Document how to use CMake on Qt Core, Qt GUI's central pages

Add documentation on how to use a module from CMake, alongside
the existing documentation about qmake. Separate generic info
from module-specific examples, to make it possible to use one
include file in all modules.

While at it, also remove the mentioning of the central include;
it is not something we should actively advocate anymore. Instead,
the documentation of every class gives the correct include to use.

Task-number: QTBUG-73058
Change-Id: I6b3c0e5ea218dd9c06a491c8fb799a7fcf42dd92
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

3 files changed, 56 insertions, 1 deletions

diff --git a/doc/global/includes/module-use.qdocinc b/doc/global/includes/module-use.qdocinc
new file mode 100644
index 0000000000..df33d1d16d
--- /dev/null
+++ b/doc/global/includes/module-use.qdocinc
@@ -0,0 +1,52 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file. Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+//! [using qt module]
+
+    \section1 Using the Module
+
+    Using a Qt module requires linking against the module library, either
+    directly or through other dependencies. Several build tools have dedicated
+    support for this, including \l{CMake Documentation}{CMake} and
+    \l{qmake}.
+
+    \section2 Building with CMake
+
+    Use the \c{find_package()} command to locate the needed module components in
+    the \c{Qt5} package:
+
+//! [using qt module]
+
+
+//! [building with qmake]
+
+    \section2 Building with qmake
+
+    To configure the module for building with qmake, add the module as a value
+    of the \c QT variable in the project's .pro file:
+
+//! [building with qmake]
diff --git a/doc/global/qt-html-templates-offline.qdocconf b/doc/global/qt-html-templates-offline.qdocconf
index d5780a35da..0c012f11d6 100644
--- a/doc/global/qt-html-templates-offline.qdocconf
+++ b/doc/global/qt-html-templates-offline.qdocconf
@@ -16,6 +16,8 @@ HTML.extraimages += template/images/ico_out.png \
                     template/images/bullet_sq.png \
                     template/images/bgrContent.png
 
+sourcedirs += includes
+
 #specify which files in the output directory should be packed into the qch file.
 qhp.extraFiles +=   style/offline.css \
                     images/ico_out.png \
diff --git a/doc/global/qt-html-templates-online.qdocconf b/doc/global/qt-html-templates-online.qdocconf
index 69c399d05a..502c406453 100644
--- a/doc/global/qt-html-templates-online.qdocconf
+++ b/doc/global/qt-html-templates-online.qdocconf
@@ -7,4 +7,5 @@ include(html-footer-online.qdocconf)
 #uncomment if navigation bar is not wanted
 #HTML.nonavigationbar      = "true"
 
-sourcedirs += includes-online
+sourcedirs += includes-online \
+              includes