Don't allow navigation to previous/next month when dragging mouse.

When dragging the mouse over the calendar and a date from a previous
month is hit, it will change the visible month to that month.
This becomes worse when dragging the mouse between in the start/end of
the calendar, because there are usually several days shown from the
previous month, and the calendar quickly goes back several months.

[ChangeLog][Calendar] Calendar no longer selects dates
in the next/previous month when dragging the mouse.

Task-number: QTBUG-38848
Change-Id: I0b9bc727a05397a8e4f1280e16c91e39e160bf4a
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>

2 files changed, 27 insertions, 8 deletions

diff --git a/src/controls/Styles/Base/CalendarStyle.qml b/src/controls/Styles/Base/CalendarStyle.qml
index d93c8325..5f391b37 100644
--- a/src/controls/Styles/Base/CalendarStyle.qml
+++ b/src/controls/Styles/Base/CalendarStyle.qml
@@ -518,10 +518,15 @@ Style {
                                     if (hoveredCellIndex !== previousHoveredCellIndex)
                                         control.hovered(date);
 
+                                    // The date must be different for the pressed signal to be emitted.
                                     if (pressed && date.getTime() !== control.selectedDate.getTime()) {
-                                        control.selectedDate = date;
-                                        pressedCellIndex = indexOfCell;
                                         control.pressed(date);
+
+                                        // You can't select dates in a different month while dragging.
+                                        if (date.getMonth() === control.selectedDate.getMonth()) {
+                                            control.selectedDate = date;
+                                            pressedCellIndex = indexOfCell;
+                                        }
                                     }
                                 }
                             }
diff --git a/tests/auto/controls/data/tst_calendar.qml b/tests/auto/controls/data/tst_calendar.qml
index e4edf725..f2002844 100644
--- a/tests/auto/controls/data/tst_calendar.qml
+++ b/tests/auto/controls/data/tst_calendar.qml
@@ -642,13 +642,27 @@ Item {
                 dragTo(x, Math.floor(index / CalendarUtils.daysInAWeek), index, new Date(2014, 1, 24 + x));
             }
 
-            // Dragging into the next month should work.
-            var firstDateInNextMonth = new Date(2014, 2, 1);
-            dragTo(5, 4, 33, firstDateInNextMonth);
+            // Dragging into the next month shouldn't work, as it can lead to
+            // unwanted month changes if moving within a bunch of "next month" cells.
+            // We still emit the signals as usual, though.
+            var oldDate = calendar.selectedDate;
+            mouseMove(calendar, toPixelsX(5), toPixelsY(4), Qt.LeftButton);
+            compare(calendar.selectedDate, oldDate);
+            compare(calendar.__panel.pressedCellIndex, 32);
+            compare(calendar.__panel.hoveredCellIndex, 33);
+            compare(hoveredSignalSpy.count, 1);
+            compare(pressedSignalSpy.count, 1);
+            compare(releasedSignalSpy.count, 0);
+            compare(clickedSignalSpy.count, 0);
+
+            hoveredSignalSpy.clear();
+            pressedSignalSpy.clear();
+            releasedSignalSpy.clear();
+            clickedSignalSpy.clear();
 
-            // Finish the drag.
-            mouseRelease(calendar, toPixelsX(5), toPixelsY(0), Qt.LeftButton);
-            compare(calendar.selectedDate, firstDateInNextMonth);
+            // Finish the drag over the day in the next month.
+            mouseRelease(calendar, toPixelsX(5), toPixelsY(4), Qt.LeftButton);
+            compare(calendar.selectedDate, oldDate);
             compare(calendar.__panel.pressedCellIndex, -1);
             compare(hoveredSignalSpy.count, 0);
             compare(pressedSignalSpy.count, 0);