desktop: re-add WebEngine support

This reverts commit 643f4a5726 and finishes the task of adding WebEngine as an
alternate backend to be used in printing.

The ultimate goal is to be able to build without QtWebKit (as that is no longer
supported in Qt6). WebKit was used in two places: The user manual and printing.
This patch makes printing work with WebEngine.

The main obstacle is that WebEngine no longer allows accessing HTML elements
from C++ code and rendering the page to a QPainter.

The old version used this to figure out dimensions and page breaks for the
pages and then in the QPainter placed the profile images. With WebEninge, you
need to access the elements using JavaScript which is now used to place the
profile in the html proplerly as an <img> tag. To this end, both html and
profile images are written to a temporary directory on disk.

This image replacement by JavaScript is only necessary to make old templates
still work. It could be replaced by actually putting <img> tags in the
templates (but this would break user edited templates).

In my experiments, the page breaking was done great by html/css, so the
additional magic seems superflous.

What remains to be done:
* remove empty page at the end of printout
* make preview great again (in particlar needed for template editing)

Note: since QtWebEngine currently cannot be built with our toolchain on
Windows, this patch keeps QtWebKit support around by making the QtWebEngine
compile-time conditional via #ifdefs.

[Dirk Hohndel: merged a few commits to make this more logical - the resulting
commit is fairly big, but IMHO preferrable]

Signed-off-by: Robert C. Helling <helling@atdotde.de>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

CMakeLists.txt

@@ -51,6 +51,7 @@ option(NO_USERMANUAL "don't include a viewer for the user manual" OFF)
 #Options regarding enabling parts of subsurface
 option(BTSUPPORT "enable support for QtBluetooth (requires Qt5.4 or newer)" ON)
 option(FTDISUPPORT "enable support for libftdi based serial" OFF)
+option(USE_WEBENGINE "Use QWebEngine instead of QWebKit" OFF)
 
 # Options regarding What should we build on subsurface
 option(MAKE_TESTS "Make the tests" ON)

cmake/Modules/HandleUserManual.cmake

@@ -2,5 +2,11 @@ if(NO_USERMANUAL)
 	message(STATUS "building without usermanual")
 	add_definitions(-DNO_USERMANUAL)
 else()
-	list(APPEND QT_EXTRA_COMPONENTS WebKitWidgets)
+	if(USE_WEBENGINE)
+		message(STATUS "building with QWebEngine")
+		list(APPEND QT_EXTRA_COMPONENTS WebEngineWidgets)
+		add_definitions(-DUSE_WEBENGINE)
+	else()
+		list(APPEND QT_EXTRA_COMPONENTS WebKitWidgets)
+	endif()
 endif()

desktop-widgets/CMakeLists.txt

@@ -148,8 +148,6 @@ if(NOT NO_PRINTING)
 	set(SUBSURFACE_INTERFACE ${SUBSURFACE_INTERFACE}
 		printdialog.cpp
 		printdialog.h
-		printer.cpp
-		printer.h
 		printoptions.cpp
 		printoptions.h
 		templateedit.cpp
@@ -159,6 +157,18 @@ if(NOT NO_PRINTING)
 	)
 endif()
 
+if(USE_WEBENGINE)
+	set(SUBSURFACE_INTERFACE ${SUBSURFACE_INTERFACE}
+		printerwebengine.cpp
+		printerwebengine.h
+	)
+else()
+	set(SUBSURFACE_INTERFACE ${SUBSURFACE_INTERFACE}
+		printer.cpp
+		printer.h
+	)
+endif()
+
 if (BTSUPPORT)
 	set(SUBSURFACE_INTERFACE ${SUBSURFACE_INTERFACE}
 		btdeviceselectiondialog.cpp

desktop-widgets/printdialog.cpp

@@ -1,6 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0
 #include "printdialog.h"
+#ifdef USE_WEBENGINE
+#include "printerwebengine.h"
+#else
 #include "printer.h"
+#endif
 #include "core/pref.h"
 #include "core/dive.h" // for existing_filename
 
@@ -14,6 +18,9 @@
 #include <QSettings>
 #include <QMessageBox>
 #include <QDialogButtonBox>
+#ifdef USE_WEBENGINE
+#include <QWebEngineView>
+#endif
 
 #define SETTINGS_GROUP "PrintDialog"
 
@@ -215,13 +222,26 @@ void PrintDialog::printClicked(void)
 {
 	createPrinterObj();
 	QPrintDialog printDialog(qprinter, this);
+#ifdef USE_WEBENGINE
+	connect(printer, SIGNAL(progessUpdated(int)), progressBar, SLOT(setValue(int)));
+	connect(printer, &Printer::jobDone, this, &PrintDialog::printingDone);
+	printer->print();
+#else
 	if (printDialog.exec() == QDialog::Accepted) {
 		connect(printer, SIGNAL(progessUpdated(int)), progressBar, SLOT(setValue(int)));
 		printer->print();
 		close();
 	}
+#endif
 }
 
+#ifdef USE_WEBENGINE
+void PrintDialog::printingDone()
+{
+	close();
+}
+#endif
+
 void PrintDialog::onPaintRequested(QPrinter*)
 {
 	createPrinterObj();

desktop-widgets/printdialog.h

@@ -38,6 +38,13 @@ slots:
 	void printClicked();
 	void onPaintRequested(QPrinter *);
 	void createPrinterObj();
+
+#ifdef USE_WEBENGINE
+public
+slots:
+	void printingDone();
+#endif
 };
+
 #endif
 #endif // PRINTDIALOG_H

desktop-widgets/printerwebengine.cpp

@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "printerwebengine.h"
+#include "mainwindow.h"
+#include "templatelayout.h"
+#include "core/statistics.h"
+#include "core/qthelper.h"
+#include "core/settings/qPrefDisplay.h"
+#include "profile-widget/profilewidget2.h"
+
+#include <algorithm>
+#include <QPainter>
+#include <QPrinter>
+#include <QtWebEngineWidgets>
+
+extern void exportProfile(const struct dive *dive, const QString filename);
+
+Printer::Printer(QPaintDevice *paintDevice, const print_options &printOptions, const template_options &templateOptions, PrintMode printMode, bool inPlanner) :
+	webView(new QWebEngineView),
+	paintDevice(paintDevice),
+	printOptions(printOptions),
+	templateOptions(templateOptions),
+	printMode(printMode),
+	inPlanner(inPlanner),
+	done(0)
+{
+	connect(webView, &QWebEngineView::loadFinished, this, &Printer::onLoadFinished);
+	connect(this, &Printer::profilesInserted, this, &Printer::printing);
+	profilesMissing = true;
+}
+
+Printer::~Printer()
+{
+	delete webView;
+}
+
+void Printer::onLoadFinished()
+{
+	if (profilesMissing) {
+		webView->page()->runJavaScript("   var profiles = document.getElementsByClassName(\"diveProfile\");\
+				       for (let profile of profiles) { \
+					  var id = profile.attributes.getNamedItem(\"Id\").value; \
+					  var img = document.createElement(\"img\"); \
+					  img.src = id + \".png\"; \
+					  img.style.height = \"100%\"; \
+					  img.style.width = \"100%\"; \
+					  profile.appendChild(img); \
+					} \
+				", [this](const QVariant &v) { emit profilesInserted(); });
+
+	}
+	profilesMissing = false;
+	emit(progessUpdated(100));
+}
+
+void Printer::printing()
+{
+	QPrintDialog printDialog(&printer, (QWidget *) nullptr);
+	if (printDialog.exec() == QDialog::Accepted) {
+		webView->page()->print(&printer, [this](bool ok){ if (ok) emit jobDone(); });
+	}
+	printDialog.close();
+}
+
+//value: ranges from 0 : 100 and shows the progress of the templating engine
+void Printer::templateProgessUpdated(int value)
+{
+	done = value / 5; //template progess if 1/5 of total work
+	emit progessUpdated(done);
+}
+
+QString Printer::exportHtml()
+{
+	// Does anybody actually use this? It will not contian profile images!!!
+	TemplateLayout t(printOptions, templateOptions);
+	connect(&t, SIGNAL(progressUpdated(int)), this, SLOT(templateProgessUpdated(int)));
+	QString html;
+
+	if (printOptions.type == print_options::DIVELIST)
+		html = t.generate(inPlanner);
+	else if (printOptions.type == print_options::STATISTICS )
+		html = t.generateStatistics();
+
+	// TODO: write html to file
+	return html;
+}
+
+void Printer::print()
+{
+	// we can only print if "PRINT" mode is selected
+	if (printMode != Printer::PRINT) {
+		return;
+	}
+	int i;
+	struct dive *dive;
+	QString fn;
+	int dives_to_print = 0;
+	for_each_dive(i, dive)
+		if (dive->selected || !printOptions.print_selected)
+			++dives_to_print;
+
+	for_each_dive (i, dive) {
+		//TODO check for exporting selected dives only
+		if (!dive->selected && printOptions.print_selected)
+			continue;
+		exportProfile(dive, printDir.filePath(QString("dive_%1.png").arg(dive->id)));
+		emit(progessUpdated(done + lrint(i * 80.0 / dives_to_print)));
+	}
+
+	TemplateLayout t(printOptions, templateOptions);
+	connect(&t, SIGNAL(progressUpdated(int)), this, SLOT(templateProgessUpdated(int)));
+	int dpi = printer.resolution();
+	webView->page()->settings()->setAttribute(QWebEngineSettings::LocalContentCanAccessFileUrls, true);
+	connect(webView, &QWebEngineView::loadFinished, this, &Printer::onLoadFinished);
+
+	if (printOptions.type == print_options::DIVELIST) {
+		QFile printFile(printDir.filePath("print.html"));
+		printFile.open(QIODevice::WriteOnly | QIODevice::Text);
+		QTextStream out(&printFile);
+		out << t.generate(inPlanner);
+		printFile.close();
+		webView->load(QUrl::fromLocalFile(printDir.filePath("print.html")));
+	} else if (printOptions.type == print_options::STATISTICS )
+		webView->setHtml(t.generateStatistics());
+	if (printOptions.color_selected && printer.colorMode())
+		printer.setColorMode(QPrinter::Color);
+	else
+		printer.setColorMode(QPrinter::GrayScale);
+	printer.setResolution(dpi);
+}
+
+void Printer::previewOnePage()
+{
+	if (printMode == PREVIEW) {
+		TemplateLayout t(printOptions, templateOptions);
+
+		pageSize.setHeight(paintDevice->height());
+		pageSize.setWidth(paintDevice->width());
+		// initialize the border settings
+		// templateOptions.border_width = std::max(1, pageSize.width() / 1000);
+		if (printOptions.type == print_options::DIVELIST)
+			webView->setHtml(t.generate(inPlanner));
+		else if (printOptions.type == print_options::STATISTICS )
+			webView->setHtml(t.generateStatistics());
+	}
+}

desktop-widgets/printerwebengine.h

@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef PRINTER_H
+#define PRINTER_H
+
+#include "printoptions.h"
+#include "templateedit.h"
+#include <QPrinter>
+#include <QTemporaryDir>
+
+class ProfileWidget2;
+class QPainter;
+class QPaintDevice;
+class QRect;
+class QWebEngineView;
+
+
+class Printer : public QObject {
+	Q_OBJECT
+
+public:
+	QWebEngineView *webView;
+	enum PrintMode {
+		PRINT,
+		PREVIEW
+	};
+
+private:
+	QPaintDevice *paintDevice;
+	QPrinter printer;
+	QTemporaryDir printDir;
+	const print_options &printOptions;
+	const template_options &templateOptions;
+	QSize pageSize;
+	PrintMode printMode;
+	bool inPlanner;
+	int done;
+	void onLoadFinished();
+	bool profilesMissing;
+
+private slots:
+	void templateProgessUpdated(int value);
+	void printing();
+
+public:
+	Printer(QPaintDevice *paintDevice, const print_options &printOptions, const template_options &templateOptions, PrintMode printMode, bool inPlanner);
+	~Printer();
+	void print();
+	void previewOnePage();
+	QString exportHtml();
+
+signals:
+	void progessUpdated(int value);
+	void profilesInserted();
+	void jobDone();
+};
+
+#endif //PRINTER_H

desktop-widgets/usermanual.cpp

@@ -35,6 +35,26 @@ void SearchBar::enableButtons(const QString &s)
 	ui.findNext->setEnabled(s.length());
 }
 
+#ifdef USE_WEBENGINE
+MyQWebEnginePage::MyQWebEnginePage(QObject* parent) : QWebEnginePage(parent)
+{
+}
+
+bool MyQWebEnginePage::acceptNavigationRequest(const QUrl & url, QWebEnginePage::NavigationType type, bool)
+{
+	if (type == QWebEnginePage::NavigationTypeLinkClicked)
+	{
+		QDesktopServices::openUrl(url);
+		return false;
+	}
+	return true;
+}
+
+MyQWebEngineView::MyQWebEngineView(QWidget* parent)
+{
+}
+#endif
+
 UserManual::UserManual(QWidget *parent) : QDialog(parent)
 {
 	QShortcut *closeKey = new QShortcut(QKeySequence(Qt::CTRL + Qt::Key_W), this);
@@ -55,12 +75,19 @@ UserManual::UserManual(QWidget *parent) : QDialog(parent)
 	setWindowTitle(tr("User manual"));
 	setWindowIcon(QIcon(":subsurface-icon"));
 
+#ifdef USE_WEBENGINE
+	userManual = new MyQWebEngineView(this);
+	MyQWebEnginePage *page = new MyQWebEnginePage();
+	userManual->setPage(page);
+#else
 	userManual = new QWebView(this);
+	userManual->page()->setLinkDelegationPolicy(QWebPage::DelegateExternalLinks);
+#endif
+
 	QString colorBack = palette().highlight().color().name(QColor::HexRgb);
 	QString colorText = palette().highlightedText().color().name(QColor::HexRgb);
 	userManual->setStyleSheet(QString("QWebView { selection-background-color: %1; selection-color: %2; }")
 		.arg(colorBack).arg(colorText));
-	userManual->page()->setLinkDelegationPolicy(QWebPage::DelegateExternalLinks);
 	QString searchPath = getSubsurfaceDataPath("Documentation");
 	if (searchPath.size()) {
 		// look for localized versions of the manual first
@@ -85,7 +112,10 @@ UserManual::UserManual(QWidget *parent) : QDialog(parent)
 	searchBar->hide();
 	connect(actionShowSearch, SIGNAL(triggered(bool)), searchBar, SLOT(show()));
 	connect(actionHideSearch, SIGNAL(triggered(bool)), searchBar, SLOT(hide()));
+#ifndef USE_WEBENGINE
 	connect(userManual, SIGNAL(linkClicked(QUrl)), this, SLOT(linkClickedSlot(QUrl)));
+#endif
+
 	connect(searchBar, SIGNAL(searchTextChanged(QString)), this, SLOT(searchTextChanged(QString)));
 	connect(searchBar, SIGNAL(searchNext()), this, SLOT(searchNext()));
 	connect(searchBar, SIGNAL(searchPrev()), this, SLOT(searchPrev()));
@@ -97,6 +127,14 @@ UserManual::UserManual(QWidget *parent) : QDialog(parent)
 	setLayout(vboxLayout);
 }
 
+#ifdef USE_WEBENGINE
+void UserManual::search(QString text, QWebEnginePage::FindFlags flags = QFlag(0))
+{
+	userManual->findText(text, flags,
+			     [this, text](bool found) {searchBar->setStyleSheet(found || text.length() == 0 ? "" : "QLineEdit{background: red;}");});
+}
+
+#else
 void UserManual::search(QString text, QWebPage::FindFlags flags = QFlag(0))
 {
 	if (userManual->findText(text, QWebPage::FindWrapsAroundDocument | flags) || text.length() == 0) {
@@ -105,6 +143,7 @@ void UserManual::search(QString text, QWebPage::FindFlags flags = QFlag(0))
 		searchBar->setStyleSheet("QLineEdit{background: red;}");
 	}
 }
+#endif
 
 void UserManual::searchTextChanged(const QString& text)
 {
@@ -119,13 +158,21 @@ void UserManual::searchNext()
 
 void UserManual::searchPrev()
 {
+#ifdef USE_WEBENGINE
+	search(mLastText, QWebEnginePage::FindBackward);
+#else
 	search(mLastText, QWebPage::FindBackward);
+#endif
 }
 
+
+#ifndef USE_WEBENGINE
 void UserManual::linkClickedSlot(const QUrl& url)
 {
 	QDesktopServices::openUrl(url);
 }
+#endif
+
 
 #ifdef Q_OS_MAC
 void UserManual::showEvent(QShowEvent *e)

desktop-widgets/usermanual.h

@@ -2,7 +2,13 @@
 #ifndef USERMANUAL_H
 #define USERMANUAL_H
 
+#ifdef USE_WEBENGINE
+#include <QWebEngineView>
+#include <QWebEnginePage>
+#else
 #include <QWebView>
+#endif
+
 #include <QDialog>
 #include "ui_searchbar.h"
 
@@ -22,6 +28,26 @@ private:
 	Ui::SearchBar ui;
 };
 
+#ifdef USE_WEBENGINE
+class MyQWebEnginePage : public QWebEnginePage
+{
+	Q_OBJECT
+
+public:
+	MyQWebEnginePage(QObject* parent = 0);
+	bool acceptNavigationRequest(const QUrl & url, QWebEnginePage::NavigationType type, bool);
+};
+
+class MyQWebEngineView : public QWebEngineView
+{
+	Q_OBJECT
+
+public:
+	MyQWebEngineView(QWidget* parent = 0);
+	MyQWebEnginePage* page() const;
+};
+#endif
+
 class UserManual : public QDialog {
 	Q_OBJECT
 
@@ -41,11 +67,19 @@ slots:
 	void searchTextChanged(const QString& s);
 	void searchNext();
 	void searchPrev();
+#ifndef USE_WEBENGINE
 	void linkClickedSlot(const QUrl& url);
+#endif
 private:
 	SearchBar *searchBar;
 	QString mLastText;
+#ifdef USE_WEBENGINE
+	QWebEngineView *userManual;
+	void search(QString, QWebEnginePage::FindFlags);
+#else
 	QWebView *userManual;
 	void search(QString, QWebPage::FindFlags);
+#endif
 };
+
 #endif // USERMANUAL_H

scripts/smtk2ssrf-build.sh

@@ -146,6 +146,7 @@ cmake   -DBTSUPPORT=OFF \
 	-DMAKE_TESTS=OFF \
 	-DNO_DOCS=ON \
 	-DNO_PRINTING=ON \
+	-DUSE_WEBENGINE=OFF \
 	-DNO_USERMANUAL=ON \
 	-DSUBSURFACE_TARGET_EXECUTABLE=DesktopExecutable \
 	build