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 
#include "ui_GisCtrl.h"
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

class GisCtrl : public QMainWindow
{
    Q_OBJECT

public:
    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 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 
#include 
#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 
#include 
#include 
#include 
#include 
#include 
#include 


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 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);