WScrollable: Add a scrollable widget type.

CMakeLists.txt

@@ -930,6 +930,7 @@ add_library(mixxx-lib STATIC EXCLUDE_FROM_ALL
   src/widget/wpixmapstore.cpp
   src/widget/wpushbutton.cpp
   src/widget/wrecordingduration.cpp
+  src/widget/wscrollable.cpp
   src/widget/wsearchlineedit.cpp
   src/widget/wsingletoncontainer.cpp
   src/widget/wsizeawarestack.cpp

src/skin/legacy/legacyskinparser.cpp

@@ -64,6 +64,7 @@
 #include "widget/wpushbutton.h"
 #include "widget/wraterange.h"
 #include "widget/wrecordingduration.h"
+#include "widget/wscrollable.h"
 #include "widget/wsearchlineedit.h"
 #include "widget/wsingletoncontainer.h"
 #include "widget/wsizeawarestack.h"
@@ -598,6 +599,8 @@ QList<QWidget*> LegacySkinParser::parseNode(const QDomElement& node) {
         result = wrapWidget(parseBattery(node));
     } else if (nodeName == "SetVariable") {
         m_pContext->updateVariable(node);
+    } else if (nodeName == "Scrollable") {
+        result = wrapWidget(parseScrollable(node));
     } else if (nodeName == "Template") {
         result = parseTemplate(node);
     } else if (nodeName == "SingletonDefinition") {
@@ -648,6 +651,37 @@ QWidget* LegacySkinParser::parseSplitter(const QDomElement& node) {
     return pSplitter;
 }
 
+QWidget* LegacySkinParser::parseScrollable(const QDomElement& node) {
+    WScrollable* pScrollable = new WScrollable(m_pParent);
+    commonWidgetSetup(node, pScrollable);
+
+    QDomNode childrenNode = m_pContext->selectNode(node, "Children");
+    QWidget* pOldParent = m_pParent;
+    m_pParent = pScrollable;
+
+    if (!childrenNode.isNull()) {
+        QDomNodeList childNodes = childrenNode.childNodes();
+        if (childNodes.count() != 1) {
+            SKIN_WARNING(node, *m_pContext) << "Scrollables must have exactly one child";
+        }
+
+        QDomNode childnode = childNodes.at(0);
+        if (childnode.isElement()) {
+            QList<QWidget*> children = parseNode(childnode.toElement());
+            if (children.count() != 1) {
+                SKIN_WARNING(node, *m_pContext) << "Scrollables must have exactly one child";
+            } else if (children.at(0) != nullptr) {
+                pScrollable->setWidget(children.at(0));
+            }
+        }
+    }
+    pScrollable->setup(node, *m_pContext);
+    pScrollable->Init();
+
+    m_pParent = pOldParent;
+    return pScrollable;
+}
+
 void LegacySkinParser::parseChildren(
         const QDomElement& node,
         WWidgetGroup* pGroup) {

src/skin/legacy/legacyskinparser.h

@@ -103,6 +103,7 @@ class LegacySkinParser : public QObject, public SkinParser {
     QWidget* parseWidgetStack(const QDomElement& node);
     QWidget* parseSizeAwareStack(const QDomElement& node);
     QWidget* parseSplitter(const QDomElement& node);
+    QWidget* parseScrollable(const QDomElement& node);
     void parseSingletonDefinition(const QDomElement& node);
 
     // Visual widgets.

src/widget/wscrollable.cpp

@@ -0,0 +1,26 @@
+#include "widget/wscrollable.h"
+
+WScrollable::WScrollable(QWidget* pParent)
+        : QScrollArea(pParent),
+          WBaseWidget(this) {
+}
+
+void WScrollable::setup(const QDomNode& node, const SkinContext& context) {
+    QString horizontalPolicy;
+    // The QT default is "As Needed", so we don't need a selector for that.
+    if (context.hasNodeSelectString(node, "HorizontalScrollBarPolicy", &horizontalPolicy)) {
+        if (horizontalPolicy == "on") {
+            setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
+        } else if (horizontalPolicy == "off") {
+            setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+        }
+    }
+    QString verticalPolicy;
+    if (context.hasNodeSelectString(node, "VerticalScrollBarPolicy", &verticalPolicy)) {
+        if (verticalPolicy == "on") {
+            setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
+        } else if (verticalPolicy == "off") {
+            setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+        }
+    }
+}

src/widget/wscrollable.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <QDomNode>
+#include <QEvent>
+#include <QScrollArea>
+
+#include "preferences/usersettings.h"
+#include "skin/legacy/skincontext.h"
+#include "widget/wbasewidget.h"
+
+/// Creates a QScrollArea. The QT default is to show scrollbars if needed.
+class WScrollable : public QScrollArea, public WBaseWidget {
+    Q_OBJECT
+  public:
+    WScrollable(QWidget* pParent);
+
+    /// WScrollable supports the following attributes: HorizontalScrollBarPolicy, VerticalScrollBarPolicy
+    void setup(const QDomNode& node, const SkinContext& context);
+};