52 lines
1.4 KiB
TypeScript
52 lines
1.4 KiB
TypeScript
export default class SwipeHandler {
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private xDown: number;
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private yDown: number;
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constructor(element: HTMLElement, private onSwipe: (xDiff: number, yDiff: number) => boolean, private verifyTouchTarget?: (evt: TouchEvent) => boolean) {
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element.addEventListener('touchstart', this.handleTouchStart, false);
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element.addEventListener('touchmove', this.handleTouchMove, false);
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}
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handleTouchStart = (evt: TouchEvent) => {
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if(this.verifyTouchTarget && !this.verifyTouchTarget(evt)) {
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this.xDown = this.yDown = null;
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return;
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}
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const firstTouch = evt.touches[0];
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this.xDown = firstTouch.clientX;
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this.yDown = firstTouch.clientY;
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};
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handleTouchMove = (evt: TouchEvent) => {
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if(this.xDown === null || this.yDown === null) {
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return;
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}
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const xUp = evt.touches[0].clientX;
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const yUp = evt.touches[0].clientY;
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const xDiff = this.xDown - xUp;
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const yDiff = this.yDown - yUp;
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// if(Math.abs(xDiff) > Math.abs(yDiff)) { /*most significant*/
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// if(xDiff > 0) { /* left swipe */
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// } else { /* right swipe */
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// }
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// } else {
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// if(yDiff > 0) { /* up swipe */
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// } else { /* down swipe */
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// }
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// }
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/* reset values */
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if(this.onSwipe(xDiff, yDiff)) {
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this.xDown = null;
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this.yDown = null;
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}
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};
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} |