qt android开发篇之如何实现在不同分辨率手机中自适应字体大小，或者像素什么的

我们知道现在手机屏幕的分辨率跟电脑的分辨率不同，或许你直接在电脑中设置的字体像素大小为20，在电脑中运行的时候看起来很正常 的字体，但是部署到手机后大家分先那些字看起来像蚂蚁一样小，这时候改怎么办呢？小编通过调用android api来解决这个问题，本来很 高兴的说发现qt中的qpplicationwindows这个有一个devicePixelRatio属性，但是它的值我不知道怎么算到手机上，所以只能调用android API了！ 源码： Screen.java

package com.tommego.work;
//tommego
import java.util.List;
import android.content.Context;
//屏幕像素密度
import android.util.DisplayMetrics;

//蓝牙 开关
import android.bluetooth.BluetoothAdapter;

public class Screen extends org.qtproject.qt5.android.bindings.QtActivity{
private static Screen m_instance;//单例对象
private static BluetoothAdapter m_bluetoothAdapter;//蓝牙控制对象
public Screen(){
m_instance = this;//实例化单例对象

m_bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

if (!m_bluetoothAdapter.isEnabled()){
//打开蓝牙
m_bluetoothAdapter.enable();

}
}
//获取屏幕像素密度
public static double getDentisy(){
DisplayMetrics metrics=new DisplayMetrics();
m_instance.getWindowManager().getDefaultDisplay().getMetrics(metrics);
return metrics.density;
//        return 3;
}
}

devicescreen.h

#ifndef DEVICESCREEN_H
#define DEVICESCREEN_H
#include <QObject>
#include <QAndroidJniObject>
#include <QList>
#include <QString>

class DeviceScreen : public QObject
{
Q_OBJECT
public:
explicit DeviceScreen();
~DeviceScreen();

Q_PROPERTY(double dentisty READ dentisty WRITE setDentisty NOTIFY dentistyChanged)

//获取屏幕像素密度
Q_INVOKABLE double getDentisy();

double dentisty(){
return this->m_dentisty;
}
void setDentisty(double a){
this->m_dentisty=a;
}

signals:
void dentistyChanged();

public slots:
//    void onDentistyChanged
private:
double m_dentisty;
};
#endif // DEVICESCREEN_H

>##devicscreen.cpp
#include"devicescreen.h"

DeviceScreen::DeviceScreen()
{
m_dentisty=getDentisy();
dentistyChanged();

}

DeviceScreen::~DeviceScreen()
{

}

//获取屏幕像素密度
double DeviceScreen::getDentisy(){
return QAndroidJniObject::callStaticMethod<double>("com/tommego/work/Screen",
"getDentisy","()D");
}

main.cpp

#include <QApplication>
#include <QQmlApplicationEngine>
#include <QtQml>
#include <QQmlContext>
#include "Device/devicescreen.h"

int main(int argc, char *argv[])
{
QApplication app(argc, argv);

QQmlApplicationEngine engine;
qmlRegisterType<DeviceScreen>("Device",1,0,"MyDevice");

//    QQmlContext *context = new QQmlContext(engine.rootContext());
DeviceScreen device;
//    context->setContextProperty("mydevice",&device);
//    context->set
engine.rootContext()->setContextProperty("mydevice",&device);

engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

return app.exec();
}

main.qml

import QtQuick 2.4
import QtQuick.Controls 1.3
import QtQuick.Window 2.2
ApplicationWindow {
width: Screen.desktopAvailableWidth
height: Screen.desktopAvailableHeight
visible: true
Text{
text:"hello"
font.pixelSize:20*mydevice.dentisty//设置字体大小
anchors.centerIn:parent
}
}

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转载：http://ju.outofmemory.cn/entry/200667