Function plotDrag

src/plots/cartesian/dragbox.js:554–690

(dx, dy)

    // plotDrag: move the plot in response to a drag
    function plotDrag(dx, dy) {
        dx = dx * scaleX;
        dy = dy * scaleY;
        // If a transition is in progress, then disable any behavior:
        if(gd._transitioningWithDuration) {
            return;
        }

        // prevent axis drawing from monkeying with margins until we're done
        gd._fullLayout._replotting = true;

        if(xActive === 'ew' || yActive === 'ns') {
            var spDx = xActive ? -dx : 0;
            var spDy = yActive ? -dy : 0;

            if(matches.isSubplotConstrained) {
                if(xActive && yActive) {
                    var frac = (dx / pw - dy / ph) / 2;
                    dx = frac * pw;
                    dy = -frac * ph;
                    spDx = -dx;
                    spDy = -dy;
                }
                if(yActive) {
                    spDx = -spDy * pw / ph;
                } else {
                    spDy = -spDx * ph / pw;
                }
            }
            if(xActive) {
                dragAxList(xaxes, dx);
                updateMatchedAxRange('x');
            }
            if(yActive) {
                dragAxList(yaxes, dy);
                updateMatchedAxRange('y');
            }
            updateSubplots([spDx, spDy, pw, ph]);
            ticksAndAnnotations();
            gd.emit('plotly_relayouting', updates);
            return;
        }

        // dz: set a new value for one end (0 or 1) of an axis array axArray,
        // and return a pixel shift for that end for the viewbox
        // based on pixel drag distance d
        // TODO: this makes (generally non-fatal) errors when you get
        // near floating point limits
        function dz(axArray, end, d) {
            var otherEnd = 1 - end;
            var movedAx;
            var newLinearizedEnd;
            for(var i = 0; i < axArray.length; i++) {
                var axi = axArray[i];
                if(axi.fixedrange) continue;
                movedAx = axi;
                newLinearizedEnd = axi._rl[otherEnd] +
                    (axi._rl[end] - axi._rl[otherEnd]) / dZoom(d / axi._length);