How to realize the function of fade the "HintText" automatically in my Qml project?

[DidaHarp]

Well,I want to realize this function.There is a search box,which accepts user's textinput.When there is no input(in other words,TextInput's "text" is null string ""),the hint-text is visible ; when user types one character or more,the hint-text is invisible.I want to use signal&slot to realize it ,but I don't know how to emit the signal.
The code:

import QtQuick 2.2

Rectangle{
    width: 300;height:50
    color:"#787878"

    Rectangle{
        anchors.fill: parent
        anchors.margins: 5
        radius: 5

        Text{
            id:hintHere
            text:"Here is Hint"
            font.pixelSize: 22
            color:"lightgray"
            anchors{
                left:parent.left
                leftMargin: 5
                verticalCenter: parent.verticalCenter
            }
            visible:true
        }

        TextInput{
            id:input

            signal thereIsAtLeastOneChar  //monitor if user has input some character(s)
            signal thereIsZeroChar //monitor if user has not input any character

            focus:true
            font.pixelSize: 22
            anchors{
                fill:parent
                left:parent.left
                leftMargin: 5
            }
            verticalAlignment: TextInput.AlignVCenter

            onThereIsAtLeastOneChar: hintHere.visible=false  //if user has input some character(s) ,hint text should fade
            onThereIsZeroChar: hintHere.visible=true  //if user has not input any character,hint text should appear

        }
    }
}

[p3c0]

Hi @DidaHarp,
I think what you are looking for is the onTextChanged signal handler. Therein you can check whether the text is empty.

TextInput {
    onTextChanged: {
        if(text)
            console.log(text)
    }
}

[DidaHarp]

@p3c0 Yep!Got the function that I want ! Cool!