Function zoomWheel

src/plots/cartesian/dragbox.js:462–546

(e)

    var mainplot = plotinfo.mainplot ? gd._fullLayout._plots[plotinfo.mainplot] : plotinfo;

    function zoomWheel(e) {
        // deactivate mousewheel scrolling on embedded graphs
        // devs can override this with layout._enablescrollzoom,
        // but _ ensures this setting won't leave their page
        if(!gd._context._scrollZoom.cartesian && !gd._fullLayout._enablescrollzoom) {
            return;
        }

        clearAndResetSelect();

        // If a transition is in progress, then disable any behavior:
        if(gd._transitioningWithDuration) {
            e.preventDefault();
            e.stopPropagation();
            return;
        }

        recomputeAxisLists();

        clearTimeout(redrawTimer);

        var wheelDelta = -e.deltaY;
        if(!isFinite(wheelDelta)) wheelDelta = e.wheelDelta / 10;
        if(!isFinite(wheelDelta)) {
            Lib.log('Did not find wheel motion attributes: ', e);
            return;
        }

        var zoom = Math.exp(-Math.min(Math.max(wheelDelta, -20), 20) / 200);
        var gbb = mainplot.draglayer.select('.nsewdrag').node().getBoundingClientRect();
        var xfrac = (e.clientX - gbb.left) / gbb.width;
        var yfrac = (gbb.bottom - e.clientY) / gbb.height;
        var i;

        function zoomWheelOneAxis(ax, centerFraction, zoom) {
            if(ax.fixedrange) return;

            var axRange = Lib.simpleMap(ax.range, ax.r2l);
            var v0 = axRange[0] + (axRange[1] - axRange[0]) * centerFraction;
            function doZoom(v) { return ax.l2r(v0 + (v - v0) * zoom); }
            ax.range = axRange.map(doZoom);
        }

        if(editX) {
            // if we're only zooming this axis because of constraints,
            // zoom it about the center
            if(!ew) xfrac = 0.5;

            for(i = 0; i < xaxes.length; i++) {
                zoomWheelOneAxis(xaxes[i], xfrac, zoom);
            }
            updateMatchedAxRange('x');

            scrollViewBox[2] *= zoom;
            scrollViewBox[0] += scrollViewBox[2] * xfrac * (1 / zoom - 1);
        }
        if(editY) {
            if(!ns) yfrac = 0.5;