feat: 文字弹出

src/plugin/fx/pop.ts

@@ -0,0 +1,96 @@
+import { MotaOffscreenCanvas2D } from '@/core/fx/canvas2d';
+import { RenderItem, RenderItemPosition } from '@/core/render/item';
+import { Transform } from '@/core/render/transform';
+import { TimingFn } from 'mutate-animate';
+
+interface PopData {
+    cx: number;
+    cy: number;
+    path: TimingFn<2>;
+    text: string;
+    time: number;
+    start: number;
+    color: CanvasStyle;
+}
+
+function parabola(input: number): [number, number] {
+    const x = input * 100;
+    return [x, x ** 2 / 20 - 3 * x];
+}
+
+export class PopText extends RenderItem {
+    private popList: Set<PopData> = new Set();
+
+    private delegation: number = 0;
+
+    constructor(type: RenderItemPosition) {
+        super(type, false);
+        this.delegation = this.delegateTicker(() => {
+            if (this.popList.size > 0) this.update();
+        });
+    }
+
+    /**
+     * 添加一个弹出文字
+     * @param text 要显示的文字
+     * @param time 持续时长
+     * @param cx 中心点，也就是从哪弹出的
+     * @param cy 中心点，也就是从哪弹出的
+     * @param path 自定义路径，不填表示默认的抛物线路径
+     */
+    addPop(
+        text: string,
+        time: number,
+        cx: number,
+        cy: number,
+        color: CanvasStyle,
+        path?: TimingFn<2>
+    ) {
+        this.popList.add({
+            text,
+            time,
+            cx,
+            cy,
+            color,
+            path: path ?? parabola,
+            start: Date.now()
+        });
+        this.update();
+    }
+
+    protected render(
+        canvas: MotaOffscreenCanvas2D,
+        transform: Transform
+    ): void {
+        const ctx = canvas.ctx;
+        const toDelete = new Set<PopData>();
+        const now = Date.now();
+        ctx.strokeStyle = '#000';
+        ctx.font = '22px Verdana';
+        ctx.lineWidth = 3;
+        this.popList.forEach(v => {
+            const { cx, cy, path, text, color, time, start } = v;
+            const dt = now - start;
+            const progress = dt / time;
+            if (progress >= 1) {
+                toDelete.add(v);
+                return;
+            }
+            const [x, y] = path(progress);
+            const dx = cx + x;
+            const dy = cy + y;
+            ctx.globalAlpha = Math.min(1, 2 - progress * 2);
+            ctx.fillStyle = color;
+            ctx.strokeText(text, dx, dy);
+            ctx.fillText(text, dx, dy);
+        });
+        toDelete.forEach(v => {
+            this.popList.delete(v);
+        });
+    }
+
+    destroy(): void {
+        super.destroy();
+        this.removeTicker(this.delegation);
+    }
+}