我一直在关注来自这里的投票最多的答案。 Pan & Zoom Image(带有ZoomBorder.cs的那个)。
如果我将其包含到项目中,则一切正常。但是,我的项目是ReactiveUI应用程序,我努力使用ReactiveUI设计模式来复制该代码。
到目前为止我所做的:
创建了一个新的UserControl
<UserControl x:Class="ImageViewer.Controls.ZoomControl"
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"
xmlns:local="clr-namespace:ImageViewer.Controls"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800">
<Border BorderThickness="10" BorderBrush="Red">
<Image x:Name="RenderingImage" RenderTransformOrigin="0,0" Stretch="None" Source="{Binding}" ClipToBounds="True">
<Image.LayoutTransform>
<TransformGroup>
<ScaleTransform x:Name="ImageScale" ScaleX="{Binding}" ScaleY="{Binding}"/>
<TranslateTransform x:Name="ImageTranslate" X="{Binding}" Y="{Binding}" />
</TransformGroup>
</Image.LayoutTransform>
</Image>
</Border>
</UserControl>
在View-> ViewModel之间添加了绑定
public partial class ZoomControl : IViewFor<ZoomControlViewModel>
{
public static readonly DependencyProperty ViewModelProperty = DependencyProperty
.Register(nameof(ViewModel), typeof(ZoomControlViewModel), typeof(ZoomControl), null);
public ZoomControl()
{
InitializeComponent();
this.DataContextChanged += (sender, args) => ViewModel = DataContext as ZoomControlViewModel;
this.WhenActivated(cleanup =>
{
this.OneWayBind(ViewModel, vm => vm.ImageSource, v => v.RenderingImage.Source).DisposeWith(cleanup);
this.OneWayBind(ViewModel, vm => vm.ScaleX, v => v.ImageScale.ScaleX).DisposeWith(cleanup);
this.OneWayBind(ViewModel, vm => vm.ScaleY, v => v.ImageScale.ScaleY).DisposeWith(cleanup);
this.OneWayBind(ViewModel, vm => vm.TranslateX, v => v.ImageTranslate.X).DisposeWith(cleanup);
this.OneWayBind(ViewModel, vm => vm.TranslateY, v => v.ImageTranslate.Y).DisposeWith(cleanup);
RenderingImage.Events().MouseWheel.Select(e => new Tuple<int, Point>(e.Delta, e.GetPosition(RenderingImage))).InvokeCommand(ViewModel.ZoomAction).DisposeWith(cleanup);
});
}
public ZoomControlViewModel ViewModel { get => (ZoomControlViewModel)GetValue(ViewModelProperty); set => SetValue(ViewModelProperty, value); }
object IViewFor.ViewModel { get => ViewModel; set => ViewModel = (ZoomControlViewModel)value; }
}
在视图模型中,我像这样实现了zoom命令。
public ZoomControlViewModel()
{
ZoomAction = ReactiveCommand.Create<Tuple<int, Point>>(z => Zoom(z));
}
private void Zoom(Tuple<int, Point> deltaArgs)
{
int delta = deltaArgs.Item1;
Point relativePosition = deltaArgs.Item2;
//var ScaleTransform = GetScaleTransform();
//var TranslateTransform = GetTranslateTransform();
double zoom = delta > 0 ? .2 : -.2;
if (!(delta > 0) && (ScaleX < .4 || ScaleY < .4))
return;
double absoluteX;
double absoluteY;
absoluteX = relativePosition.X * ScaleX + TranslateX;
absoluteY = relativePosition.Y * ScaleY + TranslateY;
ScaleX += zoom;
ScaleY += zoom;
TranslateX = absoluteX - relativePosition.X * ScaleX;
TranslateY = absoluteY - relativePosition.Y * ScaleY;
}
现在我的问题。对于此示例,上面的缩放效果很好,但是不能缩放到鼠标位置,而是缩放到图像的LeftUp角。
据我所知(可能是问题所在),更改图像的 TranslateTransform ( TranslateX 和 TranslateY )应该将我放大到当前鼠标位置。
任何提示将不胜感激。