+
+ // this is the "swipe" component
+ // we toss it out for now, but could use it in the future.
+ var swipe = {
+ pageX: c_now.pageX - c_init.pageX,
+ pageY: c_now.pageY - c_init.pageY
+ };
+ var dataWidth = context.initialRange.x[1] - context.initialRange.x[0];
+ var dataHeight = context.initialRange.y[0] - context.initialRange.y[1];
+ swipe.dataX = (swipe.pageX / g.plotter_.area.w) * dataWidth;
+ swipe.dataY = (swipe.pageY / g.plotter_.area.h) * dataHeight;
+ var xScale, yScale;
+
+ // The residual bits are usually split into scale & rotate bits, but we split
+ // them into x-scale and y-scale bits.
+ if (touches.length == 1) {
+ xScale = 1.0;
+ yScale = 1.0;
+ } else if (touches.length >= 2) {
+ var initHalfWidth = (initialTouches[1].pageX - c_init.pageX);
+ xScale = (touches[1].pageX - c_now.pageX) / initHalfWidth;
+
+ var initHalfHeight = (initialTouches[1].pageY - c_init.pageY);
+ yScale = (touches[1].pageY - c_now.pageY) / initHalfHeight;
+ }
+
+ // Clip scaling to [1/8, 8] to prevent too much blowup.
+ xScale = Math.min(8, Math.max(0.125, xScale));
+ yScale = Math.min(8, Math.max(0.125, yScale));
+
+ var didZoom = false;
+ if (context.touchDirections.x) {
+ g.dateWindow_ = [
+ c_init.dataX - swipe.dataX + (context.initialRange.x[0] - c_init.dataX) / xScale,
+ c_init.dataX - swipe.dataX + (context.initialRange.x[1] - c_init.dataX) / xScale
+ ];
+ didZoom = true;
+ }
+
+ if (context.touchDirections.y) {
+ for (i = 0; i < 1 /*g.axes_.length*/; i++) {
+ var axis = g.axes_[i];
+ var logscale = g.attributes_.getForAxis("logscale", i);
+ if (logscale) {
+ // TODO(danvk): implement
+ } else {
+ axis.valueWindow = [
+ c_init.dataY - swipe.dataY + (context.initialRange.y[0] - c_init.dataY) / yScale,
+ c_init.dataY - swipe.dataY + (context.initialRange.y[1] - c_init.dataY) / yScale
+ ];
+ didZoom = true;
+ }
+ }
+ }
+
+ g.drawGraph_(false);
+
+ // We only call zoomCallback on zooms, not pans, to mirror desktop behavior.
+ if (didZoom && touches.length > 1 && g.getFunctionOption('zoomCallback')) {
+ var viewWindow = g.xAxisRange();
+ g.getFunctionOption("zoomCallback").call(g, viewWindow[0], viewWindow[1], g.yAxisRanges());
+ }
+};
+
+/**
+ * @private
+ */
+Dygraph.Interaction.endTouch = function(event, g, context) {
+ if (event.touches.length !== 0) {
+ // this is effectively a "reset"
+ Dygraph.Interaction.startTouch(event, g, context);
+ } else if (event.changedTouches.length == 1) {
+ // Could be part of a "double tap"
+ // The heuristic here is that it's a double-tap if the two touchend events
+ // occur within 500ms and within a 50x50 pixel box.
+ var now = new Date().getTime();
+ var t = event.changedTouches[0];
+ if (context.startTimeForDoubleTapMs &&
+ now - context.startTimeForDoubleTapMs < 500 &&
+ context.doubleTapX && Math.abs(context.doubleTapX - t.screenX) < 50 &&
+ context.doubleTapY && Math.abs(context.doubleTapY - t.screenY) < 50) {
+ g.resetZoom();
+ } else {
+ context.startTimeForDoubleTapMs = now;
+ context.doubleTapX = t.screenX;
+ context.doubleTapY = t.screenY;
+ }
+ }
+};
+
+// Determine the distance from x to [left, right].
+var distanceFromInterval = function(x, left, right) {
+ if (x < left) {
+ return left - x;
+ } else if (x > right) {
+ return x - right;
+ } else {
+ return 0;
+ }
+};
+
+/**
+ * Returns the number of pixels by which the event happens from the nearest
+ * edge of the chart. For events in the interior of the chart, this returns zero.
+ */
+var distanceFromChart = function(event, g) {
+ var chartPos = Dygraph.findPos(g.canvas_);
+ var box = {
+ left: chartPos.x,
+ right: chartPos.x + g.canvas_.offsetWidth,
+ top: chartPos.y,
+ bottom: chartPos.y + g.canvas_.offsetHeight
+ };
+
+ var pt = {
+ x: Dygraph.pageX(event),
+ y: Dygraph.pageY(event)
+ };
+
+ var dx = distanceFromInterval(pt.x, box.left, box.right),
+ dy = distanceFromInterval(pt.y, box.top, box.bottom);
+ return Math.max(dx, dy);