source: node_modules/d3-brush/src/brush.js@ e4c61dd

import {dispatch} from "d3-dispatch";
import {dragDisable, dragEnable} from "d3-drag";
import {interpolate} from "d3-interpolate";
import {pointer, select} from "d3-selection";
import {interrupt} from "d3-transition";
import constant from "./constant.js";
import BrushEvent from "./event.js";
import noevent, {nopropagation} from "./noevent.js";

var MODE_DRAG = {name: "drag"},
    MODE_SPACE = {name: "space"},
    MODE_HANDLE = {name: "handle"},
    MODE_CENTER = {name: "center"};

const {abs, max, min} = Math;

function number1(e) {
  return [+e[0], +e[1]];
}

function number2(e) {
  return [number1(e[0]), number1(e[1])];
}

var X = {
  name: "x",
  handles: ["w", "e"].map(type),
  input: function(x, e) { return x == null ? null : [[+x[0], e[0][1]], [+x[1], e[1][1]]]; },
  output: function(xy) { return xy && [xy[0][0], xy[1][0]]; }
};

var Y = {
  name: "y",
  handles: ["n", "s"].map(type),
  input: function(y, e) { return y == null ? null : [[e[0][0], +y[0]], [e[1][0], +y[1]]]; },
  output: function(xy) { return xy && [xy[0][1], xy[1][1]]; }
};

var XY = {
  name: "xy",
  handles: ["n", "w", "e", "s", "nw", "ne", "sw", "se"].map(type),
  input: function(xy) { return xy == null ? null : number2(xy); },
  output: function(xy) { return xy; }
};

var cursors = {
  overlay: "crosshair",
  selection: "move",
  n: "ns-resize",
  e: "ew-resize",
  s: "ns-resize",
  w: "ew-resize",
  nw: "nwse-resize",
  ne: "nesw-resize",
  se: "nwse-resize",
  sw: "nesw-resize"
};

var flipX = {
  e: "w",
  w: "e",
  nw: "ne",
  ne: "nw",
  se: "sw",
  sw: "se"
};

var flipY = {
  n: "s",
  s: "n",
  nw: "sw",
  ne: "se",
  se: "ne",
  sw: "nw"
};

var signsX = {
  overlay: +1,
  selection: +1,
  n: null,
  e: +1,
  s: null,
  w: -1,
  nw: -1,
  ne: +1,
  se: +1,
  sw: -1
};

var signsY = {
  overlay: +1,
  selection: +1,
  n: -1,
  e: null,
  s: +1,
  w: null,
  nw: -1,
  ne: -1,
  se: +1,
  sw: +1
};

function type(t) {
  return {type: t};
}

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

function defaultExtent() {
  var svg = this.ownerSVGElement || this;
  if (svg.hasAttribute("viewBox")) {
    svg = svg.viewBox.baseVal;
    return [[svg.x, svg.y], [svg.x + svg.width, svg.y + svg.height]];
  }
  return [[0, 0], [svg.width.baseVal.value, svg.height.baseVal.value]];
}

function defaultTouchable() {
  return navigator.maxTouchPoints || ("ontouchstart" in this);
}

// Like d3.local, but with the name “__brush” rather than auto-generated.
function local(node) {
  while (!node.__brush) if (!(node = node.parentNode)) return;
  return node.__brush;
}

function empty(extent) {
  return extent[0][0] === extent[1][0]
      || extent[0][1] === extent[1][1];
}

export function brushSelection(node) {
  var state = node.__brush;
  return state ? state.dim.output(state.selection) : null;
}

export function brushX() {
  return brush(X);
}

export function brushY() {
  return brush(Y);
}

export default function() {
  return brush(XY);
}

function brush(dim) {
  var extent = defaultExtent,
      filter = defaultFilter,
      touchable = defaultTouchable,
      keys = true,
      listeners = dispatch("start", "brush", "end"),
      handleSize = 6,
      touchending;

  function brush(group) {
    var overlay = group
        .property("__brush", initialize)
      .selectAll(".overlay")
      .data([type("overlay")]);

    overlay.enter().append("rect")
        .attr("class", "overlay")
        .attr("pointer-events", "all")
        .attr("cursor", cursors.overlay)
      .merge(overlay)
        .each(function() {
          var extent = local(this).extent;
          select(this)
              .attr("x", extent[0][0])
              .attr("y", extent[0][1])
              .attr("width", extent[1][0] - extent[0][0])
              .attr("height", extent[1][1] - extent[0][1]);
        });

    group.selectAll(".selection")
      .data([type("selection")])
      .enter().append("rect")
        .attr("class", "selection")
        .attr("cursor", cursors.selection)
        .attr("fill", "#777")
        .attr("fill-opacity", 0.3)
        .attr("stroke", "#fff")
        .attr("shape-rendering", "crispEdges");

    var handle = group.selectAll(".handle")
      .data(dim.handles, function(d) { return d.type; });

    handle.exit().remove();

    handle.enter().append("rect")
        .attr("class", function(d) { return "handle handle--" + d.type; })
        .attr("cursor", function(d) { return cursors[d.type]; });

    group
        .each(redraw)
        .attr("fill", "none")
        .attr("pointer-events", "all")
        .on("mousedown.brush", started)
      .filter(touchable)
        .on("touchstart.brush", started)
        .on("touchmove.brush", touchmoved)
        .on("touchend.brush touchcancel.brush", touchended)
        .style("touch-action", "none")
        .style("-webkit-tap-highlight-color", "rgba(0,0,0,0)");
  }

  brush.move = function(group, selection, event) {
    if (group.tween) {
      group
          .on("start.brush", function(event) { emitter(this, arguments).beforestart().start(event); })
          .on("interrupt.brush end.brush", function(event) { emitter(this, arguments).end(event); })
          .tween("brush", function() {
            var that = this,
                state = that.__brush,
                emit = emitter(that, arguments),
                selection0 = state.selection,
                selection1 = dim.input(typeof selection === "function" ? selection.apply(this, arguments) : selection, state.extent),
                i = interpolate(selection0, selection1);

            function tween(t) {
              state.selection = t === 1 && selection1 === null ? null : i(t);
              redraw.call(that);
              emit.brush();
            }

            return selection0 !== null && selection1 !== null ? tween : tween(1);
          });
    } else {
      group
          .each(function() {
            var that = this,
                args = arguments,
                state = that.__brush,
                selection1 = dim.input(typeof selection === "function" ? selection.apply(that, args) : selection, state.extent),
                emit = emitter(that, args).beforestart();

            interrupt(that);
            state.selection = selection1 === null ? null : selection1;
            redraw.call(that);
            emit.start(event).brush(event).end(event);
          });
    }
  };

  brush.clear = function(group, event) {
    brush.move(group, null, event);
  };

  function redraw() {
    var group = select(this),
        selection = local(this).selection;

    if (selection) {
      group.selectAll(".selection")
          .style("display", null)
          .attr("x", selection[0][0])
          .attr("y", selection[0][1])
          .attr("width", selection[1][0] - selection[0][0])
          .attr("height", selection[1][1] - selection[0][1]);

      group.selectAll(".handle")
          .style("display", null)
          .attr("x", function(d) { return d.type[d.type.length - 1] === "e" ? selection[1][0] - handleSize / 2 : selection[0][0] - handleSize / 2; })
          .attr("y", function(d) { return d.type[0] === "s" ? selection[1][1] - handleSize / 2 : selection[0][1] - handleSize / 2; })
          .attr("width", function(d) { return d.type === "n" || d.type === "s" ? selection[1][0] - selection[0][0] + handleSize : handleSize; })
          .attr("height", function(d) { return d.type === "e" || d.type === "w" ? selection[1][1] - selection[0][1] + handleSize : handleSize; });
    }

    else {
      group.selectAll(".selection,.handle")
          .style("display", "none")
          .attr("x", null)
          .attr("y", null)
          .attr("width", null)
          .attr("height", null);
    }
  }

  function emitter(that, args, clean) {
    var emit = that.__brush.emitter;
    return emit && (!clean || !emit.clean) ? emit : new Emitter(that, args, clean);
  }

  function Emitter(that, args, clean) {
    this.that = that;
    this.args = args;
    this.state = that.__brush;
    this.active = 0;
    this.clean = clean;
  }

  Emitter.prototype = {
    beforestart: function() {
      if (++this.active === 1) this.state.emitter = this, this.starting = true;
      return this;
    },
    start: function(event, mode) {
      if (this.starting) this.starting = false, this.emit("start", event, mode);
      else this.emit("brush", event);
      return this;
    },
    brush: function(event, mode) {
      this.emit("brush", event, mode);
      return this;
    },
    end: function(event, mode) {
      if (--this.active === 0) delete this.state.emitter, this.emit("end", event, mode);
      return this;
    },
    emit: function(type, event, mode) {
      var d = select(this.that).datum();
      listeners.call(
        type,
        this.that,
        new BrushEvent(type, {
          sourceEvent: event,
          target: brush,
          selection: dim.output(this.state.selection),
          mode,
          dispatch: listeners
        }),
        d
      );
    }
  };

  function started(event) {
    if (touchending && !event.touches) return;
    if (!filter.apply(this, arguments)) return;

    var that = this,
        type = event.target.__data__.type,
        mode = (keys && event.metaKey ? type = "overlay" : type) === "selection" ? MODE_DRAG : (keys && event.altKey ? MODE_CENTER : MODE_HANDLE),
        signX = dim === Y ? null : signsX[type],
        signY = dim === X ? null : signsY[type],
        state = local(that),
        extent = state.extent,
        selection = state.selection,
        W = extent[0][0], w0, w1,
        N = extent[0][1], n0, n1,
        E = extent[1][0], e0, e1,
        S = extent[1][1], s0, s1,
        dx = 0,
        dy = 0,
        moving,
        shifting = signX && signY && keys && event.shiftKey,
        lockX,
        lockY,
        points = Array.from(event.touches || [event], t => {
          const i = t.identifier;
          t = pointer(t, that);
          t.point0 = t.slice();
          t.identifier = i;
          return t;
        });

    interrupt(that);
    var emit = emitter(that, arguments, true).beforestart();

    if (type === "overlay") {
      if (selection) moving = true;
      const pts = [points[0], points[1] || points[0]];
      state.selection = selection = [[
          w0 = dim === Y ? W : min(pts[0][0], pts[1][0]),
          n0 = dim === X ? N : min(pts[0][1], pts[1][1])
        ], [
          e0 = dim === Y ? E : max(pts[0][0], pts[1][0]),
          s0 = dim === X ? S : max(pts[0][1], pts[1][1])
        ]];
      if (points.length > 1) move(event);
    } else {
      w0 = selection[0][0];
      n0 = selection[0][1];
      e0 = selection[1][0];
      s0 = selection[1][1];
    }

    w1 = w0;
    n1 = n0;
    e1 = e0;
    s1 = s0;

    var group = select(that)
        .attr("pointer-events", "none");

    var overlay = group.selectAll(".overlay")
        .attr("cursor", cursors[type]);

    if (event.touches) {
      emit.moved = moved;
      emit.ended = ended;
    } else {
      var view = select(event.view)
          .on("mousemove.brush", moved, true)
          .on("mouseup.brush", ended, true);
      if (keys) view
          .on("keydown.brush", keydowned, true)
          .on("keyup.brush", keyupped, true)

      dragDisable(event.view);
    }

    redraw.call(that);
    emit.start(event, mode.name);

    function moved(event) {
      for (const p of event.changedTouches || [event]) {
        for (const d of points)
          if (d.identifier === p.identifier) d.cur = pointer(p, that);
      }
      if (shifting && !lockX && !lockY && points.length === 1) {
        const point = points[0];
        if (abs(point.cur[0] - point[0]) > abs(point.cur[1] - point[1]))
          lockY = true;
        else
          lockX = true;
      }
      for (const point of points)
        if (point.cur) point[0] = point.cur[0], point[1] = point.cur[1];
      moving = true;
      noevent(event);
      move(event);
    }

    function move(event) {
      const point = points[0], point0 = point.point0;
      var t;

      dx = point[0] - point0[0];
      dy = point[1] - point0[1];

      switch (mode) {
        case MODE_SPACE:
        case MODE_DRAG: {
          if (signX) dx = max(W - w0, min(E - e0, dx)), w1 = w0 + dx, e1 = e0 + dx;
          if (signY) dy = max(N - n0, min(S - s0, dy)), n1 = n0 + dy, s1 = s0 + dy;
          break;
        }
        case MODE_HANDLE: {
          if (points[1]) {
            if (signX) w1 = max(W, min(E, points[0][0])), e1 = max(W, min(E, points[1][0])), signX = 1;
            if (signY) n1 = max(N, min(S, points[0][1])), s1 = max(N, min(S, points[1][1])), signY = 1;
          } else {
            if (signX < 0) dx = max(W - w0, min(E - w0, dx)), w1 = w0 + dx, e1 = e0;
            else if (signX > 0) dx = max(W - e0, min(E - e0, dx)), w1 = w0, e1 = e0 + dx;
            if (signY < 0) dy = max(N - n0, min(S - n0, dy)), n1 = n0 + dy, s1 = s0;
            else if (signY > 0) dy = max(N - s0, min(S - s0, dy)), n1 = n0, s1 = s0 + dy;
          }
          break;
        }
        case MODE_CENTER: {
          if (signX) w1 = max(W, min(E, w0 - dx * signX)), e1 = max(W, min(E, e0 + dx * signX));
          if (signY) n1 = max(N, min(S, n0 - dy * signY)), s1 = max(N, min(S, s0 + dy * signY));
          break;
        }
      }

      if (e1 < w1) {
        signX *= -1;
        t = w0, w0 = e0, e0 = t;
        t = w1, w1 = e1, e1 = t;
        if (type in flipX) overlay.attr("cursor", cursors[type = flipX[type]]);
      }

      if (s1 < n1) {
        signY *= -1;
        t = n0, n0 = s0, s0 = t;
        t = n1, n1 = s1, s1 = t;
        if (type in flipY) overlay.attr("cursor", cursors[type = flipY[type]]);
      }

      if (state.selection) selection = state.selection; // May be set by brush.move!
      if (lockX) w1 = selection[0][0], e1 = selection[1][0];
      if (lockY) n1 = selection[0][1], s1 = selection[1][1];

      if (selection[0][0] !== w1
          || selection[0][1] !== n1
          || selection[1][0] !== e1
          || selection[1][1] !== s1) {
        state.selection = [[w1, n1], [e1, s1]];
        redraw.call(that);
        emit.brush(event, mode.name);
      }
    }

    function ended(event) {
      nopropagation(event);
      if (event.touches) {
        if (event.touches.length) return;
        if (touchending) clearTimeout(touchending);
        touchending = setTimeout(function() { touchending = null; }, 500); // Ghost clicks are delayed!
      } else {
        dragEnable(event.view, moving);
        view.on("keydown.brush keyup.brush mousemove.brush mouseup.brush", null);
      }
      group.attr("pointer-events", "all");
      overlay.attr("cursor", cursors.overlay);
      if (state.selection) selection = state.selection; // May be set by brush.move (on start)!
      if (empty(selection)) state.selection = null, redraw.call(that);
      emit.end(event, mode.name);
    }

    function keydowned(event) {
      switch (event.keyCode) {
        case 16: { // SHIFT
          shifting = signX && signY;
          break;
        }
        case 18: { // ALT
          if (mode === MODE_HANDLE) {
            if (signX) e0 = e1 - dx * signX, w0 = w1 + dx * signX;
            if (signY) s0 = s1 - dy * signY, n0 = n1 + dy * signY;
            mode = MODE_CENTER;
            move(event);
          }
          break;
        }
        case 32: { // SPACE; takes priority over ALT
          if (mode === MODE_HANDLE || mode === MODE_CENTER) {
            if (signX < 0) e0 = e1 - dx; else if (signX > 0) w0 = w1 - dx;
            if (signY < 0) s0 = s1 - dy; else if (signY > 0) n0 = n1 - dy;
            mode = MODE_SPACE;
            overlay.attr("cursor", cursors.selection);
            move(event);
          }
          break;
        }
        default: return;
      }
      noevent(event);
    }

    function keyupped(event) {
      switch (event.keyCode) {
        case 16: { // SHIFT
          if (shifting) {
            lockX = lockY = shifting = false;
            move(event);
          }
          break;
        }
        case 18: { // ALT
          if (mode === MODE_CENTER) {
            if (signX < 0) e0 = e1; else if (signX > 0) w0 = w1;
            if (signY < 0) s0 = s1; else if (signY > 0) n0 = n1;
            mode = MODE_HANDLE;
            move(event);
          }
          break;
        }
        case 32: { // SPACE
          if (mode === MODE_SPACE) {
            if (event.altKey) {
              if (signX) e0 = e1 - dx * signX, w0 = w1 + dx * signX;
              if (signY) s0 = s1 - dy * signY, n0 = n1 + dy * signY;
              mode = MODE_CENTER;
            } else {
              if (signX < 0) e0 = e1; else if (signX > 0) w0 = w1;
              if (signY < 0) s0 = s1; else if (signY > 0) n0 = n1;
              mode = MODE_HANDLE;
            }
            overlay.attr("cursor", cursors[type]);
            move(event);
          }
          break;
        }
        default: return;
      }
      noevent(event);
    }
  }

  function touchmoved(event) {
    emitter(this, arguments).moved(event);
  }

  function touchended(event) {
    emitter(this, arguments).ended(event);
  }

  function initialize() {
    var state = this.__brush || {selection: null};
    state.extent = number2(extent.apply(this, arguments));
    state.dim = dim;
    return state;
  }

  brush.extent = function(_) {
    return arguments.length ? (extent = typeof _ === "function" ? _ : constant(number2(_)), brush) : extent;
  };

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

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

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

  brush.keyModifiers = function(_) {
    return arguments.length ? (keys = !!_, brush) : keys;
  };

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

  return brush;
}