Add itemsoverlay plugin

This change adds a new plugin that does only offer an empty transparent
map.
The intended usage is to add overlay layers into which to place only map
items.

Change-Id: I51e64b0354f533bf73480e800e0d5338920a7fc5
Reviewed-by: Thiago Marcos P. Santos <tmpsantos@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>

1 files changed, 109 insertions, 0 deletions

diff --git a/src/location/doc/src/plugins/itemsoverlay.qdoc b/src/location/doc/src/plugins/itemsoverlay.qdoc
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+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: http://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 http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://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: http://www.gnu.org/copyleft/fdl.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+\page location-plugin-itemsoverlay.html
+\title Qt Location Items Overlay Plugin
+\ingroup QtLocation-plugins
+
+\brief Provides an empty map intended to be used as background for an overlay layers for map items.
+
+\section1 Overview
+
+This geo services plugin is a special plugin providing only an empty map.
+This plugin provides no services, and is intended to be used in those cases where a \l Map element should
+only show the added map items.
+
+The Items Overlay geo services plugin can be loaded by using the plugin key "itemsoverlay".
+
+\section1 Example usage
+
+The following snippet shows how a Map using this plugin can be added as an overlay to display
+anti-aliased map items.
+Note that for such an overlay Map to be transparent, it is also necessary to set its color to
+a transparent one, such as \b transparent, like in the example.
+
+    \qml
+    Window {
+        id: win
+        visible: true
+        width: 640
+        height: 640
+
+        Map {
+            id: mapBase
+            gesture.enabled: true
+            anchors.fill: parent
+            plugin: Plugin { name: "osm" }
+            center: QtPositioning.coordinate(45,10)
+            zoomLevel: 4
+            z: parent.z + 1
+        }
+
+        Map {
+            id: mapOverlay
+            anchors.fill: parent
+            plugin: Plugin { name: "itemsoverlay" }
+            gesture.enabled: false
+            center: mapBase.center
+            color: 'transparent' // Necessary to make this map transparent
+            minimumFieldOfView: mapBase.minimumFieldOfView
+            maximumFieldOfView: mapBase.maximumFieldOfView
+            minimumTilt: mapBase.minimumTilt
+            maximumTilt: mapBase.maximumTilt
+            minimumZoomLevel: mapBase.minimumZoomLevel
+            maximumZoomLevel: mapBase.maximumZoomLevel
+            zoomLevel: mapBase.zoomLevel
+            tilt: mapBase.tilt;
+            bearing: mapBase.bearing
+            fieldOfView: mapBase.fieldOfView
+            z: mapBase.z + 1
+
+            MapCircle {
+                id: circle
+                center: QtPositioning.coordinate(44, 10)
+                radius: 200000
+                border.width: 5
+
+                MouseArea {
+                    anchors.fill: parent
+                    drag.target: parent
+                }
+            }
+
+            // The code below enables SSAA
+            layer.enabled: true
+            layer.smooth: true
+            property int w : mapOverlay.width
+            property int h : mapOverlay.height
+            property int pr: Screen.devicePixelRatio
+            layer.textureSize: Qt.size(w  * 2 * pr, h * 2 * pr)
+        }
+    }
+    \endqml
+
+*/