qt qml 高德地图--WebAPI 获取静态地图

高德地图提供了很多Web API，本文展示如何使用Qt + qml 获取静态地图

静态地图Web API https://lbs.amap.com/api/webservice/guide/api/staticmaps

效果图：

原理：
QNetworkAccessManager通过get方法发送一个URL请求出去，高德的服务器接收到这个请求，会把对应的图片以流的方式回复给你，你接收到数据后，把数据放到一个QQuickImageProvider里面，然后让qml获取这个QQuickImageProvider的图片就好了。

附一个代码下载链接（需要1分）
http://download.csdn.net/detail/d759378563/9920406

下面贴代码：

MapProvider.hpp

#pragma once

#include 
#include 
#include 
class MapProvider : public QQuickImageProvider {
public:
    MapProvider()
        : QQuickImageProvider(QQuickImageProvider::Pixmap) {
        //pixmap 初始化为800 x 600 的红色图片
        mPixmap = QPixmap(800, 600);
        mPixmap.fill(QColor("red"));
    }
     //重载， qml就是通过这个函数得到的图片
    virtual QPixmap requestPixmap(const QString &id, QSize *size, const QSize &requestedSize) override {
        return mPixmap;
    }
    //将数据设置到pixmap中
    void setData(QByteArray data) {
        mPixmap.loadFromData(data);
    }
private:
    QPixmap mPixmap;
};

Map.hpp

#pragma once

#include 
#include 
#include 

#include 
#include 
#include 
#include 
#include 

#include "MapProvider.hpp"

class Map : public QObject
{
    Q_OBJECT
public:
    explicit Map(QObject *parent = nullptr);
     //获取 provider
    MapProvider * getProvider();
    //INVOKABLE 开放给qml，用来发起GET 请求
    Q_INVOKABLE void get(QUrl url);
signals:
    void replayReady();
public slots:
    void replaySlot(QNetworkReply *reply);
private:
    //C++ std 风格的智能指针
    std::shared_ptr mManager;
    std::shared_ptr mMapProvider;
};

Map.cpp

#include "Map.hpp"

Map::Map(QObject *parent) : QObject(parent)
{
    //指针初始化
    mManager = std::make_shared<QNetworkAccessManager>();
    mMapProvider = std::make_shared<MapProvider>();
    //连接信号 槽
    connect(mManager.get(), &QNetworkAccessManager::finished, this, &Map::replaySlot);
}

MapProvider *Map::getProvider()
{
    return mMapProvider.get();
}

void Map::get(QUrl url)
{
    //GET 请求
    mManager->get(QNetworkRequest(QUrl(url)));
}
// GET请求的响应处理 
void Map::replaySlot(QNetworkReply *reply)
{
    //读取全部数据，写入provider
    mMapProvider->setData(reply->readAll());
    //通知qml，刷新图片
    emit replayReady();
}

Main.cpp

#include 
#include 
#include 
#include 
#include 
#include "Map.hpp"
#include "MapProvider.hpp"

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

    QQuickView view;
    Map map;
    //添加Provider，注意字符串中的大小写，qml中使用要一致
    view.engine()->addImageProvider(QLatin1String("Provider"), map.getProvider());
    view.engine()->rootContext()->setContextProperty("IMap", &map);
    view.setSource(QUrl("qrc:/Qml/Main.qml"));
    view.show();

    return app.exec();
}

Main.qml (注意把key换掉，我的key就不贴出来了)

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.3

Item {
    visible: true
    width: 1024
    height: 768

    readonly property var key : "此处写上你的key"

    Connections {
        target: IMap
        onReplayReady: {
            image.source = "image://Provider";
        }
    }
    Image {
        id: image
        width: 800
        height: 600
        anchors.centerIn: parent

        Component.onCompleted: {
            var url = "http://restapi.amap.com/v3/staticmap?location=116.481485,39.990464&zoom=10&size=800*600&markers=mid,,A:116.481485,39.990464&key=" + key;
            IMap.get(url);
        }
    }
}