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|
"use client";
import { useRef, useState, type PointerEvent } from "react";
import { useShiftKey } from "@/hooks/use-shift-key";
import { getBezierPoint } from "@/animation/bezier";
import type { NormalizedCubicBezier } from "@/animation/types";
import { cn } from "@/utils/ui";
const GRAPH_WIDTH = 140;
const GRAPH_HEIGHT = 94;
const GRAPH_PADDING = 12;
const SVG_WIDTH = GRAPH_WIDTH + GRAPH_PADDING * 2;
const SVG_HEIGHT = GRAPH_HEIGHT + GRAPH_PADDING * 2;
const HANDLE_RADIUS = 3.5;
const ENDPOINT_RADIUS = 2;
const SNAP_THRESHOLD = 0.06;
const SNAP_TARGETS = [0, 1];
const CURVE_SEGMENTS = 64;
const Y_CLAMP_MIN = -0.5;
const Y_CLAMP_MAX = 1.5;
type BezierHandle = "c1" | "c2";
export const BEZIER_GRAPH_MIN_HEIGHT = SVG_HEIGHT;
function snap({
value,
targets,
isEnabled,
}: {
value: number;
targets: number[];
isEnabled: boolean;
}) {
if (!isEnabled) return value;
for (const target of targets) {
if (Math.abs(value - target) < SNAP_THRESHOLD) return target;
}
return value;
}
function toSvgX({ value }: { value: number }) {
return GRAPH_PADDING + value * GRAPH_WIDTH;
}
function toSvgY({ value }: { value: number }) {
return GRAPH_PADDING + (1 - value) * GRAPH_HEIGHT;
}
function fromSvgX({ svgX }: { svgX: number }) {
return Math.max(0, Math.min(1, (svgX - GRAPH_PADDING) / GRAPH_WIDTH));
}
function fromSvgY({ svgY }: { svgY: number }) {
return Math.max(
Y_CLAMP_MIN,
Math.min(Y_CLAMP_MAX, 1 - (svgY - GRAPH_PADDING) / GRAPH_HEIGHT),
);
}
function curvePath({ curve }: { curve: NormalizedCubicBezier }) {
const points: string[] = [];
for (let i = 0; i <= CURVE_SEGMENTS; i++) {
const progress = i / CURVE_SEGMENTS;
const x = toSvgX({ value: getBezierPoint({ progress, p0: 0, p1: curve[0], p2: curve[2], p3: 1 }) });
const y = toSvgY({ value: getBezierPoint({ progress, p0: 0, p1: curve[1], p2: curve[3], p3: 1 }) });
points.push(`${x},${y}`);
}
return `M${points.join("L")}`;
}
function clampHandleY({ svgY }: { svgY: number }) {
return Math.max(HANDLE_RADIUS, Math.min(SVG_HEIGHT - HANDLE_RADIUS, svgY));
}
export function BezierGraph({
value,
onChange,
onChangeEnd,
onCancel,
}: {
value: NormalizedCubicBezier;
onChange?: (value: NormalizedCubicBezier) => void;
onChangeEnd?: (value: NormalizedCubicBezier) => void;
onCancel?: () => void;
}) {
const svgRef = useRef<SVGSVGElement>(null);
const [activeHandle, setActiveHandle] = useState<BezierHandle | null>(null);
const isShiftPressedRef = useShiftKey();
const latestValueRef = useRef(value);
latestValueRef.current = value;
function getPointerPosition({
event,
}: {
event: PointerEvent;
}): { x: number; y: number } {
const svg = svgRef.current;
if (!svg) return { x: 0, y: 0 };
const rect = svg.getBoundingClientRect();
const scale = SVG_WIDTH / rect.width;
return {
x: (event.clientX - rect.left) * scale,
y: (event.clientY - rect.top) * (SVG_HEIGHT / rect.height),
};
}
function onHandlePointerDown({ handle }: { handle: BezierHandle }) {
return (event: PointerEvent<SVGCircleElement>) => {
event.preventDefault();
event.stopPropagation();
setActiveHandle(handle);
event.currentTarget.setPointerCapture(event.pointerId);
};
}
function onPointerMove({ event }: { event: PointerEvent<SVGSVGElement> }) {
if (!activeHandle) return;
const pointerPos = getPointerPosition({ event });
const x = fromSvgX({ svgX: pointerPos.x });
const y = snap({
value: fromSvgY({ svgY: pointerPos.y }),
targets: SNAP_TARGETS,
isEnabled: !isShiftPressedRef.current,
});
const next: NormalizedCubicBezier = [...value];
if (activeHandle === "c1") {
next[0] = x;
next[1] = y;
} else {
next[2] = x;
next[3] = y;
}
latestValueRef.current = next;
onChange?.(next);
}
function onPointerUp() {
if (!activeHandle) return;
setActiveHandle(null);
onChangeEnd?.(latestValueRef.current);
}
function onPointerCancel() {
if (!activeHandle) return;
setActiveHandle(null);
onCancel?.();
}
const path = curvePath({ curve: value });
const c1 = { x: toSvgX({ value: value[0] }), y: toSvgY({ value: value[1] }) };
const c2 = { x: toSvgX({ value: value[2] }), y: toSvgY({ value: value[3] }) };
const c1Clamped = { x: c1.x, y: clampHandleY({ svgY: c1.y }) };
const c2Clamped = { x: c2.x, y: clampHandleY({ svgY: c2.y }) };
const p0 = { x: toSvgX({ value: 0 }), y: toSvgY({ value: 0 }) };
const p1 = { x: toSvgX({ value: 1 }), y: toSvgY({ value: 1 }) };
return (
<svg
ref={svgRef}
viewBox={`0 0 ${SVG_WIDTH} ${SVG_HEIGHT}`}
className="bg-foreground/3 w-full cursor-crosshair select-none"
onPointerMove={(event) => onPointerMove({ event })}
onPointerUp={onPointerUp}
onPointerCancel={onPointerCancel}
>
<title>Bezier curve editor</title>
<line
x1={p0.x}
y1={p0.y}
x2={p1.x}
y2={p1.y}
className="stroke-foreground/8"
strokeWidth={1}
strokeDasharray="3 3"
/>
<line
x1={p0.x}
y1={p0.y}
x2={c1Clamped.x}
y2={c1Clamped.y}
className="stroke-primary/30"
strokeWidth={1}
/>
<line
x1={p1.x}
y1={p1.y}
x2={c2Clamped.x}
y2={c2Clamped.y}
className="stroke-primary/30"
strokeWidth={1}
/>
<path
d={path}
fill="none"
className="stroke-primary"
strokeWidth={2}
strokeLinecap="round"
/>
<circle
cx={p0.x}
cy={p0.y}
r={ENDPOINT_RADIUS}
className="fill-foreground/20"
/>
<circle
cx={p1.x}
cy={p1.y}
r={ENDPOINT_RADIUS}
className="fill-foreground/20"
/>
<circle
cx={c1Clamped.x}
cy={c1Clamped.y}
r={HANDLE_RADIUS}
className={cn(
"fill-primary cursor-grab",
activeHandle === "c1" && "cursor-grabbing",
)}
onPointerDown={onHandlePointerDown({ handle: "c1" })}
/>
<circle
cx={c2Clamped.x}
cy={c2Clamped.y}
r={HANDLE_RADIUS}
className={cn(
"fill-primary cursor-grab",
activeHandle === "c2" && "cursor-grabbing",
)}
onPointerDown={onHandlePointerDown({ handle: "c2" })}
/>
</svg>
);
}
|
