253 lines
9.5 KiB
C#
253 lines
9.5 KiB
C#
using System;
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using System.ComponentModel;
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using System.Globalization;
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Media;
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using System.Windows.Threading;
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using System.Windows.Markup;
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using System.Windows.Media.TextFormatting;
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using System.Windows.Media.Imaging;
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using System.Windows.Documents;
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using System.Windows.Input;
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using System.Windows.Shapes;
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using System.Windows.Data;
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using System.Windows.Ink;
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using System.Windows.Interop;
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using System.Windows.Media.Animation;
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using System.Windows.Navigation;
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namespace Ink_Canvas.Helpers
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{
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/// <summary>
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/// 让 TextBlock 在可用宽度不足时自动缩小字号（只缩小不放大），用于避免英文等长文本被截断。
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/// </summary>
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public static class AutoFontSizeHelper
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{
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public static readonly DependencyProperty IsEnabledProperty =
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DependencyProperty.RegisterAttached(
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"IsEnabled",
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typeof(bool),
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typeof(AutoFontSizeHelper),
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new PropertyMetadata(false, OnIsEnabledChanged));
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public static void SetIsEnabled(DependencyObject element, bool value) => element.SetValue(IsEnabledProperty, value);
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public static bool GetIsEnabled(DependencyObject element) => (bool)element.GetValue(IsEnabledProperty);
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public static readonly DependencyProperty MinFontSizeProperty =
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DependencyProperty.RegisterAttached(
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"MinFontSize",
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typeof(double),
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typeof(AutoFontSizeHelper),
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new PropertyMetadata(6d, OnSizingPropertyChanged));
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public static void SetMinFontSize(DependencyObject element, double value) => element.SetValue(MinFontSizeProperty, value);
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public static double GetMinFontSize(DependencyObject element) => (double)element.GetValue(MinFontSizeProperty);
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public static readonly DependencyProperty MaxFontSizeProperty =
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DependencyProperty.RegisterAttached(
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"MaxFontSize",
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typeof(double),
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typeof(AutoFontSizeHelper),
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new PropertyMetadata(double.NaN, OnSizingPropertyChanged));
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public static void SetMaxFontSize(DependencyObject element, double value) => element.SetValue(MaxFontSizeProperty, value);
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public static double GetMaxFontSize(DependencyObject element) => (double)element.GetValue(MaxFontSizeProperty);
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public static readonly DependencyProperty StepProperty =
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DependencyProperty.RegisterAttached(
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"Step",
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typeof(double),
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typeof(AutoFontSizeHelper),
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new PropertyMetadata(0.5d, OnSizingPropertyChanged));
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public static void SetStep(DependencyObject element, double value) => element.SetValue(StepProperty, value);
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public static double GetStep(DependencyObject element) => (double)element.GetValue(StepProperty);
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private static readonly DependencyProperty IsAdjustingProperty =
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DependencyProperty.RegisterAttached(
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"IsAdjusting",
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typeof(bool),
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typeof(AutoFontSizeHelper),
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new PropertyMetadata(false));
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private static void SetIsAdjusting(DependencyObject element, bool value) => element.SetValue(IsAdjustingProperty, value);
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private static bool GetIsAdjusting(DependencyObject element) => (bool)element.GetValue(IsAdjustingProperty);
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private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
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{
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var tb = d as TextBlock;
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if (tb == null) return;
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if ((bool)e.NewValue)
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{
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tb.SizeChanged += TextBlock_OnSizeChanged;
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tb.Loaded += TextBlock_OnLoaded;
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tb.Unloaded += TextBlock_OnUnloaded;
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try
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{
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var dpd = DependencyPropertyDescriptor.FromProperty(TextBlock.TextProperty, typeof(TextBlock));
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dpd?.AddValueChanged(tb, TextBlock_OnTextChanged);
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}
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catch
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{
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// 忽略：极端情况下 descriptor 可能不可用
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}
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// 让第一次布局完成后再做一次调整（避免 ActualWidth=0）
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tb.Dispatcher.BeginInvoke(new Action(() => TryAdjust(tb)), DispatcherPriority.Loaded);
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}
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else
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{
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tb.SizeChanged -= TextBlock_OnSizeChanged;
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tb.Loaded -= TextBlock_OnLoaded;
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tb.Unloaded -= TextBlock_OnUnloaded;
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try
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{
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var dpd = DependencyPropertyDescriptor.FromProperty(TextBlock.TextProperty, typeof(TextBlock));
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dpd?.RemoveValueChanged(tb, TextBlock_OnTextChanged);
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}
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catch
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{
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}
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}
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}
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private static void OnSizingPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
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{
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if (d is TextBlock tb && GetIsEnabled(tb))
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{
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tb.Dispatcher.BeginInvoke(new Action(() => TryAdjust(tb)), DispatcherPriority.Loaded);
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}
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}
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private static void TextBlock_OnLoaded(object sender, RoutedEventArgs e)
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{
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if (sender is TextBlock tb) tb.Dispatcher.BeginInvoke(new Action(() => TryAdjust(tb)), DispatcherPriority.Loaded);
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}
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private static void TextBlock_OnUnloaded(object sender, RoutedEventArgs e)
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{
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// 这里不做额外处理；事件解绑由 IsEnabled 关闭或对象销毁处理
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}
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private static void TextBlock_OnSizeChanged(object sender, SizeChangedEventArgs e)
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{
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if (sender is TextBlock tb) TryAdjust(tb);
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}
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private static void TextBlock_OnTextChanged(object sender, EventArgs e)
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{
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if (sender is TextBlock tb) tb.Dispatcher.BeginInvoke(new Action(() => TryAdjust(tb)), DispatcherPriority.Loaded);
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}
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private static void TryAdjust(TextBlock tb)
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{
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if (tb == null) return;
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if (!GetIsEnabled(tb)) return;
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if (GetIsAdjusting(tb)) return;
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// 没有可用宽度时跳过
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var availableWidth = tb.ActualWidth;
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if (double.IsNaN(availableWidth) || availableWidth <= 1) return;
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// 文本为空时不需要调整
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var text = tb.Text;
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if (string.IsNullOrEmpty(text)) return;
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var min = GetMinFontSize(tb);
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if (double.IsNaN(min) || min <= 0) min = 6d;
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var step = GetStep(tb);
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if (double.IsNaN(step) || step <= 0.01) step = 0.5d;
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var max = GetMaxFontSize(tb);
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if (double.IsNaN(max) || max <= 0)
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{
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max = tb.FontSize;
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}
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if (double.IsNaN(max) || max <= 0) return;
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// 只做“缩小不放大”
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var startFont = Math.Min(tb.FontSize, max);
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if (startFont < min) startFont = min;
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SetIsAdjusting(tb, true);
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try
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{
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// 如果当前已合适，直接回到 max（但不超过原本 fontSize），避免之前缩小后再变短不恢复
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// 注意：恢复也只在不超过 max 的范围内
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var desiredAtMax = MeasureTextWidth(tb, text, max);
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if (desiredAtMax > 0 && desiredAtMax <= availableWidth + 0.5)
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{
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if (tb.FontSize != max) tb.FontSize = max;
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return;
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}
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double font = startFont;
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double desired = MeasureTextWidth(tb, text, font);
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if (desired <= 0) return;
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// 逐步减小直到适配或触底
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while (font > min && desired > availableWidth + 0.5)
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{
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font = Math.Max(min, font - step);
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desired = MeasureTextWidth(tb, text, font);
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if (desired <= 0) break;
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}
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if (!double.IsNaN(font) && font > 0 && Math.Abs(tb.FontSize - font) > 0.01)
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{
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tb.FontSize = font;
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}
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}
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finally
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{
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SetIsAdjusting(tb, false);
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}
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}
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private static double MeasureTextWidth(TextBlock tb, string text, double fontSize)
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{
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try
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{
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var dpi = VisualTreeHelper.GetDpi(tb);
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var culture = CultureInfo.CurrentUICulture;
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// 使用 TextBlock 自身的语言/流向
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if (tb.Language != null)
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{
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try
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{
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culture = tb.Language.GetEquivalentCulture();
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}
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catch
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{
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}
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}
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var typeface = new Typeface(tb.FontFamily, tb.FontStyle, tb.FontWeight, tb.FontStretch);
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var formatted = new FormattedText(
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text,
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culture,
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tb.FlowDirection,
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typeface,
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fontSize,
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tb.Foreground,
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dpi.PixelsPerDip);
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// 这里用包含尾随空白的宽度更接近实际布局
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return formatted.WidthIncludingTrailingWhitespace;
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}
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catch
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{
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return -1;
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}
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}
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}
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}
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