(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports, require('d3-dispatch'), require('d3-drag'), require('d3-interpolate'), require('d3-selection'), require('d3-transition')) :
  typeof define === 'function' && define.amd ? define(['exports', 'd3-dispatch', 'd3-drag', 'd3-interpolate', 'd3-selection', 'd3-transition'], factory) :
  (factory((global.d3 = global.d3 || {}),global.d3,global.d3,global.d3,global.d3,global.d3));
}(this, function (exports,d3Dispatch,d3Drag,d3Interpolate,d3Selection,d3Transition) { 'use strict';

  function constant(x) {
    return function() {
      return x;
    };
  }

  function ZoomEvent(target, type, transform) {
    this.target = target;
    this.type = type;
    this.transform = transform;
  }

  function Transform(x, y, kx, ky) {
    this.kx = kx;
    this.ky = ky || kx;
    this.x = x;
    this.y = y;
  }

  Transform.prototype = {
    constructor: Transform,
    scale: function(kx, ky) {
      ky = ky === undefined ? kx : ky;
      return kx === 1 && (!ky || ky === 1) ? this : new Transform(this.x, this.y, this.kx * kx, this.ky * ky);
    },
    translate: function(x, y) {
      return x === 0 & y === 0 ? this : new Transform(this.x + this.kx * x, this.y + this.ky * y, this.kx, this.ky);
    },
    apply: function(point) {
      return [point[0] * this.kx + this.x, point[1] * this.ky + this.y];
    },
    applyX: function(x) {
      return x * this.kx + this.x;
    },
    applyY: function(y) {
      return y * this.ky + this.y;
    },
    invert: function(location) {
      return [(location[0] - this.x) / this.kx, (location[1] - this.y) / this.ky];
    },
    invertX: function(x) {
      return (x - this.x) / this.kx;
    },
    invertY: function(y) {
      return (y - this.y) / this.ky;
    },
    rescaleX: function(x) {
      return x.copy().domain(x.range().map(this.invertX, this).map(x.invert, x));
    },
    rescaleY: function(y) {
      return y.copy().domain(y.range().map(this.invertY, this).map(y.invert, y));
    },
    toString: function() {
      return "translate(" + this.x + "," + this.y + ") scale(" + this.kx + "," + this.ky + ")";
    }
  };

  var identity = new Transform(0, 0, 1, 1);

  transform.prototype = Transform.prototype;

  function transform(node) {
    return node.__zoom || identity;
  }

  function nopropagation() {
    d3Selection.event.stopImmediatePropagation();
  }

  function noevent() {
    d3Selection.event.preventDefault();
    d3Selection.event.stopImmediatePropagation();
  }

  // Ignore right-click, since that should open the context menu.
  function defaultFilter() {
    return !d3Selection.event.button;
  }

  function defaultExtent() {
    var e = this, w, h;
    if (e instanceof SVGElement) {
      e = e.ownerSVGElement || e;
      w = e.width.baseVal.value;
      h = e.height.baseVal.value;
    } else {
      if (e && e.clientWidth && e.clientHeight) {
        w = e.clientWidth;
        h = e.clientHeight;
      } else {
        throw 'd3-xyzoom failed to constrain scales because extent is undefined.';
      }
    }
    return [[0, 0], [w, h]];
  }

  function defaultTransform() {
    return this.__zoom || identity;
  }

  function zoom() {
    var filter = defaultFilter,
      extent = defaultExtent,
      kx0 = 0,
      ky0 = 0,
      kx1 = Infinity,
      ky1 = Infinity,
      rx = 1,
      ry = 1,
      x0 = -Infinity,
      x1 = Infinity,
      y0 = -Infinity,
      y1 = Infinity,
      duration = 250,
      interpolate = d3Interpolate.interpolateNumber,
      gestures = [],
      listeners = d3Dispatch.dispatch("start", "zoom", "end"),
      touchstarting,
      touchending,
      touchDelay = 500,
      wheelDelay = 150;

    function zoom(selection) {
      selection
        .on("wheel.zoom", wheeled)
        .on("mousedown.zoom", mousedowned)
        .on("dblclick.zoom", dblclicked)
        .on("touchstart.zoom", touchstarted)
        .on("touchmove.zoom", touchmoved)
        .on("touchend.zoom touchcancel.zoom", touchended)
        .style("-webkit-tap-highlight-color", "rgba(0,0,0,0)")
        .property("__zoom", defaultTransform);
    }

    zoom.transform = function(collection, transform) {
      var selection = collection.selection ? collection.selection() : collection;
      selection.property("__zoom", defaultTransform);
      if (collection !== selection) {
        schedule(collection, transform);
      } else {
        selection.interrupt().each(function() {
          gesture(this, arguments)
            .start()
            .zoom(null, typeof transform === "function" ? transform.apply(this, arguments) : transform)
            .end();
        });
      }
    };

    zoom.scaleBy = function(selection, kx, ky) {
      zoom.scaleTo(selection, function() {
        var k0 = this.__zoom.kx,
          k1 = typeof kx === "function" ? kx.apply(this, arguments) : kx;
        return k0 * k1;
      }, function() {
        var k0 = this.__zoom.ky,
          k1 = typeof ky === "function" ? ky.apply(this, arguments) : ky;
        return k0 * k1;
      });
    };

    zoom.scaleTo = function(selection, kx, ky) {
      zoom.transform(selection, function() {
        var e = extent.apply(this, arguments),
          t0 = this.__zoom,
          p0 = centroid(e),
          p1 = t0.invert(p0),
          kx1 = typeof kx === "function" ? kx.apply(this, arguments) : kx,
          ky1 = typeof ky === "function" ? ky.apply(this, arguments) : ky;
        return constrain(translate(scale(t0, kx1, ky1), p0, p1), e);
      });
    };

    zoom.translateBy = function(selection, x, y) {
      zoom.transform(selection, function() {
        return constrain(this.__zoom.translate(
          typeof x === "function" ? x.apply(this, arguments) : x,
          typeof y === "function" ? y.apply(this, arguments) : y
        ), extent.apply(this, arguments));
      });
    };

    function scale(transform, kx, ky) {
      kx = Math.max(kx0, Math.min(kx1, kx));
      ky = Math.max(ky0, Math.min(ky1, ky));
      return (kx === transform.kx && ky === transform.ky) ? transform : new Transform(transform.x, transform.y, kx, ky);
    }

    function translate(transform, p0, p1) {
      var x = p0[0] - p1[0] * transform.kx, y = p0[1] - p1[1] * transform.ky;
      return x === transform.x && y === transform.y ? transform : new Transform(x, y, transform.kx, transform.ky);
    }

    function constrain(transform, extent) {
      var dx0 = transform.invertX(extent[0][0]) - x0,
        dx1 = transform.invertX(extent[1][0]) - x1,
        dy0 = transform.invertY(extent[0][1]) - y0,
        dy1 = transform.invertY(extent[1][1]) - y1;
      return transform.translate(
        dx1 > dx0 ? (dx0 + dx1) / 2 : Math.min(0, dx0) || Math.max(0, dx1),
        dy1 > dy0 ? (dy0 + dy1) / 2 : Math.min(0, dy0) || Math.max(0, dy1)
      );
    }

    function centroid(extent) {
      return [(+extent[0][0] + +extent[1][0]) / 2, (+extent[0][1] + +extent[1][1]) / 2];
    }

    function schedule(transition, transform) {
      transition
        .on("start.zoom", function() { gesture(this, arguments).start(); })
        .on("interrupt.zoom end.zoom", function() { gesture(this, arguments).end(); })
        .tween("zoom", function() {
          var that = this,
            args = arguments,
            g = gesture(that, args),
            a = that.__zoom,
            b = typeof transform === "function" ? transform.apply(that, args) : transform;
          var txi = interpolate(a.x, b.x);
          var tyi = interpolate(a.y, b.y);
          var kxi = interpolate(a.kx, b.kx);
          var kyi = interpolate(a.ky, b.ky);
          return function(t) {
            if (t === 1) t = b; // Avoid rounding error on end.
            else {
              t = new Transform(txi(t), tyi(t), kxi(t), kyi(t));
            }
            g.zoom(null, t);
          };
        });
    }

    function gesture(that, args) {
      for (var i = 0, n = gestures.length, g; i < n; ++i) {
        if ((g = gestures[i]).that === that) {
          return g;
        }
      }
      return new Gesture(that, args);
    }

    function Gesture(that, args) {
      this.that = that;
      this.args = args;
      this.index = -1;
      this.active = 0;
      this.extent = extent.apply(that, args);
    }

    Gesture.prototype = {
      start: function() {
        if (++this.active === 1) {
          this.index = gestures.push(this) - 1;
          this.emit("start");
        }
        return this;
      },
      zoom: function(key, transform) {
        if (this.mouse && key !== "mouse") this.mouse[1] = transform.invert(this.mouse[0]);
        if (this.touch0 && key !== "touch") this.touch0[1] = transform.invert(this.touch0[0]);
        if (this.touch1 && key !== "touch") this.touch1[1] = transform.invert(this.touch1[0]);
        this.that.__zoom = transform;
        this.emit("zoom");
        return this;
      },
      end: function() {
        if (--this.active === 0) {
          gestures.splice(this.index, 1);
          this.index = -1;
          this.emit("end");
        }
        return this;
      },
      emit: function(type) {
        d3Selection.customEvent(new ZoomEvent(zoom, type, this.that.__zoom), listeners.apply, listeners, [type, this.that, this.args]);
      }
    };

    function wheeled() {
      if (!filter.apply(this, arguments)) return;
      var g = gesture(this, arguments);
      var t = this.__zoom;
      var kx = Math.max(kx0, Math.min(kx1, t.kx * (1 + rx * (-1 + Math.pow(2, -d3Selection.event.deltaY * (d3Selection.event.deltaMode ? 120 : 1) / 500)))));
      var ky = Math.max(ky0, Math.min(ky1, t.ky * (1 + ry * (-1 + Math.pow(2, -d3Selection.event.deltaY * (d3Selection.event.deltaMode ? 120 : 1) / 500)))));
      var p = d3Selection.mouse(this);

      // If a scale factor has reached scale extend, sync its value with the other one
      if (t.kx === kx0) {
        kx = ky >= kx0 ? kx : kx0;
      }
      if (t.kx === kx1) {
        kx = ky <= kx1 ? kx : kx1;
      }
      if (t.ky === ky0) {
        ky = kx >= ky0 ? ky : ky0;
      }
      if (t.ky === ky1) {
        ky = kx <= ky1 ? ky : ky1;
      }

      // If the mouse is in the same location as before, reuse it.
      // If there were recent wheel events, reset the wheel idle timeout.
      if (g.wheel) {
        if (g.mouse[0][0] !== p[0] || g.mouse[0][1] !== p[1]) {
          g.mouse[1] = t.invert(g.mouse[0] = p);
        }
        clearTimeout(g.wheel);
      }


      // If this wheel event won’t trigger a transform change, ignore it.
      else if (t.kx === ky && t.ky === kx) return;

      // Otherwise, capture the mouse point and location at the start.
      else {
        g.mouse = [p, t.invert(p)];
        d3Transition.interrupt(this);
        g.start();
      }

      noevent();
      g.wheel = setTimeout(wheelidled, wheelDelay);
      g.zoom("mouse", constrain(translate(scale(t, kx, ky), g.mouse[0], g.mouse[1]), g.extent));

      function wheelidled() {
        g.wheel = null;
        g.end();
      }
    }

    function mousedowned() {
      if (touchending || !filter.apply(this, arguments)) return;
      var g = gesture(this, arguments),
        v = d3Selection.select(d3Selection.event.view).on("mousemove.zoom", mousemoved, true).on("mouseup.zoom", mouseupped, true),
        p = d3Selection.mouse(this);

      d3Drag.dragDisable(d3Selection.event.view);
      nopropagation();
      g.mouse = [p, this.__zoom.invert(p)];
      d3Transition.interrupt(this);
      g.start();

      function mousemoved() {
        noevent();
        g.moved = true;
        g.zoom("mouse", constrain(translate(g.that.__zoom, g.mouse[0] = d3Selection.mouse(g.that), g.mouse[1]), g.extent));
      }

      function mouseupped() {
        v.on("mousemove.zoom mouseup.zoom", null);
        d3Drag.dragEnable(d3Selection.event.view, g.moved);
        noevent();
        g.end();
      }
    }

    function dblclicked() {
      if (!filter.apply(this, arguments)) return;
      var t0 = this.__zoom,
        p0 = d3Selection.mouse(this),
        p1 = t0.invert(p0),
        kx1 = t0.kx * (1 + rx * (-1 + (d3Selection.event.shiftKey ? 0.5 : 2))),
        ky1 = t0.ky * (1 + ry * (-1 + (d3Selection.event.shiftKey ? 0.5 : 2))),
        t1 = constrain(translate(scale(t0, kx1, ky1), p0, p1), extent.apply(this, arguments));

      noevent();
      if (duration > 0) d3Selection.select(this).transition().duration(duration).call(schedule, t1, p0);
      else d3Selection.select(this).call(zoom.transform, t1);
    }

    function touchstarted() {
      if (!filter.apply(this, arguments)) return;
      var g = gesture(this, arguments),
        touches = d3Selection.event.changedTouches,
        n = touches.length, i, t, p;

      nopropagation();
      for (i = 0; i < n; ++i) {
        t = touches[i], p = d3Selection.touch(this, touches, t.identifier);
        p = [p, this.__zoom.invert(p), t.identifier];
        if (!g.touch0) g.touch0 = p;
        else if (!g.touch1) g.touch1 = p;
      }

      // If this is a dbltap, reroute to the (optional) dblclick.zoom handler.
      if (touchstarting) {
        touchstarting = clearTimeout(touchstarting);
        if (!g.touch1) {
          g.end();
          p = d3Selection.select(this).on("dblclick.zoom");
          if (p) p.apply(this, arguments);
          return;
        }
      }

      if (d3Selection.event.touches.length === n) {
        touchstarting = setTimeout(function() { touchstarting = null; }, touchDelay);
        d3Transition.interrupt(this);
        g.start();
      }
    }

    function touchmoved() {
      var g = gesture(this, arguments),
        touches = d3Selection.event.changedTouches,
        n = touches.length, i, t, p, l;

      noevent();
      if (touchstarting) touchstarting = clearTimeout(touchstarting);
      for (i = 0; i < n; ++i) {
        t = touches[i], p = d3Selection.touch(this, touches, t.identifier);
        if (g.touch0 && g.touch0[2] === t.identifier) g.touch0[0] = p;
        else if (g.touch1 && g.touch1[2] === t.identifier) g.touch1[0] = p;
      }
      t = g.that.__zoom;
      if (g.touch1) {
        var p0 = g.touch0[0], l0 = g.touch0[1],
          p1 = g.touch1[0], l1 = g.touch1[1],
          dp = (dp = p1[0] - p0[0]) * dp + (dp = p1[1] - p0[1]) * dp,
          dl = (dl = l1[0] - l0[0]) * dl + (dl = l1[1] - l0[1]) * dl;
        t = scale(t, Math.sqrt(dp / dl), Math.sqrt(dp / dl));
        p = [(p0[0] + p1[0]) / 2, (p0[1] + p1[1]) / 2];
        l = [(l0[0] + l1[0]) / 2, (l0[1] + l1[1]) / 2];
      }
      else if (g.touch0) p = g.touch0[0], l = g.touch0[1];
      else return;
      g.zoom("touch", constrain(translate(t, p, l), g.extent));
    }

    function touchended() {
      var g = gesture(this, arguments),
        touches = d3Selection.event.changedTouches,
        n = touches.length, i, t;

      nopropagation();
      if (touchending) clearTimeout(touchending);
      touchending = setTimeout(function() { touchending = null; }, touchDelay);
      for (i = 0; i < n; ++i) {
        t = touches[i];
        if (g.touch0 && g.touch0[2] === t.identifier) delete g.touch0;
        else if (g.touch1 && g.touch1[2] === t.identifier) delete g.touch1;
      }
      if (g.touch1 && !g.touch0) g.touch0 = g.touch1, delete g.touch1;
      if (!g.touch0) g.end();
    }

    function constrainScaleExtent() {
      kx0 = x1 !== x0 ? Math.max(kx0, (extent()[1][0] - extent()[0][0]) / (x1 - x0)) : Infinity;
      ky0 = y1 !== y0 ? Math.max(ky0, (extent()[1][1] - extent()[0][1]) / (y1 - y0)) : Infinity;
    }


    zoom.filter = function(_) {
      return arguments.length ? (filter = typeof _ === "function" ? _ : constant(!!_), zoom) : filter;
    };

    zoom.extent = function(_) {
      return arguments.length ? (extent = typeof _ === "function" ? _ : constant([[+_[0][0], +_[0][1]], [+_[1][0], +_[1][1]]]), constrainScaleExtent(), zoom) : extent;
    };

    zoom.scaleExtent = function(_) {
      if (arguments.length) {
        if (Array.isArray(_[0])) {
          kx0 = +_[0][0];
          kx1 = +_[0][1];
          ky0 = +_[1][0];
          ky1 = +_[1][1];
        } else {
          kx0 = +_[0];
          kx1 = +_[1];
          ky0 = kx0;
          ky1 = kx1;
        }
        constrainScaleExtent();
        return zoom;
      }
      return [[kx0, kx1], [ky0, ky1]];
    };

    zoom.scaleRatio = function(_) {
      return arguments.length ? (rx = +_[0], ry = +_[1], zoom) : [rx, ry];
    };

    zoom.translateExtent = function(_) {
      return arguments.length ? (x0 = +_[0][0], x1 = +_[1][0], y0 = +_[0][1], y1 = +_[1][1], constrainScaleExtent(), zoom) : [[x0, y0], [x1, y1]];
    };

    zoom.duration = function(_) {
      return arguments.length ? (duration = +_, zoom) : duration;
    };

    zoom.interpolate = function(_) {
      return arguments.length ? (interpolate = _, zoom) : interpolate;
    };

    zoom.on = function() {
      var value = listeners.on.apply(listeners, arguments);
      return value === listeners ? zoom : value;
    };

    return zoom;
  }

  exports.xyzoom = zoom;
  exports.xyzoomTransform = transform;
  exports.xyzoomIdentity = identity;

  Object.defineProperty(exports, '__esModule', { value: true });

}));