feat: Add fitToContent and animate to scrollToContent (#6319)

Co-authored-by: Brice Leroy <brice@brigalabs.com>
Co-authored-by: dwelle <luzar.david@gmail.com>

src/tests/fitToContent.test.tsx

@@ -0,0 +1,189 @@
+import { render } from "./test-utils";
+import { API } from "./helpers/api";
+
+import ExcalidrawApp from "../excalidraw-app";
+
+const { h } = window;
+
+describe("fitToContent", () => {
+  it("should zoom to fit the selected element", async () => {
+    await render(<ExcalidrawApp />);
+
+    h.state.width = 10;
+    h.state.height = 10;
+
+    const rectElement = API.createElement({
+      width: 50,
+      height: 100,
+      x: 50,
+      y: 100,
+    });
+
+    expect(h.state.zoom.value).toBe(1);
+
+    h.app.scrollToContent(rectElement, { fitToContent: true });
+
+    // element is 10x taller than the viewport size,
+    // zoom should be at least 1/10
+    expect(h.state.zoom.value).toBeLessThanOrEqual(0.1);
+  });
+
+  it("should zoom to fit multiple elements", async () => {
+    await render(<ExcalidrawApp />);
+
+    const topLeft = API.createElement({
+      width: 20,
+      height: 20,
+      x: 0,
+      y: 0,
+    });
+
+    const bottomRight = API.createElement({
+      width: 20,
+      height: 20,
+      x: 80,
+      y: 80,
+    });
+
+    h.state.width = 10;
+    h.state.height = 10;
+
+    expect(h.state.zoom.value).toBe(1);
+
+    h.app.scrollToContent([topLeft, bottomRight], {
+      fitToContent: true,
+    });
+
+    // elements take 100x100, which is 10x bigger than the viewport size,
+    // zoom should be at least 1/10
+    expect(h.state.zoom.value).toBeLessThanOrEqual(0.1);
+  });
+
+  it("should scroll the viewport to the selected element", async () => {
+    await render(<ExcalidrawApp />);
+
+    h.state.width = 10;
+    h.state.height = 10;
+
+    const rectElement = API.createElement({
+      width: 100,
+      height: 100,
+      x: 100,
+      y: 100,
+    });
+
+    expect(h.state.zoom.value).toBe(1);
+    expect(h.state.scrollX).toBe(0);
+    expect(h.state.scrollY).toBe(0);
+
+    h.app.scrollToContent(rectElement);
+
+    // zoom level should stay the same
+    expect(h.state.zoom.value).toBe(1);
+
+    // state should reflect some scrolling
+    expect(h.state.scrollX).not.toBe(0);
+    expect(h.state.scrollY).not.toBe(0);
+  });
+});
+
+const waitForNextAnimationFrame = () => {
+  return new Promise((resolve) => {
+    requestAnimationFrame(() => {
+      requestAnimationFrame(resolve);
+    });
+  });
+};
+
+describe("fitToContent animated", () => {
+  beforeEach(() => {
+    jest.spyOn(window, "requestAnimationFrame");
+  });
+
+  afterEach(() => {
+    jest.restoreAllMocks();
+  });
+
+  it("should ease scroll the viewport to the selected element", async () => {
+    await render(<ExcalidrawApp />);
+
+    h.state.width = 10;
+    h.state.height = 10;
+
+    const rectElement = API.createElement({
+      width: 100,
+      height: 100,
+      x: -100,
+      y: -100,
+    });
+
+    h.app.scrollToContent(rectElement, { animate: true });
+
+    expect(window.requestAnimationFrame).toHaveBeenCalled();
+
+    // Since this is an animation, we expect values to change through time.
+    // We'll verify that the scroll values change at 50ms and 100ms
+    expect(h.state.scrollX).toBe(0);
+    expect(h.state.scrollY).toBe(0);
+
+    await waitForNextAnimationFrame();
+
+    const prevScrollX = h.state.scrollX;
+    const prevScrollY = h.state.scrollY;
+
+    expect(h.state.scrollX).not.toBe(0);
+    expect(h.state.scrollY).not.toBe(0);
+
+    await waitForNextAnimationFrame();
+
+    expect(h.state.scrollX).not.toBe(prevScrollX);
+    expect(h.state.scrollY).not.toBe(prevScrollY);
+  });
+
+  it("should animate the scroll but not the zoom", async () => {
+    await render(<ExcalidrawApp />);
+
+    h.state.width = 50;
+    h.state.height = 50;
+
+    const rectElement = API.createElement({
+      width: 100,
+      height: 100,
+      x: 100,
+      y: 100,
+    });
+
+    expect(h.state.scrollX).toBe(0);
+    expect(h.state.scrollY).toBe(0);
+
+    h.app.scrollToContent(rectElement, { animate: true, fitToContent: true });
+
+    expect(window.requestAnimationFrame).toHaveBeenCalled();
+
+    // Since this is an animation, we expect values to change through time.
+    // We'll verify that the zoom/scroll values change in each animation frame
+
+    // zoom is not animated, it should be set to its final value, which in our
+    // case zooms out to 50% so that th element is fully visible (it's 2x large
+    // as the canvas)
+    expect(h.state.zoom.value).toBeLessThanOrEqual(0.5);
+
+    // FIXME I think this should be [-100, -100] so we may have a bug in our zoom
+    // hadnling, alas
+    expect(h.state.scrollX).toBe(25);
+    expect(h.state.scrollY).toBe(25);
+
+    await waitForNextAnimationFrame();
+
+    const prevScrollX = h.state.scrollX;
+    const prevScrollY = h.state.scrollY;
+
+    expect(h.state.scrollX).not.toBe(0);
+    expect(h.state.scrollY).not.toBe(0);
+
+    await waitForNextAnimationFrame();
+
+    expect(h.state.scrollX).not.toBe(prevScrollX);
+    expect(h.state.scrollY).not.toBe(prevScrollY);
+  });
+});