QtQuick获取屏幕信息

/******************************************************************************** Copyright (C) 2015 The Qt Company Ltd.** Contact: http://www.qt.io/licensing/**** This file is part of the examples of the Qt Toolkit.**** $QT_BEGIN_LICENSE:BSD$** You may use this file under the terms of the BSD license as follows:**** "Redistribution and use in source and binary forms, with or without** modification, are permitted provided that the following conditions are** met:**   * Redistributions of source code must retain the above copyright**     notice, this list of conditions and the following disclaimer.**   * Redistributions in binary form must reproduce the above copyright**     notice, this list of conditions and the following disclaimer in**     the documentation and/or other materials provided with the**     distribution.**   * Neither the name of The Qt Company Ltd nor the names of its**     contributors may be used to endorse or promote products derived**     from this software without specific prior written permission.****** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."**** $QT_END_LICENSE$******************************************************************************/import QtQuick 2.3import QtQuick.Window 2.1Item {    id: root    width: 400    height: propertyGrid.implicitHeight + 16    function orientationToString(o) {        switch (o) {        case Qt.PrimaryOrientation:            return "primary";        case Qt.PortraitOrientation:            return "portrait";        case Qt.LandscapeOrientation:            return "landscape";        case Qt.InvertedPortraitOrientation:            return "inverted portrait";        case Qt.InvertedLandscapeOrientation:            return "inverted landscape";        }        return "unknown";    }    Grid {        id: propertyGrid        columns: 2        spacing: 8        x: spacing        y: spacing        Text {            text: "Screen \"" + Screen.name + "\":"            font.bold: true        }        Item { width: 1; height: 1 } // spacer        Text { text: "dimensions" }        Text { text: Screen.width + "x" + Screen.height }        Text { text: "pixel density" }        Text { text: Screen.pixelDensity.toFixed(2) + " dots/mm (" + (Screen.pixelDensity * 25.4).toFixed(2) + " dots/inch)" }        Text { text: "logical pixel density" }        Text { text: Screen.logicalPixelDensity.toFixed(2) + " dots/mm (" + (Screen.logicalPixelDensity * 25.4).toFixed(2) + " dots/inch)" }        Text { text: "device pixel ratio" }        Text { text: Screen.devicePixelRatio.toFixed(2) }        Text { text: "available virtual desktop" }        Text { text: Screen.desktopAvailableWidth + "x" + Screen.desktopAvailableHeight }        Text { text: "orientation" }        Text { text: orientationToString(Screen.orientation) + " (" + Screen.orientation + ")" }        Text { text: "primary orientation" }        Text { text: orientationToString(Screen.primaryOrientation) + " (" + Screen.primaryOrientation + ")" }    }}

http://doc.qt.io/qt-5/qtquick-window-screeninfo-qml.html

设置屏幕方向为横向，在AndroidManifest.xml文件中:

<activity android:screenOrientation="portrait" ... 

http://stackoverflow.com/questions/20774498/qml-screen-orientation-lock
https://forum.qt.io/topic/49120/how-to-lock-screen-orientation-qml-android-ios/3
屏幕方向选项值：
1.landscape：横屏(风景照)，显示时宽度大于高度；
2.portrait：竖屏(肖像照)， 显示时高度大于宽度；
3.user：用户当前的首选方向；
4.behind：继承Activity堆栈中当前Activity下面的那个Activity的方向；
5.sensor：由物理感应器决定显示方向，它取决于用户如何持有设备，当设备被旋转时方向会随之变化——在横屏与竖屏之间；
6.nosensor：忽略物理感应器——即显示方向与物理感应器无关，不管用户如何旋转设备显示方向都不会随着改变(“unspecified”设置除外)；
7.unspecified：未指定，此为默认值，由Android系统自己选择适当的方向，选择策略视具体设备的配置情况而定，因此不同的设备会有不同的方向选择；

其他信息：
为app添加收费功能:
http://blog.qt.io/blog/2013/12/12/implementing-in-app-purchase-on-android/