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Allow set axis direction & inversion in DragPlugin #13

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Merged
Drafteed merged 1 commit into from
May 7, 2026
Merged

Allow set axis direction & inversion in DragPlugin #13

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28 changes: 16 additions & 12 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -261,6 +261,8 @@ const reeller = new Reeller({
drag: {
speed: 1,
multiplier: 1,
axis: 'y',
invertAxis: true,
changeDirection: true,
inertiaMultiplier: 0.2,
},
Expand All @@ -270,18 +272,20 @@ const reeller = new Reeller({

The following options of DragPlugin is available:

| Option | Type | Default | Description |
| :------------------- | :---------------------------------: | :----------: | :------------------------------------------------------------------------ |
| `speed` | `number` | `1` | Inertia duration in seconds. |
| `multiplier` | `number` | `1` | Drag movement multiplier. |
| `threshold` | `number` | `50` | Minimum release velocity in px/s required to start inertia. |
| `inertiaMultiplier` | `number` | `0.2` | Inertia distance multiplier. |
| `activationDistance` | `number` | `3` | Minimum pointer movement in px before drag starts. |
| `maxVelocity` | `number` | `3000` | Maximum release velocity in px/s used for inertia calculation. |
| `ease` | `string` | `'expo.out'` | Timing function. See [gsap easing](https://greensock.com/docs/v3/Eases). |
| `changeDirection` | `boolean` | `false` | Change autoplay direction to match the last drag direction after release. |
| `target` | `string` \| `HTMLElement` \| `null` | `null` | Drag target element or selector. Defaults to the Reeller container. |
| `preventDefault` | `boolean` | `true` | Prevent default pointer behaviour while dragging. |
| Option | Type | Default | Description |
| :------------------- | :---------------------------------: | :----------: | :-------------------------------------------------------------------------- |
| `speed` | `number` | `1` | Inertia duration in seconds. |
| `multiplier` | `number` | `1` | Drag movement multiplier. |
| `threshold` | `number` | `50` | Minimum release velocity in px/s required to start inertia. |
| `inertiaMultiplier` | `number` | `0.2` | Inertia distance multiplier. |
| `activationDistance` | `number` | `3` | Minimum pointer movement in px before drag starts. |
| `maxVelocity` | `number` | `3000` | Maximum release velocity in px/s used for inertia calculation. |
| `ease` | `string` | `'expo.out'` | Timing function. See [gsap easing](https://greensock.com/docs/v3/Eases). |
| `changeDirection` | `boolean` | `false` | Change autoplay direction to match the last drag direction after release. |
| `axis` | `'x' \| 'y'` | `'x'` | Pointer axis used for drag. Set `'y'` when the reel is rotated by `-90deg`. |
| `invertAxis` | `boolean` | `false` | Invert drag direction on the selected axis. Useful with rotated reels. |
| `target` | `string` \| `HTMLElement` \| `null` | `null` | Drag target element or selector. Defaults to the Reeller container. |
| `preventDefault` | `boolean` | `true` | Prevent default pointer behaviour while dragging. |

## Filler

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61 changes: 40 additions & 21 deletions src/plugin/DragPlugin.js
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,8 @@ export default class DragPlugin {
* @property {number} [maxVelocity] Maximum release velocity in px/s.
* @property {string} [ease] Timing function.
* @property {boolean} [changeDirection] Change autoplay direction after drag.
* @property {'x'|'y'} [axis] Pointer axis used for drag.
* @property {boolean} [invertAxis] Invert drag direction on the selected axis.
* @property {string|HTMLElement|null} [target] Drag target element or selector.
* @property {boolean} [preventDefault] Prevent default pointer behaviour while dragging.
*/
Expand All @@ -34,6 +36,8 @@ export default class DragPlugin {
maxVelocity: 3000,
ease: 'expo.out',
changeDirection: false,
axis: 'x',
invertAxis: false,
target: null,
preventDefault: true,
};
Expand Down Expand Up @@ -74,25 +78,36 @@ export default class DragPlugin {
/**
* Move timeline by drag delta.
*
* @param {number} deltaX Horizontal movement delta in pixels.
* @param {number} delta Movement delta in pixels.
*/
applyDelta(deltaX) {
applyDelta(delta) {
const trackWidth = this.getTrackWidth();
if (!trackWidth || !deltaX) return;
if (!trackWidth || !delta) return;

const timeDelta = (deltaX * this.options.multiplier * this.reeller.options.speed) / trackWidth;
const timeDelta = (delta * this.options.multiplier * this.reeller.options.speed) / trackWidth;
this.tl.totalTime(this.tl.totalTime() + timeDelta);
}

/**
* Return pointer position for active drag axis.
*
* @param {PointerEvent} event Pointer event.
* @return {number} Pointer position.
*/
getPointerPosition(event) {
const position = this.options.axis === 'y' ? event.clientY : event.clientX;
return this.options.invertAxis ? -position : position;
}

/**
* Save point for release velocity calculation.
*
* @param {number} x Pointer x position.
* @param {number} position Pointer position.
*/
pushSample(x) {
pushSample(position) {
const time = performance.now();

this.samples.push({x, time});
this.samples.push({position, time});

while (this.samples.length > 5 || time - this.samples[0].time > 120) {
this.samples.shift();
Expand All @@ -112,7 +127,7 @@ export default class DragPlugin {
const deltaTime = last.time - first.time;

if (!deltaTime) return 0;
return ((last.x - first.x) / deltaTime) * 1000;
return ((last.position - first.position) / deltaTime) * 1000;
}

/**
Expand Down Expand Up @@ -143,7 +158,7 @@ export default class DragPlugin {
this.tl.pause();

this.samples = [];
this.pushSample(this.lastX);
this.pushSample(this.lastPos);
}

/**
Expand Down Expand Up @@ -215,8 +230,8 @@ export default class DragPlugin {
resetPointer() {
this.pointerId = null;
this.dragging = false;
this.startX = 0;
this.lastX = 0;
this.startPos = 0;
this.lastPos = 0;
this.dragDirection = 0;
this.samples = [];
}
Expand All @@ -243,10 +258,12 @@ export default class DragPlugin {
if (this.pointerId !== null) return;
if (event.pointerType === 'mouse' && event.button !== 0) return;

const position = this.getPointerPosition(event);

this.stopInertia();
this.pointerId = event.pointerId;
this.startX = event.clientX;
this.lastX = event.clientX;
this.startPos = position;
this.lastPos = position;
this.samples = [];

if (this.target.setPointerCapture) {
Expand All @@ -257,21 +274,23 @@ export default class DragPlugin {
this.onPointerMove = (event) => {
if (event.pointerId !== this.pointerId) return;

const position = this.getPointerPosition(event);

if (!this.dragging) {
if (Math.abs(event.clientX - this.startX) < this.options.activationDistance) return;
if (Math.abs(position - this.startPos) < this.options.activationDistance) return;
this.beginDrag();
}

if (this.options.preventDefault) event.preventDefault();

const deltaX = event.clientX - this.lastX;
this.lastX = event.clientX;
const delta = position - this.lastPos;
this.lastPos = position;

if (!deltaX) return;
if (!delta) return;

this.dragDirection = Math.sign(deltaX);
this.pushSample(event.clientX);
this.applyDelta(deltaX);
this.dragDirection = Math.sign(delta);
this.pushSample(position);
this.applyDelta(delta);
};

this.onPointerUp = (event) => {
Expand All @@ -294,7 +313,7 @@ export default class DragPlugin {

if (this.options.preventDefault) event.preventDefault();

this.pushSample(event.clientX);
this.pushSample(this.getPointerPosition(event));

const velocity = this.getVelocity();
this.saveDirection(velocity);
Expand Down