feat: add a simple paused and progress with event to control transition animation.

README.md

@@ -362,6 +362,27 @@ If a *value* is not specified, returns the current easing function for the first
 
 ### Control Flow
 
+The [paused](#transition_paused) and [progress](#transition_progress) of a transition is configurable in runtime.
+
+<a name="transition_paused" href="#transition_paused">#</a> <i>transition</i>.<b>paused</b>([<i>value</i>]) [<>](https://github.com/d3/d3-transition/blob/master/src/transition/paused.js "Source")
+
+To pause the transition animation, set the transition paused to `true`, or `false` to resume. he *value* may be specified either as a constant or a function.
+
+```js
+transition.paused(true);
+```
+
+If a *value* is not specified, returns the current value of the paused for the first (non-null) element in the transition. This is generally useful only if you know that the transition contains exactly one element.
+
+
+<a name="transition_progress" href="#transition_progress">#</a> <i>transition</i>.<b>progress</b>([<i>value</i>]) [<>](https://github.com/d3/d3-transition/blob/master/src/transition/progress.js "Source")
+
+The progress is a value between 0(begin) to 1(end). You can set or get the progress of the transition at any time.
+
+```js
+transition.progress(0.5);
+```
+
 For advanced usage, transitions provide methods for custom control flow.
 
 <a name="transition_end" href="#transition_end">#</a> <i>transition</i>.<b>end</b>() [<>](https://github.com/d3/d3-transition/blob/master/src/transition/end.js "Source")
@@ -373,6 +394,7 @@ Returns a promise that resolves when every selected element finishes transitioni
 Adds or removes a *listener* to each selected element for the specified event *typenames*. The *typenames* is one of the following string event types:
 
 * `start` - when the transition starts.
+* `progress` - notify the the transition progress.
 * `end` - when the transition ends.
 * `interrupt` - when the transition is interrupted.
 * `cancel` - when the transition is cancelled.

src/transition/index.js

@@ -18,6 +18,8 @@ import transition_textTween from "./textTween.js";
 import transition_transition from "./transition.js";
 import transition_tween from "./tween.js";
 import transition_end from "./end.js";
+import transition_paused from "./paused.js";
+import transition_progress from "./progress.js";
 
 var id = 0;
 
@@ -63,6 +65,8 @@ Transition.prototype = transition.prototype = {
   tween: transition_tween,
   delay: transition_delay,
   duration: transition_duration,
+  paused: transition_paused,
+  progress: transition_progress,
   ease: transition_ease,
   end: transition_end
 };

src/transition/paused.js

@@ -0,0 +1,23 @@
+import {get} from "./schedule.js";
+
+function pausedFunction(id, value) {
+  return function() {
+    get(this, id).paused = Boolean(value.apply(this, arguments));
+  };
+}
+
+function pausedConstant(id, value) {
+  return value = Boolean(value), function() {
+    get(this, id).paused = value;
+  };
+}
+
+export default function(value) {
+  var id = this._id;
+
+  return arguments.length
+      ? this.each((typeof value === "function"
+          ? pausedFunction
+          : pausedConstant)(id, value))
+      : get(this.node(), id).paused;
+}

src/transition/progress.js

@@ -0,0 +1,28 @@
+import {get} from "./schedule.js";
+
+function progressFunction(id, value) {
+  return function() {
+    get(this, id).progress = +value.apply(this, arguments);
+  };
+}
+
+function progressConstant(id, value) {
+  return value = +value, function() {
+    get(this, id).progress = value;
+  };
+}
+
+function abs(value) {
+  if (value < 0) value = -value;
+  return value;
+}
+
+export default function(value) {
+  var id = this._id;
+
+  return arguments.length
+      ? this.each((typeof value === "function"
+          ? progressFunction
+          : progressConstant)(id, value))
+      : abs(get(this.node(), id).progress);
+}

src/transition/schedule.js

@@ -1,7 +1,7 @@
 import {dispatch} from "d3-dispatch";
 import {timer, timeout} from "d3-timer";
 
-var emptyOn = dispatch("start", "end", "cancel", "interrupt");
+var emptyOn = dispatch("start", "end", "cancel", "interrupt", "progress");
 var emptyTween = [];
 
 export var CREATED = 0;
@@ -127,7 +127,34 @@ function create(node, id, self) {
     tween.length = j + 1;
   }
 
+  function getProgress(elapsed) {
+    if (self.paused) {
+      if (self.progress >= 0) {
+        elapsed = self._lastprogress !== self.progress ? self.progress * self.duration : -1;
+      } else {
+        self.progress = elapsed / self.duration;
+      }
+      if (self._lastprogress !== self.progress) {
+        self.on.call("progress", node, node.__data__, self.index, self.group, self.progress);
+        self._lastprogress = self.progress;
+      }
+    } else if (self.progress >= 0) {
+      self.timer.restart(tick, 0, self.time + self.progress * self.duration);
+      elapsed = self.progress = - (self.progress + 1e-10);
+    } else {
+      if (elapsed >= self.duration) {
+        self.progress = -1;
+      } else {
+        self.progress = - (elapsed / self.duration);
+      }
+      self.on.call("progress", node, node.__data__, self.index, self.group, -self.progress);
+    }
+    return elapsed;
+  }
+
   function tick(elapsed) {
+    elapsed = getProgress(elapsed);
+    if (elapsed < 0) return;
     var t = elapsed < self.duration ? self.ease.call(null, elapsed / self.duration) : (self.timer.restart(stop), self.state = ENDING, 1),
         i = -1,
         n = tween.length;

test/transition/paused-test.js

@@ -0,0 +1,161 @@
+var tape = require("tape"),
+    jsdom = require("../jsdom"),
+    d3_ease = require("d3-ease"),
+    d3_timer = require("d3-timer"),
+    d3_interpolate = require("d3-interpolate"),
+    d3_selection = require("d3-selection");
+
+require("../../");
+
+tape("transition.paused(true) allows pause the transition animation", function(test) {
+  var root = jsdom().documentElement,
+      ease = d3_ease.easeCubic,
+      duration = 100,
+      interpolate = d3_interpolate.interpolateNumber(0, 100),
+      selection = d3_selection.select(root).attr("t", 0),
+      transition = selection.transition().duration(duration).attr("t", 100).on("end", ended);
+  var beginTime = d3_timer.now();
+
+  d3_timer.timeout(function(elapsed) {
+    transition.paused(true);
+    test.strictEqual(root.__transition[transition._id].paused, true);
+    test.strictEqual(transition.paused(), true);
+    test.strictEqual(Number(root.getAttribute("t")), interpolate(ease(elapsed / duration)));
+  }, 50);
+
+  d3_timer.timeout(function(elapsed) {
+    var progress = root.__transition[transition._id].progress;
+    test.strictEqual(transition.progress(), progress);
+    test.ok(progress >= 0.5);
+    test.strictEqual(Number(root.getAttribute("t")), interpolate(ease(progress)));
+    transition.paused(false);
+    test.strictEqual(root.__transition[transition._id].paused, false);
+    test.strictEqual(transition.paused(), false);
+  }, 150);
+
+  function ended() {
+    var t = d3_timer.now() - beginTime;
+    test.ok(t > 150);
+    test.end();
+  }
+});
+
+tape("transition.progress() allows get the progrss of the transition animation", function(test) {
+  var root = jsdom().documentElement,
+      ease = d3_ease.easeCubic,
+      duration = 100,
+      interpolate = d3_interpolate.interpolateNumber(0, 100),
+      selection = d3_selection.select(root).attr("t", 0),
+      transition = selection.transition().duration(duration).attr("t", 100).on("end", ended);
+  var beginTime = d3_timer.now();
+  var oldProgress;
+
+  d3_timer.timeout(function(elapsed) {
+    // get the progress on runtime
+    var progress = -root.__transition[transition._id].progress;
+    test.strictEqual(transition.progress(), progress);
+    test.ok(progress >= 0.5);
+    test.strictEqual(Number(root.getAttribute("t")), interpolate(ease(progress)));
+    transition.paused(true);
+    oldProgress = progress;
+    transition.progress(progress);
+  }, 50);
+
+  d3_timer.timeout(function(elapsed) {
+    var progress = root.__transition[transition._id].progress;
+    test.strictEqual(transition.progress(), progress);
+    test.strictEqual(oldProgress, progress);
+    test.ok(progress >= 0.5);
+    test.strictEqual(Number(root.getAttribute("t")), interpolate(ease(progress)));
+    transition.paused(false);
+  }, 150);
+
+  function ended() {
+    var t = d3_timer.now() - beginTime;
+    test.ok(t > 150);
+    test.strictEqual(transition.progress(), 1);
+    test.end();
+  }
+});
+
+tape("transition.on(\"progress\", listener) event to notify animation progress", function(test) {
+  var root = jsdom().documentElement,
+      duration = 100,
+      selection = d3_selection.select(root).attr("t", 0),
+      transition = selection.transition().duration(duration).attr("t", 100)
+      .on('progress', onProgress)
+      .on("end", ended);
+  var beginTime = d3_timer.now();
+  var oldProgress;
+  var lastProgress = 0;
+
+  d3_timer.timeout(function(elapsed) {
+    // get the progress on runtime
+    var progress = -root.__transition[transition._id].progress;
+    test.strictEqual(transition.progress(), progress);
+    test.strictEqual(lastProgress, progress);
+    test.ok(progress >= 0.5);
+    transition.paused(true);
+    oldProgress = progress;
+    transition.progress(progress);
+  }, 50);
+
+  d3_timer.timeout(function(elapsed) {
+    var progress = root.__transition[transition._id].progress;
+    test.strictEqual(transition.progress(), progress);
+    test.strictEqual(oldProgress, progress);
+    test.strictEqual(lastProgress, progress);
+    test.ok(progress >= 0.5);
+    transition.paused(false);
+  }, 150);
+
+  function onProgress(data, index, grp, progress) {
+    test.ok(progress >= lastProgress, `${progress} >= ${lastProgress}`);
+    lastProgress = progress;
+  }
+
+  function ended() {
+    var t = d3_timer.now() - beginTime;
+    test.ok(t > 150);
+    test.strictEqual(transition.progress(), 1);
+    test.strictEqual(lastProgress, 1);
+    test.end();
+  }
+});
+
+tape("transition.on(\"progress\", listener) event should work on paused status", function(test) {
+  var root = jsdom().documentElement,
+      duration = 100,
+      selection = d3_selection.select(root).attr("t", 0),
+      transition = selection.transition().duration(duration).attr("t", 100).paused(true)
+      .on('progress', onProgress)
+      .on("end", ended);
+  var beginTime = d3_timer.now();
+  var progresses = [];
+
+  d3_timer.timeout(function(elapsed) {
+    test.ok(progresses.length);
+    test.strictEqual(transition.progress(), progresses[0]);
+    transition.progress(0.2);
+  }, 50);
+
+  d3_timer.timeout(function(elapsed) {
+    test.ok(progresses.length === 2, `progresses.length(${progresses.length}) === 2`);
+    test.strictEqual(transition.progress(), progresses[1]);
+    transition.progress(1);
+  }, 100);
+
+  function onProgress(data, index, grp, progress) {
+    progresses.push(progress);
+  }
+
+  function ended() {
+    var t = d3_timer.now() - beginTime;
+    test.ok(t >= 100);
+    test.ok(t < 150);
+    test.ok(progresses.length === 3, `progresses.length(${progresses.length}) === 3`);
+    test.strictEqual(progresses[2], 1);
+    test.strictEqual(transition.progress(), 1);
+    test.end();
+  }
+});