QCustomPlot的使用之四-响应鼠标移动和弹起事件

在项目中使用QCustomPlot过程中，会有新的需求需要满足，比如在显示的数据表格中，鼠标移动到数据线上的时候，需要实时显示当前显示的线上点的具体数据；点击这条线的时候，弹出对话框展现出数据线段的详细信息。

解决思路：在不改变QCustomPlot的前提下，在其外层封装一层类，使其外层实现相应的功能。
需要到的类图继续关系图：

先看实现的效果：

首先要找到QCustomPlot的相应的鼠标信息：鼠标移动和鼠标弹起。

void QCustomPlot::mouseMoveEvent(QMouseEvent *event) {
	emit mouseMove(event);

	if (!mMouseHasMoved && (mMousePressPos - event->pos()).manhattanLength() > 3)
		mMouseHasMoved = true; // moved too far from mouse press position, don't handle as click on mouse release

	if (mSelectionRect && mSelectionRect->isActive())
		mSelectionRect->moveSelection(event);
	else if (mMouseEventLayerable) // call event of affected layerable:
		mMouseEventLayerable->mouseMoveEvent(event, mMousePressPos);

	event->accept(); // in case QCPLayerable reimplementation manipulates event accepted state. In QWidget event system, QCustomPlot wants to accept the event.
}

void QCustomPlot::mouseReleaseEvent(QMouseEvent *event) {
	emit mouseRelease(event);

	if (!mMouseHasMoved) // mouse hasn't moved (much) between press and release, so handle as click
	{
		if (mSelectionRect && mSelectionRect->isActive()) // a simple click shouldn't successfully finish a selection rect, so cancel it here
			mSelectionRect->cancel();
		if (event->button() == Qt::LeftButton)
			processPointSelection(event);
...

在鼠标弹起事情中可以看到，当按键书鼠标左键的时候调用函数

processPointSelection(event);

然后看看这个函数的定义：

void QCustomPlot::processPointSelection(QMouseEvent *event) {
	QVariant details;
	QCPLayerable *clickedLayerable = layerableAt(event->pos(), true, &details);
	...

通过调用layerableAt(event->pos(), true, &details);来获取当前鼠标选中的是哪个图层，返回值就是选中的图层。既然已经找到了选中的图层，剩下的就是做出相应判断了，但是咱们的前提是不能在文件中修改，所用需要重新定义一个新类继承自QCustomPlot；

class MYCUSTOMPLOT_EXPORT MyCustomPlot :public QCustomPlot {
public:
	MyCustomPlot();

	//注册鼠标操作
	void registerMouse(IPlotMouse* mouse);
private:
	virtual void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
	virtual void mouseMoveEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
	virtual void mouseReleaseEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
private:
	IPlotMouse* _mousePlot = nullptr;
};

MyCustomPlot::MyCustomPlot()
:QCustomPlot(nullptr) {
}

void MyCustomPlot::registerMouse(IPlotMouse* mouse) {
	_mousePlot = mouse;
}

void MyCustomPlot::mousePressEvent(QMouseEvent *event) {
	QCustomPlot::mousePressEvent(event);
}

void MyCustomPlot::mouseMoveEvent(QMouseEvent *event) {
	QCustomPlot::mouseMoveEvent(event);

	QVariant details;
	QCPLayerable *clickedLayerable = layerableAt(event->pos(), true, &details);

	if (clickedLayerable != nullptr) {
		double xValue = 0.0;
		double yValue = 0.0;
		if (dynamic_cast<QCPGraph*>(clickedLayerable) != 0) {
			((QCPGraph*)clickedLayerable)->pixelsToCoords(event->pos(), xValue, yValue);
			if (_mousePlot != nullptr){
				_mousePlot->plotMouseMove(event->pos().x(), event->pos().y(), xValue, yValue, (QCPGraph*)clickedLayerable);
			}
		}
	}
}

void MyCustomPlot::mouseReleaseEvent(QMouseEvent *event) {
	QCustomPlot::mouseReleaseEvent(event);

	if (event->button() == Qt::LeftButton) {
		QVariant details;
		QCPLayerable *clickedLayerable = layerableAt(event->pos(), true, &details);

		if (clickedLayerable != nullptr) {
			double xValue = 0.0;
			double yValue = 0.0;
			if (dynamic_cast<QCPGraph*>(clickedLayerable) != 0) {
				((QCPGraph*)clickedLayerable)->pixelsToCoords(event->pos(), xValue, yValue);
				if (_mousePlot != nullptr) {
					_mousePlot->plotMouseRelease(event->pos().x(), event->pos().y(), xValue, yValue, (QCPGraph*)clickedLayerable);
				}
			}
		}
	}
}

新类已经定义完了，新类中同样也需要实现鼠标事情：

	virtual void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
	virtual void mouseMoveEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
	virtual void mouseReleaseEvent(QMouseEvent *event) Q_DECL_OVERRIDE;

在实现自定义类的鼠标函数中，首先要调用QCustomPlot中的鼠标函数，之后才可以实现自己新添加的功能。

在新添加的类中，注册了一个新的接口，这个接口用来对外通信的。比如我想让其他的界面响应鼠标事件，就需要其他的界面来继承这个接口并且实现相应的接口函数。如果不要相应那就不用调用下面这个注册函数就可以了

//注册鼠标操作
	void registerMouse(IPlotMouse* mouse);

注册接口：

_horRightAnglePlot = new /*QCustomPlot*/MyCustomPlot;
	_horRightAnglePlot->registerMouse(this);

实现接口响应：

void RadarDirectGraph::plotMouseRelease(double xPixel, double yPixel, double xValue, double yValue, void*graph) {
	QtGuiDirectDetail* guiDetail = new QtGuiDirectDetail;
	guiDetail->show();
}

void RadarDirectGraph::plotMouseMove(double xPixel, double yPixel, double xValue, double yValue, void*graph) {
	QString msg = QStringLiteral("(%1：%2)").arg(xValue).arg(yValue);
	QToolTip::showText(QCursor::pos(), msg);
}

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