上的比例。希望您会在代码示例中看到我在做什么。

我确定我的问题与我对变换及其与 WPF 布局系统的关系缺乏了解有关。希望展示我到目前为止所完成的代码的再现会有所帮助(见下文)。

仅供引用，如果建议使用装饰器，那在我的场景中可能不起作用，因为我最终可能会得到比支持更多的装饰器(谣言 144 装饰器是事情开始崩溃的时候)。

首先，下面是显示具有 ROI(文本和形状)的图像的屏幕截图。矩形、椭圆和文本需要跟随图像上的区域进行缩放和旋转，但它们不应该在粗细或字体大小上缩放。



这是显示上图的 XAML，以及用于缩放的 slider (鼠标滚轮缩放稍后会出现)

<Window x:Class="PanZoomStackOverflow.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    mc:Ignorable="d"
    Title="MainWindow" Height="768" Width="1024">

<DockPanel>
  <Slider x:Name="_ImageZoomSlider" DockPanel.Dock="Bottom"
          Value="2"
          HorizontalAlignment="Center" Margin="6,0,0,0" 
          Width="143" Minimum=".5" Maximum="20" SmallChange=".1" 
          LargeChange=".2" TickFrequency="2" 
          TickPlacement="BottomRight" Padding="0" Height="23"/>

  <!-- This resides in a user control in my solution -->
  <Grid x:Name="LayoutRoot">
    <ScrollViewer Name="border" HorizontalScrollBarVisibility="Auto" 
                  VerticalScrollBarVisibility="Auto">
      <Grid x:Name="_ImageDisplayGrid">
        <Image x:Name="_DisplayImage" Margin="2" Stretch="None"
               Source="Untitled.bmp"
               RenderTransformOrigin ="0.5,0.5"
               RenderOptions.BitmapScalingMode="NearestNeighbor"
               MouseLeftButtonDown="ImageScrollArea_MouseLeftButtonDown"
               MouseLeftButtonUp="ImageScrollArea_MouseLeftButtonUp"
               MouseMove="ImageScrollArea_MouseMove">                            
           <Image.LayoutTransform>
             <TransformGroup>
               <ScaleTransform />
               <TranslateTransform />
             </TransformGroup>
           </Image.LayoutTransform>
         </Image>
         <AdornerDecorator> <!-- Using this Adorner Decorator for Move, Resize and Rotation and feedback adornernments -->
           <Canvas x:Name="_ROICollectionCanvas"
                   Width="{Binding ElementName=_DisplayImage, Path=ActualWidth, Mode=OneWay}"
                   Height="{Binding ElementName=_DisplayImage, Path=ActualHeight, Mode=OneWay}"
                   Margin="{Binding ElementName=_DisplayImage, Path=Margin, Mode=OneWay}">

             <!-- This is a user control in my solution -->
             <Grid IsHitTestVisible="False" Canvas.Left="138" Canvas.Top="58" Height="25" Width="186">
               <TextBlock Text="Rectangle ROI" HorizontalAlignment="Center" VerticalAlignment="Top" 
                          Foreground="Orange" FontWeight="Bold" Margin="0,-15,0,0"/>
                 <Rectangle StrokeThickness="2" Stroke="Orange"/>
             </Grid>

             <!-- This is a user control in my solution -->
             <Grid IsHitTestVisible="False" Canvas.Left="176" Canvas.Top="154" Height="65" Width="69">
               <TextBlock Text="Ellipse ROI" HorizontalAlignment="Center" VerticalAlignment="Top" 
                          Foreground="Orange" FontWeight="Bold" Margin="0,-15,0,0"/>
               <Ellipse StrokeThickness="2" Stroke="Orange"/>
             </Grid>
           </Canvas>
         </AdornerDecorator>
       </Grid>
     </ScrollViewer>
  </Grid>
</DockPanel>

这是管理平移和缩放的 C#。

public partial class MainWindow : Window
{
private Point origin;
private Point start;
private Slider _slider;

public MainWindow()
{
    this.InitializeComponent();

    //Setup a transform group that we'll use to manage panning of the image area
    TransformGroup group = new TransformGroup();
    ScaleTransform st = new ScaleTransform();
    group.Children.Add(st);
    TranslateTransform tt = new TranslateTransform();
    group.Children.Add(tt);
    //Wire up the slider to the image for zooming
    _slider = _ImageZoomSlider;
    _slider.ValueChanged += _ImageZoomSlider_ValueChanged;
    st.ScaleX = _slider.Value;
    st.ScaleY = _slider.Value;
    //_ImageScrollArea.RenderTransformOrigin = new Point(0.5, 0.5);
    //_ImageScrollArea.LayoutTransform = group;
    _DisplayImage.RenderTransformOrigin = new Point(0.5, 0.5);
    _DisplayImage.RenderTransform = group;
    _ROICollectionCanvas.RenderTransformOrigin = new Point(0.5, 0.5);
    _ROICollectionCanvas.RenderTransform = group;
}

//Captures the mouse to prepare for panning the scrollable image area
private void ImageScrollArea_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
    _DisplayImage.ReleaseMouseCapture();
}

//Moves/Pans the scrollable image area  assuming mouse is captured.
private void ImageScrollArea_MouseMove(object sender, MouseEventArgs e)
{
    if (!_DisplayImage.IsMouseCaptured) return;

    var tt = (TranslateTransform)((TransformGroup)_DisplayImage.RenderTransform).Children.First(tr => tr is TranslateTransform);

    Vector v = start - e.GetPosition(border);
    tt.X = origin.X - v.X;
    tt.Y = origin.Y - v.Y;
}

//Cleanup for Move/Pan when mouse is released
private void ImageScrollArea_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    _DisplayImage.CaptureMouse();
    var tt = (TranslateTransform)((TransformGroup)_DisplayImage.RenderTransform).Children.First(tr => tr is TranslateTransform);
    start = e.GetPosition(border);
    origin = new Point(tt.X, tt.Y);
}

//Zoom according to the slider changes
private void _ImageZoomSlider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
    //Panel panel = _ImageScrollArea;
    Image panel = _DisplayImage;

    //Set the scale coordinates on the ScaleTransform from the slider
    ScaleTransform transform = (ScaleTransform)((TransformGroup)panel.RenderTransform).Children.First(tr => tr is ScaleTransform);
    transform.ScaleX = _slider.Value;
    transform.ScaleY = _slider.Value;


    //Set the zoom (this will affect rotate too) origin to the center of the panel
    panel.RenderTransformOrigin = new Point(0.5, 0.5);

    foreach (UIElement child in _ROICollectionCanvas.Children)
    {
        //Assume all shapes are contained in a panel
        Panel childPanel = child as Panel;

        var x = childPanel.Children;

        //Shape width and heigh should scale, but not StrokeThickness
        foreach (var shape in childPanel.Children.OfType<Shape>())
        {
            if (shape.Tag == null)
            {
                //Hack: This is be a property on a usercontrol in my solution
                shape.Tag = shape.StrokeThickness;
            }
            double orignalStrokeThickness = (double)shape.Tag;

            //Attempt to keep the underlying shape border/stroke from thickening as well
            double newThickness = shape.StrokeThickness - (orignalStrokeThickness / transform.ScaleX);

            shape.StrokeThickness -= newThickness;
        }
    }
}
}

假设没有剪切/粘贴错误，代码应该在 .NET 4.0 或 4.5 项目和解决方案中工作。

有什么想法吗？欢迎提出建议。

Answer 1

行。这是我对你所描述的看法。

它看起来像这样:

由于我没有应用任何 RenderTransforms ，因此我获得了所需的 Scrollbar/ScrollViewer 功能。

MVVM，这是进入 WPF 的方式。 UI 和数据是独立的，因此 DataItems 只有 X、Y、宽度、高度等的 double 和 int 属性，您可以将它们用于任何目的，甚至将它们存储在数据库中。

我在 Thumb 中添加了所有内容来处理平移。您仍然需要对通过 ResizerControl 拖动/调整 ROI 大小时发生的平移做一些事情。我想你可以检查一下 Mouse.DirectlyOver 什么的。

我实际上使用了 ListBox 来处理 ROI，因此您可以在任何给定时间选择 1 个 ROI。这将切换调整大小功能。因此，如果您单击 ROI，您将看到调整大小。

缩放在 ViewModel 级别处理，因此无需自定义 Panels 或类似的东西(尽管@Clemens 的解决方案也很好)

我使用 Enum 和一些 DataTriggers 来定义形状。请参阅 DataTemplate DataType={x:Type local:ROI} 部分。

WPF 摇滚。只需将我的代码复制并粘贴到 File -> New Project -> WPF Application 中，然后自己查看结果。

<Window x:Class="MiscSamples.PanZoomStackOverflow_MVVM"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:MiscSamples"
        Title="PanZoomStackOverflow_MVVM" Height="300" Width="300">
   <Window.Resources>
    <DataTemplate DataType="{x:Type local:ROI}">
        <Grid Background="#01FFFFFF">
            <Path x:Name="Path" StrokeThickness="2" Stroke="Black"
                  Stretch="Fill"/>
            <local:ResizerControl Visibility="Collapsed" Background="#30FFFFFF"
                                  X="{Binding X}" Y="{Binding Y}"
                                  ItemWidth="{Binding Width}"
                                  ItemHeight="{Binding Height}"
                                  x:Name="Resizer"/>
        </Grid>
        <DataTemplate.Triggers>
            <DataTrigger Binding="{Binding IsSelected, RelativeSource={RelativeSource AncestorType=ListBoxItem}}" Value="True">
                <Setter TargetName="Resizer" Property="Visibility" Value="Visible"/>
            </DataTrigger>
            <DataTrigger Binding="{Binding Shape}" Value="{x:Static local:Shapes.Square}">
                <Setter TargetName="Path" Property="Data">
                    <Setter.Value>
                        <RectangleGeometry Rect="0,0,10,10"/>
                    </Setter.Value>
                </Setter>
            </DataTrigger>

            <DataTrigger Binding="{Binding Shape}" Value="{x:Static local:Shapes.Round}">
                <Setter TargetName="Path" Property="Data">
                    <Setter.Value>
                        <EllipseGeometry RadiusX="10" RadiusY="10"/>
                    </Setter.Value>
                </Setter>
            </DataTrigger>
        </DataTemplate.Triggers>
    </DataTemplate>

    <Style TargetType="ListBox" x:Key="ROIListBoxStyle">
        <Setter Property="ItemsPanel">
            <Setter.Value>
                <ItemsPanelTemplate>
                    <Canvas/>
                </ItemsPanelTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate>
                    <ItemsPresenter/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    <Style TargetType="ListBoxItem" x:Key="ROIItemStyle">
        <Setter Property="Canvas.Left" Value="{Binding ActualX}"/>
        <Setter Property="Canvas.Top" Value="{Binding ActualY}"/>
        <Setter Property="Height" Value="{Binding ActualHeight}"/>
        <Setter Property="Width" Value="{Binding ActualWidth}"/>

        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="ListBoxItem">
                    <ContentPresenter ContentSource="Content"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</Window.Resources>

<DockPanel>
    <Slider VerticalAlignment="Center" 
            Maximum="2" Minimum="0" Value="{Binding ScaleFactor}" SmallChange=".1"
            DockPanel.Dock="Bottom"/>

    <ScrollViewer VerticalScrollBarVisibility="Visible"
                  HorizontalScrollBarVisibility="Visible" x:Name="scr"
                  ScrollChanged="ScrollChanged">
        <Thumb DragDelta="Thumb_DragDelta">
            <Thumb.Template>
                <ControlTemplate>
                    <Grid>
                        <Image Source="/Images/Homer.jpg" Stretch="None" x:Name="Img"
                                VerticalAlignment="Top" HorizontalAlignment="Left">
                            <Image.LayoutTransform>
                                <TransformGroup>
                                    <ScaleTransform ScaleX="{Binding ScaleFactor}" ScaleY="{Binding ScaleFactor}"/>
                                </TransformGroup>
                            </Image.LayoutTransform>
                        </Image>

                        <ListBox ItemsSource="{Binding ROIs}"
                                 Width="{Binding ActualWidth, ElementName=Img}"
                                 Height="{Binding ActualHeight,ElementName=Img}"
                                 VerticalAlignment="Top" HorizontalAlignment="Left"
                                 Style="{StaticResource ROIListBoxStyle}"
                                 ItemContainerStyle="{StaticResource ROIItemStyle}"/>
                    </Grid>
                </ControlTemplate>
            </Thumb.Template>
        </Thumb>
    </ScrollViewer>
</DockPanel>

代码背后:

public partial class PanZoomStackOverflow_MVVM : Window
    {
        public PanZoomViewModel ViewModel { get; set; }

        public PanZoomStackOverflow_MVVM()
        {
            InitializeComponent();
            DataContext = ViewModel = new PanZoomViewModel();

            ViewModel.ROIs.Add(new ROI() {ScaleFactor = ViewModel.ScaleFactor, X = 150, Y = 150, Height = 200, Width = 200, Shape = Shapes.Square});

            ViewModel.ROIs.Add(new ROI() { ScaleFactor = ViewModel.ScaleFactor, X = 50, Y = 230, Height = 102, Width = 300, Shape = Shapes.Round });
        }

        private void Thumb_DragDelta(object sender, DragDeltaEventArgs e)
        {
            //TODO: Detect whether a ROI is being resized / dragged and prevent Panning if so.
            IsPanning = true;
            ViewModel.OffsetX = (ViewModel.OffsetX + (((e.HorizontalChange/10) * -1) * ViewModel.ScaleFactor));
            ViewModel.OffsetY = (ViewModel.OffsetY + (((e.VerticalChange/10) * -1) * ViewModel.ScaleFactor));

            scr.ScrollToVerticalOffset(ViewModel.OffsetY);
            scr.ScrollToHorizontalOffset(ViewModel.OffsetX);

            IsPanning = false;
        }

        private bool IsPanning { get; set; }

        private void ScrollChanged(object sender, ScrollChangedEventArgs e)
        {
            if (!IsPanning)
            {
                ViewModel.OffsetX = e.HorizontalOffset;
                ViewModel.OffsetY = e.VerticalOffset;
            }
        }
    }

主视图模型:

public class PanZoomViewModel:PropertyChangedBase
{
    private double _offsetX;
    public double OffsetX
    {
        get { return _offsetX; }
        set
        {
            _offsetX = value;
            OnPropertyChanged("OffsetX");
        }
    }

    private double _offsetY;
    public double OffsetY
    {
        get { return _offsetY; }
        set
        {
            _offsetY = value;
            OnPropertyChanged("OffsetY");
        }
    }

    private double _scaleFactor = 1;
    public double ScaleFactor
    {
        get { return _scaleFactor; }
        set
        {
            _scaleFactor = value;
            OnPropertyChanged("ScaleFactor");
            ROIs.ToList().ForEach(x => x.ScaleFactor = value);
        }
    }

    private ObservableCollection<ROI> _rois;
    public ObservableCollection<ROI> ROIs
    {
        get { return _rois ?? (_rois = new ObservableCollection<ROI>()); }
    }
}

投资返回率 View 模型:

public class ROI:PropertyChangedBase
{
    private Shapes _shape;
    public Shapes Shape
    {
        get { return _shape; }
        set
        {
            _shape = value;
            OnPropertyChanged("Shape");
        }
    }

    private double _scaleFactor;
    public double ScaleFactor
    {
        get { return _scaleFactor; }
        set
        {
            _scaleFactor = value;
            OnPropertyChanged("ScaleFactor");
            OnPropertyChanged("ActualX");
            OnPropertyChanged("ActualY");
            OnPropertyChanged("ActualHeight");
            OnPropertyChanged("ActualWidth");
        }
    }

    private double _x;
    public double X
    {
        get { return _x; }
        set
        {
            _x = value;
            OnPropertyChanged("X");
            OnPropertyChanged("ActualX");
        }
    }

    private double _y;
    public double Y
    {
        get { return _y; }
        set
        {
            _y = value;
            OnPropertyChanged("Y");
            OnPropertyChanged("ActualY");
        }
    }

    private double _height;
    public double Height
    {
        get { return _height; }
        set
        {
            _height = value;
            OnPropertyChanged("Height");
            OnPropertyChanged("ActualHeight");
        }
    }

    private double _width;
    public double Width
    {
        get { return _width; }
        set
        {
            _width = value;
            OnPropertyChanged("Width");
            OnPropertyChanged("ActualWidth");
        }
    }

    public double ActualX { get { return X*ScaleFactor; }}
    public double ActualY { get { return Y*ScaleFactor; }}
    public double ActualWidth { get { return Width*ScaleFactor; }}
    public double ActualHeight { get { return Height * ScaleFactor; } }
}

形状枚举:

public enum Shapes
{
    Round = 1,
    Square = 2,
    AnyOther
}

PropertyChangedBase(MVVM Helper 类):

    public class PropertyChangedBase:INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged(string propertyName)
        {
            Application.Current.Dispatcher.BeginInvoke((Action) (() =>
                                                                     {
                                                                         PropertyChangedEventHandler handler = PropertyChanged;
                                                                         if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
                                                                     }));
        }
    }

调整大小控制:

<UserControl x:Class="MiscSamples.ResizerControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300">
    <Grid>
        <Thumb DragDelta="Center_DragDelta" Height="10" Width="10"
               VerticalAlignment="Center" HorizontalAlignment="Center"/>

        <Thumb DragDelta="UpperLeft_DragDelta" Height="10" Width="10"
               VerticalAlignment="Top" HorizontalAlignment="Left"/>

        <Thumb DragDelta="UpperRight_DragDelta" Height="10" Width="10"
               VerticalAlignment="Top" HorizontalAlignment="Right"/>

        <Thumb DragDelta="LowerLeft_DragDelta" Height="10" Width="10"
               VerticalAlignment="Bottom" HorizontalAlignment="Left"/>

        <Thumb DragDelta="LowerRight_DragDelta" Height="10" Width="10"
               VerticalAlignment="Bottom" HorizontalAlignment="Right"/>

    </Grid>
</UserControl>

代码背后:

 public partial class ResizerControl : UserControl
    {
        public static readonly DependencyProperty XProperty = DependencyProperty.Register("X", typeof(double), typeof(ResizerControl), new FrameworkPropertyMetadata(0d,FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
        public static readonly DependencyProperty YProperty = DependencyProperty.Register("Y", typeof(double), typeof(ResizerControl), new FrameworkPropertyMetadata(0d, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
        public static readonly DependencyProperty ItemWidthProperty = DependencyProperty.Register("ItemWidth", typeof(double), typeof(ResizerControl), new FrameworkPropertyMetadata(0d, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
        public static readonly DependencyProperty ItemHeightProperty = DependencyProperty.Register("ItemHeight", typeof(double), typeof(ResizerControl), new FrameworkPropertyMetadata(0d, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));

        public double X
        {
            get { return (double) GetValue(XProperty); }
            set { SetValue(XProperty, value); }
        }

        public double Y
        {
            get { return (double)GetValue(YProperty); }
            set { SetValue(YProperty, value); }
        }

        public double ItemHeight
        {
            get { return (double) GetValue(ItemHeightProperty); }
            set { SetValue(ItemHeightProperty, value); }
        }

        public double ItemWidth
        {
            get { return (double) GetValue(ItemWidthProperty); }
            set { SetValue(ItemWidthProperty, value); }
        }

        public ResizerControl()
        {
            InitializeComponent();
        }

        private void UpperLeft_DragDelta(object sender, DragDeltaEventArgs e)
        {
            X = X + e.HorizontalChange;
            Y = Y + e.VerticalChange;

            ItemHeight = ItemHeight + e.VerticalChange * -1;
            ItemWidth = ItemWidth + e.HorizontalChange * -1;
        }

        private void UpperRight_DragDelta(object sender, DragDeltaEventArgs e)
        {
            Y = Y + e.VerticalChange;

            ItemHeight = ItemHeight + e.VerticalChange * -1;
            ItemWidth = ItemWidth + e.HorizontalChange;
        }

        private void LowerLeft_DragDelta(object sender, DragDeltaEventArgs e)
        {
            X = X + e.HorizontalChange;

            ItemHeight = ItemHeight + e.VerticalChange;
            ItemWidth = ItemWidth + e.HorizontalChange * -1;
        }

        private void LowerRight_DragDelta(object sender, DragDeltaEventArgs e)
        {
            ItemHeight = ItemHeight + e.VerticalChange;
            ItemWidth = ItemWidth + e.HorizontalChange;
        }

        private void Center_DragDelta(object sender, DragDeltaEventArgs e)
        {
            X = X + e.HorizontalChange;
            Y = Y + e.VerticalChange;
        }
    }