source: branches/2929_PrioritizedGrammarEnumeration/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Folding/FoldingMargin.cs

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
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// 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
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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.TextFormatting;
using ICSharpCode.AvalonEdit.Editing;
using ICSharpCode.AvalonEdit.Rendering;
using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.Folding
{
  /// <summary>
  /// A margin that shows markers for foldings and allows to expand/collapse the foldings.
  /// </summary>
  public class FoldingMargin : AbstractMargin
  {
    /// <summary>
    /// Gets/Sets the folding manager from which the foldings should be shown.
    /// </summary>
    public FoldingManager FoldingManager { get; set; }
    
    internal const double SizeFactor = Constants.PixelPerPoint;
    
    #region Brushes
    /// <summary>
    /// FoldingMarkerBrush dependency property.
    /// </summary>
    public static readonly DependencyProperty FoldingMarkerBrushProperty =
      DependencyProperty.RegisterAttached("FoldingMarkerBrush", typeof(Brush), typeof(FoldingMargin),
                                          new FrameworkPropertyMetadata(Brushes.Gray, FrameworkPropertyMetadataOptions.Inherits, OnUpdateBrushes));
    
    /// <summary>
    /// Gets/sets the Brush used for displaying the lines of folding markers.
    /// </summary>
    public Brush FoldingMarkerBrush {
      get { return (Brush)GetValue(FoldingMarkerBrushProperty); }
      set { SetValue(FoldingMarkerBrushProperty, value); }
    }
    
    /// <summary>
    /// FoldingMarkerBackgroundBrush dependency property.
    /// </summary>
    public static readonly DependencyProperty FoldingMarkerBackgroundBrushProperty =
      DependencyProperty.RegisterAttached("FoldingMarkerBackgroundBrush", typeof(Brush), typeof(FoldingMargin),
                                          new FrameworkPropertyMetadata(Brushes.White, FrameworkPropertyMetadataOptions.Inherits, OnUpdateBrushes));
    
    /// <summary>
    /// Gets/sets the Brush used for displaying the background of folding markers.
    /// </summary>
    public Brush FoldingMarkerBackgroundBrush {
      get { return (Brush)GetValue(FoldingMarkerBackgroundBrushProperty); }
      set { SetValue(FoldingMarkerBackgroundBrushProperty, value); }
    }
    
    /// <summary>
    /// SelectedFoldingMarkerBrush dependency property.
    /// </summary>
    public static readonly DependencyProperty SelectedFoldingMarkerBrushProperty =
      DependencyProperty.RegisterAttached("SelectedFoldingMarkerBrush",
                                          typeof(Brush), typeof(FoldingMargin),
                                          new FrameworkPropertyMetadata(Brushes.Black, FrameworkPropertyMetadataOptions.Inherits, OnUpdateBrushes));
    
    /// <summary>
    /// Gets/sets the Brush used for displaying the lines of selected folding markers.
    /// </summary>
    public Brush SelectedFoldingMarkerBrush {
      get { return (Brush)GetValue(SelectedFoldingMarkerBrushProperty); }
      set { SetValue(SelectedFoldingMarkerBrushProperty, value); }
    }
    
    /// <summary>
    /// SelectedFoldingMarkerBackgroundBrush dependency property.
    /// </summary>
    public static readonly DependencyProperty SelectedFoldingMarkerBackgroundBrushProperty =
      DependencyProperty.RegisterAttached("SelectedFoldingMarkerBackgroundBrush",
                                          typeof(Brush), typeof(FoldingMargin),
                                          new FrameworkPropertyMetadata(Brushes.White, FrameworkPropertyMetadataOptions.Inherits, OnUpdateBrushes));
    
    /// <summary>
    /// Gets/sets the Brush used for displaying the background of selected folding markers.
    /// </summary>
    public Brush SelectedFoldingMarkerBackgroundBrush {
      get { return (Brush)GetValue(SelectedFoldingMarkerBackgroundBrushProperty); }
      set { SetValue(SelectedFoldingMarkerBackgroundBrushProperty, value); }
    }
    
    static void OnUpdateBrushes(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
      FoldingMargin m = null;
      if (d is FoldingMargin)
        m = (FoldingMargin)d;
      else if (d is TextEditor)
        m = ((TextEditor)d).TextArea.LeftMargins.FirstOrDefault(c => c is FoldingMargin) as FoldingMargin;
      if (m == null) return;
      if (e.Property.Name == FoldingMarkerBrushProperty.Name)
        m.foldingControlPen = MakeFrozenPen((Brush)e.NewValue);
      if (e.Property.Name == SelectedFoldingMarkerBrushProperty.Name)
        m.selectedFoldingControlPen = MakeFrozenPen((Brush)e.NewValue);
    }
    #endregion
    
    /// <inheritdoc/>
    protected override Size MeasureOverride(Size availableSize)
    {
      foreach (FoldingMarginMarker m in markers) {
        m.Measure(availableSize);
      }
      double width = SizeFactor * (double)GetValue(TextBlock.FontSizeProperty);
      return new Size(PixelSnapHelpers.RoundToOdd(width, PixelSnapHelpers.GetPixelSize(this).Width), 0);
    }
    
    /// <inheritdoc/>
    protected override Size ArrangeOverride(Size finalSize)
    {
      Size pixelSize = PixelSnapHelpers.GetPixelSize(this);
      foreach (FoldingMarginMarker m in markers) {
        int visualColumn = m.VisualLine.GetVisualColumn(m.FoldingSection.StartOffset - m.VisualLine.FirstDocumentLine.Offset);
        TextLine textLine = m.VisualLine.GetTextLine(visualColumn);
        double yPos = m.VisualLine.GetTextLineVisualYPosition(textLine, VisualYPosition.TextMiddle) - TextView.VerticalOffset;
        yPos -= m.DesiredSize.Height / 2;
        double xPos = (finalSize.Width - m.DesiredSize.Width) / 2;
        m.Arrange(new Rect(PixelSnapHelpers.Round(new Point(xPos, yPos), pixelSize), m.DesiredSize));
      }
      return base.ArrangeOverride(finalSize);
    }
    
    /// <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;
      }
      TextViewVisualLinesChanged(null, null);
    }
    
    List<FoldingMarginMarker> markers = new List<FoldingMarginMarker>();
    
    void TextViewVisualLinesChanged(object sender, EventArgs e)
    {
      foreach (FoldingMarginMarker m in markers) {
        RemoveVisualChild(m);
      }
      markers.Clear();
      InvalidateVisual();
      if (TextView != null && FoldingManager != null && TextView.VisualLinesValid) {
        foreach (VisualLine line in TextView.VisualLines) {
          FoldingSection fs = FoldingManager.GetNextFolding(line.FirstDocumentLine.Offset);
          if (fs == null)
            continue;
          if (fs.StartOffset <= line.LastDocumentLine.Offset + line.LastDocumentLine.Length) {
            FoldingMarginMarker m = new FoldingMarginMarker {
              IsExpanded = !fs.IsFolded,
              VisualLine = line,
              FoldingSection = fs
            };
            
            markers.Add(m);
            AddVisualChild(m);
            
            m.IsMouseDirectlyOverChanged += delegate { InvalidateVisual(); };
            
            InvalidateMeasure();
            continue;
          }
        }
      }
    }
    
    /// <inheritdoc/>
    protected override int VisualChildrenCount {
      get { return markers.Count; }
    }
    
    /// <inheritdoc/>
    protected override Visual GetVisualChild(int index)
    {
      return markers[index];
    }
    
    Pen foldingControlPen = MakeFrozenPen((Brush)FoldingMarkerBrushProperty.DefaultMetadata.DefaultValue);
    Pen selectedFoldingControlPen = MakeFrozenPen((Brush)SelectedFoldingMarkerBrushProperty.DefaultMetadata.DefaultValue);
    
    static Pen MakeFrozenPen(Brush brush)
    {
      Pen pen = new Pen(brush, 1);
      pen.Freeze();
      return pen;
    }
    
    /// <inheritdoc/>
    protected override void OnRender(DrawingContext drawingContext)
    {
      if (TextView == null || !TextView.VisualLinesValid)
        return;
      if (TextView.VisualLines.Count == 0 || FoldingManager == null)
        return;
      
      var allTextLines = TextView.VisualLines.SelectMany(vl => vl.TextLines).ToList();
      Pen[] colors = new Pen[allTextLines.Count + 1];
      Pen[] endMarker = new Pen[allTextLines.Count];
      
      CalculateFoldLinesForFoldingsActiveAtStart(allTextLines, colors, endMarker);
      CalculateFoldLinesForMarkers(allTextLines, colors, endMarker);
      DrawFoldLines(drawingContext, colors, endMarker);
      
      base.OnRender(drawingContext);
    }

    /// <summary>
    /// Calculates fold lines for all folding sections that start in front of the current view
    /// and run into the current view.
    /// </summary>
    void CalculateFoldLinesForFoldingsActiveAtStart(List<TextLine> allTextLines, Pen[] colors, Pen[] endMarker)
    {
      int viewStartOffset = TextView.VisualLines[0].FirstDocumentLine.Offset;
      int viewEndOffset = TextView.VisualLines.Last().LastDocumentLine.EndOffset;
      var foldings = FoldingManager.GetFoldingsContaining(viewStartOffset);
      int maxEndOffset = 0;
      foreach (FoldingSection fs in foldings) {
        int end = fs.EndOffset;
        if (end <= viewEndOffset && !fs.IsFolded) {
          int textLineNr = GetTextLineIndexFromOffset(allTextLines, end);
          if (textLineNr >= 0) {
            endMarker[textLineNr] = foldingControlPen;
          }
        }
        if (end > maxEndOffset && fs.StartOffset < viewStartOffset) {
          maxEndOffset = end;
        }
      }
      if (maxEndOffset > 0) {
        if (maxEndOffset > viewEndOffset) {
          for (int i = 0; i < colors.Length; i++) {
            colors[i] = foldingControlPen;
          }
        } else {
          int maxTextLine = GetTextLineIndexFromOffset(allTextLines, maxEndOffset);
          for (int i = 0; i <= maxTextLine; i++) {
            colors[i] = foldingControlPen;
          }
        }
      }
    }
    
    /// <summary>
    /// Calculates fold lines for all folding sections that start inside the current view
    /// </summary>
    void CalculateFoldLinesForMarkers(List<TextLine> allTextLines, Pen[] colors, Pen[] endMarker)
    {
      foreach (FoldingMarginMarker marker in markers) {
        int end = marker.FoldingSection.EndOffset;
        int endTextLineNr = GetTextLineIndexFromOffset(allTextLines, end);
        if (!marker.FoldingSection.IsFolded && endTextLineNr >= 0) {
          if (marker.IsMouseDirectlyOver)
            endMarker[endTextLineNr] = selectedFoldingControlPen;
          else if (endMarker[endTextLineNr] == null)
            endMarker[endTextLineNr] = foldingControlPen;
        }
        int startTextLineNr = GetTextLineIndexFromOffset(allTextLines, marker.FoldingSection.StartOffset);
        if (startTextLineNr >= 0) {
          for (int i = startTextLineNr + 1; i < colors.Length && i - 1 != endTextLineNr; i++) {
            if (marker.IsMouseDirectlyOver)
              colors[i] = selectedFoldingControlPen;
            else if (colors[i] == null)
              colors[i] = foldingControlPen;
          }
        }
      }
    }
    
    /// <summary>
    /// Draws the lines for the folding sections (vertical line with 'color', horizontal lines with 'endMarker')
    /// Each entry in the input arrays corresponds to one TextLine.
    /// </summary>
    void DrawFoldLines(DrawingContext drawingContext, Pen[] colors, Pen[] endMarker)
    {
      // Because we are using PenLineCap.Flat (the default), for vertical lines,
      // Y coordinates must be on pixel boundaries, whereas the X coordinate must be in the
      // middle of a pixel. (and the other way round for horizontal lines)
      Size pixelSize = PixelSnapHelpers.GetPixelSize(this);
      double markerXPos = PixelSnapHelpers.PixelAlign(RenderSize.Width / 2, pixelSize.Width);
      double startY = 0;
      Pen currentPen = colors[0];
      int tlNumber = 0;
      foreach (VisualLine vl in TextView.VisualLines) {
        foreach (TextLine tl in vl.TextLines) {
          if (endMarker[tlNumber] != null) {
            double visualPos = GetVisualPos(vl, tl, pixelSize.Height);
            drawingContext.DrawLine(endMarker[tlNumber], new Point(markerXPos - pixelSize.Width / 2, visualPos), new Point(RenderSize.Width, visualPos));
          }
          if (colors[tlNumber + 1] != currentPen) {
            double visualPos = GetVisualPos(vl, tl, pixelSize.Height);
            if (currentPen != null) {
              drawingContext.DrawLine(currentPen, new Point(markerXPos, startY + pixelSize.Height / 2), new Point(markerXPos, visualPos - pixelSize.Height / 2));
            }
            currentPen = colors[tlNumber + 1];
            startY = visualPos;
          }
          tlNumber++;
        }
      }
      if (currentPen != null) {
        drawingContext.DrawLine(currentPen, new Point(markerXPos, startY + pixelSize.Height / 2), new Point(markerXPos, RenderSize.Height));
      }
    }
    
    double GetVisualPos(VisualLine vl, TextLine tl, double pixelHeight)
    {
      double pos = vl.GetTextLineVisualYPosition(tl, VisualYPosition.TextMiddle) - TextView.VerticalOffset;
      return PixelSnapHelpers.PixelAlign(pos, pixelHeight);
    }
    
    int GetTextLineIndexFromOffset(List<TextLine> textLines, int offset)
    {
      int lineNumber = TextView.Document.GetLineByOffset(offset).LineNumber;
      VisualLine vl = TextView.GetVisualLine(lineNumber);
      if (vl != null) {
        int relOffset = offset - vl.FirstDocumentLine.Offset;
        TextLine line = vl.GetTextLine(vl.GetVisualColumn(relOffset));
        return textLines.IndexOf(line);
      }
      return -1;
    }
  }
}