source: stable/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Editing/LineNumberMargin.cs @ 15377

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

using System;
using System.ComponentModel;
using System.Globalization;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.TextFormatting;

using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Rendering;
using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.Editing
{
  /// <summary>
  /// Margin showing line numbers.
  /// </summary>
  public class LineNumberMargin : AbstractMargin, IWeakEventListener
  {
    static LineNumberMargin()
    {
      DefaultStyleKeyProperty.OverrideMetadata(typeof(LineNumberMargin),
                                               new FrameworkPropertyMetadata(typeof(LineNumberMargin)));
    }
    
    TextArea textArea;
    
    /// <summary>
    /// The typeface used for rendering the line number margin.
    /// This field is calculated in MeasureOverride() based on the FontFamily etc. properties.
    /// </summary>
    protected Typeface typeface;
    
    /// <summary>
    /// The font size used for rendering the line number margin.
    /// This field is calculated in MeasureOverride() based on the FontFamily etc. properties.
    /// </summary>
    protected double emSize;
    
    /// <inheritdoc/>
    protected override Size MeasureOverride(Size availableSize)
    {
      typeface = this.CreateTypeface();
      emSize = (double)GetValue(TextBlock.FontSizeProperty);
      
      FormattedText text = TextFormatterFactory.CreateFormattedText(
        this,
        new string('9', maxLineNumberLength),
        typeface,
        emSize,
        (Brush)GetValue(Control.ForegroundProperty)
      );
      return new Size(text.Width, 0);
    }
    
    /// <inheritdoc/>
    protected override void OnRender(DrawingContext drawingContext)
    {
      TextView textView = this.TextView;
      Size renderSize = this.RenderSize;
      if (textView != null && textView.VisualLinesValid) {
        var foreground = (Brush)GetValue(Control.ForegroundProperty);
        foreach (VisualLine line in textView.VisualLines) {
          int lineNumber = line.FirstDocumentLine.LineNumber;
          FormattedText text = TextFormatterFactory.CreateFormattedText(
            this,
            lineNumber.ToString(CultureInfo.CurrentCulture),
            typeface, emSize, foreground
          );
          double y = line.GetTextLineVisualYPosition(line.TextLines[0], VisualYPosition.TextTop);
          drawingContext.DrawText(text, new Point(renderSize.Width - text.Width, y - textView.VerticalOffset));
        }
      }
    }
    
    /// <inheritdoc/>
    protected override void OnTextViewChanged(TextView oldTextView, TextView newTextView)
    {
      if (oldTextView != null) {
        oldTextView.VisualLinesChanged -= TextViewVisualLinesChanged;
      }
      base.OnTextViewChanged(oldTextView, newTextView);
      if (newTextView != null) {
        newTextView.VisualLinesChanged += TextViewVisualLinesChanged;
        
        // find the text area belonging to the new text view
        textArea = newTextView.GetService(typeof(TextArea)) as TextArea;
      } else {
        textArea = null;
      }
      InvalidateVisual();
    }
    
    /// <inheritdoc/>
    protected override void OnDocumentChanged(TextDocument oldDocument, TextDocument newDocument)
    {
      if (oldDocument != null) {
        PropertyChangedEventManager.RemoveListener(oldDocument, this, "LineCount");
      }
      base.OnDocumentChanged(oldDocument, newDocument);
      if (newDocument != null) {
        PropertyChangedEventManager.AddListener(newDocument, this, "LineCount");
      }
      OnDocumentLineCountChanged();
    }
    
    /// <inheritdoc cref="IWeakEventListener.ReceiveWeakEvent"/>
    protected virtual bool ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
    {
      if (managerType == typeof(PropertyChangedEventManager)) {
        OnDocumentLineCountChanged();
        return true;
      }
      return false;
    }
    
    bool IWeakEventListener.ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
    {
      return ReceiveWeakEvent(managerType, sender, e);
    }
    
    /// <summary>
    /// Maximum length of a line number, in characters
    /// </summary>
    protected int maxLineNumberLength = 1;
    
    void OnDocumentLineCountChanged()
    {
      int documentLineCount = Document != null ? Document.LineCount : 1;
      int newLength = documentLineCount.ToString(CultureInfo.CurrentCulture).Length;
      
      // The margin looks too small when there is only one digit, so always reserve space for
      // at least two digits
      if (newLength < 2)
        newLength = 2;
      
      if (newLength != maxLineNumberLength) {
        maxLineNumberLength = newLength;
        InvalidateMeasure();
      }
    }
    
    void TextViewVisualLinesChanged(object sender, EventArgs e)
    {
      InvalidateVisual();
    }
    
    AnchorSegment selectionStart;
    bool selecting;
    
    /// <inheritdoc/>
    protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
    {
      base.OnMouseLeftButtonDown(e);
      if (!e.Handled && TextView != null && textArea != null) {
        e.Handled = true;
        textArea.Focus();
        
        SimpleSegment currentSeg = GetTextLineSegment(e);
        if (currentSeg == SimpleSegment.Invalid)
          return;
        textArea.Caret.Offset = currentSeg.Offset + currentSeg.Length;
        if (CaptureMouse()) {
          selecting = true;
          selectionStart = new AnchorSegment(Document, currentSeg.Offset, currentSeg.Length);
          if ((Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift) {
            SimpleSelection simpleSelection = textArea.Selection as SimpleSelection;
            if (simpleSelection != null)
              selectionStart = new AnchorSegment(Document, simpleSelection.SurroundingSegment);
          }
          textArea.Selection = Selection.Create(textArea, selectionStart);
          if ((Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift) {
            ExtendSelection(currentSeg);
          }
        }
      }
    }
    
    SimpleSegment GetTextLineSegment(MouseEventArgs e)
    {
      Point pos = e.GetPosition(TextView);
      pos.X = 0;
      pos.Y += TextView.VerticalOffset;
      VisualLine vl = TextView.GetVisualLineFromVisualTop(pos.Y);
      if (vl == null)
        return SimpleSegment.Invalid;
      TextLine tl = vl.GetTextLineByVisualYPosition(pos.Y);
      int visualStartColumn = vl.GetTextLineVisualStartColumn(tl);
      int visualEndColumn = visualStartColumn + tl.Length;
      int relStart = vl.FirstDocumentLine.Offset;
      int startOffset = vl.GetRelativeOffset(visualStartColumn) + relStart;
      int endOffset = vl.GetRelativeOffset(visualEndColumn) + relStart;
      if (endOffset == vl.LastDocumentLine.Offset + vl.LastDocumentLine.Length)
        endOffset += vl.LastDocumentLine.DelimiterLength;
      return new SimpleSegment(startOffset, endOffset - startOffset);
    }
    
    void ExtendSelection(SimpleSegment currentSeg)
    {
      if (currentSeg.Offset < selectionStart.Offset) {
        textArea.Caret.Offset = currentSeg.Offset;
        textArea.Selection = Selection.Create(textArea, currentSeg.Offset, selectionStart.Offset + selectionStart.Length);
      } else {
        textArea.Caret.Offset = currentSeg.Offset + currentSeg.Length;
        textArea.Selection = Selection.Create(textArea, selectionStart.Offset, currentSeg.Offset + currentSeg.Length);
      }
    }
    
    /// <inheritdoc/>
    protected override void OnMouseMove(MouseEventArgs e)
    {
      if (selecting && textArea != null && TextView != null) {
        e.Handled = true;
        SimpleSegment currentSeg = GetTextLineSegment(e);
        if (currentSeg == SimpleSegment.Invalid)
          return;
        ExtendSelection(currentSeg);
      }
      base.OnMouseMove(e);
    }
    
    /// <inheritdoc/>
    protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
    {
      if (selecting) {
        selecting = false;
        selectionStart = null;
        ReleaseMouseCapture();
        e.Handled = true;
      }
      base.OnMouseLeftButtonUp(e);
    }
    
    /// <inheritdoc/>
    protected override HitTestResult HitTestCore(PointHitTestParameters hitTestParameters)
    {
      // accept clicks even when clicking on the background
      return new PointHitTestResult(this, hitTestParameters.HitPoint);
    }
  }
}