Qgis二次开发-QgsMapTool地图交互工具详解

1.简介

QgsMapTool地图工具是用于操作地图画布的用户交互式工具。例如，地图平移和缩放功能被实现为地图工具。

QgsMapTool是抽象基类，以下是类的继承关系：

2.常用接口

virtual void canvasDoubleClickEvent (QgsMapMouseEvent *e)	重写鼠标双击事件
virtual void canvasMoveEvent (QgsMapMouseEvent *e)	重写鼠标移动事件
virtual void canvasPressEvent (QgsMapMouseEvent *e)	重写鼠标按下事件
virtual void canvasReleaseEvent (QgsMapMouseEvent *e)	重写鼠标抬起事件
virtual void setCursor (const QCursor &cursor)	设置光标
QgsPointXY toMapCoordinates (QPoint point)	将点从屏幕坐标转换为地图坐标。

3.示例 

示例1：画布移动、放大、缩小

源码：

#pragma once#include <QtWidgets/QMainWindow>
#include "ui_GisCtrl.h"
#include <QDebug>
#include <QFileInfo>
#include <qgsmaptoolpan.h>
#include <qgsrasterlayer.h>
#include <qgsmapcanvas.h>
#include <qgspoint.h>
#include <QMouseEvent>
#include <qgsmaptoolzoom.h>
#include <QActionGroup>class GisCtrl : public QMainWindow
{Q_OBJECTpublic:GisCtrl(QWidget *parent = Q_NULLPTR);private:Ui::GisCtrlClass ui;private slots:void slotXyCoordinates(const QgsPointXY &p);void slotMove();void slotZoomIn();void slotZoomOut();private:QgsMapCanvas *m_mapCanvas = nullptr;QList<QgsMapLayer *> m_layers;QgsMapToolPan *m_toolPan = nullptr;	// 新建移动工具QgsMapToolZoom *m_toolZoomIn = nullptr;//放大QgsMapToolZoom *m_toolZoomOut = nullptr;//缩小QActionGroup *m_actionGroup = nullptr;
};#include "GisCtrl.h"
#include <qgsrasterlayer.h>
#include <qgsrubberband.h>
#pragma execution_character_set("utf-8")GisCtrl::GisCtrl(QWidget *parent): QMainWindow(parent)
{ui.setupUi(this);//创建画布m_mapCanvas = new QgsMapCanvas(this);QString url = "F:/arcgis/TMS.xml";m_mapCanvas->setCanvasColor(QColor(255, 255, 255));//加载瓦片地图QgsRasterLayer *layer = new QgsRasterLayer(url);if (!layer->isValid()){qDebug() << "load map faild";}m_layers.append(layer);// 新建移动工具m_toolPan = new QgsMapToolPan(m_mapCanvas);m_mapCanvas->setExtent(layer->extent());m_mapCanvas->enableAntiAliasing(true);m_mapCanvas->setLayers(m_layers);m_mapCanvas->setMapTool(m_toolPan);m_toolZoomIn = new QgsMapToolZoom(m_mapCanvas, false);m_toolZoomOut = new QgsMapToolZoom(m_mapCanvas, true);m_actionGroup = new QActionGroup(this);m_actionGroup->addAction(ui.actionMove);m_actionGroup->addAction(ui.actionZoomIn);m_actionGroup->addAction(ui.actionZoomOut);m_actionGroup->setExclusive(true);connect(m_mapCanvas, &QgsMapCanvas::xyCoordinates, this, &GisCtrl::slotXyCoordinates);connect(ui.actionMove, &QAction::triggered, this, &GisCtrl::slotMove);connect(ui.actionZoomIn, &QAction::triggered, this, &GisCtrl::slotZoomIn);connect(ui.actionZoomOut, &QAction::triggered, this, &GisCtrl::slotZoomOut);setCentralWidget(m_mapCanvas);ui.actionMove->setChecked(true);ui.actionLineManager->setVisible(false);ui.actionLayer->setVisible(false);ui.actionSelect->setVisible(false);ui.actionItem->setVisible(false);
}void GisCtrl::slotXyCoordinates(const QgsPointXY &p)
{QString str = QString("经度= %1，纬度=%2").arg(QString::number(p.x(), 'f', 6)).arg(QString::number(p.y(), 'f', 6));this->statusBar()->showMessage(str);
}void GisCtrl::slotMove()
{m_mapCanvas->setMapTool(m_toolPan);
}void GisCtrl::slotZoomIn()
{m_mapCanvas->setMapTool(m_toolZoomIn);
}void GisCtrl::slotZoomOut()
{m_mapCanvas->setMapTool(m_toolZoomOut);
}

示例2：鼠标点击画矩形

源码：

自定义一个地图交互工具继承QgsMapToolIdentify

#pragma once
#include <QObject>
#include <QList>
#include <QScopedPointer>
#include <qgsmapcanvas.h>
#include <qgsmaptoolidentify.h>
#include <qgsrubberband.h>
#include <qgsmapmouseevent.h>class QgsMapToolSelectFeatures : public QgsMapToolIdentify
{Q_OBJECT
public:QgsMapToolSelectFeatures(QgsMapCanvas *mapCanvas);protected://重写鼠标移动void canvasMoveEvent(QgsMapMouseEvent *e) override;//重写鼠标按下void canvasPressEvent(QgsMapMouseEvent *e) override;void initRubberBand();private:// 是否正在选择bool mSelectionActive = false;QScopedPointer<QgsRubberBand> mSelectionRubberBand;QColor mFillColor = QColor(255, 255, 0, 63);QColor mStrokeColor = QColor(255, 255, 0, 100);QPoint mInitDragPos;
};//cpp
#include "QgsMapToolSelectFeatures.h"
#include "QgsMapToolIdentify.h"QgsMapToolSelectFeatures::QgsMapToolSelectFeatures(QgsMapCanvas *mapCanvas): QgsMapToolIdentify(mapCanvas)
{
}void QgsMapToolSelectFeatures::canvasMoveEvent(QgsMapMouseEvent * e)
{if (e->buttons() != Qt::LeftButton)return;QRect rect;if (!mSelectionActive){mSelectionActive = true;rect = QRect(e->pos(), e->pos());}else{rect = QRect(e->pos(), mInitDragPos);}if (mSelectionRubberBand)mSelectionRubberBand->setToCanvasRectangle(rect);
}void QgsMapToolSelectFeatures::canvasPressEvent(QgsMapMouseEvent * e)
{if (!mSelectionRubberBand)initRubberBand();mInitDragPos = e->pos();
}void QgsMapToolSelectFeatures::initRubberBand()
{mSelectionRubberBand.reset(new QgsRubberBand(mCanvas, QgsWkbTypes::PolygonGeometry));mSelectionRubberBand->setFillColor(mFillColor);mSelectionRubberBand->setStrokeColor(mStrokeColor);
}

使用

QgsMapToolSelectFeatures *m_tool = new QgsMapToolSelectFeatures(m_mapCanvas);
m_mapCanvas->setMapTool(m_tool);