HTML Canvas infinite looping tile map camera and positioning

[kiksy]

Trying to get my head around canvas, camera views and tile maps. I'm trying to create a tile map that loops infinitely on drag.

I'm struggling to keep the camera and the objects in sync. I only want to redraw items as needed. The logic is explained here In this Stack Exchange post , except I want it to loop round. 

I'm using KonvaJs, below is a fiddle where you can see the 4 tiles loop perfectly, but the text doesn't stay in line as I can't workout how to get the x y on the redraw.

const stage = new Konva.Stage({
        container: 'container',
        width: window.innerWidth,
        height: window.innerHeight,
        draggable: true
    });

    const layer = new Konva.Layer();
    stage.add(layer);


    const WIDTH = 100;
    const HEIGHT = 100;

    const grid = [
        ['red', 'yellow'],
        ['green', 'blue']
    ];

    const blocks = [
        { w: 150, h: 150 , background: "white" , image: "/img/test2.png" , fullImage: false, title: "" , text: "" },
        { w: 150, h: 150 , background: "white" , image: "/img/person-icon.png" ,  fullImage: false ,title: "" , text: "" },
        { w: 150, h: 150 , background: "#575756" , image: "" ,  fullImage: false, title: "Title" , text: "" },
        { w: 300, h: 300 , background: "white" , image: "/img/test.png", fullImage: true, title: "" , text: "" }

    ];

        function checkShapes() {
        const startX = Math.floor((-stage.x() - stage.width()) / WIDTH) * WIDTH;
        const endX = Math.floor((-stage.x() + stage.width() * 2) / WIDTH) * WIDTH;

        const startY = Math.floor((-stage.y() - stage.height()) / HEIGHT) * HEIGHT;
        const endY = Math.floor((-stage.y() + stage.height() * 2) / HEIGHT) * HEIGHT;



        var i = 0;
        for(var x = startX; x < endX; x += WIDTH) {
            for(var y = startY; y < endY; y += HEIGHT) {

                if(i === 4)
                {
                    i = 0;
                }

                const indexX = Math.abs(x / WIDTH) % grid.length;
                const indexY = Math.abs(y / HEIGHT) % grid[0].length;

                layer.add(new Konva.Rect({
                    x,
                    y,
                    width: WIDTH,
                    height: HEIGHT,
                    fill: grid[indexX][indexY],
                    stroke: 'black',
                    strokeWidth: 4
                }))

                if(blocks[i].title != ""){

                    var complexText = new Konva.Text({
                        x,
                        y,
                        text: "TEST TEXT",
                        fontSize: 14,
                        fontFamily: 'Calibri',
                        fill: 'white',
                        width: WIDTH,
                        height: HEIGHT,
                        verticalAlign: 'middle',
                        align : "center"
                    });

                    layer.add(complexText);

                }



            }
            i++
        }

    }

    checkShapes();
    layer.draw();

    stage.on('dragend', () => {
        layer.destroyChildren();
        checkShapes();
        layer.draw();
    })

 

https://jsfiddle.net/kiksy/jqo2h3dx/2/

Any pointers?