[Icon Item] Fix updating implicit size when icon sizes change

The old code was connecting the KIconLoader signal to implicitWidth/HeightChanged
but never actually set a new implicit size.
Also, while at it use "setImplicitSize" - it's also marked internal but public
like setSize and uses qreal instead of QSizeF.

Differential Revision: https://phabricator.kde.org/D4011

autotests/iconitemtest.cpp

@@ -480,5 +480,37 @@ void IconItemTest::paintedSize()
     QCOMPARE(item->property("paintedHeight").toInt(), 400);
 }
 
+void IconItemTest::implicitSize()
+{
+    KConfigGroup cg(KSharedConfig::openConfig(), "DialogIcons");
+    cg.writeEntry("Size", 22);
+    cg.sync();
+    KIconLoader::global()->reconfigure(QString());
+
+    QQuickItem *item = createIconItem();
+
+    // qreal cast needed as QTest::qCompare<double, int> fails to link
+    QCOMPARE(item->implicitWidth(), qreal(22));
+    QCOMPARE(item->implicitHeight(), qreal(22));
+
+    QSignalSpy widthSpy(item, &QQuickItem::implicitWidthChanged);
+    QVERIFY(widthSpy.isValid());
+    QSignalSpy heightSpy(item, &QQuickItem::implicitHeightChanged);
+    QVERIFY(heightSpy.isValid());
+
+    cg.writeEntry("Size", 64);
+    cg.sync();
+    KIconLoader::global()->reconfigure(QString());
+    // merely changing the setting and calling reconfigure won't emit this signal,
+    // the KCM uses a method "newIconLoader" method which does that but it's deprecated
+    emit KIconLoader::global()->iconLoaderSettingsChanged();
+
+    QCOMPARE(widthSpy.count(), 1);
+    QCOMPARE(heightSpy.count(), 1);
+
+    QCOMPARE(item->implicitWidth(), qreal(64));
+    QCOMPARE(item->implicitHeight(), qreal(64));
+}
+
 QTEST_MAIN(IconItemTest)
 

autotests/iconitemtest.h

@@ -55,6 +55,7 @@ private Q_SLOTS:
     void animatingEnabledChange();
     void windowChanged();
     void paintedSize();
+    void implicitSize();
 
 private:
     QQuickItem *createIconItem();

src/declarativeimports/core/iconitem.cpp

@@ -62,10 +62,8 @@ IconItem::IconItem(QQuickItem *parent)
 
     setFlag(ItemHasContents, true);
 
-    connect(KIconLoader::global(), SIGNAL(iconLoaderSettingsChanged()),
-            this, SIGNAL(implicitWidthChanged()));
-    connect(KIconLoader::global(), SIGNAL(iconLoaderSettingsChanged()),
-            this, SIGNAL(implicitHeightChanged()));
+    connect(KIconLoader::global(), &KIconLoader::iconLoaderSettingsChanged,
+            this, &IconItem::updateImplicitSize);
 
     connect(this, &QQuickItem::enabledChanged,
             this, &IconItem::enabledChanged);
@@ -76,15 +74,20 @@ IconItem::IconItem(QQuickItem *parent)
     connect(this, SIGNAL(overlaysChanged()),
             this, SLOT(schedulePixmapUpdate()));
 
-    //initialize implicit size to the Dialog size
-    setImplicitWidth(KIconLoader::global()->currentSize(KIconLoader::Dialog));
-    setImplicitHeight(KIconLoader::global()->currentSize(KIconLoader::Dialog));
+    updateImplicitSize();
 }
 
 IconItem::~IconItem()
 {
 }
 
+void IconItem::updateImplicitSize()
+{
+    //initialize implicit size to the Dialog size
+    const int implicitSize = KIconLoader::global()->currentSize(KIconLoader::Dialog);
+    setImplicitSize(implicitSize, implicitSize);
+}
+
 void IconItem::setSource(const QVariant &source)
 {
     if (source == m_source) {

src/declarativeimports/core/iconitem.h

@@ -177,6 +177,7 @@ private Q_SLOTS:
 private:
     void loadPixmap();
     QSize paintedSize(const QSizeF &containerSize = QSizeF()) const;
+    void updateImplicitSize();
 
     //all the ways we can set an source. Only one of them will be valid
     QIcon m_icon;