纯 QWidget 实现电子地图控件：多线程瓦片加载与图形覆盖

前言

之前开发的地图组件依赖浏览器控件，在嵌入式板子或低配置国产硬件上性能受限。经过改造，实现了不依赖浏览器控件和 QML 的纯 QWidget 绘制方案，利用 Qt 的 Painter 灵活可靠特性，显著提升性能和控制度。

该方案主要解决两个难点：一是地理坐标到像素绘制坐标的映射；二是快速加载瓦片的多线程绘制机制。采用分层绘制，支持面积自适应（如多边形）和固定大小（如标注点）的图形，拖动时自动同步位置。

效果图

代码示例

#include "frmoverlay.h"
#include "ui_frmoverlay.h"
#include "qthelper.h"
#include "maphelper.h"
#include "overlayhelper.h"
#include "magicfish.h"

frmOverlay::frmOverlay(QWidget *parent) : QWidget(parent), ui(new Ui::frmOverlay) {
    ui->setupUi(this);
    this->initForm();
    this->initConfig();
    this->loadMap();
}

frmOverlay::~frmOverlay() {
    delete ui;
}

void  {
    lng = ;
    lat = ;
    (ui->mapWidget, ((qreal, qreal)), , ((qreal, qreal)));
    (ui->cboxFlag->(), ((QString)), , ((QString)));
}

{
    MapHelper::(ui->cboxTileSource, AppConfig::OverlaySource);
    (ui->cboxTileSource, (()), , (()));
    (ui->cboxTileSource, (()), , (()));
    MapHelper::(ui->cboxTileType, AppConfig::OverlayType);
    (ui->cboxTileType, (()), , (()));
    (ui->cboxTileType, (()), , (()));
    ui->cboxOffline->(AppConfig::OverlayOffline);
    (ui->cboxOffline, (()), , (()));
    (ui->cboxOffline, (()), , (()));
    ui->cboxCache->(AppConfig::OverlayCache);
    (ui->cboxCache, (()), , (()));
    (ui->cboxCache, (()), , (()));
}

{
    AppConfig::OverlaySource = ui->cboxTileSource->(ui->cboxTileSource->()).();
    AppConfig::OverlayType = ui->cboxTileType->(ui->cboxTileType->()).();
    AppConfig::OverlayOffline = ui->cboxOffline->();
    AppConfig::OverlayCache = ui->cboxCache->();
    AppConfig::();
}

{
    index = ;
    flag = ;
    ui->cboxFlag->();
    ui->cboxFlag->()->(flag);
}

{
    ->();
     tileSource = ui->cboxTileSource->(ui->cboxTileSource->()).();
    ui->mapWidget->((tileSource));
     tileType = ui->cboxTileType->(ui->cboxTileType->()).();
    ui->mapWidget->((tileType));
    QString offlinePath = TileHelper::((tileSource));
    ui->mapWidget->(ui->cboxOffline->() == );
    ui->mapWidget->(offlinePath);
    QString cachePath = (ui->cboxCache->() ==  ? QtHelper::() +  : );
    ui->mapWidget->(cachePath);
}

{
    ->lng = lng;
    ->lat = lat;
    ui->txtLng->(QString::(lng, , ));
    ui->txtLat->(QString::(lat, , ));
}

{
    index++;
    QString text = ().(index);
    QString item = ().(index - );
    ui->cboxFlag->(item);
    ui->cboxFlag->()->(text);
}

{
     (!arg()) {
        ->flag = arg1;
    }
}

{
    QString file = ;
    OverlayBase *marker = ui->mapWidget->(flag, lng, lat, file);
    OverlayHelper::(marker, , , , , );
    ->();
}

{
    ui->mapWidget->(flag);
}

{
    QString file = ;
    OverlayBase *marker = ui->mapWidget->(flag, lng, lat, file);
    OverlayHelper::(marker, , , , , , );
}

{
    ui->mapWidget->(flag, , , (), (), );
}

{
    ui->mapWidget->(flag, lng, lat, , , );
    ->();
}

{
    ui->mapWidget->(flag, lng, lat, , , , );
}

{
    ;
    QList<QPointF> points = MapHelper::(point, , );
    ui->mapWidget->(flag, points, , );
    ->();
}

{
    ui->mapWidget->(flag, (), (, , , ), );
}

{
    ;
    QList<QPointF> points = MapHelper::(point, , );
    ui->mapWidget->(flag, points, , , (, , , ));
    ->();
}

{
    ui->mapWidget->(flag, (), Qt::yellow, , (, , , ));
}

{
    ;
    QList<QPointF> points = MapHelper::(point, , );
    ui->mapWidget->(flag, points.(), points.(), , , (, , , ));
    ->();
}

{
    ui->mapWidget->(flag, (), (), Qt::red, , (, , , ));
}

{
     distance = MapHelper::(ui->mapWidget->());
    qreal radius = MapHelper::(distance);
    ui->mapWidget->(flag, lng, lat, radius, , , (, , , ));
    ->();
}

{
    qreal radius = MapHelper::();
    ui->mapWidget->(flag, lng, lat, radius, );
}

{
    MagicFish *widget =  (ui->mapWidget);
    ui->mapWidget->(flag, lng, lat, widget);
    ->();
}

{
    ui->mapWidget->(flag, lng, lat);
}

{
    ();
    QString fileName = QtHelper::(, QtHelper::() + );
     (!fileName.()) {
        ;
         (file.(QFile::ReadOnly | QFile::Text)) {
            QString points = file.();
            ui->mapWidget->(, points, , , (, , , ));
        }
    }
}

{
    OverlayHelper::redraw = ;
    ();
    ui->mapWidget->();
    ui->mapWidget->(, );
     ( i = ; i < ; ++i) {
        qreal lng = QtHelper::(, );
        qreal lat = QtHelper::(, );
        qreal r = QtHelper::(, );
        QColor color = QtHelper::();
        QColor bgColor = color;
        bgColor.();
        ui->mapWidget->(().(i), lng, lat, r, color, , bgColor);
    }
    OverlayHelper::redraw = ;
}

{
    ui->mapWidget->(flag);
}

{
    ui->mapWidget->();
}

{
    ->();
    ui->mapWidget->();
}

{
     (ui->btnVisibleOverlay->() == ) {
        ui->mapWidget->(, );
        ui->btnVisibleOverlay->();
    }  {
        ui->mapWidget->(, );
        ui->btnVisibleOverlay->();
    }
}