Make the expose region local on all platforms

QExposeEvent::region() reports a region in a random coordinate system.
The behavior is undocumented and the platform plugins do different things.

xcb, offscreen and ios are correct. These set the region in local coordinates,
which is the most logical interpretation of the expose region.

windows is almost correct, except for one occurrence.

cocoa and others need changes: passing in geometry() as the exposed region is
always wrong.

The patch documents the expected behavior both for QExposeEvent and
internally in QWindowSystemInterface. The problematic plugins are fixed to
use local coordinates.

Task-number: QTBUG-40470
Change-Id: I6ded3154d14254fa71d4292d8e1b5e6cf696c81a
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp b/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp
index 02f3959802..b4659b7caf 100644
--- a/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp
+++ b/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp
@@ -164,6 +164,8 @@ public:
     {
         m_received[event->type()]++;
         m_order << event->type();
+        if (event->type() == QEvent::Expose)
+            m_exposeRegion = static_cast<QExposeEvent *>(event)->region();
 
         return QWindow::event(event);
     }
@@ -178,9 +180,15 @@ public:
         return m_order.indexOf(type);
     }
 
+    QRegion exposeRegion() const
+    {
+        return m_exposeRegion;
+    }
+
 private:
     QHash<QEvent::Type, int> m_received;
     QVector<QEvent::Type> m_order;
+    QRegion m_exposeRegion;
 };
 
 void tst_QWindow::eventOrderOnShow()
@@ -358,6 +366,14 @@ void tst_QWindow::isExposed()
     QTRY_VERIFY(window.received(QEvent::Expose) > 0);
     QTRY_VERIFY(window.isExposed());
 
+    // This is a top-level window so assuming it is completely exposed, the
+    // expose region must be (0, 0), (width, height). If this is not the case,
+    // the platform plugin is sending expose events with a region in an
+    // incorrect coordinate system.
+    QRect r = window.exposeRegion().boundingRect();
+    r = QRect(window.mapToGlobal(r.topLeft()), r.size());
+    QCOMPARE(r, window.geometry());
+
     window.hide();
 
     QCoreApplication::processEvents();