source: stable/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Editing/CaretLayer.cs @ 13397

// 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.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Threading;

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

namespace ICSharpCode.AvalonEdit.Editing
{
  sealed class CaretLayer : Layer
  {
    TextArea textArea;
    
    bool isVisible;
    Rect caretRectangle;
    
    DispatcherTimer caretBlinkTimer = new DispatcherTimer();
    bool blink;
    
    public CaretLayer(TextArea textArea) : base(textArea.TextView, KnownLayer.Caret)
    {
      this.textArea = textArea;
      this.IsHitTestVisible = false;
      caretBlinkTimer.Tick += new EventHandler(caretBlinkTimer_Tick);
    }

    void caretBlinkTimer_Tick(object sender, EventArgs e)
    {
      blink = !blink;
      InvalidateVisual();
    }
    
    public void Show(Rect caretRectangle)
    {
      this.caretRectangle = caretRectangle;
      this.isVisible = true;
      StartBlinkAnimation();
      InvalidateVisual();
    }
    
    public void Hide()
    {
      if (isVisible) {
        isVisible = false;
        StopBlinkAnimation();
        InvalidateVisual();
      }
    }
    
    void StartBlinkAnimation()
    {
      TimeSpan blinkTime = Win32.CaretBlinkTime;
      blink = true; // the caret should visible initially
      // This is important if blinking is disabled (system reports a negative blinkTime)
      if (blinkTime.TotalMilliseconds > 0) {
        caretBlinkTimer.Interval = blinkTime;
        caretBlinkTimer.Start();
      }
    }
    
    void StopBlinkAnimation()
    {
      caretBlinkTimer.Stop();
    }
    
    internal Brush CaretBrush;
    
    protected override void OnRender(DrawingContext drawingContext)
    {
      base.OnRender(drawingContext);
      if (isVisible && blink) {
        Brush caretBrush = this.CaretBrush;
        if (caretBrush == null)
          caretBrush = (Brush)textView.GetValue(TextBlock.ForegroundProperty);
        
        if (this.textArea.OverstrikeMode) {
          SolidColorBrush scBrush = caretBrush as SolidColorBrush;
          if (scBrush != null) {
            Color brushColor = scBrush.Color;
            Color newColor = Color.FromArgb(100, brushColor.R, brushColor.G, brushColor.B);
            caretBrush = new SolidColorBrush(newColor);
            caretBrush.Freeze();
          }
        }
        
        Rect r = new Rect(caretRectangle.X - textView.HorizontalOffset,
                          caretRectangle.Y - textView.VerticalOffset,
                          caretRectangle.Width,
                          caretRectangle.Height);
        drawingContext.DrawRectangle(caretBrush, null, PixelSnapHelpers.Round(r, PixelSnapHelpers.GetPixelSize(this)));
      }
    }
  }
}