Add CPDB support to Qt print dialog

The Common Print Dialog Backends (CPDB) concept has
GUI-toolkit-independent backends for each print technology (CUPS, Print
to File, cloud printing services, ...) and each print dialog (GTK, Qt,
Chromium, Firefox, ...) is supposed to use this backend, so that changes
in print technologies can be centrally and quickly covered by changing
the backends and everything new gets available in all print dialogs.

This commit provides Qt print dialog implementation which adds support
for the CPDB concept. It communincates with all the installed CPDB
backends and so gives support for all these print technologies to the Qt
print dialog.

To make use of CPDB, Qt should be configured with cpdb and cpdbjobwidget
enabled and other print technologies (eg. cups and cupsjobwidget)
disabled to prevent printer duplication.

Change-Id: Ic97c41979040adb6e9ffab540c09edadb6b5de3e

Author: TinyTrebuchet

cmake/FindWrapCPDB.cmake

@@ -0,0 +1,25 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+if (TARGET WrapCPDB::WrapCPDB)
+    set(WrapCPDB_FOUND ON)
+    return()
+endif()
+
+find_package(PkgConfig QUIET)
+if (PKG_CONFIG_FOUND)
+    pkg_check_modules(CPDB QUIET cpdb-frontend)
+    if (CPDB_FOUND)
+        add_library(WrapCPDB::WrapCPDB INTERFACE IMPORTED)
+        target_compile_definitions(WrapCPDB::WrapCPDB INTERFACE -DQT_NO_KEYWORDS)
+        set_target_properties(WrapCPDB::WrapCPDB PROPERTIES
+            INTERFACE_INCLUDE_DIRECTORIES "${CPDB_INCLUDE_DIRS}")
+        set_target_properties(WrapCPDB::WrapCPDB PROPERTIES
+            INTERFACE_LINK_LIBRARIES "${CPDB_LIBRARIES}")
+    endif()
+endif()
+
+find_package_handle_standard_args(WrapCPDB
+                                  REQUIRED_VARS CPDB_INCLUDE_DIRS CPDB_LIBRARIES
+                                  VERSION_VAR CPDB_VERSION)
+

src/gui/painting/qpagesize.cpp

@@ -692,6 +692,8 @@ class QPageSizePrivate : public QSharedData
                      const QString &name,
                      QPageSize::SizeMatchPolicy matchPolicy);
     QPageSizePrivate(const QString &key, const QSize &size, const QString &name);
+    QPageSizePrivate(const QString &key, const QSizeF &size,
+                     QPageSize::Unit units, const QString &name);
     QPageSizePrivate(int windowsId, const QSize &pointSize, const QString &name);
     ~QPageSizePrivate();
 
@@ -773,6 +775,15 @@ QPageSizePrivate::QPageSizePrivate(const QString &key, const QSize &pointSize, c
     }
 }
 
+QPageSizePrivate::QPageSizePrivate(const QString &key, const QSizeF &size,
+                                   QPageSize::Unit units, const QString &name)
+    : m_id(QPageSize::Custom),
+      m_windowsId(0)
+{
+    init(size, units, name);
+    m_key = key;
+}
+
 QPageSizePrivate::QPageSizePrivate(int windowsId, const QSize &pointSize, const QString &name)
     : m_id(QPageSize::Custom),
       m_windowsId(0),
@@ -1156,6 +1167,18 @@ QPageSize::QPageSize(const QString &key, const QSize &pointSize, const QString &
 {
 }
 
+/*!
+    \internal
+
+    Create page with given key, size, units and name, for use by printer plugin.
+*/
+
+QPageSize::QPageSize(const QString &key, const QSizeF &size,
+                     QPageSize::Unit units, const QString &name)
+    : d(new QPageSizePrivate(key, size, units, name))
+{
+}
+
 /*!
     \internal
 

src/gui/painting/qpagesize.h

@@ -255,6 +255,8 @@ class Q_GUI_EXPORT QPageSize
     { return !(lhs == rhs); }
 
     QPageSize(const QString &key, const QSize &pointSize, const QString &name);
+    QPageSize(const QString &key, const QSizeF &size,
+              QPageSize::Unit units, const QString &name);
     QPageSize(int windowsId, const QSize &pointSize, const QString &name);
     QPageSize(QPageSizePrivate &dd);
     QSharedDataPointer<QPageSizePrivate> d;

src/plugins/printsupport/CMakeLists.txt

@@ -1,6 +1,10 @@
 # Copyright (C) 2022 The Qt Company Ltd.
 # SPDX-License-Identifier: BSD-3-Clause
 
-if(QT_FEATURE_cups AND UNIX AND NOT APPLE)
+# Generated from printsupport.pro.
+
+if(QT_FEATURE_cpdb AND UNIX AND NOT APPLE)
+    add_subdirectory(cpdb)
+elseif(QT_FEATURE_cups AND UNIX AND NOT APPLE)
     add_subdirectory(cups)
 endif()

src/plugins/printsupport/cpdb/CMakeLists.txt

@@ -0,0 +1,23 @@
+
+qt_find_package(WrapCPDB
+                PROVIDED_TARGETS WrapCPDB::WrapCPDB MODULE_NAME printsupport QMAKE_LIB cpdb)
+
+qt_internal_add_plugin(QCpdbPrinterSupportPlugin
+    OUTPUT_NAME cpdbprintersupport
+    PLUGIN_TYPE printsupport
+    SOURCES
+        main.cpp
+        qcpdbprintengine.cpp qcpdbprintengine_p.h
+        qcpdbprintersupport.cpp qcpdbprintersupport_p.h
+        qcpdbprintdevice.cpp qcpdbprintdevice.h
+    INCLUDE_DIRECTORIES
+        ../../../printsupport/kernel
+    LIBRARIES
+        WrapCPDB::WrapCPDB
+        Qt::Core
+        Qt::CorePrivate
+        Qt::Gui
+        Qt::GuiPrivate
+        Qt::PrintSupport
+        Qt::PrintSupportPrivate
+)

src/plugins/printsupport/cpdb/cpdb.json

@@ -0,0 +1,3 @@
+{
+    "Keys": [ "cpdbprintersupport" ]
+}

src/plugins/printsupport/cpdb/main.cpp

@@ -0,0 +1,37 @@
+// Copyright (C) 2022-2023 Gaurav Guleria <tinytrebuchet@protonmail.com>
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include "qcpdbprintersupport_p.h"
+
+#include <qpa/qplatformprintplugin.h>
+#include <QtCore/QStringList>
+
+QT_BEGIN_NAMESPACE
+
+using namespace Qt::StringLiterals;
+
+class QCpdbPrinterSupportPlugin : public QPlatformPrinterSupportPlugin
+{
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID QPlatformPrinterSupportFactoryInterface_iid FILE "cpdb.json")
+
+public:
+    QStringList keys() const;
+    QPlatformPrinterSupport *create(const QString &) override;
+};
+
+QStringList QCpdbPrinterSupportPlugin::keys() const
+{
+    return QStringList(QStringLiteral("cpdbprintersupport"));
+}
+
+QPlatformPrinterSupport *QCpdbPrinterSupportPlugin::create(const QString &key)
+{
+    if (key.compare(key, "cpdbprintersupport"_L1, Qt::CaseInsensitive) == 0)
+        return new QCpdbPrinterSupport;
+    return 0;
+}
+
+QT_END_NAMESPACE
+
+#include "main.moc"