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Draggable Reference Line

Designed for reading long articles, it helps remember the current reading progress.

目前为 2021-09-13 提交的版本。查看 最新版本。

  1. // ==UserScript==
  2. // @name         Draggable Reference Line
  3. // @description  Designed for reading long articles, it helps remember the current reading progress.
  4. // @version      1.0
  5. // @author       Rui LIU (@liurui39660)
  6. // @match        *://*/*
  7. // @icon         https://icons.duckduckgo.com/ip2/example.com.ico
  8. // @run-at       document-body
  9. // @namespace https://greasyfork.org/users/193469
  10. // ==/UserScript==
  11.  
  12. (function () {
  13. 	'use strict';
  14.  
  15. 	const height = 2; // px, height of the visible line
  16. 	const padding = 2; // px, additional draggable area above and below the line, not the sum of them
  17. 	const color = 'red'; // or #-string
  18.  
  19. 	const initPos = -padding - height / 2;
  20. 	const body = document.getElementsByTagName('body')[0];
  21. 	const line = document.createElement('div');
  22. 	line.textContent = '#DraggableReferenceLine';
  23. 	line.style = `margin: 0; padding: ${padding}px 0; cursor: n-resize; font-size: 0; color: #fff0; background: ${color}; background-clip: content-box; width: 100vw; height: ${height}px; position: absolute; top: ${localStorage[`DraggableLine_${window.location.pathname}${window.location.search}`] || initPos}px; z-index: 10;`;
  24.  
  25. 	const reset = () => {
  26. 		line.style.top = `${initPos}px`;
  27. 		localStorage.removeItem(`DraggableLine_${window.location.pathname}${window.location.search}`);
  28. 	}
  29. 	const set = top => {
  30. 		line.style.top = `${top}px`;
  31. 		localStorage[`DraggableLine_${window.location.pathname}${window.location.search}`] = top;
  32. 	}
  33. 	let callbackMouseMove = ev => {
  34. 		line.style.top = `${ev.pageY + initPos}px`; // initPos is also the offset to line center
  35. 	};
  36. 	let callbackMouseUp = ev => {
  37. 		if (ev.detail === 1) { // Don't overwrite dblclick
  38. 			body.releasePointerCapture(ev.pointerId);
  39. 			body.style.cursor = null;
  40. 			const top = parseFloat(line.style.top);
  41. 			top > initPos ? set(top) : reset();
  42. 			[onmouseup, onmousemove, callbackMouseUp, callbackMouseMove] = [callbackMouseUp, callbackMouseMove, onmouseup, onmousemove];
  43. 		}
  44. 	};
  45. 	line.addEventListener('mousedown', ev => {
  46. 		if (ev.detail === 1) {
  47. 			ev.preventDefault(); // Don't select text
  48. 			body.setPointerCapture(ev.pointerId); // The cursor won't change back to pointer when out of browser
  49. 			body.style.cursor = 'n-resize';
  50. 			[onmouseup, onmousemove, callbackMouseUp, callbackMouseMove] = [callbackMouseUp, callbackMouseMove, onmouseup, onmousemove];
  51. 		}
  52. 	});
  53. 	line.addEventListener('dblclick', reset);
  54. 	body.appendChild(line);
  55. })();