From e1f73494ca529a0901b72b7caefb55ab20c48487 Mon Sep 17 00:00:00 2001
From: David Edmundson <davidedmundson@kde.org>
Date: Tue, 7 Apr 2020 17:36:19 +0100
Subject: [PATCH] Client: Fix scroll direction with touchpads

Wayland axis events and QWheelEvents are opposite way rounds. This was
handled for the case of discrete events, but not continuous events.

This leads to touchpads moving the wrong way round compared to other
clients.

Change-Id: Iee4f5c620940a491949d4039cb3ac70649d83a2b
Pick-to: 5.15
Task-number: QTBUG-85767
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
---
 .../platforms/wayland/qwaylandinputdevice.cpp |  6 ++++
 tests/auto/wayland/seatv5/tst_seatv5.cpp      | 35 ++++++++++++++++---
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/src/plugins/platforms/wayland/qwaylandinputdevice.cpp b/src/plugins/platforms/wayland/qwaylandinputdevice.cpp
index 343ccc8d7e2..5be49993a46 100644
--- a/src/plugins/platforms/wayland/qwaylandinputdevice.cpp
+++ b/src/plugins/platforms/wayland/qwaylandinputdevice.cpp
@@ -1041,6 +1041,12 @@ QPoint QWaylandInputDevice::Pointer::FrameData::pixelDeltaAndError(QPointF *accu
     *accumulatedError += delta - pixelDelta;
     Q_ASSERT(qAbs(accumulatedError->x()) < 1.0);
     Q_ASSERT(qAbs(accumulatedError->y()) < 1.0);
+
+    // for continuous scroll events things should be
+    // in the same direction
+    // i.e converted so downwards surface co-ordinates (positive axis_value)
+    // goes to downwards in wheel event (negative value)
+    pixelDelta *= -1;
     return pixelDelta;
 }
 
diff --git a/tests/auto/wayland/seatv5/tst_seatv5.cpp b/tests/auto/wayland/seatv5/tst_seatv5.cpp
index 701c5ede9d9..0c4dcfe0699 100644
--- a/tests/auto/wayland/seatv5/tst_seatv5.cpp
+++ b/tests/auto/wayland/seatv5/tst_seatv5.cpp
@@ -63,6 +63,7 @@ private slots:
     void simpleAxis();
     void fingerScroll();
     void fingerScrollSlow();
+    void continuousScroll();
     void wheelDiscreteScroll();
 
     // Touch tests
@@ -252,7 +253,7 @@ void tst_seatv5::fingerScroll()
         QCOMPARE(e.phase, Qt::ScrollUpdate);
         QVERIFY(qAbs(e.angleDelta.x()) <= qAbs(e.angleDelta.y())); // Vertical scroll
 //        QCOMPARE(e.angleDelta, angleDelta); // TODO: what should this be?
-        QCOMPARE(e.pixelDelta, QPoint(0, 10));
+        QCOMPARE(e.pixelDelta, QPoint(0, -10));
         QCOMPARE(e.source, Qt::MouseEventSynthesizedBySystem); // A finger is not a wheel
     }
 
@@ -269,7 +270,7 @@ void tst_seatv5::fingerScroll()
         auto e = window.m_events.takeFirst();
         QCOMPARE(e.phase, Qt::ScrollUpdate);
         QVERIFY(qAbs(e.angleDelta.x()) > qAbs(e.angleDelta.y())); // Horizontal scroll
-        QCOMPARE(e.pixelDelta, QPoint(10, 0));
+        QCOMPARE(e.pixelDelta, QPoint(-10, 0));
         QCOMPARE(e.source, Qt::MouseEventSynthesizedBySystem); // A finger is not a wheel
     }
 
@@ -284,7 +285,7 @@ void tst_seatv5::fingerScroll()
     {
         auto e = window.m_events.takeFirst();
         QCOMPARE(e.phase, Qt::ScrollUpdate);
-        QCOMPARE(e.pixelDelta, QPoint(10, 10));
+        QCOMPARE(e.pixelDelta, QPoint(-10, -10));
         QCOMPARE(e.source, Qt::MouseEventSynthesizedBySystem); // A finger is not a wheel
     }
 
@@ -338,7 +339,7 @@ void tst_seatv5::fingerScrollSlow()
         accumulated += e.pixelDelta;
         QTRY_VERIFY(!window.m_events.empty());
     }
-    QCOMPARE(accumulated.y(), 1);
+    QCOMPARE(accumulated.y(), -1);
 }
 void tst_seatv5::wheelDiscreteScroll()
 {
@@ -370,6 +371,32 @@ void tst_seatv5::wheelDiscreteScroll()
     }
 }
 
+void tst_seatv5::continuousScroll()
+{
+    WheelWindow window;
+    QCOMPOSITOR_TRY_VERIFY(xdgSurface() && xdgSurface()->m_committedConfigureSerial);
+
+    exec([=] {
+        auto *p = pointer();
+        auto *c = client();
+        p->sendEnter(xdgToplevel()->surface(), {32, 32});
+        p->sendFrame(c);
+        p->sendAxisSource(c, Pointer::axis_source_continuous);
+        p->sendAxis(c, Pointer::axis_vertical_scroll, 10);
+        p->sendAxis(c, Pointer::axis_horizontal_scroll, -5);
+        p->sendFrame(c);
+    });
+
+    QTRY_VERIFY(!window.m_events.empty());
+    {
+        auto e = window.m_events.takeFirst();
+        QCOMPARE(e.phase, Qt::NoScrollPhase);
+        QCOMPARE(e.pixelDelta, QPoint(5, -10));
+        QCOMPARE(e.source, Qt::MouseEventSynthesizedBySystem); // touchpads are not wheels
+    }
+    // Sending axis_stop is not mandatory when axis source != finger
+}
+
 void tst_seatv5::createsTouch()
 {
     QCOMPOSITOR_TRY_COMPARE(touch()->resourceMap().size(), 1);