gui: Remove QT_VERSION fallbacks for Qt < 5

There were surprisingly many `#ifdef` fallbacks for Qt 4.

Remiving them simplifies maintenance, as well as adding new GUI
functionality.

Author: laanwj

src/qt/addressbookpage.cpp

@@ -160,13 +160,8 @@ void AddressBookPage::setModel(AddressTableModel *_model)
     ui->tableView->sortByColumn(0, Qt::AscendingOrder);
 
     // Set column widths
-#if QT_VERSION < 0x050000
-    ui->tableView->horizontalHeader()->setResizeMode(AddressTableModel::Label, QHeaderView::Stretch);
-    ui->tableView->horizontalHeader()->setResizeMode(AddressTableModel::Address, QHeaderView::ResizeToContents);
-#else
     ui->tableView->horizontalHeader()->setSectionResizeMode(AddressTableModel::Label, QHeaderView::Stretch);
     ui->tableView->horizontalHeader()->setSectionResizeMode(AddressTableModel::Address, QHeaderView::ResizeToContents);
-#endif
 
     connect(ui->tableView->selectionModel(), SIGNAL(selectionChanged(QItemSelection,QItemSelection)),
         this, SLOT(selectionChanged()));

src/qt/bantablemodel.cpp

@@ -52,9 +52,7 @@ class BanTablePriv
         node.getBanned(banMap);
 
         cachedBanlist.clear();
-#if QT_VERSION >= 0x040700
         cachedBanlist.reserve(banMap.size());
-#endif
         for (const auto& entry : banMap)
         {
             CCombinedBan banEntry;

src/qt/bitcoin.cpp

@@ -55,13 +55,6 @@
 
 #if defined(QT_STATICPLUGIN)
 #include <QtPlugin>
-#if QT_VERSION < 0x050000
-Q_IMPORT_PLUGIN(qcncodecs)
-Q_IMPORT_PLUGIN(qjpcodecs)
-Q_IMPORT_PLUGIN(qtwcodecs)
-Q_IMPORT_PLUGIN(qkrcodecs)
-Q_IMPORT_PLUGIN(qtaccessiblewidgets)
-#else
 #if QT_VERSION < 0x050400
 Q_IMPORT_PLUGIN(AccessibleFactory)
 #endif
@@ -73,11 +66,6 @@ Q_IMPORT_PLUGIN(QWindowsIntegrationPlugin);
 Q_IMPORT_PLUGIN(QCocoaIntegrationPlugin);
 #endif
 #endif
-#endif
-
-#if QT_VERSION < 0x050000
-#include <QTextCodec>
-#endif
 
 // Declare meta types used for QMetaObject::invokeMethod
 Q_DECLARE_METATYPE(bool*)
@@ -151,16 +139,6 @@ static void initTranslations(QTranslator &qtTranslatorBase, QTranslator &qtTrans
 }
 
 /* qDebug() message handler --> debug.log */
-#if QT_VERSION < 0x050000
-void DebugMessageHandler(QtMsgType type, const char *msg)
-{
-    if (type == QtDebugMsg) {
-        LogPrint(BCLog::QT, "GUI: %s\n", msg);
-    } else {
-        LogPrintf("GUI: %s\n", msg);
-    }
-}
-#else
 void DebugMessageHandler(QtMsgType type, const QMessageLogContext& context, const QString &msg)
 {
     Q_UNUSED(context);
@@ -170,7 +148,6 @@ void DebugMessageHandler(QtMsgType type, const QMessageLogContext& context, cons
         LogPrintf("GUI: %s\n", msg.toStdString());
     }
 }
-#endif
 
 /** Class encapsulating Bitcoin Core startup and shutdown.
  * Allows running startup and shutdown in a different thread from the UI thread.
@@ -572,12 +549,6 @@ int main(int argc, char *argv[])
     // Do not refer to data directory yet, this can be overridden by Intro::pickDataDirectory
 
     /// 1. Basic Qt initialization (not dependent on parameters or configuration)
-#if QT_VERSION < 0x050000
-    // Internal string conversion is all UTF-8
-    QTextCodec::setCodecForTr(QTextCodec::codecForName("UTF-8"));
-    QTextCodec::setCodecForCStrings(QTextCodec::codecForTr());
-#endif
-
     Q_INIT_RESOURCE(bitcoin);
     Q_INIT_RESOURCE(bitcoin_locale);
 
@@ -708,17 +679,12 @@ int main(int argc, char *argv[])
     /// 9. Main GUI initialization
     // Install global event filter that makes sure that long tooltips can be word-wrapped
     app.installEventFilter(new GUIUtil::ToolTipToRichTextFilter(TOOLTIP_WRAP_THRESHOLD, &app));
-#if QT_VERSION < 0x050000
-    // Install qDebug() message handler to route to debug.log
-    qInstallMsgHandler(DebugMessageHandler);
-#else
 #if defined(Q_OS_WIN)
     // Install global event filter for processing Windows session related Windows messages (WM_QUERYENDSESSION and WM_ENDSESSION)
     qApp->installNativeEventFilter(new WinShutdownMonitor());
 #endif
     // Install qDebug() message handler to route to debug.log
     qInstallMessageHandler(DebugMessageHandler);
-#endif
     // Allow parameter interaction before we create the options model
     app.parameterSetup();
     // Load GUI settings from QSettings
@@ -739,7 +705,7 @@ int main(int argc, char *argv[])
         // so the GUI thread won't be held up.
         if (node->baseInitialize()) {
             app.requestInitialize();
-#if defined(Q_OS_WIN) && QT_VERSION >= 0x050000
+#if defined(Q_OS_WIN)
             WinShutdownMonitor::registerShutdownBlockReason(QObject::tr("%1 didn't yet exit safely...").arg(QObject::tr(PACKAGE_NAME)), (HWND)app.getMainWinId());
 #endif
             app.exec();

src/qt/bitcoingui.cpp

@@ -55,14 +55,8 @@
 #include <QStyle>
 #include <QTimer>
 #include <QToolBar>
-#include <QVBoxLayout>
-
-#if QT_VERSION < 0x050000
-#include <QTextDocument>
-#include <QUrl>
-#else
 #include <QUrlQuery>
-#endif
+#include <QVBoxLayout>
 
 const std::string BitcoinGUI::DEFAULT_UIPLATFORM =
 #if defined(Q_OS_MAC)
@@ -147,12 +141,6 @@ BitcoinGUI::BitcoinGUI(interfaces::Node& node, const PlatformStyle *_platformSty
 #endif
     setWindowTitle(windowTitle);
 
-#if defined(Q_OS_MAC) && QT_VERSION < 0x050000
-    // This property is not implemented in Qt 5. Setting it has no effect.
-    // A replacement API (QtMacUnifiedToolBar) is available in QtMacExtras.
-    setUnifiedTitleAndToolBarOnMac(true);
-#endif
-
     rpcConsole = new RPCConsole(node, _platformStyle, 0);
     helpMessageDialog = new HelpMessageDialog(node, this, false);
 #ifdef ENABLE_WALLET
@@ -229,7 +217,7 @@ BitcoinGUI::BitcoinGUI(interfaces::Node& node, const PlatformStyle *_platformSty
 
     // Override style sheet for progress bar for styles that have a segmented progress bar,
     // as they make the text unreadable (workaround for issue #1071)
-    // See https://qt-project.org/doc/qt-4.8/gallery.html
+    // See https://doc.qt.io/qt-5/gallery.html
     QString curStyle = QApplication::style()->metaObject()->className();
     if(curStyle == "QWindowsStyle" || curStyle == "QWindowsXPStyle")
     {

src/qt/coincontroldialog.cpp

@@ -109,11 +109,7 @@ CoinControlDialog::CoinControlDialog(const PlatformStyle *_platformStyle, QWidge
     connect(ui->treeWidget, SIGNAL(itemChanged(QTreeWidgetItem*, int)), this, SLOT(viewItemChanged(QTreeWidgetItem*, int)));
 
     // click on header
-#if QT_VERSION < 0x050000
-    ui->treeWidget->header()->setClickable(true);
-#else
     ui->treeWidget->header()->setSectionsClickable(true);
-#endif
     connect(ui->treeWidget->header(), SIGNAL(sectionClicked(int)), this, SLOT(headerSectionClicked(int)));
 
     // ok button
@@ -392,13 +388,11 @@ void CoinControlDialog::viewItemChanged(QTreeWidgetItem* item, int column)
 
     // TODO: Remove this temporary qt5 fix after Qt5.3 and Qt5.4 are no longer used.
     //       Fixed in Qt5.5 and above: https://bugreports.qt.io/browse/QTBUG-43473
-#if QT_VERSION >= 0x050000
     else if (column == COLUMN_CHECKBOX && item->childCount() > 0)
     {
         if (item->checkState(COLUMN_CHECKBOX) == Qt::PartiallyChecked && item->child(0)->checkState(COLUMN_CHECKBOX) == Qt::PartiallyChecked)
             item->setCheckState(COLUMN_CHECKBOX, Qt::Checked);
     }
-#endif
 }
 
 // shows count of locked unspent outputs

src/qt/guiutil.cpp

@@ -53,13 +53,9 @@
 #include <QSettings>
 #include <QTextDocument> // for Qt::mightBeRichText
 #include <QThread>
+#include <QUrlQuery>
 #include <QMouseEvent>
 
-#if QT_VERSION < 0x050000
-#include <QUrl>
-#else
-#include <QUrlQuery>
-#endif
 
 #if QT_VERSION >= 0x50200
 #include <QFontDatabase>
@@ -95,11 +91,7 @@ QFont fixedPitchFont()
     return QFontDatabase::systemFont(QFontDatabase::FixedFont);
 #else
     QFont font("Monospace");
-#if QT_VERSION >= 0x040800
     font.setStyleHint(QFont::Monospace);
-#else
-    font.setStyleHint(QFont::TypeWriter);
-#endif
     return font;
 #endif
 }
@@ -127,12 +119,10 @@ void setupAddressWidget(QValidatedLineEdit *widget, QWidget *parent)
     parent->setFocusProxy(widget);
 
     widget->setFont(fixedPitchFont());
-#if QT_VERSION >= 0x040700
     // We don't want translators to use own addresses in translations
     // and this is the only place, where this address is supplied.
     widget->setPlaceholderText(QObject::tr("Enter a Bitcoin address (e.g. %1)").arg(
         QString::fromStdString(DummyAddress(Params()))));
-#endif
     widget->setValidator(new BitcoinAddressEntryValidator(parent));
     widget->setCheckValidator(new BitcoinAddressCheckValidator(parent));
 }
@@ -151,12 +141,8 @@ bool parseBitcoinURI(const QUrl &uri, SendCoinsRecipient *out)
     }
     rv.amount = 0;
 
-#if QT_VERSION < 0x050000
-    QList<QPair<QString, QString> > items = uri.queryItems();
-#else
     QUrlQuery uriQuery(uri);
     QList<QPair<QString, QString> > items = uriQuery.queryItems();
-#endif
     for (QList<QPair<QString, QString> >::iterator i = items.begin(); i != items.end(); i++)
     {
         bool fShouldReturnFalse = false;
@@ -242,11 +228,7 @@ bool isDust(interfaces::Node& node, const QString& address, const CAmount& amoun
 
 QString HtmlEscape(const QString& str, bool fMultiLine)
 {
-#if QT_VERSION < 0x050000
-    QString escaped = Qt::escape(str);
-#else
     QString escaped = str.toHtmlEscaped();
-#endif
     if(fMultiLine)
     {
         escaped = escaped.replace("\n", "<br>\n");
@@ -287,11 +269,7 @@ QString getSaveFileName(QWidget *parent, const QString &caption, const QString &
     QString myDir;
     if(dir.isEmpty()) // Default to user documents location
     {
-#if QT_VERSION < 0x050000
-        myDir = QDesktopServices::storageLocation(QDesktopServices::DocumentsLocation);
-#else
         myDir = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
-#endif
     }
     else
     {
@@ -337,11 +315,7 @@ QString getOpenFileName(QWidget *parent, const QString &caption, const QString &
     QString myDir;
     if(dir.isEmpty()) // Default to user documents location
     {
-#if QT_VERSION < 0x050000
-        myDir = QDesktopServices::storageLocation(QDesktopServices::DocumentsLocation);
-#else
         myDir = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
-#endif
     }
     else
     {
@@ -495,11 +469,7 @@ void TableViewLastColumnResizingFixer::disconnectViewHeadersSignals()
 // Refactored here for readability.
 void TableViewLastColumnResizingFixer::setViewHeaderResizeMode(int logicalIndex, QHeaderView::ResizeMode resizeMode)
 {
-#if QT_VERSION < 0x050000
-    tableView->horizontalHeader()->setResizeMode(logicalIndex, resizeMode);
-#else
     tableView->horizontalHeader()->setSectionResizeMode(logicalIndex, resizeMode);
-#endif
 }
 
 void TableViewLastColumnResizingFixer::resizeColumn(int nColumnIndex, int width)

src/qt/guiutil.h

@@ -233,7 +233,7 @@ namespace GUIUtil
         void mouseReleaseEvent(QMouseEvent *event);
     };
 
-#if defined(Q_OS_MAC) && QT_VERSION >= 0x050000
+#if defined(Q_OS_MAC)
     // workaround for Qt OSX Bug:
     // https://bugreports.qt-project.org/browse/QTBUG-15631
     // QProgressBar uses around 10% CPU even when app is in background

src/qt/macdockiconhandler.mm

@@ -14,10 +14,6 @@
 #include <objc/objc.h>
 #include <objc/message.h>
 
-#if QT_VERSION < 0x050000
-extern void qt_mac_set_dock_menu(QMenu *);
-#endif
-
 static MacDockIconHandler *s_instance = nullptr;
 
 bool dockClickHandler(id self,SEL _cmd,...) {
@@ -54,9 +50,7 @@ void setupDockClickHandler() {
     this->m_dummyWidget = new QWidget();
     this->m_dockMenu = new QMenu(this->m_dummyWidget);
     this->setMainWindow(nullptr);
-#if QT_VERSION < 0x050000
-    qt_mac_set_dock_menu(this->m_dockMenu);
-#elif QT_VERSION >= 0x050200
+#if QT_VERSION >= 0x050200
     this->m_dockMenu->setAsDockMenu();
 #endif
     [pool release];

src/qt/networkstyle.cpp

@@ -68,11 +68,7 @@ NetworkStyle::NetworkStyle(const QString &_appName, const int iconColorHueShift,
         }
 
         //convert back to QPixmap
-#if QT_VERSION >= 0x040700
         pixmap.convertFromImage(img);
-#else
-        pixmap = QPixmap::fromImage(img);
-#endif
     }
 
     appIcon             = QIcon(pixmap);

src/qt/openuridialog.cpp

@@ -15,9 +15,7 @@ OpenURIDialog::OpenURIDialog(QWidget *parent) :
     ui(new Ui::OpenURIDialog)
 {
     ui->setupUi(this);
-#if QT_VERSION >= 0x040700
     ui->uriEdit->setPlaceholderText("bitcoin:");
-#endif
 }
 
 OpenURIDialog::~OpenURIDialog()