Using Observable for software engineering, programming language and user interface research.
Public
Edited
Dec 16, 2022
Importers
dallE20221210204519MouseCursorsFollowingCurvesOnAW = FileAttachment("DALL·E 2022-12-10 20.45.19 - mouse cursors following curves on a white background.png").image()
Drag = (callback) => {
const reset = {
event: null,
xo: 0,
yo: 0,
x: 0,
y: 0,
dx: 0,
dy: 0,
};
const context = { node: undefined };
const behaviour = {
context,
on: node => {
context.node = node;
on(node, behaviour.start);
return behaviour;
},
off: node => {
context.node = undefined;
off(node, behaviour.start);
off(node, behaviour.drag);
return behaviour;
},
start: {
mousedown: event => {
Object.assign(context, reset);
off(context.node, behaviour["start"]);
context.xo = event.pageX;
context.yo = event.pageY;
callback && callback(event, context, "dragstart");
on(context.overlay||window.document.body, behaviour["drag"]);
}
},
drag: {
mousemove: event => {
context.x = event.pageX;
context.y = event.pageY;
context.dx = context.x - context.xo;
context.dy = context.y - context.yo;
callback && callback(event, context, "drag");
},
mouseup: event => {
callback && callback(event, context, "dragend");
off(context.overlay||window.document.body, behaviour["drag"]);
on(context.node, behaviour["start"]);
}
}
};
return behaviour;
}
draggable = (node, callback) => {
Drag(callback).on(node);
return node
}
draggable(html.div({style:"position:relative;width:100px;height:100px;background:red;"}), (event,_,state)=>{
switch (state) {
case "dragend":
_.node.style.cursor = "default";
_.node.style.left = null;
_.node.style.top = null;
_.node.style.zIndex = null;
break
default:
_.node.style.cursor = "move";
_.node.style.left = _.dx + "px";
_.node.style.top = _.dy + "px";
_.node.style.zIndex = 100;
}})
editable = (node, callback) => {
const absorb = _ => _.preventDefault()
const behaviour = {
}
node.setAttribute("contenteditable", true);
return on(node, behaviour)
}
editable(html.div({style:"position:relative;width:100px;border:1px solid blue;overflow-wrap: break-word;"}))
Type JavaScript, then Shift-Enter. Ctrl-space for more options. Arrow ↑/↓ to switch modes.
import {on,off,html,style,idem} from "@sebastien/boilerplate"
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