Merge branch 'master' of github.com:excalidraw/excalibur

.gitignore

@@ -17,3 +17,4 @@ yarn.lock
 # Editors
 .vscode/
 
+.DS_Store

src/components/ButtonSelect.tsx

@@ -0,0 +1,25 @@
+import React from "react";
+
+export function ButtonSelect<T>({
+  options,
+  value,
+  onChange
+}: {
+  options: { value: T; text: string }[];
+  value: T | null;
+  onChange: (value: T) => void;
+}) {
+  return (
+    <div className="buttonList">
+      {options.map(option => (
+        <button
+          key={option.text}
+          onClick={() => onChange(option.value)}
+          className={value === option.value ? "active" : ""}
+        >
+          {option.text}
+        </button>
+      ))}
+    </div>
+  );
+}

src/components/ColorPicker.tsx

@@ -0,0 +1,52 @@
+import React from "react";
+import { TwitterPicker } from "react-color";
+
+export function ColorPicker({
+  color,
+  onChange
+}: {
+  color: string | null;
+  onChange: (color: string) => void;
+}) {
+  const [isActive, setActive] = React.useState(false);
+  return (
+    <div>
+      <button
+        className="swatch"
+        style={color ? { backgroundColor: color } : undefined}
+        onClick={() => setActive(!isActive)}
+      />
+      {isActive ? (
+        <div className="popover">
+          <div className="cover" onClick={() => setActive(false)} />
+          <TwitterPicker
+            colors={[
+              "#000000",
+              "#ABB8C3",
+              "#FFFFFF",
+              "#FF6900",
+              "#FCB900",
+              "#00D084",
+              "#8ED1FC",
+              "#0693E3",
+              "#EB144C",
+              "#F78DA7",
+              "#9900EF"
+            ]}
+            width="205px"
+            color={color || undefined}
+            onChange={changedColor => {
+              onChange(changedColor.hex);
+            }}
+          />
+        </div>
+      ) : null}
+      <input
+        type="text"
+        className="swatch-input"
+        value={color || ""}
+        onChange={e => onChange(e.target.value)}
+      />
+    </div>
+  );
+}

src/components/EditableText.tsx

@@ -10,7 +10,7 @@ type Props = {
   onChange: (value: string) => void;
 };
 
-export default class EditableText extends Component<Props, InputState> {
+export class EditableText extends Component<Props, InputState> {
   constructor(props: Props) {
     super(props);
 

src/element/bounds.ts

@@ -0,0 +1,52 @@
+import { ExcalidrawElement } from "./types";
+import { rotate } from "../math";
+
+// If the element is created from right to left, the width is going to be negative
+// This set of functions retrieves the absolute position of the 4 points.
+// We can't just always normalize it since we need to remember the fact that an arrow
+// is pointing left or right.
+export function getElementAbsoluteX1(element: ExcalidrawElement) {
+  return element.width >= 0 ? element.x : element.x + element.width;
+}
+export function getElementAbsoluteX2(element: ExcalidrawElement) {
+  return element.width >= 0 ? element.x + element.width : element.x;
+}
+export function getElementAbsoluteY1(element: ExcalidrawElement) {
+  return element.height >= 0 ? element.y : element.y + element.height;
+}
+export function getElementAbsoluteY2(element: ExcalidrawElement) {
+  return element.height >= 0 ? element.y + element.height : element.y;
+}
+
+export function getDiamondPoints(element: ExcalidrawElement) {
+  const topX = Math.floor(element.width / 2) + 1;
+  const topY = 0;
+  const rightX = element.width;
+  const rightY = Math.floor(element.height / 2) + 1;
+  const bottomX = topX;
+  const bottomY = element.height;
+  const leftX = topY;
+  const leftY = rightY;
+
+  return [topX, topY, rightX, rightY, bottomX, bottomY, leftX, leftY];
+}
+
+export function getArrowPoints(element: ExcalidrawElement) {
+  const x1 = 0;
+  const y1 = 0;
+  const x2 = element.width;
+  const y2 = element.height;
+
+  const size = 30; // pixels
+  const distance = Math.hypot(x2 - x1, y2 - y1);
+  // Scale down the arrow until we hit a certain size so that it doesn't look weird
+  const minSize = Math.min(size, distance / 2);
+  const xs = x2 - ((x2 - x1) / distance) * minSize;
+  const ys = y2 - ((y2 - y1) / distance) * minSize;
+
+  const angle = 20; // degrees
+  const [x3, y3] = rotate(xs, ys, x2, y2, (-angle * Math.PI) / 180);
+  const [x4, y4] = rotate(xs, ys, x2, y2, (angle * Math.PI) / 180);
+
+  return [x1, y1, x2, y2, x3, y3, x4, y4];
+}

src/element/collision.ts

@@ -0,0 +1,124 @@
+import { distanceBetweenPointAndSegment } from "../math";
+
+import { ExcalidrawElement } from "./types";
+import {
+  getElementAbsoluteX1,
+  getElementAbsoluteX2,
+  getElementAbsoluteY1,
+  getElementAbsoluteY2,
+  getArrowPoints,
+  getDiamondPoints
+} from "./bounds";
+
+export function hitTest(
+  element: ExcalidrawElement,
+  x: number,
+  y: number
+): boolean {
+  // For shapes that are composed of lines, we only enable point-selection when the distance
+  // of the click is less than x pixels of any of the lines that the shape is composed of
+  const lineThreshold = 10;
+
+  if (element.type === "ellipse") {
+    // https://stackoverflow.com/a/46007540/232122
+    const px = Math.abs(x - element.x - element.width / 2);
+    const py = Math.abs(y - element.y - element.height / 2);
+
+    let tx = 0.707;
+    let ty = 0.707;
+
+    const a = Math.abs(element.width) / 2;
+    const b = Math.abs(element.height) / 2;
+
+    [0, 1, 2, 3].forEach(x => {
+      const xx = a * tx;
+      const yy = b * ty;
+
+      const ex = ((a * a - b * b) * tx ** 3) / a;
+      const ey = ((b * b - a * a) * ty ** 3) / b;
+
+      const rx = xx - ex;
+      const ry = yy - ey;
+
+      const qx = px - ex;
+      const qy = py - ey;
+
+      const r = Math.hypot(ry, rx);
+      const q = Math.hypot(qy, qx);
+
+      tx = Math.min(1, Math.max(0, ((qx * r) / q + ex) / a));
+      ty = Math.min(1, Math.max(0, ((qy * r) / q + ey) / b));
+      const t = Math.hypot(ty, tx);
+      tx /= t;
+      ty /= t;
+    });
+
+    return Math.hypot(a * tx - px, b * ty - py) < lineThreshold;
+  } else if (element.type === "rectangle") {
+    const x1 = getElementAbsoluteX1(element);
+    const x2 = getElementAbsoluteX2(element);
+    const y1 = getElementAbsoluteY1(element);
+    const y2 = getElementAbsoluteY2(element);
+
+    // (x1, y1) --A-- (x2, y1)
+    //    |D             |B
+    // (x1, y2) --C-- (x2, y2)
+    return (
+      distanceBetweenPointAndSegment(x, y, x1, y1, x2, y1) < lineThreshold || // A
+      distanceBetweenPointAndSegment(x, y, x2, y1, x2, y2) < lineThreshold || // B
+      distanceBetweenPointAndSegment(x, y, x2, y2, x1, y2) < lineThreshold || // C
+      distanceBetweenPointAndSegment(x, y, x1, y2, x1, y1) < lineThreshold // D
+    );
+  } else if (element.type === "diamond") {
+    x -= element.x;
+    y -= element.y;
+
+    const [
+      topX,
+      topY,
+      rightX,
+      rightY,
+      bottomX,
+      bottomY,
+      leftX,
+      leftY
+    ] = getDiamondPoints(element);
+
+    return (
+      distanceBetweenPointAndSegment(x, y, topX, topY, rightX, rightY) <
+        lineThreshold ||
+      distanceBetweenPointAndSegment(x, y, rightX, rightY, bottomX, bottomY) <
+        lineThreshold ||
+      distanceBetweenPointAndSegment(x, y, bottomX, bottomY, leftX, leftY) <
+        lineThreshold ||
+      distanceBetweenPointAndSegment(x, y, leftX, leftY, topX, topY) <
+        lineThreshold
+    );
+  } else if (element.type === "arrow") {
+    let [x1, y1, x2, y2, x3, y3, x4, y4] = getArrowPoints(element);
+    // The computation is done at the origin, we need to add a translation
+    x -= element.x;
+    y -= element.y;
+
+    return (
+      //    \
+      distanceBetweenPointAndSegment(x, y, x3, y3, x2, y2) < lineThreshold ||
+      // -----
+      distanceBetweenPointAndSegment(x, y, x1, y1, x2, y2) < lineThreshold ||
+      //    /
+      distanceBetweenPointAndSegment(x, y, x4, y4, x2, y2) < lineThreshold
+    );
+  } else if (element.type === "text") {
+    const x1 = getElementAbsoluteX1(element);
+    const x2 = getElementAbsoluteX2(element);
+    const y1 = getElementAbsoluteY1(element);
+    const y2 = getElementAbsoluteY2(element);
+
+    return x >= x1 && x <= x2 && y >= y1 && y <= y2;
+  } else if (element.type === "selection") {
+    console.warn("This should not happen, we need to investigate why it does.");
+    return false;
+  } else {
+    throw new Error("Unimplemented type " + element.type);
+  }
+}

src/element/generateDraw.ts

@@ -0,0 +1,145 @@
+import rough from "roughjs/bin/wrappers/rough";
+
+import { withCustomMathRandom } from "../random";
+
+import { ExcalidrawElement } from "./types";
+import { isTextElement } from "./typeChecks";
+import { getDiamondPoints, getArrowPoints } from "./bounds";
+
+// Casting second argument (DrawingSurface) to any,
+// because it is requred by TS definitions and not required at runtime
+const generator = rough.generator(null, null as any);
+
+export function generateDraw(element: ExcalidrawElement) {
+  if (element.type === "selection") {
+    element.draw = (rc, context, { scrollX, scrollY }) => {
+      const fillStyle = context.fillStyle;
+      context.fillStyle = "rgba(0, 0, 255, 0.10)";
+      context.fillRect(
+        element.x + scrollX,
+        element.y + scrollY,
+        element.width,
+        element.height
+      );
+      context.fillStyle = fillStyle;
+    };
+  } else if (element.type === "rectangle") {
+    const shape = withCustomMathRandom(element.seed, () => {
+      return generator.rectangle(0, 0, element.width, element.height, {
+        stroke: element.strokeColor,
+        fill: element.backgroundColor,
+        fillStyle: element.fillStyle,
+        strokeWidth: element.strokeWidth,
+        roughness: element.roughness
+      });
+    });
+    element.draw = (rc, context, { scrollX, scrollY }) => {
+      context.globalAlpha = element.opacity / 100;
+      context.translate(element.x + scrollX, element.y + scrollY);
+      rc.draw(shape);
+      context.translate(-element.x - scrollX, -element.y - scrollY);
+      context.globalAlpha = 1;
+    };
+  } else if (element.type === "diamond") {
+    const shape = withCustomMathRandom(element.seed, () => {
+      const [
+        topX,
+        topY,
+        rightX,
+        rightY,
+        bottomX,
+        bottomY,
+        leftX,
+        leftY
+      ] = getDiamondPoints(element);
+      return generator.polygon(
+        [
+          [topX, topY],
+          [rightX, rightY],
+          [bottomX, bottomY],
+          [leftX, leftY]
+        ],
+        {
+          stroke: element.strokeColor,
+          fill: element.backgroundColor,
+          fillStyle: element.fillStyle,
+          strokeWidth: element.strokeWidth,
+          roughness: element.roughness
+        }
+      );
+    });
+    element.draw = (rc, context, { scrollX, scrollY }) => {
+      context.globalAlpha = element.opacity / 100;
+      context.translate(element.x + scrollX, element.y + scrollY);
+      rc.draw(shape);
+      context.translate(-element.x - scrollX, -element.y - scrollY);
+      context.globalAlpha = 1;
+    };
+  } else if (element.type === "ellipse") {
+    const shape = withCustomMathRandom(element.seed, () =>
+      generator.ellipse(
+        element.width / 2,
+        element.height / 2,
+        element.width,
+        element.height,
+        {
+          stroke: element.strokeColor,
+          fill: element.backgroundColor,
+          fillStyle: element.fillStyle,
+          strokeWidth: element.strokeWidth,
+          roughness: element.roughness
+        }
+      )
+    );
+    element.draw = (rc, context, { scrollX, scrollY }) => {
+      context.globalAlpha = element.opacity / 100;
+      context.translate(element.x + scrollX, element.y + scrollY);
+      rc.draw(shape);
+      context.translate(-element.x - scrollX, -element.y - scrollY);
+      context.globalAlpha = 1;
+    };
+  } else if (element.type === "arrow") {
+    const [x1, y1, x2, y2, x3, y3, x4, y4] = getArrowPoints(element);
+    const options = {
+      stroke: element.strokeColor,
+      strokeWidth: element.strokeWidth,
+      roughness: element.roughness
+    };
+
+    const shapes = withCustomMathRandom(element.seed, () => [
+      //    \
+      generator.line(x3, y3, x2, y2, options),
+      // -----
+      generator.line(x1, y1, x2, y2, options),
+      //    /
+      generator.line(x4, y4, x2, y2, options)
+    ]);
+
+    element.draw = (rc, context, { scrollX, scrollY }) => {
+      context.globalAlpha = element.opacity / 100;
+      context.translate(element.x + scrollX, element.y + scrollY);
+      shapes.forEach(shape => rc.draw(shape));
+      context.translate(-element.x - scrollX, -element.y - scrollY);
+      context.globalAlpha = 1;
+    };
+    return;
+  } else if (isTextElement(element)) {
+    element.draw = (rc, context, { scrollX, scrollY }) => {
+      context.globalAlpha = element.opacity / 100;
+      const font = context.font;
+      context.font = element.font;
+      const fillStyle = context.fillStyle;
+      context.fillStyle = element.strokeColor;
+      context.fillText(
+        element.text,
+        element.x + scrollX,
+        element.y + element.actualBoundingBoxAscent + scrollY
+      );
+      context.fillStyle = fillStyle;
+      context.font = font;
+      context.globalAlpha = 1;
+    };
+  } else {
+    throw new Error("Unimplemented type " + element.type);
+  }
+}

src/element/handlerRectangles.ts

@@ -0,0 +1,85 @@
+import { SceneState } from "../scene/types";
+import { ExcalidrawElement } from "./types";
+
+export function handlerRectangles(
+  element: ExcalidrawElement,
+  sceneState: SceneState
+) {
+  const elementX1 = element.x;
+  const elementX2 = element.x + element.width;
+  const elementY1 = element.y;
+  const elementY2 = element.y + element.height;
+
+  const margin = 4;
+  const minimumSize = 40;
+  const handlers: { [handler: string]: number[] } = {};
+
+  const marginX = element.width < 0 ? 8 : -8;
+  const marginY = element.height < 0 ? 8 : -8;
+
+  if (Math.abs(elementX2 - elementX1) > minimumSize) {
+    handlers["n"] = [
+      elementX1 + (elementX2 - elementX1) / 2 + sceneState.scrollX - 4,
+      elementY1 - margin + sceneState.scrollY + marginY,
+      8,
+      8
+    ];
+
+    handlers["s"] = [
+      elementX1 + (elementX2 - elementX1) / 2 + sceneState.scrollX - 4,
+      elementY2 - margin + sceneState.scrollY - marginY,
+      8,
+      8
+    ];
+  }
+
+  if (Math.abs(elementY2 - elementY1) > minimumSize) {
+    handlers["w"] = [
+      elementX1 - margin + sceneState.scrollX + marginX,
+      elementY1 + (elementY2 - elementY1) / 2 + sceneState.scrollY - 4,
+      8,
+      8
+    ];
+
+    handlers["e"] = [
+      elementX2 - margin + sceneState.scrollX - marginX,
+      elementY1 + (elementY2 - elementY1) / 2 + sceneState.scrollY - 4,
+      8,
+      8
+    ];
+  }
+
+  handlers["nw"] = [
+    elementX1 - margin + sceneState.scrollX + marginX,
+    elementY1 - margin + sceneState.scrollY + marginY,
+    8,
+    8
+  ]; // nw
+  handlers["ne"] = [
+    elementX2 - margin + sceneState.scrollX - marginX,
+    elementY1 - margin + sceneState.scrollY + marginY,
+    8,
+    8
+  ]; // ne
+  handlers["sw"] = [
+    elementX1 - margin + sceneState.scrollX + marginX,
+    elementY2 - margin + sceneState.scrollY - marginY,
+    8,
+    8
+  ]; // sw
+  handlers["se"] = [
+    elementX2 - margin + sceneState.scrollX - marginX,
+    elementY2 - margin + sceneState.scrollY - marginY,
+    8,
+    8
+  ]; // se
+
+  if (element.type === "arrow") {
+    return {
+      nw: handlers.nw,
+      se: handlers.se
+    };
+  }
+
+  return handlers;
+}

src/element/index.ts

@@ -0,0 +1,15 @@
+export { newElement } from "./newElement";
+export {
+  getElementAbsoluteX1,
+  getElementAbsoluteX2,
+  getElementAbsoluteY1,
+  getElementAbsoluteY2,
+  getDiamondPoints,
+  getArrowPoints
+} from "./bounds";
+
+export { handlerRectangles } from "./handlerRectangles";
+export { hitTest } from "./collision";
+export { resizeTest } from "./resizeTest";
+export { generateDraw } from "./generateDraw";
+export { isTextElement } from "./typeChecks";

src/element/newElement.ts

@@ -0,0 +1,40 @@
+import { RoughCanvas } from "roughjs/bin/canvas";
+
+import { SceneState } from "../scene/types";
+import { randomSeed } from "../random";
+
+export function newElement(
+  type: string,
+  x: number,
+  y: number,
+  strokeColor: string,
+  backgroundColor: string,
+  fillStyle: string,
+  strokeWidth: number,
+  roughness: number,
+  opacity: number,
+  width = 0,
+  height = 0
+) {
+  const element = {
+    type: type,
+    x: x,
+    y: y,
+    width: width,
+    height: height,
+    isSelected: false,
+    strokeColor: strokeColor,
+    backgroundColor: backgroundColor,
+    fillStyle: fillStyle,
+    strokeWidth: strokeWidth,
+    roughness: roughness,
+    opacity: opacity,
+    seed: randomSeed(),
+    draw(
+      rc: RoughCanvas,
+      context: CanvasRenderingContext2D,
+      sceneState: SceneState
+    ) {}
+  };
+  return element;
+}

src/element/resizeTest.ts

@@ -0,0 +1,32 @@
+import { ExcalidrawElement } from "./types";
+import { SceneState } from "../scene/types";
+
+import { handlerRectangles } from "./handlerRectangles";
+
+export function resizeTest(
+  element: ExcalidrawElement,
+  x: number,
+  y: number,
+  sceneState: SceneState
+): string | false {
+  if (element.type === "text") return false;
+
+  const handlers = handlerRectangles(element, sceneState);
+
+  const filter = Object.keys(handlers).filter(key => {
+    const handler = handlers[key];
+
+    return (
+      x + sceneState.scrollX >= handler[0] &&
+      x + sceneState.scrollX <= handler[0] + handler[2] &&
+      y + sceneState.scrollY >= handler[1] &&
+      y + sceneState.scrollY <= handler[1] + handler[3]
+    );
+  });
+
+  if (filter.length > 0) {
+    return filter[0];
+  }
+
+  return false;
+}

src/element/typeChecks.ts

@@ -0,0 +1,7 @@
+import { ExcalidrawElement, ExcalidrawTextElement } from "./types";
+
+export function isTextElement(
+  element: ExcalidrawElement
+): element is ExcalidrawTextElement {
+  return element.type === "text";
+}

src/element/types.ts

@@ -0,0 +1,9 @@
+import { newElement } from "./newElement";
+
+export type ExcalidrawElement = ReturnType<typeof newElement>;
+export type ExcalidrawTextElement = ExcalidrawElement & {
+  type: "text";
+  font: string;
+  text: string;
+  actualBoundingBoxAscent: number;
+};

src/history.ts

@@ -0,0 +1,80 @@
+import { ExcalidrawElement } from "./element/types";
+import { generateDraw } from "./element";
+
+class SceneHistory {
+  private recording: boolean = true;
+  private stateHistory: string[] = [];
+  private redoStack: string[] = [];
+
+  generateCurrentEntry(elements: ExcalidrawElement[]) {
+    return JSON.stringify(
+      elements.map(element => ({ ...element, isSelected: false }))
+    );
+  }
+
+  pushEntry(newEntry: string) {
+    if (
+      this.stateHistory.length > 0 &&
+      this.stateHistory[this.stateHistory.length - 1] === newEntry
+    ) {
+      // If the last entry is the same as this one, ignore it
+      return;
+    }
+    this.stateHistory.push(newEntry);
+  }
+
+  restoreEntry(elements: ExcalidrawElement[], entry: string) {
+    const newElements = JSON.parse(entry);
+    elements.splice(0, elements.length);
+    newElements.forEach((newElement: ExcalidrawElement) => {
+      generateDraw(newElement);
+      elements.push(newElement);
+    });
+    // When restoring, we shouldn't add an history entry otherwise we'll be stuck with it and can't go back
+    this.skipRecording();
+  }
+
+  clearRedoStack() {
+    this.redoStack.splice(0, this.redoStack.length);
+  }
+
+  redoOnce(elements: ExcalidrawElement[]) {
+    const currentEntry = this.generateCurrentEntry(elements);
+    const entryToRestore = this.redoStack.pop();
+    if (entryToRestore !== undefined) {
+      this.restoreEntry(elements, entryToRestore);
+      this.stateHistory.push(currentEntry);
+    }
+  }
+
+  undoOnce(elements: ExcalidrawElement[]) {
+    const currentEntry = this.generateCurrentEntry(elements);
+    let entryToRestore = this.stateHistory.pop();
+
+    // If nothing was changed since last, take the previous one
+    if (currentEntry === entryToRestore) {
+      entryToRestore = this.stateHistory.pop();
+    }
+    if (entryToRestore !== undefined) {
+      this.restoreEntry(elements, entryToRestore);
+      this.redoStack.push(currentEntry);
+    }
+  }
+
+  isRecording() {
+    return this.recording;
+  }
+
+  skipRecording() {
+    this.recording = false;
+  }
+
+  resumeRecording() {
+    this.recording = true;
+  }
+}
+
+export const createHistory: () => { history: SceneHistory } = () => {
+  const history = new SceneHistory();
+  return { history };
+};

src/math.ts

@@ -36,3 +36,19 @@ export function distanceBetweenPointAndSegment(
   const dy = y - yy;
   return Math.hypot(dx, dy);
 }
+
+export function rotate(
+  x1: number,
+  y1: number,
+  x2: number,
+  y2: number,
+  angle: number
+) {
+  // 𝑎′𝑥=(𝑎𝑥−𝑐𝑥)cos𝜃−(𝑎𝑦−𝑐𝑦)sin𝜃+𝑐𝑥
+  // 𝑎′𝑦=(𝑎𝑥−𝑐𝑥)sin𝜃+(𝑎𝑦−𝑐𝑦)cos𝜃+𝑐𝑦.
+  // https://math.stackexchange.com/questions/2204520/how-do-i-rotate-a-line-segment-in-a-specific-point-on-the-line
+  return [
+    (x1 - x2) * Math.cos(angle) - (y1 - y2) * Math.sin(angle) + x2,
+    (x1 - x2) * Math.sin(angle) + (y1 - y2) * Math.cos(angle) + y2
+  ];
+}

src/scene/comparisons.ts

@@ -0,0 +1,38 @@
+import { ExcalidrawElement } from "../element/types";
+import { hitTest } from "../element/collision";
+
+export const hasBackground = (elements: ExcalidrawElement[]) =>
+  elements.some(
+    element =>
+      element.isSelected &&
+      (element.type === "rectangle" ||
+        element.type === "ellipse" ||
+        element.type === "diamond")
+  );
+
+export const hasStroke = (elements: ExcalidrawElement[]) =>
+  elements.some(
+    element =>
+      element.isSelected &&
+      (element.type === "rectangle" ||
+        element.type === "ellipse" ||
+        element.type === "diamond" ||
+        element.type === "arrow")
+  );
+
+export function getElementAtPosition(
+  elements: ExcalidrawElement[],
+  x: number,
+  y: number
+) {
+  let hitElement = null;
+  // We need to to hit testing from front (end of the array) to back (beginning of the array)
+  for (let i = elements.length - 1; i >= 0; --i) {
+    if (hitTest(elements[i], x, y)) {
+      hitElement = elements[i];
+      break;
+    }
+  }
+
+  return hitElement;
+}

src/scene/createScene.ts

@@ -0,0 +1,6 @@
+import { ExcalidrawElement } from "../element/types";
+
+export const createScene = () => {
+  const elements = Array.of<ExcalidrawElement>();
+  return { elements };
+};

src/scene/data.ts

@@ -0,0 +1,183 @@
+import rough from "roughjs/bin/wrappers/rough";
+
+import { ExcalidrawElement } from "../element/types";
+
+import {
+  getElementAbsoluteX1,
+  getElementAbsoluteX2,
+  getElementAbsoluteY1,
+  getElementAbsoluteY2,
+  generateDraw
+} from "../element";
+
+import { renderScene } from "./render";
+import { AppState } from "../types";
+
+const LOCAL_STORAGE_KEY = "excalidraw";
+const LOCAL_STORAGE_KEY_STATE = "excalidraw-state";
+
+function saveFile(name: string, data: string) {
+  // create a temporary <a> elem which we'll use to download the image
+  const link = document.createElement("a");
+  link.setAttribute("download", name);
+  link.setAttribute("href", data);
+  link.click();
+
+  // clean up
+  link.remove();
+}
+
+export function saveAsJSON(elements: ExcalidrawElement[], name: string) {
+  const serialized = JSON.stringify({
+    version: 1,
+    source: window.location.origin,
+    elements
+  });
+
+  saveFile(
+    `${name}.json`,
+    "data:text/plain;charset=utf-8," + encodeURIComponent(serialized)
+  );
+}
+
+export function loadFromJSON(elements: ExcalidrawElement[]) {
+  const input = document.createElement("input");
+  const reader = new FileReader();
+  input.type = "file";
+  input.accept = ".json";
+
+  input.onchange = () => {
+    if (!input.files!.length) {
+      alert("A file was not selected.");
+      return;
+    }
+
+    reader.readAsText(input.files![0], "utf8");
+  };
+
+  input.click();
+
+  return new Promise(resolve => {
+    reader.onloadend = () => {
+      if (reader.readyState === FileReader.DONE) {
+        const data = JSON.parse(reader.result as string);
+        restore(elements, data.elements, null);
+        resolve();
+      }
+    };
+  });
+}
+
+export function exportAsPNG(
+  elements: ExcalidrawElement[],
+  canvas: HTMLCanvasElement,
+  {
+    exportBackground,
+    exportPadding = 10,
+    viewBackgroundColor,
+    name
+  }: {
+    exportBackground: boolean;
+    exportPadding?: number;
+    viewBackgroundColor: string;
+    scrollX: number;
+    scrollY: number;
+    name: string;
+  }
+) {
+  if (!elements.length) return window.alert("Cannot export empty canvas.");
+  // calculate smallest area to fit the contents in
+
+  let subCanvasX1 = Infinity;
+  let subCanvasX2 = 0;
+  let subCanvasY1 = Infinity;
+  let subCanvasY2 = 0;
+
+  elements.forEach(element => {
+    subCanvasX1 = Math.min(subCanvasX1, getElementAbsoluteX1(element));
+    subCanvasX2 = Math.max(subCanvasX2, getElementAbsoluteX2(element));
+    subCanvasY1 = Math.min(subCanvasY1, getElementAbsoluteY1(element));
+    subCanvasY2 = Math.max(subCanvasY2, getElementAbsoluteY2(element));
+  });
+
+  function distance(x: number, y: number) {
+    return Math.abs(x > y ? x - y : y - x);
+  }
+
+  const tempCanvas = document.createElement("canvas");
+  tempCanvas.style.display = "none";
+  document.body.appendChild(tempCanvas);
+  tempCanvas.width = distance(subCanvasX1, subCanvasX2) + exportPadding * 2;
+  tempCanvas.height = distance(subCanvasY1, subCanvasY2) + exportPadding * 2;
+
+  renderScene(
+    elements,
+    rough.canvas(tempCanvas),
+    tempCanvas,
+    {
+      viewBackgroundColor: exportBackground ? viewBackgroundColor : null,
+      scrollX: 0,
+      scrollY: 0
+    },
+    {
+      offsetX: -subCanvasX1 + exportPadding,
+      offsetY: -subCanvasY1 + exportPadding,
+      renderScrollbars: false,
+      renderSelection: false
+    }
+  );
+
+  saveFile(`${name}.png`, tempCanvas.toDataURL("image/png"));
+
+  // clean up the DOM
+  if (tempCanvas !== canvas) tempCanvas.remove();
+}
+
+function restore(
+  elements: ExcalidrawElement[],
+  savedElements: string | ExcalidrawElement[] | null,
+  savedState: string | null
+) {
+  try {
+    if (savedElements) {
+      elements.splice(
+        0,
+        elements.length,
+        ...(typeof savedElements === "string"
+          ? JSON.parse(savedElements)
+          : savedElements)
+      );
+      elements.forEach((element: ExcalidrawElement) => {
+        element.fillStyle = element.fillStyle || "hachure";
+        element.strokeWidth = element.strokeWidth || 1;
+        element.roughness = element.roughness || 1;
+        element.opacity =
+          element.opacity === null || element.opacity === undefined
+            ? 100
+            : element.opacity;
+
+        generateDraw(element);
+      });
+    }
+
+    return savedState ? JSON.parse(savedState) : null;
+  } catch (e) {
+    elements.splice(0, elements.length);
+    return null;
+  }
+}
+
+export function restoreFromLocalStorage(elements: ExcalidrawElement[]) {
+  const savedElements = localStorage.getItem(LOCAL_STORAGE_KEY);
+  const savedState = localStorage.getItem(LOCAL_STORAGE_KEY_STATE);
+
+  return restore(elements, savedElements, savedState);
+}
+
+export function saveToLocalStorage(
+  elements: ExcalidrawElement[],
+  state: AppState
+) {
+  localStorage.setItem(LOCAL_STORAGE_KEY, JSON.stringify(elements));
+  localStorage.setItem(LOCAL_STORAGE_KEY_STATE, JSON.stringify(state));
+}

src/scene/index.ts

@@ -0,0 +1,19 @@
+export { isOverScrollBars } from "./scrollbars";
+export { renderScene } from "./render";
+export {
+  clearSelection,
+  getSelectedIndices,
+  deleteSelectedElements,
+  someElementIsSelected,
+  setSelection,
+  getSelectedAttribute
+} from "./selection";
+export {
+  exportAsPNG,
+  loadFromJSON,
+  saveAsJSON,
+  restoreFromLocalStorage,
+  saveToLocalStorage
+} from "./data";
+export { hasBackground, hasStroke, getElementAtPosition } from "./comparisons";
+export { createScene } from "./createScene";

src/scene/render.ts

@@ -0,0 +1,109 @@
+import { RoughCanvas } from "roughjs/bin/canvas";
+
+import { ExcalidrawElement } from "../element/types";
+import {
+  getElementAbsoluteX1,
+  getElementAbsoluteX2,
+  getElementAbsoluteY1,
+  getElementAbsoluteY2,
+  handlerRectangles
+} from "../element";
+
+import { roundRect } from "./roundRect";
+import { SceneState } from "./types";
+import { getScrollBars, SCROLLBAR_COLOR, SCROLLBAR_WIDTH } from "./scrollbars";
+import { getSelectedIndices } from "./selection";
+
+export function renderScene(
+  elements: ExcalidrawElement[],
+  rc: RoughCanvas,
+  canvas: HTMLCanvasElement,
+  sceneState: SceneState,
+  // extra options, currently passed by export helper
+  {
+    offsetX,
+    offsetY,
+    renderScrollbars = true,
+    renderSelection = true
+  }: {
+    offsetX?: number;
+    offsetY?: number;
+    renderScrollbars?: boolean;
+    renderSelection?: boolean;
+  } = {}
+) {
+  if (!canvas) return;
+  const context = canvas.getContext("2d")!;
+
+  const fillStyle = context.fillStyle;
+  if (typeof sceneState.viewBackgroundColor === "string") {
+    context.fillStyle = sceneState.viewBackgroundColor;
+    context.fillRect(0, 0, canvas.width, canvas.height);
+  } else {
+    context.clearRect(0, 0, canvas.width, canvas.height);
+  }
+  context.fillStyle = fillStyle;
+
+  const selectedIndices = getSelectedIndices(elements);
+
+  sceneState = {
+    ...sceneState,
+    scrollX: typeof offsetX === "number" ? offsetX : sceneState.scrollX,
+    scrollY: typeof offsetY === "number" ? offsetY : sceneState.scrollY
+  };
+
+  elements.forEach(element => {
+    element.draw(rc, context, sceneState);
+    if (renderSelection && element.isSelected) {
+      const margin = 4;
+
+      const elementX1 = getElementAbsoluteX1(element);
+      const elementX2 = getElementAbsoluteX2(element);
+      const elementY1 = getElementAbsoluteY1(element);
+      const elementY2 = getElementAbsoluteY2(element);
+      const lineDash = context.getLineDash();
+      context.setLineDash([8, 4]);
+      context.strokeRect(
+        elementX1 - margin + sceneState.scrollX,
+        elementY1 - margin + sceneState.scrollY,
+        elementX2 - elementX1 + margin * 2,
+        elementY2 - elementY1 + margin * 2
+      );
+      context.setLineDash(lineDash);
+
+      if (element.type !== "text" && selectedIndices.length === 1) {
+        const handlers = handlerRectangles(element, sceneState);
+        Object.values(handlers).forEach(handler => {
+          context.strokeRect(handler[0], handler[1], handler[2], handler[3]);
+        });
+      }
+    }
+  });
+
+  if (renderScrollbars) {
+    const scrollBars = getScrollBars(
+      elements,
+      context.canvas.width / window.devicePixelRatio,
+      context.canvas.height / window.devicePixelRatio,
+      sceneState.scrollX,
+      sceneState.scrollY
+    );
+
+    const strokeStyle = context.strokeStyle;
+    context.fillStyle = SCROLLBAR_COLOR;
+    context.strokeStyle = "rgba(255,255,255,0.8)";
+    [scrollBars.horizontal, scrollBars.vertical].forEach(scrollBar => {
+      if (scrollBar)
+        roundRect(
+          context,
+          scrollBar.x,
+          scrollBar.y,
+          scrollBar.width,
+          scrollBar.height,
+          SCROLLBAR_WIDTH / 2
+        );
+    });
+    context.strokeStyle = strokeStyle;
+    context.fillStyle = fillStyle;
+  }
+}

src/scene/scrollbars.ts

@@ -0,0 +1,115 @@
+import { ExcalidrawElement } from "../element/types";
+import {
+  getElementAbsoluteX1,
+  getElementAbsoluteX2,
+  getElementAbsoluteY1,
+  getElementAbsoluteY2
+} from "../element";
+
+const SCROLLBAR_MIN_SIZE = 15;
+const SCROLLBAR_MARGIN = 4;
+export const SCROLLBAR_WIDTH = 6;
+export const SCROLLBAR_COLOR = "rgba(0,0,0,0.3)";
+
+export function getScrollBars(
+  elements: ExcalidrawElement[],
+  canvasWidth: number,
+  canvasHeight: number,
+  scrollX: number,
+  scrollY: number
+) {
+  let minX = Infinity;
+  let maxX = 0;
+  let minY = Infinity;
+  let maxY = 0;
+
+  elements.forEach(element => {
+    minX = Math.min(minX, getElementAbsoluteX1(element));
+    maxX = Math.max(maxX, getElementAbsoluteX2(element));
+    minY = Math.min(minY, getElementAbsoluteY1(element));
+    maxY = Math.max(maxY, getElementAbsoluteY2(element));
+  });
+
+  minX += scrollX;
+  maxX += scrollX;
+  minY += scrollY;
+  maxY += scrollY;
+  const leftOverflow = Math.max(-minX, 0);
+  const rightOverflow = Math.max(-(canvasWidth - maxX), 0);
+  const topOverflow = Math.max(-minY, 0);
+  const bottomOverflow = Math.max(-(canvasHeight - maxY), 0);
+
+  // horizontal scrollbar
+  let horizontalScrollBar = null;
+  if (leftOverflow || rightOverflow) {
+    horizontalScrollBar = {
+      x: Math.min(
+        leftOverflow + SCROLLBAR_MARGIN,
+        canvasWidth - SCROLLBAR_MIN_SIZE - SCROLLBAR_MARGIN
+      ),
+      y: canvasHeight - SCROLLBAR_WIDTH - SCROLLBAR_MARGIN,
+      width: Math.max(
+        canvasWidth - rightOverflow - leftOverflow - SCROLLBAR_MARGIN * 2,
+        SCROLLBAR_MIN_SIZE
+      ),
+      height: SCROLLBAR_WIDTH
+    };
+  }
+
+  // vertical scrollbar
+  let verticalScrollBar = null;
+  if (topOverflow || bottomOverflow) {
+    verticalScrollBar = {
+      x: canvasWidth - SCROLLBAR_WIDTH - SCROLLBAR_MARGIN,
+      y: Math.min(
+        topOverflow + SCROLLBAR_MARGIN,
+        canvasHeight - SCROLLBAR_MIN_SIZE - SCROLLBAR_MARGIN
+      ),
+      width: SCROLLBAR_WIDTH,
+      height: Math.max(
+        canvasHeight - bottomOverflow - topOverflow - SCROLLBAR_WIDTH * 2,
+        SCROLLBAR_MIN_SIZE
+      )
+    };
+  }
+
+  return {
+    horizontal: horizontalScrollBar,
+    vertical: verticalScrollBar
+  };
+}
+
+export function isOverScrollBars(
+  elements: ExcalidrawElement[],
+  x: number,
+  y: number,
+  canvasWidth: number,
+  canvasHeight: number,
+  scrollX: number,
+  scrollY: number
+) {
+  const scrollBars = getScrollBars(
+    elements,
+    canvasWidth,
+    canvasHeight,
+    scrollX,
+    scrollY
+  );
+
+  const [isOverHorizontalScrollBar, isOverVerticalScrollBar] = [
+    scrollBars.horizontal,
+    scrollBars.vertical
+  ].map(
+    scrollBar =>
+      scrollBar &&
+      scrollBar.x <= x &&
+      x <= scrollBar.x + scrollBar.width &&
+      scrollBar.y <= y &&
+      y <= scrollBar.y + scrollBar.height
+  );
+
+  return {
+    isOverHorizontalScrollBar,
+    isOverVerticalScrollBar
+  };
+}

src/scene/selection.ts

@@ -0,0 +1,70 @@
+import { ExcalidrawElement } from "../element/types";
+import {
+  getElementAbsoluteX1,
+  getElementAbsoluteX2,
+  getElementAbsoluteY1,
+  getElementAbsoluteY2
+} from "../element";
+
+export function setSelection(
+  elements: ExcalidrawElement[],
+  selection: ExcalidrawElement
+) {
+  const selectionX1 = getElementAbsoluteX1(selection);
+  const selectionX2 = getElementAbsoluteX2(selection);
+  const selectionY1 = getElementAbsoluteY1(selection);
+  const selectionY2 = getElementAbsoluteY2(selection);
+  elements.forEach(element => {
+    const elementX1 = getElementAbsoluteX1(element);
+    const elementX2 = getElementAbsoluteX2(element);
+    const elementY1 = getElementAbsoluteY1(element);
+    const elementY2 = getElementAbsoluteY2(element);
+    element.isSelected =
+      element.type !== "selection" &&
+      selectionX1 <= elementX1 &&
+      selectionY1 <= elementY1 &&
+      selectionX2 >= elementX2 &&
+      selectionY2 >= elementY2;
+  });
+}
+
+export function clearSelection(elements: ExcalidrawElement[]) {
+  elements.forEach(element => {
+    element.isSelected = false;
+  });
+}
+
+export function deleteSelectedElements(elements: ExcalidrawElement[]) {
+  for (let i = elements.length - 1; i >= 0; --i) {
+    if (elements[i].isSelected) {
+      elements.splice(i, 1);
+    }
+  }
+}
+
+export function getSelectedIndices(elements: ExcalidrawElement[]) {
+  const selectedIndices: number[] = [];
+  elements.forEach((element, index) => {
+    if (element.isSelected) {
+      selectedIndices.push(index);
+    }
+  });
+  return selectedIndices;
+}
+
+export const someElementIsSelected = (elements: ExcalidrawElement[]) =>
+  elements.some(element => element.isSelected);
+
+export function getSelectedAttribute<T>(
+  elements: ExcalidrawElement[],
+  getAttribute: (element: ExcalidrawElement) => T
+): T | null {
+  const attributes = Array.from(
+    new Set(
+      elements
+        .filter(element => element.isSelected)
+        .map(element => getAttribute(element))
+    )
+  );
+  return attributes.length === 1 ? attributes[0] : null;
+}

src/scene/types.ts

@@ -0,0 +1,12 @@
+import { ExcalidrawTextElement } from "../element/types";
+
+export type SceneState = {
+  scrollX: number;
+  scrollY: number;
+  // null indicates transparent bg
+  viewBackgroundColor: string | null;
+};
+
+export interface Scene {
+  elements: ExcalidrawTextElement[];
+}

src/shapes.tsx

@@ -0,0 +1,70 @@
+import React from "react";
+
+// We inline font-awesome icons in order to save on js size rather than including the font awesome react library
+export const SHAPES = [
+  {
+    icon: (
+      // fa-mouse-pointer
+      <svg viewBox="0 0 320 512">
+        <path d="M302.189 329.126H196.105l55.831 135.993c3.889 9.428-.555 19.999-9.444 23.999l-49.165 21.427c-9.165 4-19.443-.571-23.332-9.714l-53.053-129.136-86.664 89.138C18.729 472.71 0 463.554 0 447.977V18.299C0 1.899 19.921-6.096 30.277 5.443l284.412 292.542c11.472 11.179 3.007 31.141-12.5 31.141z" />
+      </svg>
+    ),
+    value: "selection"
+  },
+  {
+    icon: (
+      // fa-square
+      <svg viewBox="0 0 448 512">
+        <path d="M400 32H48C21.5 32 0 53.5 0 80v352c0 26.5 21.5 48 48 48h352c26.5 0 48-21.5 48-48V80c0-26.5-21.5-48-48-48z" />
+      </svg>
+    ),
+    value: "rectangle"
+  },
+  {
+    icon: (
+      // custom
+      <svg viewBox="0 0 223.646 223.646">
+        <path d="M111.823 0L16.622 111.823 111.823 223.646 207.025 111.823z" />
+      </svg>
+    ),
+    value: "diamond"
+  },
+  {
+    icon: (
+      // fa-circle
+      <svg viewBox="0 0 512 512">
+        <path d="M256 8C119 8 8 119 8 256s111 248 248 248 248-111 248-248S393 8 256 8z" />
+      </svg>
+    ),
+    value: "ellipse"
+  },
+  {
+    icon: (
+      // fa-long-arrow-alt-right
+      <svg viewBox="0 0 448 512">
+        <path d="M313.941 216H12c-6.627 0-12 5.373-12 12v56c0 6.627 5.373 12 12 12h301.941v46.059c0 21.382 25.851 32.09 40.971 16.971l86.059-86.059c9.373-9.373 9.373-24.569 0-33.941l-86.059-86.059c-15.119-15.119-40.971-4.411-40.971 16.971V216z" />
+      </svg>
+    ),
+    value: "arrow"
+  },
+  {
+    icon: (
+      // fa-font
+      <svg viewBox="0 0 448 512">
+        <path d="M432 416h-23.41L277.88 53.69A32 32 0 0 0 247.58 32h-47.16a32 32 0 0 0-30.3 21.69L39.41 416H16a16 16 0 0 0-16 16v32a16 16 0 0 0 16 16h128a16 16 0 0 0 16-16v-32a16 16 0 0 0-16-16h-19.58l23.3-64h152.56l23.3 64H304a16 16 0 0 0-16 16v32a16 16 0 0 0 16 16h128a16 16 0 0 0 16-16v-32a16 16 0 0 0-16-16zM176.85 272L224 142.51 271.15 272z" />
+      </svg>
+    ),
+    value: "text"
+  }
+];
+
+export const shapesShortcutKeys = SHAPES.map(shape => shape.value[0]);
+
+export function findShapeByKey(key: string) {
+  const defaultElement = "selection";
+  return SHAPES.reduce((element, shape) => {
+    if (shape.value[0] !== key) return element;
+
+    return shape.value;
+  }, defaultElement);
+}

src/types.ts

@@ -0,0 +1,14 @@
+import { ExcalidrawElement } from "./element/types";
+
+export type AppState = {
+  draggingElement: ExcalidrawElement | null;
+  resizingElement: ExcalidrawElement | null;
+  elementType: string;
+  exportBackground: boolean;
+  currentItemStrokeColor: string;
+  currentItemBackgroundColor: string;
+  viewBackgroundColor: string;
+  scrollX: number;
+  scrollY: number;
+  name: string;
+};

src/utils.ts

@@ -0,0 +1,25 @@
+export function getDateTime() {
+  const date = new Date();
+  const year = date.getFullYear();
+  const month = date.getMonth() + 1;
+  const day = date.getDate();
+  const hr = date.getHours();
+  const min = date.getMinutes();
+  const secs = date.getSeconds();
+
+  return `${year}${month}${day}${hr}${min}${secs}`;
+}
+
+export function capitalizeString(str: string) {
+  return str.charAt(0).toUpperCase() + str.slice(1);
+}
+
+export function isInputLike(
+  target: Element | EventTarget | null
+): target is HTMLInputElement | HTMLTextAreaElement | HTMLSelectElement {
+  return (
+    target instanceof HTMLInputElement ||
+    target instanceof HTMLTextAreaElement ||
+    target instanceof HTMLSelectElement
+  );
+}