EffectMagnify.qml Example File

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import QtQuick 2.1
import QtQuick.Window 2.1

Effect {
    id: root
    divider: false
    parameters: ListModel {
        ListElement {
            name: "Radius"
            value: 0.5
        }
        ListElement {
            name: "Diffraction"
            value: 0.5
        }
        onDataChanged: updateParameters()
    }

    function updateParameters()
    {
        radius   = parameters.get(0).value * 100;
        diffractionIndex = parameters.get(1).value;
    }

    property real posX: -1
    property real posY: -1
    property real pixDens: Screen.pixelDensity

    QtObject {
        id: d
        property real oldTargetWidth: root.targetWidth
        property real oldTargetHeight: root.targetHeight
    }

    // Transform slider values, and bind result to shader uniforms
    property real radius: 0.5 * 100
    property real diffractionIndex: 0.5

    onTargetWidthChanged: {
        if (posX == -1)
            posX = targetWidth / 2
        else if (d.oldTargetWidth != 0)
            posX *= (targetWidth / d.oldTargetWidth)
        d.oldTargetWidth = targetWidth
    }

    onTargetHeightChanged: {
        if (posY == -1)
            posY = targetHeight / 2
        else if (d.oldTargetHeight != 0)
            posY *= (targetHeight / d.oldTargetHeight)
        d.oldTargetHeight = targetHeight
    }

    fragmentShaderFilename: "magnify.fsh"

    MouseArea {
        anchors.fill: parent
        onPositionChanged: { root.posX = mouse.x; root.posY = root.targetHeight - mouse.y }
    }
}