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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
// Description:
// ErasingBehavior for Ink
// Features:
//
using System.Windows.Input;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Ink;
using System.Windows.Media;
namespace MS.Internal.Ink
{
/// <summary>
/// Eraser Behavior
/// </summary>
internal sealed class EraserBehavior : StylusEditingBehavior
{
//-------------------------------------------------------------------------------
//
// Constructors
//
//-------------------------------------------------------------------------------
#region Constructors
internal EraserBehavior(EditingCoordinator editingCoordinator, InkCanvas inkCanvas)
: base(editingCoordinator, inkCanvas)
{
}
#endregion Constructors
//-------------------------------------------------------------------------------
//
// Protected Methods
//
//-------------------------------------------------------------------------------
#region Protected Methods
/// <summary>
/// Overrides SwitchToMode as the following expectations
/// 19. From EraseByPoint To InkAndGesture
/// After mode change ink is being collected. On StylusUp gesture event fires. If it’s not a gesture, StrokeCollected event fires.
/// 20. From EraseByPoint To GestureOnly
/// After mode change ink is being collected. On StylusUp gesture event fires. Stroke gets removed on StylusUp even if it’s not a gesture.
/// 21. From EraseByPoint To Ink
/// Ink collection starts when changing the mode.
/// 22. From EraseByPoint To EraseByStroke
/// After mode change StrokeErasing is performed.
/// 23. From EraseByPoint To Select
/// Lasso is drawn for all packets between StylusDown and StylusUp. Strokes/elements within the lasso will be selected.
/// 24. From EraseByPoint To None
/// No erasing is performed after mode change.
/// 25. From EraseByStroke To InkAndGesture
/// After mode change ink is being collected. On StylusUp gesture event fires. If it’s not a gesture, StrokeCollected event fires.
/// 26. From EraseByStroke To GestureOnly
/// After mode change ink is being collected. On StylusUp gesture event fires. Stroke gets removed on StylusUp even if it’s not a gesture.
/// 27. From EraseByStroke To EraseByPoint
/// After mode change PointErasing is performed.
/// 28. From EraseByStroke To Ink
/// Ink collection starts when changing the mode.
/// 29. From EraseByStroke To Select
/// Lasso is drawn for all packets between StylusDown and StylusUp. Strokes/elements within the lasso will be selected
/// 30. From EraseByStroke To None
/// No erasing is performed after mode change.
/// </summary>
/// <param name="mode"></param>
protected override void OnSwitchToMode(InkCanvasEditingMode mode)
{
Debug.Assert(EditingCoordinator.IsInMidStroke, "SwitchToMode should only be called in a mid-stroke");
switch ( mode )
{
case InkCanvasEditingMode.Ink:
case InkCanvasEditingMode.InkAndGesture:
case InkCanvasEditingMode.GestureOnly:
{
// Commit the current behavior
Commit(true);
// Change the mode. The dynamic renderer will be reset automatically.
EditingCoordinator.ChangeStylusEditingMode(this, mode);
break;
}
case InkCanvasEditingMode.EraseByPoint:
case InkCanvasEditingMode.EraseByStroke:
{
Debug.Assert(_cachedEraseMode != mode);
// Commit the current behavior
Commit(true);
// Change the mode
EditingCoordinator.ChangeStylusEditingMode(this, mode);
break;
}
case InkCanvasEditingMode.Select:
{
// Make a copy of the current cached points.
StylusPointCollection cachedPoints = _stylusPoints != null ?
_stylusPoints.Clone() : null;
// Commit the current behavior.
Commit(true);
// Change the Select mode
IStylusEditing newBehavior = EditingCoordinator.ChangeStylusEditingMode(this, mode);
if ( cachedPoints != null
// NOTICE-2006/04/27-WAYNEZEN,
// EditingCoordinator.ChangeStylusEditingMode raises external event.
// The user code could take any arbitrary action for instance calling InkCanvas.ReleaseMouseCapture()
// So there is no guarantee that we could receive the newBehavior.
&& newBehavior != null )
{
// Now add the previous points to the lasso behavior
newBehavior.AddStylusPoints(cachedPoints, false/*userInitiated*/);
}
break;
}
case InkCanvasEditingMode.None:
{
// Discard the collected ink.
Commit(true);
// Change to the None mode
EditingCoordinator.ChangeStylusEditingMode(this, mode);
break;
}
default:
Debug.Assert(false, "Unknown InkCanvasEditingMode!");
break;
}
}
protected override void OnActivate()
{
base.OnActivate();
InkCanvasEditingMode newEraseMode = EditingCoordinator.ActiveEditingMode;
Debug.Assert(newEraseMode == InkCanvasEditingMode.EraseByPoint
|| newEraseMode == InkCanvasEditingMode.EraseByStroke);
// Check whether we have to update cursor.
if ( _cachedEraseMode != newEraseMode )
{
// EraseMode is changed
_cachedEraseMode = newEraseMode;
EditingCoordinator.InvalidateBehaviorCursor(this);
}
else if ( newEraseMode == InkCanvasEditingMode.EraseByPoint )
{
// Invalidate the PointEraser if we don't have the cache yet.
bool isPointEraserCursorValid = _cachedStylusShape != null;
//
// If the cached EraserShape is different from the current EraserShape, we shoud just reset the cache.
// The new cursor will be generated when it's needed later.
if ( isPointEraserCursorValid
&& ( _cachedStylusShape.Width != InkCanvas.EraserShape.Width
|| _cachedStylusShape.Height != InkCanvas.EraserShape.Height
|| _cachedStylusShape.Rotation != InkCanvas.EraserShape.Rotation
|| _cachedStylusShape.GetType() != InkCanvas.EraserShape.GetType()) )
{
Debug.Assert(_cachedPointEraserCursor != null, "_cachedPointEraserCursor shouldn't be null.");
ResetCachedPointEraserCursor();
isPointEraserCursorValid = false;
}
if ( !isPointEraserCursorValid )
{
// EraserShape is changed when the new mode is EraseByPoint
EditingCoordinator.InvalidateBehaviorCursor(this);
}
}
}
/// <summary>
/// StylusInputBegin
/// </summary>
/// <param name="stylusPoints">stylusPoints</param>
/// <param name="userInitiated">true if the source eventArgs.UserInitiated flag was set to true</param>
protected override void StylusInputBegin(StylusPointCollection stylusPoints, bool userInitiated)
{
//
// get a disposable dynamic hit-tester and add event handler
//
_incrementalStrokeHitTester =
this.InkCanvas.Strokes.GetIncrementalStrokeHitTester(this.InkCanvas.EraserShape);
if ( InkCanvasEditingMode.EraseByPoint == _cachedEraseMode )
{
_incrementalStrokeHitTester.StrokeHit += new StrokeHitEventHandler(OnPointEraseResultChanged);
}
else
{
//we're in stroke hit test mode
_incrementalStrokeHitTester.StrokeHit += new StrokeHitEventHandler(OnStrokeEraseResultChanged);
}
_stylusPoints = new StylusPointCollection(stylusPoints.Description, 100);
_stylusPoints.Add(stylusPoints);
//
// start erasing
//
_incrementalStrokeHitTester.AddPoints(stylusPoints);
//
// Since InkCanvas will ignore the animated tranforms when it receives the property changes.
// So we should update our cursor when the stylus is down if there are animated transforms applied to InkCanvas.
if ( InkCanvasEditingMode.EraseByPoint == _cachedEraseMode )
{
// Call InvalidateBehaviorCursor at the end of the routine. The method will cause an external event fired.
// So it should be invoked after we set up our states.
EditingCoordinator.InvalidateBehaviorCursor(this);
}
}
/// <summary>
/// StylusInputContinue
/// </summary>
/// <param name="stylusPoints">stylusPoints</param>
/// <param name="userInitiated">true if the source eventArgs.UserInitiated flag was set to true</param>
protected override void StylusInputContinue(StylusPointCollection stylusPoints, bool userInitiated)
{
_stylusPoints.Add(stylusPoints);
_incrementalStrokeHitTester.AddPoints(stylusPoints);
}
/// <summary>
/// StylusInputEnd
/// </summary>
/// <param name="commit">commit</param>
protected override void StylusInputEnd(bool commit)
{
if ( InkCanvasEditingMode.EraseByPoint == _cachedEraseMode )
{
_incrementalStrokeHitTester.StrokeHit-= new StrokeHitEventHandler(OnPointEraseResultChanged);
}
else
{
//we're in stroke hit test mode
_incrementalStrokeHitTester.StrokeHit -= new StrokeHitEventHandler(OnStrokeEraseResultChanged);
}
_stylusPoints = null;
//
// Don't forget ending the current incremental hit testing.
_incrementalStrokeHitTester.EndHitTesting();
_incrementalStrokeHitTester = null;
}
/// <summary>
/// Get eraser cursor.
/// </summary>
/// <returns></returns>
protected override Cursor GetCurrentCursor()
{
if ( InkCanvasEditingMode.EraseByPoint == _cachedEraseMode )
{
if ( _cachedPointEraserCursor == null )
{
_cachedStylusShape = InkCanvas.EraserShape;
//
// The eraser cursor should respect the InkCanvas' Transform properties as the pen tip.
Matrix xf = GetElementTransformMatrix();
if ( !xf.IsIdentity )
{
// Zero the offsets if the element's transform in invertable.
// Otherwise fallback the matrix to the identity.
if ( xf.HasInverse )
{
xf.OffsetX = 0;
xf.OffsetY = 0;
}
else
{
xf = Matrix.Identity;
}
}
DpiScale dpi = this.InkCanvas.GetDpi();
_cachedPointEraserCursor = PenCursorManager.GetPointEraserCursor(_cachedStylusShape, xf, dpi.DpiScaleX, dpi.DpiScaleY);
}
return _cachedPointEraserCursor;
}
else
{
return PenCursorManager.GetStrokeEraserCursor();
}
}
/// <summary>
/// ApplyTransformToCursor
/// </summary>
protected override void OnTransformChanged()
{
// Reset the cached point eraser cursor.
ResetCachedPointEraserCursor();
}
#endregion Protected Methods
//-------------------------------------------------------------------------------
//
// Private Methods
//
//-------------------------------------------------------------------------------
#region Private Methods
/// <summary>
/// Reset the cached point eraser cursor.
/// </summary>
private void ResetCachedPointEraserCursor()
{
_cachedPointEraserCursor = null;
_cachedStylusShape = null;
}
/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void OnStrokeEraseResultChanged(object sender, StrokeHitEventArgs e)
{
Debug.Assert(null != e.HitStroke);
bool fSucceeded = false;
// The below code calls out StrokeErasing or StrokeErased event.
// The out-side code could throw exception.
// We use try/finally block to protect our status.
try
{
InkCanvasStrokeErasingEventArgs args = new InkCanvasStrokeErasingEventArgs(e.HitStroke);
this.InkCanvas.RaiseStrokeErasing(args);
if ( !args.Cancel )
{
// Erase only if the event wasn't cancelled
InkCanvas.Strokes.Remove(e.HitStroke);
this.InkCanvas.RaiseInkErased();
}
fSucceeded = true;
}
finally
{
if ( !fSucceeded )
{
// Abort the editing.
Commit(false);
}
}
}
/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void OnPointEraseResultChanged(object sender, StrokeHitEventArgs e)
{
Debug.Assert(null != e.HitStroke, "e.HitStroke cannot be null");
bool fSucceeded = false;
// The below code might call out StrokeErasing or StrokeErased event.
// The out-side code could throw exception.
// We use try/finally block to protect our status.
try
{
InkCanvasStrokeErasingEventArgs args = new InkCanvasStrokeErasingEventArgs(e.HitStroke);
this.InkCanvas.RaiseStrokeErasing(args);
if ( !args.Cancel )
{
// Erase only if the event wasn't cancelled
StrokeCollection eraseResult = e.GetPointEraseResults();
Debug.Assert(eraseResult != null, "eraseResult cannot be null");
StrokeCollection strokesToReplace = new StrokeCollection();
strokesToReplace.Add(e.HitStroke);
try
{
// replace or remove the stroke
if (eraseResult.Count > 0)
{
this.InkCanvas.Strokes.Replace(strokesToReplace, eraseResult);
}
else
{
this.InkCanvas.Strokes.Remove(strokesToReplace);
}
}
catch (ArgumentException ex)
{
//this can happen if someone sits in an event handler
//for StrokeErasing and removes the stroke.
//this to harden against failure here.
if (!ex.Data.Contains("System.Windows.Ink.StrokeCollection"))
{
//System.Windows.Ink.StrokeCollection didn't throw this,
//we need to just throw the original exception
throw;
}
}
//raise ink erased
this.InkCanvas.RaiseInkErased();
}
fSucceeded = true;
}
finally
{
if ( !fSucceeded )
{
// Abort the editing.
Commit(false);
}
}
}
#endregion Private Methods
//-------------------------------------------------------------------------------
//
// Private Fields
//
//-------------------------------------------------------------------------------
#region Private Fields
private InkCanvasEditingMode _cachedEraseMode;
private IncrementalStrokeHitTester _incrementalStrokeHitTester;
private Cursor _cachedPointEraserCursor;
private StylusShape _cachedStylusShape;
private StylusPointCollection _stylusPoints = null;
#endregion Private Fields
}
}
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