source: trunk/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Editing/Caret.cs @ 18209

// 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.Diagnostics;
using System.Linq;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Media;
using System.Windows.Media.TextFormatting;
using System.Windows.Threading;
using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Rendering;
using ICSharpCode.AvalonEdit.Utils;
#if NREFACTORY
using ICSharpCode.NRefactory;
using ICSharpCode.NRefactory.Editor;
#endif

namespace ICSharpCode.AvalonEdit.Editing
{
  /// <summary>
  /// Helper class with caret-related methods.
  /// </summary>
  public sealed class Caret
  {
    readonly TextArea textArea;
    readonly TextView textView;
    readonly CaretLayer caretAdorner;
    bool visible;
    
    internal Caret(TextArea textArea)
    {
      this.textArea = textArea;
      this.textView = textArea.TextView;
      position = new TextViewPosition(1, 1, 0);
      
      caretAdorner = new CaretLayer(textArea);
      textView.InsertLayer(caretAdorner, KnownLayer.Caret, LayerInsertionPosition.Replace);
      textView.VisualLinesChanged += TextView_VisualLinesChanged;
      textView.ScrollOffsetChanged += TextView_ScrollOffsetChanged;
    }
    
    internal void UpdateIfVisible()
    {
      if (visible) {
        Show();
      }
    }
    
    void TextView_VisualLinesChanged(object sender, EventArgs e)
    {
      if (visible) {
        Show();
      }
      // required because the visual columns might have changed if the
      // element generators did something differently than on the last run
      // (e.g. a FoldingSection was collapsed)
      InvalidateVisualColumn();
    }
    
    void TextView_ScrollOffsetChanged(object sender, EventArgs e)
    {
      if (caretAdorner != null) {
        caretAdorner.InvalidateVisual();
      }
    }
    
    double desiredXPos = double.NaN;
    TextViewPosition position;
    
    /// <summary>
    /// Gets/Sets the position of the caret.
    /// Retrieving this property will validate the visual column (which can be expensive).
    /// Use the <see cref="Location"/> property instead if you don't need the visual column.
    /// </summary>
    public TextViewPosition Position {
      get {
        ValidateVisualColumn();
        return position;
      }
      set {
        if (position != value) {
          position = value;
          
          storedCaretOffset = -1;
          
          //Debug.WriteLine("Caret position changing to " + value);
          
          ValidatePosition();
          InvalidateVisualColumn();
          RaisePositionChanged();
          Log("Caret position changed to " + value);
          if (visible)
            Show();
        }
      }
    }
    
    /// <summary>
    /// Gets the caret position without validating it.
    /// </summary>
    internal TextViewPosition NonValidatedPosition {
      get {
        return position;
      }
    }
    
    /// <summary>
    /// Gets/Sets the location of the caret.
    /// The getter of this property is faster than <see cref="Position"/> because it doesn't have
    /// to validate the visual column.
    /// </summary>
    public TextLocation Location {
      get {
        return position.Location;
      }
      set {
        this.Position = new TextViewPosition(value);
      }
    }
    
    /// <summary>
    /// Gets/Sets the caret line.
    /// </summary>
    public int Line {
      get { return position.Line; }
      set {
        this.Position = new TextViewPosition(value, position.Column);
      }
    }
    
    /// <summary>
    /// Gets/Sets the caret column.
    /// </summary>
    public int Column {
      get { return position.Column; }
      set {
        this.Position = new TextViewPosition(position.Line, value);
      }
    }
    
    /// <summary>
    /// Gets/Sets the caret visual column.
    /// </summary>
    public int VisualColumn {
      get {
        ValidateVisualColumn();
        return position.VisualColumn;
      }
      set {
        this.Position = new TextViewPosition(position.Line, position.Column, value);
      }
    }
    
    bool isInVirtualSpace;
    
    /// <summary>
    /// Gets whether the caret is in virtual space.
    /// </summary>
    public bool IsInVirtualSpace {
      get {
        ValidateVisualColumn();
        return isInVirtualSpace;
      }
    }
    
    int storedCaretOffset;
    
    internal void OnDocumentChanging()
    {
      storedCaretOffset = this.Offset;
      InvalidateVisualColumn();
    }
    
    internal void OnDocumentChanged(DocumentChangeEventArgs e)
    {
      InvalidateVisualColumn();
      if (storedCaretOffset >= 0) {
        // If the caret is at the end of a selection, we don't expand the selection if something
        // is inserted at the end. Thus we also need to keep the caret in front of the insertion.
        AnchorMovementType caretMovementType;
        if (!textArea.Selection.IsEmpty && storedCaretOffset == textArea.Selection.SurroundingSegment.EndOffset)
          caretMovementType = AnchorMovementType.BeforeInsertion;
        else
          caretMovementType = AnchorMovementType.Default;
        int newCaretOffset = e.GetNewOffset(storedCaretOffset, caretMovementType);
        TextDocument document = textArea.Document;
        if (document != null) {
          // keep visual column
          this.Position = new TextViewPosition(document.GetLocation(newCaretOffset), position.VisualColumn);
        }
      }
      storedCaretOffset = -1;
    }
    
    /// <summary>
    /// Gets/Sets the caret offset.
    /// Setting the caret offset has the side effect of setting the <see cref="DesiredXPos"/> to NaN.
    /// </summary>
    public int Offset {
      get {
        TextDocument document = textArea.Document;
        if (document == null) {
          return 0;
        } else {
          return document.GetOffset(position.Location);
        }
      }
      set {
        TextDocument document = textArea.Document;
        if (document != null) {
          this.Position = new TextViewPosition(document.GetLocation(value));
          this.DesiredXPos = double.NaN;
        }
      }
    }
    
    /// <summary>
    /// Gets/Sets the desired x-position of the caret, in device-independent pixels.
    /// This property is NaN if the caret has no desired position.
    /// </summary>
    public double DesiredXPos {
      get { return desiredXPos; }
      set { desiredXPos = value; }
    }
    
    void ValidatePosition()
    {
      if (position.Line < 1)
        position.Line = 1;
      if (position.Column < 1)
        position.Column = 1;
      if (position.VisualColumn < -1)
        position.VisualColumn = -1;
      TextDocument document = textArea.Document;
      if (document != null) {
        if (position.Line > document.LineCount) {
          position.Line = document.LineCount;
          position.Column = document.GetLineByNumber(position.Line).Length + 1;
          position.VisualColumn = -1;
        } else {
          DocumentLine line = document.GetLineByNumber(position.Line);
          if (position.Column > line.Length + 1) {
            position.Column = line.Length + 1;
            position.VisualColumn = -1;
          }
        }
      }
    }
    
    /// <summary>
    /// Event raised when the caret position has changed.
    /// If the caret position is changed inside a document update (between BeginUpdate/EndUpdate calls),
    /// the PositionChanged event is raised only once at the end of the document update.
    /// </summary>
    public event EventHandler PositionChanged;
    
    bool raisePositionChangedOnUpdateFinished;
    
    void RaisePositionChanged()
    {
      if (textArea.Document != null && textArea.Document.IsInUpdate) {
        raisePositionChangedOnUpdateFinished = true;
      } else {
        if (PositionChanged != null) {
          PositionChanged(this, EventArgs.Empty);
        }
      }
    }
    
    internal void OnDocumentUpdateFinished()
    {
      if (raisePositionChangedOnUpdateFinished) {
        if (PositionChanged != null) {
          PositionChanged(this, EventArgs.Empty);
        }
      }
    }
    
    bool visualColumnValid;
    
    void ValidateVisualColumn()
    {
      if (!visualColumnValid) {
        TextDocument document = textArea.Document;
        if (document != null) {
          Debug.WriteLine("Explicit validation of caret column");
          var documentLine = document.GetLineByNumber(position.Line);
          RevalidateVisualColumn(textView.GetOrConstructVisualLine(documentLine));
        }
      }
    }
    
    void InvalidateVisualColumn()
    {
      visualColumnValid = false;
    }
    
    /// <summary>
    /// Validates the visual column of the caret using the specified visual line.
    /// The visual line must contain the caret offset.
    /// </summary>
    void RevalidateVisualColumn(VisualLine visualLine)
    {
      if (visualLine == null)
        throw new ArgumentNullException("visualLine");
      
      // mark column as validated
      visualColumnValid = true;
      
      int caretOffset = textView.Document.GetOffset(position.Location);
      int firstDocumentLineOffset = visualLine.FirstDocumentLine.Offset;
      position.VisualColumn = visualLine.ValidateVisualColumn(position, textArea.Selection.EnableVirtualSpace);
      
      // search possible caret positions
      int newVisualColumnForwards = visualLine.GetNextCaretPosition(position.VisualColumn - 1, LogicalDirection.Forward, CaretPositioningMode.Normal, textArea.Selection.EnableVirtualSpace);
      // If position.VisualColumn was valid, we're done with validation.
      if (newVisualColumnForwards != position.VisualColumn) {
        // also search backwards so that we can pick the better match
        int newVisualColumnBackwards = visualLine.GetNextCaretPosition(position.VisualColumn + 1, LogicalDirection.Backward, CaretPositioningMode.Normal, textArea.Selection.EnableVirtualSpace);
        
        if (newVisualColumnForwards < 0 && newVisualColumnBackwards < 0)
          throw ThrowUtil.NoValidCaretPosition();
        
        // determine offsets for new visual column positions
        int newOffsetForwards;
        if (newVisualColumnForwards >= 0)
          newOffsetForwards = visualLine.GetRelativeOffset(newVisualColumnForwards) + firstDocumentLineOffset;
        else
          newOffsetForwards = -1;
        int newOffsetBackwards;
        if (newVisualColumnBackwards >= 0)
          newOffsetBackwards = visualLine.GetRelativeOffset(newVisualColumnBackwards) + firstDocumentLineOffset;
        else
          newOffsetBackwards = -1;
        
        int newVisualColumn, newOffset;
        // if there's only one valid position, use it
        if (newVisualColumnForwards < 0) {
          newVisualColumn = newVisualColumnBackwards;
          newOffset = newOffsetBackwards;
        } else if (newVisualColumnBackwards < 0) {
          newVisualColumn = newVisualColumnForwards;
          newOffset = newOffsetForwards;
        } else {
          // two valid positions: find the better match
          if (Math.Abs(newOffsetBackwards - caretOffset) < Math.Abs(newOffsetForwards - caretOffset)) {
            // backwards is better
            newVisualColumn = newVisualColumnBackwards;
            newOffset = newOffsetBackwards;
          } else {
            // forwards is better
            newVisualColumn = newVisualColumnForwards;
            newOffset = newOffsetForwards;
          }
        }
        this.Position = new TextViewPosition(textView.Document.GetLocation(newOffset), newVisualColumn);
      }
      isInVirtualSpace = (position.VisualColumn > visualLine.VisualLength);
    }
    
    Rect CalcCaretRectangle(VisualLine visualLine)
    {
      if (!visualColumnValid) {
        RevalidateVisualColumn(visualLine);
      }
      
      TextLine textLine = visualLine.GetTextLine(position.VisualColumn, position.IsAtEndOfLine);
      double xPos = visualLine.GetTextLineVisualXPosition(textLine, position.VisualColumn);
      double lineTop = visualLine.GetTextLineVisualYPosition(textLine, VisualYPosition.TextTop);
      double lineBottom = visualLine.GetTextLineVisualYPosition(textLine, VisualYPosition.TextBottom);
      
      return new Rect(xPos,
                      lineTop,
                      SystemParameters.CaretWidth,
                      lineBottom - lineTop);
    }
    
    Rect CalcCaretOverstrikeRectangle(VisualLine visualLine)
    {
      if (!visualColumnValid) {
        RevalidateVisualColumn(visualLine);
      }
      
      int currentPos = position.VisualColumn;
      // The text being overwritten in overstrike mode is everything up to the next normal caret stop
      int nextPos = visualLine.GetNextCaretPosition(currentPos, LogicalDirection.Forward, CaretPositioningMode.Normal, true);
      TextLine textLine = visualLine.GetTextLine(currentPos);
      
      Rect r;
      if (currentPos < visualLine.VisualLength) {
        // If the caret is within the text, use GetTextBounds() for the text being overwritten.
        // This is necessary to ensure the rectangle is calculated correctly in bidirectional text.
        var textBounds = textLine.GetTextBounds(currentPos, nextPos - currentPos)[0];
        r = textBounds.Rectangle;
        r.Y += visualLine.GetTextLineVisualYPosition(textLine, VisualYPosition.LineTop);
      } else {
        // If the caret is at the end of the line (or in virtual space),
        // use the visual X position of currentPos and nextPos (one or more of which will be in virtual space)
        double xPos = visualLine.GetTextLineVisualXPosition(textLine, currentPos);
        double xPos2 = visualLine.GetTextLineVisualXPosition(textLine, nextPos);
        double lineTop = visualLine.GetTextLineVisualYPosition(textLine, VisualYPosition.TextTop);
        double lineBottom = visualLine.GetTextLineVisualYPosition(textLine, VisualYPosition.TextBottom);
        r = new Rect(xPos, lineTop, xPos2 - xPos, lineBottom - lineTop);
      }
      // If the caret is too small (e.g. in front of zero-width character), ensure it's still visible
      if (r.Width < SystemParameters.CaretWidth)
        r.Width = SystemParameters.CaretWidth;
      return r;
    }
    
    /// <summary>
    /// Returns the caret rectangle. The coordinate system is in device-independent pixels from the top of the document.
    /// </summary>
    public Rect CalculateCaretRectangle()
    {
      if (textView != null && textView.Document != null) {
        VisualLine visualLine = textView.GetOrConstructVisualLine(textView.Document.GetLineByNumber(position.Line));
        return textArea.OverstrikeMode ? CalcCaretOverstrikeRectangle(visualLine) : CalcCaretRectangle(visualLine);
      } else {
        return Rect.Empty;
      }
    }
    
    /// <summary>
    /// Minimum distance of the caret to the view border.
    /// </summary>
    internal const double MinimumDistanceToViewBorder = 30;
    
    /// <summary>
    /// Scrolls the text view so that the caret is visible.
    /// </summary>
    public void BringCaretToView()
    {
      BringCaretToView(MinimumDistanceToViewBorder);
    }
    
    internal void BringCaretToView(double border)
    {
      Rect caretRectangle = CalculateCaretRectangle();
      if (!caretRectangle.IsEmpty) {
        caretRectangle.Inflate(border, border);
        textView.MakeVisible(caretRectangle);
      }
    }
    
    /// <summary>
    /// Makes the caret visible and updates its on-screen position.
    /// </summary>
    public void Show()
    {
      Log("Caret.Show()");
      visible = true;
      if (!showScheduled) {
        showScheduled = true;
        textArea.Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action(ShowInternal));
      }
    }
    
    bool showScheduled;
    bool hasWin32Caret;
    
    void ShowInternal()
    {
      showScheduled = false;
      
      // if show was scheduled but caret hidden in the meantime
      if (!visible)
        return;
      
      if (caretAdorner != null && textView != null) {
        VisualLine visualLine = textView.GetVisualLine(position.Line);
        if (visualLine != null) {
          Rect caretRect = this.textArea.OverstrikeMode ? CalcCaretOverstrikeRectangle(visualLine) : CalcCaretRectangle(visualLine);
          // Create Win32 caret so that Windows knows where our managed caret is. This is necessary for
          // features like 'Follow text editing' in the Windows Magnifier.
          if (!hasWin32Caret) {
            hasWin32Caret = Win32.CreateCaret(textView, caretRect.Size);
          }
          if (hasWin32Caret) {
            Win32.SetCaretPosition(textView, caretRect.Location - textView.ScrollOffset);
          }
          caretAdorner.Show(caretRect);
          textArea.ime.UpdateCompositionWindow();
        } else {
          caretAdorner.Hide();
        }
      }
    }
    
    /// <summary>
    /// Makes the caret invisible.
    /// </summary>
    public void Hide()
    {
      Log("Caret.Hide()");
      visible = false;
      if (hasWin32Caret) {
        Win32.DestroyCaret();
        hasWin32Caret = false;
      }
      if (caretAdorner != null) {
        caretAdorner.Hide();
      }
    }
    
    [Conditional("DEBUG")]
    static void Log(string text)
    {
      // commented out to make debug output less noisy - add back if there are any problems with the caret
      //Debug.WriteLine(text);
    }
    
    /// <summary>
    /// Gets/Sets the color of the caret.
    /// </summary>
    public Brush CaretBrush {
      get { return caretAdorner.CaretBrush; }
      set { caretAdorner.CaretBrush = value; }
    }
  }
}