QLineEdit: don't emit editingFinished if nothing was done

When a modal dialog is called from a slot connected to the
editingFinished signal, the chain of events resulting from the focus
returning to this widget will make the editingFinished signal emitted
again. This patch uses a new variable to keep track of the fact that
there was a modification. Once editingFinished was emitted, that flag
is cleared so next time the signal will be emitted again only if a
modification was made to the line edit content.

[ChangeLog][QtWidget][QLineEdit] Behavior change: now the
editingFinished signal is emitted only once after the line edit content
was edited.

Fixes: QTBUG-40
Change-Id: Ia4760bad8717f1758c3939132c446b4b4c6cd498
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

src/widgets/widgets/qlineedit.cpp

@@ -315,7 +315,7 @@ QString QLineEdit::text() const
 void QLineEdit::setText(const QString& text)
 {
     Q_D(QLineEdit);
-    d->control->setText(text);
+    d->setText(text);
 }
 
 /*!
@@ -1483,8 +1483,11 @@ bool QLineEdit::event(QEvent * e)
         } else if (e->type() == QEvent::LeaveEditFocus) {
             d->setCursorVisible(false);
             d->control->setCursorBlinkEnabled(false);
-            if (d->control->hasAcceptableInput() || d->control->fixup())
+            if (d->edited && (d->control->hasAcceptableInput()
+                              || d->control->fixup())) {
                 emit editingFinished();
+                d->edited = false;
+            }
         }
     }
 #endif
@@ -1891,7 +1894,6 @@ void QLineEdit::focusInEvent(QFocusEvent *e)
 
 /*!\reimp
 */
-
 void QLineEdit::focusOutEvent(QFocusEvent *e)
 {
     Q_D(QLineEdit);
@@ -1914,8 +1916,10 @@ void QLineEdit::focusOutEvent(QFocusEvent *e)
 #endif
     if (reason != Qt::PopupFocusReason
         || !(QApplication::activePopupWidget() && QApplication::activePopupWidget()->parentWidget() == this)) {
-            if (hasAcceptableInput() || d->control->fixup())
+            if (d->edited && (hasAcceptableInput() || d->control->fixup())) {
                 emit editingFinished();
+                d->edited = false;
+            }
     }
 #ifdef QT_KEYPAD_NAVIGATION
     d->control->setCancelText(QString());

src/widgets/widgets/qlineedit_p.cpp

@@ -127,6 +127,7 @@ void QLineEditPrivate::_q_handleWindowActivate()
 void QLineEditPrivate::_q_textEdited(const QString &text)
 {
     Q_Q(QLineEdit);
+    edited = true;
     emit q->textEdited(text);
 #if QT_CONFIG(completer)
     if (control->completer()
@@ -272,6 +273,12 @@ void QLineEditPrivate::setCursorVisible(bool visible)
         q->update();
 }
 
+void QLineEditPrivate::setText(const QString& text)
+{
+    edited = true;
+    control->setText(text);
+}
+
 void QLineEditPrivate::updatePasswordEchoEditing(bool editing)
 {
     Q_Q(QLineEdit);

src/widgets/widgets/qlineedit_p.h

@@ -151,7 +151,7 @@ public:
 
     QLineEditPrivate()
         : control(0), frame(1), contextMenuEnabled(1), cursorVisible(0),
-        dragEnabled(0), clickCausedFocus(0), hscroll(0), vscroll(0),
+        dragEnabled(0), clickCausedFocus(0), edited(0), hscroll(0), vscroll(0),
         alignment(Qt::AlignLeading | Qt::AlignVCenter),
         leftTextMargin(0), topTextMargin(0), rightTextMargin(0), bottomTextMargin(0),
         lastTextSize(0), mouseYThreshold(0)
@@ -176,6 +176,7 @@ public:
     bool inSelection(int x) const;
     QRect cursorRect() const;
     void setCursorVisible(bool visible);
+    void setText(const QString& text);
 
     void updatePasswordEchoEditing(bool);
 
@@ -202,6 +203,7 @@ public:
     uint cursorVisible : 1;
     uint dragEnabled : 1;
     uint clickCausedFocus : 1;
+    uint edited : 1;
     int hscroll;
     int vscroll;
     uint alignment;

tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp

@@ -3613,6 +3613,14 @@ void tst_QLineEdit::task174640_editingFinished()
     QTRY_VERIFY(le1->hasFocus());
     QCOMPARE(editingFinishedSpy.count(), 0);
 
+    le2->setFocus();
+    QTRY_VERIFY(le2->hasFocus());
+    // editingFinished will not be emitted anew because no editing happened
+    QCOMPARE(editingFinishedSpy.count(), 0);
+
+    le1->setFocus();
+    QTRY_VERIFY(le1->hasFocus());
+    QTest::keyPress(le1, Qt::Key_Plus);
     le2->setFocus();
     QTRY_VERIFY(le2->hasFocus());
     QCOMPARE(editingFinishedSpy.count(), 1);
@@ -3632,6 +3640,8 @@ void tst_QLineEdit::task174640_editingFinished()
     delete testMenu1;
     QCOMPARE(editingFinishedSpy.count(), 0);
     QTRY_VERIFY(le1->hasFocus());
+    // Ensure le1 has been edited
+    QTest::keyPress(le1, Qt::Key_Plus);
 
     QMenu *testMenu2 = new QMenu(le2);
     testMenu2->addAction("foo2");