QSplitterHandle: Ensure a minimum grab area

This used to work only for 0- and 1-pixel wide handles. However,
and paradoxically, 2- and 3-pixel wide handles would end up with
narrower grab areas. We now ensure a 4 or 5 minimum grab area,
depending on the handle width parity.

The patch also clears the margins and mask if the handle size is
increased at some point.

Change-Id: I8a16e39fb34b5452d9021dbde8c22bec79df0243
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 24 insertions, 0 deletions

diff --git a/tests/auto/widgets/widgets/qsplitter/tst_qsplitter.cpp b/tests/auto/widgets/widgets/qsplitter/tst_qsplitter.cpp
index c4cd771f92..72e6ffdeb5 100644
--- a/tests/auto/widgets/widgets/qsplitter/tst_qsplitter.cpp
+++ b/tests/auto/widgets/widgets/qsplitter/tst_qsplitter.cpp
@@ -81,6 +81,7 @@ private slots:
     void replaceWidget();
     void replaceWidgetWithSplitterChild_data();
     void replaceWidgetWithSplitterChild();
+    void handleMinimumWidth();
 
     // task-specific tests below me:
     void task187373_addAbstractScrollAreas();
@@ -820,6 +821,29 @@ void tst_QSplitter::replaceWidgetWithSplitterChild()
     }
 }
 
+void tst_QSplitter::handleMinimumWidth()
+{
+    MyFriendlySplitter split;
+    split.addWidget(new QLabel("Number Wan"));
+    split.addWidget(new QLabel("Number Too"));
+
+    split.show();
+    QTest::qWaitForWindowExposed(&split);
+    for (int i = 0; i < 10; i++) {
+        split.setHandleWidth(i);
+        QTest::qWait(100); // resizing
+        QCOMPARE(split.handle(1)->width(), qMax(4 + (i & 1), i));
+    }
+
+    split.setOrientation(Qt::Vertical);
+    QTest::qWait(100);
+    for (int i = 0; i < 10; i++) {
+        split.setHandleWidth(i);
+        QTest::qWait(100); // resizing
+        QCOMPARE(split.handle(1)->height(), qMax(4 + (i & 1), i));
+    }
+}
+
 void tst_QSplitter::rubberBandNotInSplitter()
 {
     MyFriendlySplitter split;