QLineEdit: Fix icons being too small on a High DPI screen without scaling.

Remove the hardcoded size 16 from QLineEditIconButton. Replace
QLineEditPrivate::iconSize() by QLineEditPrivate::sideWidgetParameters()
returning a struct SideWidgetParameters containing icon size, widget size and
margins. The 32x32 icon will then be used on a High DPI screen without scaling.

Task-number: QTBUG-49374
Change-Id: I23c4a0cd078a58581c940aacfa65a3ad493c12dc
Reviewed-by: Alessandro Portale <alessandro.portale@theqtcompany.com>

3 files changed, 52 insertions, 22 deletions

diff --git a/src/widgets/widgets/qlineedit.cpp b/src/widgets/widgets/qlineedit.cpp
index 6b32665065..2cad5d325c 100644
--- a/src/widgets/widgets/qlineedit.cpp
+++ b/src/widgets/widgets/qlineedit.cpp
@@ -2176,7 +2176,6 @@ void QLineEdit::changeEvent(QEvent *ev)
             d->control->setPasswordCharacter(style()->styleHint(QStyle::SH_LineEdit_PasswordCharacter, &opt, this));
             d->control->setPasswordMaskDelay(style()->styleHint(QStyle::SH_LineEdit_PasswordMaskDelay, &opt, this));
         }
-        d->m_iconSize = QSize();
         update();
         break;
     case QEvent::LayoutDirectionChange:
diff --git a/src/widgets/widgets/qlineedit_p.cpp b/src/widgets/widgets/qlineedit_p.cpp
index ff80c45c9a..b90ddacb7e 100644
--- a/src/widgets/widgets/qlineedit_p.cpp
+++ b/src/widgets/widgets/qlineedit_p.cpp
@@ -314,6 +314,12 @@ QLineEditIconButton::QLineEditIconButton(QWidget *parent)
     setFocusPolicy(Qt::NoFocus);
 }
 
+QLineEditPrivate *QLineEditIconButton::lineEditPrivate() const
+{
+    QLineEdit *le = qobject_cast<QLineEdit *>(parentWidget());
+    return le ? static_cast<QLineEditPrivate *>(qt_widget_private(le)) : Q_NULLPTR;
+}
+
 void QLineEditIconButton::paintEvent(QPaintEvent *)
 {
     QPainter painter(this);
@@ -325,7 +331,9 @@ void QLineEditIconButton::paintEvent(QPaintEvent *)
     QIcon::Mode state = QIcon::Disabled;
     if (isEnabled())
         state = isDown() ? QIcon::Selected : QIcon::Normal;
-    const QSize iconSize(IconButtonSize, IconButtonSize);
+    const QLineEditPrivate *lep = lineEditPrivate();
+    const int iconWidth = lep ? lep->sideWidgetParameters().iconSize : 16;
+    const QSize iconSize(iconWidth, iconWidth);
     const QPixmap iconPixmap = icon().pixmap(window, iconSize, state, QIcon::Off);
     QRect pixmapRect = QRect(QPoint(0, 0), iconSize);
     pixmapRect.moveCenter(rect().center());
@@ -340,8 +348,8 @@ void QLineEditIconButton::actionEvent(QActionEvent *e)
         const QAction *action = e->action();
         if (isVisibleTo(parentWidget()) != action->isVisible()) {
             setVisible(action->isVisible());
-            if (QLineEdit *le = qobject_cast<QLineEdit *>(parentWidget()))
-                static_cast<QLineEditPrivate *>(qt_widget_private(le))->positionSideWidgets();
+            if (QLineEditPrivate *lep = lineEditPrivate())
+                lep->positionSideWidgets();
         }
     }
         break;
@@ -407,11 +415,15 @@ void QLineEditPrivate::_q_clearButtonClicked()
     }
 }
 
-QSize QLineEditPrivate::iconSize() const
+QLineEditPrivate::SideWidgetParameters QLineEditPrivate::sideWidgetParameters() const
 {
-    if (!m_iconSize.isValid()) // This might require style-specific handling (pixel metric).
-        m_iconSize = QSize(QLineEditIconButton::IconButtonSize + 6, QLineEditIconButton::IconButtonSize + 2);
-    return m_iconSize;
+    Q_Q(const QLineEdit);
+    SideWidgetParameters result;
+    result.iconSize = q->height() < 34 ? 16 : 32;
+    result.margin = result.iconSize / 4;
+    result.widgetWidth = result.iconSize + 6;
+    result.widgetHeight = result.iconSize + 2;
+    return result;
 }
 
 QIcon QLineEditPrivate::clearButtonIcon() const
@@ -437,15 +449,16 @@ void QLineEditPrivate::positionSideWidgets()
     Q_Q(QLineEdit);
     if (hasSideWidgets()) {
         const QRect contentRect = q->rect();
-        const QSize iconSize = QLineEditPrivate::iconSize();
-        const int delta = QLineEditIconButton::IconMargin + iconSize.width();
-        QRect widgetGeometry(QPoint(QLineEditIconButton::IconMargin, (contentRect.height() - iconSize.height()) / 2), iconSize);
+        const SideWidgetParameters p = sideWidgetParameters();
+        const int delta = p.margin + p.widgetWidth;
+        QRect widgetGeometry(QPoint(p.margin, (contentRect.height() - p.widgetHeight) / 2),
+                             QSize(p.widgetWidth, p.widgetHeight));
         foreach (const SideWidgetEntry &e, leftSideWidgetList()) {
             e.widget->setGeometry(widgetGeometry);
             if (e.action->isVisible())
                 widgetGeometry.moveLeft(widgetGeometry.left() + delta);
         }
-        widgetGeometry.moveLeft(contentRect.width() - iconSize.width() - QLineEditIconButton::IconMargin);
+        widgetGeometry.moveLeft(contentRect.width() - p.widgetWidth - p.margin);
         foreach (const SideWidgetEntry &e, rightSideWidgetList()) {
             e.widget->setGeometry(widgetGeometry);
             if (e.action->isVisible())
diff --git a/src/widgets/widgets/qlineedit_p.h b/src/widgets/widgets/qlineedit_p.h
index 60372ab393..1d81090b0f 100644
--- a/src/widgets/widgets/qlineedit_p.h
+++ b/src/widgets/widgets/qlineedit_p.h
@@ -65,6 +65,8 @@
 
 QT_BEGIN_NAMESPACE
 
+class QLineEditPrivate;
+
 // QLineEditIconButton: This is a simple helper class that represents clickable icons that fade in with text
 
 class Q_AUTOTEST_EXPORT QLineEditIconButton : public QToolButton
@@ -72,8 +74,6 @@ class Q_AUTOTEST_EXPORT QLineEditIconButton : public QToolButton
     Q_OBJECT
     Q_PROPERTY(qreal opacity READ opacity WRITE setOpacity)
 public:
-    enum { IconMargin = 4, IconButtonSize = 16 };
-
     explicit QLineEditIconButton(QWidget *parent =  0);
 
     qreal opacity() const { return m_opacity; }
@@ -93,6 +93,7 @@ private:
 #ifndef QT_NO_ANIMATION
     void startOpacityAnimation(qreal endValue);
 #endif
+    QLineEditPrivate *lineEditPrivate() const;
 
     qreal m_opacity;
 };
@@ -116,6 +117,13 @@ public:
     };
     typedef QVector<SideWidgetEntry> SideWidgetEntryList;
 
+    struct SideWidgetParameters {
+        int iconSize;
+        int widgetWidth;
+        int widgetHeight;
+        int margin;
+    };
+
     QLineEditPrivate()
         : control(0), frame(1), contextMenuEnabled(1), cursorVisible(0),
         dragEnabled(0), clickCausedFocus(0), hscroll(0), vscroll(0),
@@ -206,7 +214,7 @@ public:
 
     QWidget *addAction(QAction *newAction, QAction *before, QLineEdit::ActionPosition, int flags = 0);
     void removeAction(QAction *action);
-    QSize iconSize() const;
+    SideWidgetParameters sideWidgetParameters() const;
     QIcon clearButtonIcon() const;
     void setClearButtonEnabled(bool enabled);
     void positionSideWidgets();
@@ -227,7 +235,6 @@ private:
     SideWidgetEntryList leadingSideWidgets;
     SideWidgetEntryList trailingSideWidgets;
     int lastTextSize;
-    mutable QSize m_iconSize;
 };
 Q_DECLARE_TYPEINFO(QLineEditPrivate::SideWidgetEntry, Q_PRIMITIVE_TYPE);
 
@@ -238,18 +245,29 @@ static bool isSideWidgetVisible(const QLineEditPrivate::SideWidgetEntry &e)
 
 inline int QLineEditPrivate::effectiveLeftTextMargin() const
 {
-    return leftTextMargin + (QLineEditIconButton::IconMargin + iconSize().width())
-        * int(std::count_if(leftSideWidgetList().constBegin(), leftSideWidgetList().constEnd(),
-                            isSideWidgetVisible));
+    int result = leftTextMargin;
+    if (!leftSideWidgetList().isEmpty()) {
+        const SideWidgetParameters p = sideWidgetParameters();
+        result += (p.margin + p.widgetWidth)
+            * int(std::count_if(leftSideWidgetList().constBegin(), leftSideWidgetList().constEnd(),
+                                isSideWidgetVisible));
+    }
+    return result;
 }
 
 inline int QLineEditPrivate::effectiveRightTextMargin() const
 {
-    return rightTextMargin + (QLineEditIconButton::IconMargin + iconSize().width())
-        * int(std::count_if(rightSideWidgetList().constBegin(), rightSideWidgetList().constEnd(),
-                            isSideWidgetVisible));
+    int result = rightTextMargin;
+    if (!rightSideWidgetList().isEmpty()) {
+        const SideWidgetParameters p = sideWidgetParameters();
+        result += (p.margin + p.widgetWidth)
+            * int(std::count_if(rightSideWidgetList().constBegin(), rightSideWidgetList().constEnd(),
+                                isSideWidgetVisible));
+    }
+    return result;
 }
 
+
 #endif // QT_NO_LINEEDIT
 
 QT_END_NAMESPACE