react-native-gesture-handler
Version:
Declarative API exposing native platform touch and gesture system to React Native
152 lines (151 loc) • 6.28 kB
JavaScript
import Hammer from '@egjs/hammerjs';
import { MULTI_FINGER_PAN_MAX_PINCH_THRESHOLD, MULTI_FINGER_PAN_MAX_ROTATION_THRESHOLD, } from './constants';
import DraggingGestureHandler from './DraggingGestureHandler';
import { isValidNumber, isnan, TEST_MIN_IF_NOT_NAN, VEC_LEN_SQ } from './utils';
import { State } from '../State';
class PanGestureHandler extends DraggingGestureHandler {
get name() {
return 'pan';
}
get NativeGestureClass() {
return Hammer.Pan;
}
getHammerConfig() {
return {
...super.getHammerConfig(),
direction: this.getDirection(),
};
}
getState(type) {
const nextState = super.getState(type);
// Ensure that the first state sent is `BEGAN` and not `ACTIVE`
if (this.previousState === State.UNDETERMINED &&
nextState === State.ACTIVE) {
return State.BEGAN;
}
return nextState;
}
getDirection() {
const config = this.getConfig();
const { activeOffsetXStart, activeOffsetXEnd, activeOffsetYStart, activeOffsetYEnd, minDist, } = config;
let directions = [];
let horizontalDirections = [];
if (!isnan(minDist)) {
return Hammer.DIRECTION_ALL;
}
if (!isnan(activeOffsetXStart)) {
horizontalDirections.push(Hammer.DIRECTION_LEFT);
}
if (!isnan(activeOffsetXEnd)) {
horizontalDirections.push(Hammer.DIRECTION_RIGHT);
}
if (horizontalDirections.length === 2) {
horizontalDirections = [Hammer.DIRECTION_HORIZONTAL];
}
directions = directions.concat(horizontalDirections);
let verticalDirections = [];
if (!isnan(activeOffsetYStart)) {
verticalDirections.push(Hammer.DIRECTION_UP);
}
if (!isnan(activeOffsetYEnd)) {
verticalDirections.push(Hammer.DIRECTION_DOWN);
}
if (verticalDirections.length === 2) {
verticalDirections = [Hammer.DIRECTION_VERTICAL];
}
directions = directions.concat(verticalDirections);
if (!directions.length) {
return Hammer.DIRECTION_NONE;
}
if (directions[0] === Hammer.DIRECTION_HORIZONTAL &&
directions[1] === Hammer.DIRECTION_VERTICAL) {
return Hammer.DIRECTION_ALL;
}
if (horizontalDirections.length && verticalDirections.length) {
return Hammer.DIRECTION_ALL;
}
return directions[0];
}
getConfig() {
if (!this.hasCustomActivationCriteria) {
// Default config
// If no params have been defined then this config should emulate the native gesture as closely as possible.
return {
minDistSq: 10,
};
}
return this.config;
}
shouldFailUnderCustomCriteria({ deltaX, deltaY }, criteria) {
return ((!isnan(criteria.failOffsetXStart) &&
deltaX < criteria.failOffsetXStart) ||
(!isnan(criteria.failOffsetXEnd) && deltaX > criteria.failOffsetXEnd) ||
(!isnan(criteria.failOffsetYStart) &&
deltaY < criteria.failOffsetYStart) ||
(!isnan(criteria.failOffsetYEnd) && deltaY > criteria.failOffsetYEnd));
}
shouldActivateUnderCustomCriteria({ deltaX, deltaY, velocity }, criteria) {
return ((!isnan(criteria.activeOffsetXStart) &&
deltaX < criteria.activeOffsetXStart) ||
(!isnan(criteria.activeOffsetXEnd) &&
deltaX > criteria.activeOffsetXEnd) ||
(!isnan(criteria.activeOffsetYStart) &&
deltaY < criteria.activeOffsetYStart) ||
(!isnan(criteria.activeOffsetYEnd) &&
deltaY > criteria.activeOffsetYEnd) ||
TEST_MIN_IF_NOT_NAN(VEC_LEN_SQ({ x: deltaX, y: deltaY }), criteria.minDistSq) ||
TEST_MIN_IF_NOT_NAN(velocity.x, criteria.minVelocityX) ||
TEST_MIN_IF_NOT_NAN(velocity.y, criteria.minVelocityY) ||
TEST_MIN_IF_NOT_NAN(VEC_LEN_SQ(velocity), criteria.minVelocitySq));
}
shouldMultiFingerPanFail({ pointerLength, scale, deltaRotation, }) {
if (pointerLength <= 1) {
return false;
}
// Test if the pan had too much pinching or rotating.
const deltaScale = Math.abs(scale - 1);
const absDeltaRotation = Math.abs(deltaRotation);
if (deltaScale > MULTI_FINGER_PAN_MAX_PINCH_THRESHOLD) {
// > If the threshold doesn't seem right.
// You can log the value which it failed at here:
return true;
}
if (absDeltaRotation > MULTI_FINGER_PAN_MAX_ROTATION_THRESHOLD) {
// > If the threshold doesn't seem right.
// You can log the value which it failed at here:
return true;
}
return false;
}
updateHasCustomActivationCriteria(criteria) {
return (isValidNumber(criteria.minDistSq) ||
isValidNumber(criteria.minVelocityX) ||
isValidNumber(criteria.minVelocityY) ||
isValidNumber(criteria.minVelocitySq) ||
isValidNumber(criteria.activeOffsetXStart) ||
isValidNumber(criteria.activeOffsetXEnd) ||
isValidNumber(criteria.activeOffsetYStart) ||
isValidNumber(criteria.activeOffsetYEnd));
}
isGestureEnabledForEvent(props, _recognizer, inputData) {
if (this.shouldFailUnderCustomCriteria(inputData, props)) {
return { failed: true };
}
const velocity = { x: inputData.velocityX, y: inputData.velocityY };
if (this.hasCustomActivationCriteria &&
this.shouldActivateUnderCustomCriteria({ deltaX: inputData.deltaX, deltaY: inputData.deltaY, velocity }, props)) {
if (this.shouldMultiFingerPanFail({
pointerLength: inputData.maxPointers,
scale: inputData.scale,
deltaRotation: inputData.deltaRotation,
})) {
return {
failed: true,
};
}
return { success: true };
}
return { success: false };
}
}
export default PanGestureHandler;