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refactor _touchIdsMap (#2224)
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* move comments

* update comments

* move touchId remove

* update bad nativeTouchId check

* invert register touchId check
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@nkast
nkast authored Feb 18, 2025
1 parent 698b3c4 commit 86c5c6f
Showing 1 changed file with 26 additions and 57 deletions.
83 changes: 26 additions & 57 deletions src/Xna.Framework.Input/Input/Touch/TouchPanelStrategy.Legacy.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,18 @@ private void UpdateCurrentTimestamp()
/// <summary>
/// The mapping between platform specific touch ids
/// and the touch ids we assign to touch locations.
///
/// Different platforms return different touch identifiers
/// based on the specifics of their implementation and the
/// system drivers.
///
/// Sometimes these ids are suitable for our use, but other
/// times it can recycle ids or do cute things like return
/// the same id for double tap events.
///
/// We instead provide consistent ids by generating them
/// ourselves on the press and looking them up on move
/// and release events.
/// </summary>
private readonly Dictionary<int, int> _touchIdsMap = new Dictionary<int, int>();

Expand Down Expand Up @@ -121,21 +133,13 @@ private TouchCollection LegacyGetState()

protected void AddPressedEvent(int nativeTouchId, Vector2 position, Point winSize)
{
// Different platforms return different touch identifiers
// based on the specifics of their implementation and the
// system drivers.
//
// Sometimes these ids are suitable for our use, but other
// times it can recycle ids or do cute things like return
// the same id for double tap events.
//
// We instead provide consistent ids by generating them
// ourselves on the press and looking them up on move
// and release events.
//
// Register touchId.
int touchId;
// Try to find the touch id.
if (!_touchIdsMap.TryGetValue(nativeTouchId, out touchId))
if (_touchIdsMap.TryGetValue(nativeTouchId, out touchId))
{
System.Diagnostics.Debug.Assert(false, "nativeTouchId already registered.");
}
else
{
touchId = _nextTouchId;
_touchIdsMap[nativeTouchId] = touchId;
Expand All @@ -145,11 +149,6 @@ protected void AddPressedEvent(int nativeTouchId, Vector2 position, Point winSiz
else
_nextTouchId = StartingTouchId;
}
else
{
System.Diagnostics.Debug.Assert(false);
// did we miss some event to clear old events?
}

// scale position
position.X = position.X * DisplayWidth / winSize.X;
Expand All @@ -170,26 +169,11 @@ protected void AddPressedEvent(int nativeTouchId, Vector2 position, Point winSiz

protected void AddMovedEvent(int nativeTouchId, Vector2 position, Point winSize)
{
// Different platforms return different touch identifiers
// based on the specifics of their implementation and the
// system drivers.
//
// Sometimes these ids are suitable for our use, but other
// times it can recycle ids or do cute things like return
// the same id for double tap events.
//
// We instead provide consistent ids by generating them
// ourselves on the press and looking them up on move
// and release events.
//
// Find touchId.
int touchId;
// Try to find the touch id.
if (!_touchIdsMap.TryGetValue(nativeTouchId, out touchId))
{
System.Diagnostics.Debug.Assert(false);
// If we got here that means either the device is sending
// us bad, out of order, or old touch events.
// In any case just ignore them.
System.Diagnostics.Debug.Assert(false, "nativeTouchId not found.");
return;
}

Expand Down Expand Up @@ -235,28 +219,14 @@ protected void AddMovedEvent(int nativeTouchId, Vector2 position, Point winSize)

protected void AddReleasedEvent(int nativeTouchId, Vector2 position, Point winSize)
{
// Different platforms return different touch identifiers
// based on the specifics of their implementation and the
// system drivers.
//
// Sometimes these ids are suitable for our use, but other
// times it can recycle ids or do cute things like return
// the same id for double tap events.
//
// We instead provide consistent ids by generating them
// ourselves on the press and looking them up on move
// and release events.
//
// Find and unregister touchId.
int touchId;
// Try to find the touch id.
if (!_touchIdsMap.TryGetValue(nativeTouchId, out touchId))
{
System.Diagnostics.Debug.Assert(false);
// If we got here that means either the device is sending
// us bad, out of order, or old touch events.
// In any case just ignore them.
System.Diagnostics.Debug.Assert(false, "nativeTouchId not found.");
return;
}
_touchIdsMap.Remove(nativeTouchId);

// scale position
position.X = position.X * DisplayWidth / winSize.X;
Expand Down Expand Up @@ -318,19 +288,18 @@ protected void AddReleasedEvent(int nativeTouchId, Vector2 position, Point winSi
// If we have gestures enabled then collect events for those too.
// We also have to keep tracking any touches while we know about touches so we don't miss releases even if gesture recognition is disabled
GesturesAddReleasedEvent(touchId, position, currentTimestamp, currentFramestamp);

// unmap the hardware id.
_touchIdsMap.Remove(nativeTouchId);
}

protected void AddCanceledEvent(int nativeTouchId, Vector2 position, Point winSize)
{
// Find and unregister touchId.
int touchId;
if (!_touchIdsMap.TryGetValue(nativeTouchId, out touchId))
{
System.Diagnostics.Debug.Assert(false);
System.Diagnostics.Debug.Assert(false, "nativeTouchId not found.");
return;
}
_touchIdsMap.Remove(nativeTouchId);

throw new NotImplementedException();
}
Expand Down

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