import QtQuick 1.0

Item {
    id: root
    width: 800
    height: 600

    property double x1: 0
    property double y1: 0
    property bool isSecondPoint: false

    function createSceneItem(x,y) {
        var component = Qt.createComponent("Item.qml")
        var object = component.createObject(root)
        object.x =x
        object.y =y
        object.myclick.connect(click)
    }

    function click(xPos, yPos){
        console.log("click",xPos,yPos)
        if(isSecondPoint && (xPos!=x1 && yPos!=y1)) { drawLine(x1,y1,xPos,yPos) }
        else { x1 = xPos; y1 = yPos }
        isSecondPoint = !isSecondPoint
    }

    function drawLine(x1,y1,x2,y2) {
        var component = Qt.createComponent("Line.qml")
        var object = component.createObject(root)
        object.x1 = x1
        object.y1 = y1
        object.x2 = x2
        object.y2 = y2
        var alpha = Math.atan( (y2-y1)/(x2-x1)) * 180/ Math.PI
        alpha = (x2<x1) ? alpha+180 : alpha
        object.alpha = alpha
    }

    MouseArea{
        anchors.fill: root
        acceptedButtons: Qt.RightButton | Qt.LeftButton
        onClicked: {
            createSceneItem( mouseX, mouseY)
        }
    }
}

import QtQuick 1.0

Item {
    id: item
    signal myclick(double xPos, double yPos)

    Rectangle{
        id: back
        color: "lime"
        width: 100
        height: 50
        anchors.centerIn: item
    }

    MouseArea  {
        id: mousearea
        anchors.fill: back
        drag.target: item
        drag.minimumX: 0; drag.maximumX: 800-back.width
        drag.minimumY: 0; drag.maximumY: 600-back.height

        onClicked: { click(item.x,item.y) }
    }
}

import QtQuick 1.0

Item {
    id: line
    property double x1: 0
    property double y1: 0
    property double x2: 0
    property double y2: 0
    property double alpha: 0

    Rectangle {
        x: x1
        y: y1
        width: Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1))
        height: 3
        color: "tomato"
        transform: Rotation { origin.x: x; origin.y: y; angle: alpha}
    }
}

    onXChanged: posChanged(item.num,item.x,item.y)
    onYChanged: posChanged(item.num,item.x,item.y)

import QtQuick 1.0

Item {
    id: root
    width: 800
    height: 600

    signal newPos(int num, double x, double y)

    property int maxNum : 0
    property int lastNum : 0
    property double lastX : 0
    property double lastY : 0
    property bool isSecondPoint : false

    function createSceneItem(x,y) {
        var component = Qt.createComponent("Item.qml")
        var object = component.createObject(root)
        object.x =x
        object.y =y
        object.num = maxNum
        maxNum++
    }

    function click(itemNum, xPos, yPos){
        console.log("click",itemNum,xPos,yPos, isSecondPoint)
        if(isSecondPoint && (xPos!=lastX && yPos!=lastY)) {
            drawLine(lastX,lastY,lastNum, xPos,yPos, itemNum)
        }
        else { lastX = xPos; lastY = yPos; lastNum = itemNum }

        isSecondPoint = (!isSecondPoint)
    }

    function drawLine(x1,y1,num1,x2,y2,num2) {
        var component = Qt.createComponent("Line.qml")
        var object = component.createObject(root)
        object.x1 = x1
        object.y1 = y1
        object.num1 = num1
        object.x2 = x2
        object.y2 = y2
        object.num2 = num2

        newPos.connect(object.repaint)
    }

    function posChanged(itemNum,newX,newY) {
        newPos(itemNum,newX,newY)
    }

    MouseArea{
        anchors.fill: root
        acceptedButtons: Qt.RightButton | Qt.LeftButton
        onClicked: {
            createSceneItem( mouseX, mouseY)
        }
    }
}

import QtQuick 1.0

Item {
    id: line
    property int num1: 0
    property int num2: 0
    property double x1: 0
    property double y1: 0
    property double x2: 0
    property double y2: 0

    Rectangle {
        x: x1
        y: y1
        width: Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1))
        height: 3
        color: "tomato"        
        transform: Rotation { origin.x: x; origin.y: y; angle: calcAlpha(x1,y1,x2,y2)}
    }

    function calcAlpha(x1,y1,x2,y2){
        var alpha = Math.atan( (y2-y1)/(x2-x1)) * 180/ Math.PI
        alpha = (x2<x1) ? alpha+180 : alpha
        return alpha
    }

    function repaint(num,x,y){
        if      (num == num1) { x1 = x; y1 = y}
        else if (num == num2) { x2 = x; y2 = y}
    }
}