From 1783b048fd4c97e86de4a1122f64eb2afa603cbf Mon Sep 17 00:00:00 2001
From: Shawn Rutledge <shawn.rutledge@qt.io>
Date: Wed, 16 Sep 2020 21:44:33 +0200
Subject: [PATCH] Get rid of QMutableEventPoint::stationaryWithModifiedProperty

Omitting stationary points from touch events is such a marginal
optimization that this code probably isn't worth maintaining.
It wasn't implemented correctly this time either, according to the
tst_QQuickMultiPointTouchArea::stationaryTouchWithChangingPressure()
test.

[ChangeLog][QtGui][QPointerEvent] We no longer attempt to avoid
delivery of stationary points within QTouchEvent: every pressed point
is now included in every TouchUpdate event.

Task-number: QTBUG-77142
Change-Id: If1fd666fb3057a17e0dffdd7ca7138693126b02b
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
---
 src/gui/kernel/qevent.cpp          | 9 ---------
 src/gui/kernel/qevent_p.h          | 5 -----
 src/gui/kernel/qguiapplication.cpp | 6 ------
 3 files changed, 20 deletions(-)

diff --git a/src/gui/kernel/qevent.cpp b/src/gui/kernel/qevent.cpp
index 322e5aeb316..91ebb9f7846 100644
--- a/src/gui/kernel/qevent.cpp
+++ b/src/gui/kernel/qevent.cpp
@@ -472,15 +472,6 @@ void QMutableEventPoint::updateFrom(const QEventPoint &other)
         setPressure(0);
         break;
 
-    case QEventPoint::State::Stationary:
-        // Stationary points might not be delivered down to the receiving item
-        // and get their position transformed, keep the old values instead.
-        if (other.velocity() != velocity() ||
-                !qFuzzyCompare(other.pressure(), pressure())) {
-            setStationaryWithModifiedProperty();
-        }
-        Q_FALLTHROUGH();
-
     default: // update or stationary
         if (globalPosition() != other.globalPosition())
             setGlobalLastPosition(globalPosition());
diff --git a/src/gui/kernel/qevent_p.h b/src/gui/kernel/qevent_p.h
index 23a171e6ab3..c923af92c96 100644
--- a/src/gui/kernel/qevent_p.h
+++ b/src/gui/kernel/qevent_p.h
@@ -88,7 +88,6 @@ struct QEventPointPrivate {
     int pointId = -1;
     QEventPoint::State state = QEventPoint::State::Unknown;
     bool accept = false;
-    bool stationaryWithModifiedProperty = false;
 };
 
 // Private subclasses to allow accessing and modifying protected variables.
@@ -119,8 +118,6 @@ public:
 
     void detach();
 
-    bool stationaryWithModifiedProperty() const { return d->stationaryWithModifiedProperty; }
-
     void setId(int pointId) { d->pointId = pointId; }
 
     void setDevice(const QPointingDevice *device) { d->device = device; }
@@ -163,8 +160,6 @@ public:
 
     void setVelocity(const QVector2D &v) { d->velocity = v; }
 
-    void setStationaryWithModifiedProperty(bool s = true) { d->stationaryWithModifiedProperty = s; }
-
     QWindow *window() const { return d->window.data(); }
 
     void setWindow(const QPointer<QWindow> &w) { d->window = w; }
diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index ffb9b26ee7e..a0ab112c8e9 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -2856,7 +2856,6 @@ void QGuiApplicationPrivate::processTouchEvent(QWindowSystemInterfacePrivate::To
 
     self->lastTouchType = e->touchType;
 
-    bool stationaryTouchPointChangedProperty = false;
     QPointer<QWindow> window = e->window;  // the platform hopefully tells us which window received the event
     QVarLengthArray<QMutableTouchEvent, 2> touchEvents;
 
@@ -2944,11 +2943,6 @@ void QGuiApplicationPrivate::processTouchEvent(QWindowSystemInterfacePrivate::To
         case QEventPoint::State::Released:
             eventType = QEvent::TouchEnd;
             break;
-        case QEventPoint::State::Stationary:
-            // don't send the event if nothing changed
-            if (!stationaryTouchPointChangedProperty)
-                continue;
-            Q_FALLTHROUGH();
         default:
             eventType = QEvent::TouchUpdate;
             break;