452 lines
12 KiB
C#
452 lines
12 KiB
C#
using System;
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using System.IO;
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Input;
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using System.Windows.Media;
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using System.Windows.Media.Imaging;
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namespace WxOrder.Framework.Controls;
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/// <summary>
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/// 图片查看弹窗，直接静态调用：
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/// ImageViewerWindow.Open(@"C:\a.jpg");
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/// ImageViewerWindow.OpenDialog("https://example.com/a.png", "预览");
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/// source 支持 string(路径/URL) / Uri / ImageSource / byte[] / Stream
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/// </summary>
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public partial class ImageViewerWindow : Window
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{
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private readonly object _source;
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private ImageViewerWindow(object source, string title)
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{
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InitializeComponent();
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// 保证 Img 位于 Canvas 中：
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// 如果 Img 直接放在 Grid 里，图片比窗口大时会被 WPF 按窗口大小做布局裁剪，
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// 缩放后只剩左上角一块，表现为“图片没居中”。
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EnsureImageInCanvas();
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var group = new TransformGroup();
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group.Children.Add(_scaleT);
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group.Children.Add(_translateT);
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Img.RenderTransform = group;
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Img.RenderTransformOrigin = new Point(0, 0);
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_source = source;
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Title = title ?? GuessTitle(source);
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// 默认大小：屏幕工作区的 70%
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Width = Math.Max(MinWidth, SystemParameters.WorkArea.Width * 0.7);
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Height = Math.Max(MinHeight, SystemParameters.WorkArea.Height * 0.7);
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ImageFailed += (s, ex) =>
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{
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MessageBox.Show(this, "图片加载失败：" + ex.Message, "提示",
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MessageBoxButton.OK, MessageBoxImage.Warning);
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Close();
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};
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// 放到 Loaded 里设置，这样加载失败时可以安全地关闭窗口
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Loaded += (s, e) => Source = _source;
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}
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/// <summary>如果 Img 的父级不是 Canvas，就在原位置包一层 Canvas。</summary>
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private void EnsureImageInCanvas()
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{
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if (Img.Parent is Canvas) return;
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if (Img.Parent is not Panel parent) return;
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int index = parent.Children.IndexOf(Img);
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parent.Children.RemoveAt(index);
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Img.Stretch = Stretch.None;
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Img.HorizontalAlignment = HorizontalAlignment.Left;
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Img.VerticalAlignment = VerticalAlignment.Top;
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Canvas.SetLeft(Img, 0);
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Canvas.SetTop(Img, 0);
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var canvas = new Canvas { IsHitTestVisible = false };
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canvas.Children.Add(Img);
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parent.Children.Insert(index, canvas);
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}
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#region 静态调用入口
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/// <summary>非模态弹出（不阻塞调用方）</summary>
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public static void Open(object source, string title = null, Window owner = null)
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{
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RunOnUi(() => Create(source, title, owner).Show());
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}
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/// <summary>模态弹出（关闭前阻塞调用方）</summary>
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public static void OpenDialog(object source, string title = null, Window owner = null)
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{
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RunOnUi(() => Create(source, title, owner).ShowDialog());
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}
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#endregion
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private static ImageViewerWindow Create(object source, string title, Window owner)
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{
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var win = new ImageViewerWindow(source, title);
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owner = owner ?? Application.Current?.MainWindow;
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if (owner != null && owner.IsLoaded && owner != win)
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{
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win.Owner = owner;
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win.WindowStartupLocation = WindowStartupLocation.CenterOwner;
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}
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else
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{
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win.WindowStartupLocation = WindowStartupLocation.CenterScreen;
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}
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return win;
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}
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private static void RunOnUi(Action action)
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{
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var dispatcher = Application.Current?.Dispatcher
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?? throw new InvalidOperationException("没有可用的 WPF Application。");
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if (dispatcher.CheckAccess()) action();
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else dispatcher.Invoke(action); // 支持从后台线程调用
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}
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private static string GuessTitle(object source)
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{
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try
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{
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if (source is string s && !string.IsNullOrWhiteSpace(s))
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{
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if (Uri.TryCreate(s, UriKind.Absolute, out var u))
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return Path.GetFileName(u.IsFile ? u.LocalPath : u.AbsolutePath);
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return Path.GetFileName(s);
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}
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if (source is Uri uri)
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return Path.GetFileName(uri.IsFile ? uri.LocalPath : uri.AbsolutePath);
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}
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catch { /* 忽略，使用默认标题 */ }
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return "图片查看";
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}
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private void Window_KeyDown(object sender, KeyEventArgs e)
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{
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switch (e.Key)
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{
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case Key.Escape: Close(); break;
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case Key.Add:
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case Key.OemPlus: ZoomIn(); break;
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case Key.Subtract:
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case Key.OemMinus: ZoomOut(); break;
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case Key.D0:
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case Key.NumPad0: FitToView(); break;
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case Key.D1:
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case Key.NumPad1: ActualSize(); break;
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}
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}
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#region 依赖属性
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/// <summary>图片来源：string(路径或URL) / Uri / ImageSource / byte[] / Stream</summary>
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public static readonly DependencyProperty SourceProperty =
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DependencyProperty.Register(nameof(Source), typeof(object), typeof(ImageViewerWindow),
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new PropertyMetadata(null, (d, e) => ((ImageViewerWindow)d).LoadSource(e.NewValue)));
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public static readonly DependencyProperty ShowToolbarProperty =
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DependencyProperty.Register(nameof(ShowToolbar), typeof(bool), typeof(ImageViewerWindow),
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new PropertyMetadata(true, (d, e) =>
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((ImageViewerWindow)d).ToolBar.Visibility = (bool)e.NewValue ? Visibility.Visible : Visibility.Collapsed));
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public object Source
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{
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get => GetValue(SourceProperty);
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set => SetValue(SourceProperty, value);
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}
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public bool ShowToolbar
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{
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get => (bool)GetValue(ShowToolbarProperty);
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set => SetValue(ShowToolbarProperty, value);
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}
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#endregion
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#region 公共属性 / 事件
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public double MinZoom { get; set; } = 0.05;
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public double MaxZoom { get; set; } = 32;
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/// <summary>当前缩放比例（1 = 100%）</summary>
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public double Zoom
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{
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get => _scale;
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set => ZoomAt(ViewCenter, value);
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}
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public event EventHandler ZoomChanged;
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public event EventHandler<Exception> ImageFailed;
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#endregion
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private readonly ScaleTransform _scaleT = new ScaleTransform();
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private readonly TranslateTransform _translateT = new TranslateTransform();
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private ImageSource _image;
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private BitmapSource _pending; // 正在下载的网络图片
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private double _scale = 1, _tx, _ty;
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private bool _fit = true; // 是否处于"适应窗口"状态（窗口大小变化时自动重新适应）
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private bool _dragging;
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private Point _lastPos;
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private Point ViewCenter => new Point(Root.ActualWidth / 2, Root.ActualHeight / 2);
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#region 加载图片
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private void LoadSource(object src)
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{
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DetachPending();
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try
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{
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var img = CreateImage(src);
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if (img is BitmapSource bs && bs.IsDownloading)
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{
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_pending = bs;
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bs.DownloadCompleted += OnDownloadCompleted;
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bs.DownloadFailed += OnDownloadFailed;
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SetImage(null);
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return;
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}
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SetImage(img);
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}
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catch (Exception ex)
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{
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SetImage(null);
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ImageFailed?.Invoke(this, ex);
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}
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}
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private void DetachPending()
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{
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if (_pending == null) return;
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_pending.DownloadCompleted -= OnDownloadCompleted;
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_pending.DownloadFailed -= OnDownloadFailed;
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_pending = null;
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}
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private void OnDownloadCompleted(object sender, EventArgs e)
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{
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var bs = (BitmapSource)sender;
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if (bs != _pending) return;
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DetachPending();
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if (bs.CanFreeze) bs.Freeze();
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SetImage(bs);
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}
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private void OnDownloadFailed(object sender, ExceptionEventArgs e)
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{
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DetachPending();
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SetImage(null);
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ImageFailed?.Invoke(this, e.ErrorException);
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}
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private static ImageSource CreateImage(object src)
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{
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switch (src)
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{
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case null: return null;
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case ImageSource s: return s;
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case Uri u: return FromUri(u);
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case string str:
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var uri = ToUri(str);
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return uri == null ? null : FromUri(uri);
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case byte[] bytes:
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using (var ms = new MemoryStream(bytes)) return FromStream(ms);
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case Stream stream: return FromStream(stream);
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default:
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throw new NotSupportedException("不支持的图片来源类型：" + src.GetType().FullName);
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}
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}
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private static Uri ToUri(string s)
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{
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if (string.IsNullOrWhiteSpace(s)) return null;
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if (Uri.TryCreate(s, UriKind.Absolute, out var u)) return u; // C:\a.png / http://... / pack://...
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return new Uri(Path.GetFullPath(s)); // 相对路径
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}
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private static BitmapImage FromUri(Uri uri)
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{
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var bmp = new BitmapImage();
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bmp.BeginInit();
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bmp.UriSource = uri;
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bmp.CacheOption = BitmapCacheOption.OnLoad; // 加载后不占用文件
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bmp.CreateOptions = BitmapCreateOptions.IgnoreImageCache; // 文件被替换后能刷新
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bmp.EndInit();
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if (!bmp.IsDownloading && bmp.CanFreeze) bmp.Freeze();
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return bmp;
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}
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private static BitmapImage FromStream(Stream stream)
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{
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var bmp = new BitmapImage();
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bmp.BeginInit();
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bmp.StreamSource = stream;
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bmp.CacheOption = BitmapCacheOption.OnLoad;
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bmp.EndInit();
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bmp.Freeze();
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return bmp;
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}
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private void SetImage(ImageSource img)
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{
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_image = img;
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Img.Source = img;
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_fit = true;
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FitToView();
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}
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#endregion
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#region 缩放 / 平移
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/// <summary>适应窗口（只缩小，不放大小图）</summary>
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public void FitToView()
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{
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_fit = true;
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if (_image == null) return;
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double cw = Root.ActualWidth, ch = Root.ActualHeight;
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if (cw <= 0 || ch <= 0 || _image.Width <= 0 || _image.Height <= 0) return;
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CenterAtScale(Math.Min(1.0, Math.Min(cw / _image.Width, ch / _image.Height)));
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}
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/// <summary>按原始大小显示，并将图片几何中心放到视口中心。</summary>
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public void ActualSize()
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{
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CenterAtScale(1.0);
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_fit = false;
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}
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public void ZoomIn() => ZoomAt(ViewCenter, _scale * 1.25);
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public void ZoomOut() => ZoomAt(ViewCenter, _scale / 1.25);
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/// <summary>以 p（控件坐标）为不动点缩放到 newScale</summary>
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private void ZoomAt(Point p, double newScale)
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{
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if (_image == null) return;
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newScale = Math.Max(MinZoom, Math.Min(MaxZoom, newScale));
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double ratio = newScale / _scale;
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_tx = p.X - (p.X - _tx) * ratio;
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_ty = p.Y - (p.Y - _ty) * ratio;
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_scale = newScale;
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_fit = false;
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ApplyTransform();
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}
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/// <summary>按指定比例显示，并将图片几何中心与视口中心对齐。</summary>
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private void CenterAtScale(double newScale)
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{
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if (_image == null) return;
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_scale = Math.Max(MinZoom, Math.Min(MaxZoom, newScale));
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_tx = (Root.ActualWidth - _image.Width * _scale) / 2;
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_ty = (Root.ActualHeight - _image.Height * _scale) / 2;
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ApplyTransform();
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}
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private void ApplyTransform()
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{
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if (_image == null)
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{
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ZoomText.Text = "--";
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return;
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}
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ClampOffset();
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_scaleT.ScaleX = _scaleT.ScaleY = _scale;
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_translateT.X = _tx;
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_translateT.Y = _ty;
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// 缩小用高质量，放大到像素级时用最近邻（能看清像素）
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RenderOptions.SetBitmapScalingMode(Img,
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_scale >= 3 ? BitmapScalingMode.NearestNeighbor :
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_scale < 1 ? BitmapScalingMode.Fant : BitmapScalingMode.Linear);
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ZoomText.Text = $"{_scale * 100:0}%";
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ZoomChanged?.Invoke(this, EventArgs.Empty);
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}
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/// <summary>图片小于视口时居中；大于视口时不允许拖出空白</summary>
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private void ClampOffset()
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{
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double cw = Root.ActualWidth, ch = Root.ActualHeight;
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double w = _image.Width * _scale, h = _image.Height * _scale;
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_tx = w <= cw ? (cw - w) / 2 : Math.Min(0, Math.Max(cw - w, _tx));
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_ty = h <= ch ? (ch - h) / 2 : Math.Min(0, Math.Max(ch - h, _ty));
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}
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#endregion
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#region 事件处理
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private void Root_SizeChanged(object sender, SizeChangedEventArgs e)
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{
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if (_image == null) return;
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if (_fit) FitToView();
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else ApplyTransform();
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}
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private void Root_MouseWheel(object sender, MouseWheelEventArgs e)
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{
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if (_image == null) return;
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double factor = Math.Pow(1.001, e.Delta); // 一格滚轮约 ×1.13，触摸板更平滑
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ZoomAt(e.GetPosition(Root), _scale * factor);
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e.Handled = true;
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}
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private void Root_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
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{
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if (_image == null) return;
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if (e.ClickCount == 2) // 双击：适应窗口 <-> 100%
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{
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if (_fit) ZoomAt(e.GetPosition(Root), 1.0);
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else FitToView();
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return;
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}
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_dragging = true;
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_lastPos = e.GetPosition(Root);
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Root.CaptureMouse();
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Root.Cursor = Cursors.SizeAll;
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}
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private void Root_MouseMove(object sender, MouseEventArgs e)
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{
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if (!_dragging) return;
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var pos = e.GetPosition(Root);
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_tx += pos.X - _lastPos.X;
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_ty += pos.Y - _lastPos.Y;
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_lastPos = pos;
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_fit = false;
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ApplyTransform();
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}
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private void Root_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) => EndDrag();
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private void Root_LostMouseCapture(object sender, MouseEventArgs e) => EndDrag();
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private void EndDrag()
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{
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if (!_dragging) return;
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_dragging = false;
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Root.ReleaseMouseCapture();
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Root.Cursor = null;
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}
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private void ZoomIn_Click(object sender, RoutedEventArgs e) => ZoomIn();
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private void ZoomOut_Click(object sender, RoutedEventArgs e) => ZoomOut();
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private void Fit_Click(object sender, RoutedEventArgs e) => FitToView();
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private void Actual_Click(object sender, RoutedEventArgs e) => ActualSize();
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#endregion
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} |