QmlDesigner: Enable transient ScrollBars for StudioStyle

- Transient scroll bar is available for StudioStyle.
- Some changes are applied to slider style, because scrollBar and
sliders have some common usages within the style.

Task-number: QDS-9283
Change-Id: I7a8b7997cf4d20142a0524c4a071b93dfd06321d
Reviewed-by: Henning Gründl <henning.gruendl@qt.io>

src/libs/utils/CMakeLists.txt

@@ -183,6 +183,7 @@ add_qtc_library(Utils
     tooltip/tips.cpp tooltip/tips.h
     tooltip/tooltip.cpp tooltip/tooltip.h
     touchbar/touchbar.h
+    transientscroll.cpp transientscroll.h
     treemodel.cpp treemodel.h
     treeviewcombobox.cpp treeviewcombobox.h
     uncommentselection.cpp uncommentselection.h

src/libs/utils/transientscroll.cpp

@@ -0,0 +1,215 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0
+
+#include "transientscroll.h"
+
+#include <QAbstractScrollArea>
+#include <QMouseEvent>
+#include <QPointer>
+#include <QStyle>
+#include <QStyleOption>
+
+using namespace Utils;
+
+static constexpr char transientScrollAreaSupportName[] = "transientScrollAreSupport";
+
+class Utils::ScrollAreaPrivate
+{
+public:
+    ScrollAreaPrivate(QAbstractScrollArea *area)
+        : area(area)
+    {
+        verticalScrollBar = new ScrollBar(area);
+        area->setVerticalScrollBar(verticalScrollBar);
+
+        horizontalScrollBar = new ScrollBar(area);
+        area->setHorizontalScrollBar(horizontalScrollBar);
+
+        area->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded);
+        area->setHorizontalScrollBarPolicy(Qt::ScrollBarAsNeeded);
+    }
+
+    inline QRect scrollBarRect(ScrollBar *scrollBar)
+    {
+        QRect rect = viewPort ? viewPort->rect() : area->rect();
+        if (scrollBar->orientation() == Qt::Vertical) {
+            int mDiff = rect.width() - scrollBar->sizeHint().width();
+            return rect.adjusted(mDiff, 0, mDiff, 0);
+        } else {
+            int mDiff = rect.height() - scrollBar->sizeHint().height();
+            return rect.adjusted(0, mDiff, 0, mDiff);
+        }
+    }
+
+    inline void checkToFlashScroll(QPointer<ScrollBar> scrollBar, const QPoint &pos)
+    {
+        if (scrollBar.isNull())
+            return;
+
+        if (!scrollBar->style()->styleHint(
+                QStyle::SH_ScrollBar_Transient,
+                nullptr, scrollBar))
+            return;
+
+        if (scrollBarRect(scrollBar).contains(pos))
+            scrollBar->flash();
+    }
+
+    inline void checkToFlashScroll(const QPoint &pos)
+    {
+        checkToFlashScroll(verticalScrollBar, pos);
+        checkToFlashScroll(horizontalScrollBar, pos);
+    }
+
+    inline void installViewPort(QObject *eventHandler) {
+        QWidget *viewPort = area->viewport();
+        if (viewPort
+            && viewPort != this->viewPort
+            && viewPort->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, viewPort)
+            && (area->verticalScrollBarPolicy() != Qt::ScrollBarAlwaysOff
+                || area->horizontalScrollBarPolicy() != Qt::ScrollBarAlwaysOff)) {
+            viewPort->installEventFilter(eventHandler);
+            this->viewPort = viewPort;
+        }
+    }
+
+    inline void uninstallViewPort(QObject *eventHandler) {
+        if (viewPort) {
+            viewPort->removeEventFilter(eventHandler);
+            this->viewPort = nullptr;
+        }
+    }
+
+    QAbstractScrollArea *area = nullptr;
+    QPointer<QWidget> viewPort = nullptr;
+    QPointer<ScrollBar> verticalScrollBar;
+    QPointer<ScrollBar> horizontalScrollBar;
+};
+
+TransientScrollAreaSupport::TransientScrollAreaSupport(QAbstractScrollArea *scrollArea)
+    : QObject(scrollArea)
+    , d(new ScrollAreaPrivate(scrollArea))
+{
+    scrollArea->installEventFilter(this);
+}
+
+void TransientScrollAreaSupport::support(QAbstractScrollArea *scrollArea)
+{
+    QObject *prevSupport = scrollArea->property(transientScrollAreaSupportName)
+                               .value<QObject *>();
+    if (!prevSupport)
+        scrollArea->setProperty(transientScrollAreaSupportName,
+                                QVariant::fromValue(
+                                    new TransientScrollAreaSupport(scrollArea))
+                                );
+}
+
+TransientScrollAreaSupport::~TransientScrollAreaSupport()
+{
+    delete d;
+}
+
+bool TransientScrollAreaSupport::eventFilter(QObject *watched, QEvent *event)
+{
+    switch (event->type()) {
+    case QEvent::Enter: {
+        if (watched == d->area)
+            d->installViewPort(this);
+    }
+    break;
+    case QEvent::Leave: {
+        if (watched == d->area)
+            d->uninstallViewPort(this);
+    }
+    break;
+    case QEvent::MouseMove: {
+        if (watched == d->viewPort){
+            QMouseEvent *mouseEvent = static_cast<QMouseEvent *>(event);
+            if (mouseEvent) {
+                d->checkToFlashScroll(mouseEvent->pos());
+                return true;
+            }
+        }
+    }
+    break;
+    default:
+        break;
+    }
+    return QObject::eventFilter(watched, event);
+}
+
+class Utils::ScrollBarPrivate {
+public:
+    bool flashed = false;
+    int flashTimer = 0;
+};
+
+ScrollBar::ScrollBar(QWidget *parent)
+    : QScrollBar(parent)
+    , d(new ScrollBarPrivate)
+{
+}
+
+ScrollBar::~ScrollBar()
+{
+    delete d;
+}
+
+QSize ScrollBar::sizeHint() const
+{
+    QSize sh = QScrollBar::sizeHint();
+    if (style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, this)) {
+        constexpr int thickness = 10;
+        if (orientation() == Qt::Horizontal)
+            sh.setHeight(thickness);
+        else
+            sh.setWidth(thickness);
+    } else {
+        constexpr int thickness = 12;
+        if (orientation() == Qt::Horizontal)
+            sh.setHeight(thickness);
+        else
+            sh.setWidth(thickness);
+    }
+    return sh;
+}
+
+void ScrollBar::flash()
+{
+    if (!d->flashed && style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, this)) {
+        d->flashed = true;
+        if (!isVisible())
+            show();
+        else
+            update();
+    }
+    if (!d->flashTimer)
+        d->flashTimer = startTimer(0);
+}
+
+void ScrollBar::initStyleOption(QStyleOptionSlider *option) const
+{
+    QScrollBar::initStyleOption(option);
+
+    if (d->flashed && style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, this))
+        option->state |= QStyle::State_On;
+}
+
+bool ScrollBar::event(QEvent *event)
+{
+    switch (event->type()) {
+    case QEvent::Timer:
+        if (static_cast<QTimerEvent *>(event)->timerId() == d->flashTimer) {
+            if (d->flashed && style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, this)) {
+                d->flashed = false;
+                update();
+            }
+            killTimer(d->flashTimer);
+            d->flashTimer = 0;
+        }
+        break;
+    default:
+        break;
+    }
+    return QScrollBar::event(event);
+}

src/libs/utils/transientscroll.h

@@ -0,0 +1,51 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0
+
+#pragma once
+
+#include "utils_global.h"
+
+#include <QScrollBar>
+
+class QAbstractScrollArea;
+
+namespace Utils {
+class ScrollAreaPrivate;
+class ScrollBarPrivate;
+
+class QTCREATOR_UTILS_EXPORT TransientScrollAreaSupport : public QObject
+{
+    Q_OBJECT
+public:
+    static void support(QAbstractScrollArea *scrollArea);
+    virtual ~TransientScrollAreaSupport();
+
+protected:
+    virtual bool eventFilter(QObject *watched, QEvent *event) override;
+
+private:
+    explicit TransientScrollAreaSupport(QAbstractScrollArea *scrollArea);
+
+    ScrollAreaPrivate *d = nullptr;
+};
+
+class QTCREATOR_UTILS_EXPORT ScrollBar : public QScrollBar
+{
+    Q_OBJECT
+public:
+    explicit ScrollBar(QWidget *parent = nullptr);
+    virtual ~ScrollBar();
+
+    QSize sizeHint() const override;
+
+    virtual void flash();
+
+protected:
+    virtual void initStyleOption(QStyleOptionSlider *option) const override;
+    bool event(QEvent *event) override;
+
+private:
+    ScrollBarPrivate *d = nullptr;
+};
+
+}

src/plugins/qmldesigner/components/formeditor/formeditorgraphicsview.cpp

@@ -6,6 +6,7 @@
 #include "formeditorwidget.h"
 #include "navigation2d.h"
 #include <utils/hostosinfo.h>
+#include <utils/transientscroll.h>
 
 #include <QAction>
 #include <QCoreApplication>
@@ -36,6 +37,7 @@ FormEditorGraphicsView::FormEditorGraphicsView(QWidget *parent)
     setBackgroundRole(QPalette::Window);
 
     activateCheckboardBackground();
+    Utils::TransientScrollAreaSupport::support(this);
 
     // as mousetracking only works for mouse key it is better to handle it in the
     // eventFilter method so it works also for the space scrolling case as expected

src/plugins/qmldesigner/components/resources/dockwidgets.css

@@ -113,40 +113,6 @@ QScrollArea#dockWidgetScrollArea {
     background: creatorTheme.DStabInactiveButtonPress;
 }
 
-QScrollBar {
-    background: creatorTheme.DSscrollBarTrack;
-}
-
-QScrollBar:vertical {
-    width: 10px;
-}
-
-QScrollBar:horizontal {
-    height: 10px;
-}
-
-QScrollBar::handle {
-    background: creatorTheme.DSscrollBarHandle;
-}
-
-QScrollBar::handle:vertical {
-    min-height: 30px;
-}
-
-QScrollBar::handle:horizontal {
-    min-width: 30px;
-}
-
-QScrollBar::add-line,
-QScrollBar::sub-line,
-QScrollBar::left-arrow,
-QScrollBar::right-arrow,
-QScrollBar::add-page,
-QScrollBar::sub-page {
-    height: 0px;
-    width: 0px;
-}
-
 /* Focus related styling */
 ADS--DockWidgetTab[focused="true"] {
     background: creatorTheme.DStabFocusBackground;

src/plugins/qmldesigner/components/texteditor/texteditorwidget.cpp

@@ -70,11 +70,6 @@ void TextEditorWidget::setTextEditor(Utils::UniqueObjectLatePtr<TextEditor::Base
         });
 
         m_textEditor->editorWidget()->installEventFilter(this);
-
-        static QString styleSheet = Theme::replaceCssColors(
-            QString::fromUtf8(Utils::FileReader::fetchQrc(":/qmldesigner/scrollbar.css")));
-        m_textEditor->editorWidget()->verticalScrollBar()->setStyleSheet(styleSheet);
-        m_textEditor->editorWidget()->horizontalScrollBar()->setStyleSheet(styleSheet);
     }
 }
 

src/plugins/qmldesignerbase/utils/studiostyle.cpp

@@ -615,7 +615,6 @@ void StudioStyle::drawComplexControl(
             painter->save();
             painter->setRenderHint(QPainter::RenderHint::Antialiasing);
 
-            int lineWidth = pixelMetric(QStyle::PM_DefaultFrameWidth, option, widget);
             Theme::Color themeframeColor = enabled
                     ? interaction
                       ? Theme::DSstateControlBackgroundColor_hover // Pressed
@@ -627,14 +626,15 @@ void StudioStyle::drawComplexControl(
             QColor frameColor = creatorTheme()->color(themeframeColor);
 
             if ((option->subControls & SC_SliderGroove) && groove.isValid()) {
-                Theme::Color bgPlusColor = enabled
+                Theme::Color themeBgPlusColor = enabled
                         ? interaction
                           ? Theme::DSstateControlBackgroundColor_hover // Pressed
                           : grooveHover
                               ? Theme::DSstateSeparatorColor // GrooveHover
-                              : Theme::DStoolbarBackground // Idle
+                              : Theme::DSstateControlBackgroundColor_hover // Idle should be the same as pressed
                         : Theme::DStoolbarBackground; // Disabled
-                Theme::Color bgMinusColor = Theme::DSpopupBackground;
+
+                Theme::Color themeBgMinusColor = Theme::DSpopupBackground;
 
                 QRect minusRect(groove);
                 QRect plusRect(groove);
@@ -659,9 +659,9 @@ void StudioStyle::drawComplexControl(
 
                 painter->save();
                 painter->setPen(Qt::NoPen);
-                painter->setBrush(creatorTheme()->color(bgPlusColor));
+                painter->setBrush(creatorTheme()->color(themeBgPlusColor));
                 painter->drawRoundedRect(plusRect, borderRadius, borderRadius);
-                painter->setBrush(creatorTheme()->color(bgMinusColor));
+                painter->setBrush(creatorTheme()->color(themeBgMinusColor));
                 painter->drawRoundedRect(minusRect, borderRadius, borderRadius);
                 painter->restore();
             }
@@ -673,7 +673,8 @@ void StudioStyle::drawComplexControl(
                           : Theme::DSBackgroundColorAlternate
                         : Theme::DScontrolBackgroundDisabled;
 
-                painter->setPen(tickPen);
+                painter->setBrush(Qt::NoBrush);
+                painter->setPen(creatorTheme()->color(tickPen));
                 int tickSize = proxy()->pixelMetric(PM_SliderTickmarkOffset, option, widget);
                 int available = proxy()->pixelMetric(PM_SliderSpaceAvailable, slider, widget);
                 int interval = slider->tickInterval;
@@ -729,7 +730,7 @@ void StudioStyle::drawComplexControl(
             }
 
             // draw handle
-            if ((option->subControls & SC_SliderHandle) ) {
+            if (option->subControls & SC_SliderHandle) {
                 Theme::Color handleColor = enabled
                         ? interaction
                             ? Theme::DSinteraction  // Interaction
@@ -749,8 +750,9 @@ void StudioStyle::drawComplexControl(
             }
 
             if (groove.isValid()) {
+                int borderWidth = pixelMetric(QStyle::PM_DefaultFrameWidth, option, widget);
                 painter->setBrush(Qt::NoBrush);
-                painter->setPen(QPen(frameColor, lineWidth));
+                painter->setPen(QPen(frameColor, borderWidth));
                 painter->drawRoundedRect(groove, borderRadius, borderRadius);
             }
             painter->restore();
@@ -853,29 +855,48 @@ QRect StudioStyle::subControlRect(
     }
 #endif
 
-    if (const QStyleOptionSlider *slider = qstyleoption_cast<const QStyleOptionSlider *>(option)) {
+    switch (control)
+    {
+    case CC_Slider:
+        if (const auto slider = qstyleoption_cast<const QStyleOptionSlider *>(option)) {
             switch (subControl) {
             case SubControl::SC_SliderGroove:
-            return option->rect;
+                return slider->rect;
             case SubControl::SC_SliderHandle:
             {
                 QRect retval = Super::subControlRect(control, option, subControl, widget);
-            int thickness = 2;
+                return (slider->orientation == Qt::Horizontal)
-            QPoint center = retval.center();
+                    ? retval.adjusted(0, 1, 0, 0)
-            const QRect &rect = slider->rect;
+                    : retval.adjusted(1, 0, 0, 0);
-            if (slider->orientation == Qt::Horizontal)
-                return {center.x() - thickness, rect.top(), (thickness * 2) + 1, rect.height()};
-            else
-                return {rect.left(), center.y() - thickness, rect.width(), (thickness * 2) + 1};
             }
                 break;
             default:
                 break;
             }
         }
+        break;
+    default:
+        break;
+    }
+
     return Super::subControlRect(control, option, subControl, widget);
 }
 
+int StudioStyle::styleHint(
+        StyleHint hint,
+        const QStyleOption *option,
+        const QWidget *widget,
+        QStyleHintReturn *returnData) const
+{
+    switch (hint) {
+    case SH_ScrollBar_Transient:
+        return true;
+    default:
+        break;
+    }
+    return Super::styleHint(hint, option, widget, returnData);
+}
+
 int StudioStyle::pixelMetric(
         PixelMetric metric,
         const QStyleOption *option,
@@ -926,6 +947,21 @@ int StudioStyle::pixelMetric(
         return 4;
     case PM_ToolBarExtensionExtent:
         return 29;
+    case PM_ScrollBarExtent:
+        return 20;
+    case PM_ScrollBarSliderMin:
+        return 30;
+    case PM_SliderLength:
+        return 5;
+    case PM_SliderThickness:
+        if (const auto *slider = qstyleoption_cast<const QStyleOptionSlider *>(option)) {
+            return (slider->orientation == Qt::Horizontal
+                        ? slider->rect.height()
+                        : slider->rect.width()) - 1;
+        }
+        break;
+    case PM_SliderControlThickness:
+        return 2;
     default:
         break;
     }

src/plugins/qmldesignerbase/utils/studiostyle.h

@@ -51,6 +51,12 @@ public:
             SubControl subControl,
             const QWidget *widget) const override;
 
+    int styleHint(
+            StyleHint hint,
+            const QStyleOption *option,
+            const QWidget *widget,
+            QStyleHintReturn *returnData) const override;
+
     int pixelMetric(
             PixelMetric metric,
             const QStyleOption *option = nullptr,

src/plugins/texteditor/texteditor.cpp

@@ -66,6 +66,7 @@
 #include <utils/textutils.h>
 #include <utils/theme/theme.h>
 #include <utils/tooltip/tooltip.h>
+#include <utils/transientscroll.h>
 #include <utils/uncommentselection.h>
 
 #include <QAbstractTextDocumentLayout>
@@ -1144,6 +1145,7 @@ TextEditorWidget::TextEditorWidget(QWidget *parent)
     setLayoutDirection(Qt::LeftToRight);
     viewport()->setMouseTracking(true);
     setFrameStyle(QFrame::NoFrame);
+    TransientScrollAreaSupport::support(this);
 }
 
 void TextEditorWidget::setTextDocument(const QSharedPointer<TextDocument> &doc)