Qml之坐标轴的实现及曲线添加

      前面一张文章介绍过在利用QPainter接口画可拖动的圆，通过官方介绍：

Graphics in Qt 5 is primarily done either through the imperative QPainter API, or through Qt’s declarative UI language, Qt Quick, and its scene graph back-end. 

我们知道在Qt5中使用Qt Quick模块也可以实现简单图形的绘制。可是当我们需要在QML中实现坐标轴的时候，感觉用QtQuick实现起来有点力不从心了。不过先别沮丧，看看这个QQuickPaintedItem：

The QQuickPaintedItem class provides a way to use the QPainter API in the QML Scene Graph.

Qt的大牛应该考虑到了QtQuick的不足了，有了这个东东，你就可以在QML上发挥你的想象力了。

 

我继承了QQuickPaintedItem，实现了它的paint方法，在此方法里画坐标轴及添加曲线。代码如下：

 

void QAxis::paint(QPainter *painter)
{

    m_painter = painter;

    //随坐标轴取值范围变化，更新坐标标签及其位置
    if(m_xAutoScale)
        upDateXLabels();
    if(m_yAutoScale)
        upDateYLabels();

    initXYState();

    m_painter->setRenderHint(QPainter::Antialiasing);

    QMap::const_iterator cur;
    for(cur=m_curveList.begin(); cur!=m_curveList.end(); cur++)
    {       
        for(int j=0; jgetDataSize(); j++)
        {
            QPointF tmp = cur.value()->getPosData(j);
            m_painter->setPen(cur.value()->getPointPen());
            m_painter->drawEllipse(tmp.x()-1, tmp.y()-1, 2, 2);

            //draw curve title
            if(j == cur.value()->getDataSize() - 1)
            {
                if(cur.value()->getTitleShow())
                {
                    QPen pen;
                    pen.setColor(Qt::red);
                    m_painter->setPen(pen);

                    double x = tmp.x()+8;
                    double y = tmp.y();
                    if(x > m_xPosMax - 20)
                        x = x - 25;
                    if(y > m_yPosMax - 20)
                        y = y - 25;

                    m_painter->drawText(QPointF(x, y), cur.value()->getTitle());
                }

                break;
            }

            m_painter->setPen(cur.value()->getLinePen());
            m_painter->drawLine(cur.value()->getPosData(j), cur.value()->getPosData(j+1));
        }
    }
}

 

 

在QML中显示坐标轴：

 

import QtQuick 2.3
import QtQuick.Window 2.0
import QtQuick.Controls 1.1
//import QtQuick.Controls.Styles 1.1

import QtQml 2.2

import com.robinson.qaxis 1.0

ApplicationWindow {
    id: mainWindow
    visible: true
    width: Screen.width/2
    height: Screen.height/2

    QAxis {
        id: qAxis
        anchors.fill: parent

        Component.onCompleted: {
            //setDirection("down");
            setXValueRange(0, 10);
            setYValueRange(0, 10);

            setXLabels("0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10");
            setYLabels("0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10");

            setAutoScale("X", true);
            setAutoScale("Y", true);

            addCurve("testCurve");
            setGridShow(true);
            addData("testCurve", 0, 0);
            addData("testCurve", 2, 2);
            addData("testCurve", 5, 3);
        }
    }

    //使坐标轴自适应窗口大小
    onWidthChanged: qAxis.setAxisSize(mainWindow.width, mainWindow.height);
    onHeightChanged: qAxis.setAxisSize(mainWindow.width, mainWindow.height);
}

最后看下效果图：

 

 

源码下载地址1：CSDN

源码下载地址2：https://github.com/RobinsonSir/QmlQAxis