excalidraw/src/renderer/renderScene.ts

import { RoughCanvas } from "roughjs/bin/canvas";
import { RoughSVG } from "roughjs/bin/svg";
import oc from "open-color";

import { AppState, BinaryFiles, Zoom } from "../types";
import {
  ExcalidrawElement,
  NonDeletedExcalidrawElement,
  ExcalidrawLinearElement,
  NonDeleted,
  GroupId,
  ExcalidrawBindableElement,
} from "../element/types";
import {
  getElementAbsoluteCoords,
  OMIT_SIDES_FOR_MULTIPLE_ELEMENTS,
  getTransformHandlesFromCoords,
  getTransformHandles,
  getElementBounds,
  getCommonBounds,
} from "../element";

import { roundRect } from "./roundRect";
import { RenderConfig } from "../scene/types";
import {
  getScrollBars,
  SCROLLBAR_COLOR,
  SCROLLBAR_WIDTH,
} from "../scene/scrollbars";
import { getSelectedElements } from "../scene/selection";

import { renderElement, renderElementToSvg } from "./renderElement";
import { getClientColors } from "../clients";
import { LinearElementEditor } from "../element/linearElementEditor";
import {
  isSelectedViaGroup,
  getSelectedGroupIds,
  getElementsInGroup,
} from "../groups";
import { maxBindingGap } from "../element/collision";
import {
  SuggestedBinding,
  SuggestedPointBinding,
  isBindingEnabled,
} from "../element/binding";
import {
  TransformHandles,
  TransformHandleType,
} from "../element/transformHandles";
import {
  viewportCoordsToSceneCoords,
  supportsEmoji,
  throttleRAF,
} from "../utils";
import { UserIdleState } from "../types";
import { THEME_FILTER } from "../constants";
import {
  EXTERNAL_LINK_IMG,
  getLinkHandleFromCoords,
} from "../element/Hyperlink";
import { isLinearElement } from "../element/typeChecks";

const hasEmojiSupport = supportsEmoji();

const strokeRectWithRotation = (
  context: CanvasRenderingContext2D,
  x: number,
  y: number,
  width: number,
  height: number,
  cx: number,
  cy: number,
  angle: number,
  fill: boolean = false,
) => {
  context.save();
  context.translate(cx, cy);
  context.rotate(angle);
  if (fill) {
    context.fillRect(x - cx, y - cy, width, height);
  }
  context.strokeRect(x - cx, y - cy, width, height);
  context.restore();
};

const strokeDiamondWithRotation = (
  context: CanvasRenderingContext2D,
  width: number,
  height: number,
  cx: number,
  cy: number,
  angle: number,
) => {
  context.save();
  context.translate(cx, cy);
  context.rotate(angle);
  context.beginPath();
  context.moveTo(0, height / 2);
  context.lineTo(width / 2, 0);
  context.lineTo(0, -height / 2);
  context.lineTo(-width / 2, 0);
  context.closePath();
  context.stroke();
  context.restore();
};

const strokeEllipseWithRotation = (
  context: CanvasRenderingContext2D,
  width: number,
  height: number,
  cx: number,
  cy: number,
  angle: number,
) => {
  context.beginPath();
  context.ellipse(cx, cy, width / 2, height / 2, angle, 0, Math.PI * 2);
  context.stroke();
};

const fillCircle = (
  context: CanvasRenderingContext2D,
  cx: number,
  cy: number,
  radius: number,
  stroke = true,
) => {
  context.beginPath();
  context.arc(cx, cy, radius, 0, Math.PI * 2);
  context.fill();
  if (stroke) {
    context.stroke();
  }
};

const strokeGrid = (
  context: CanvasRenderingContext2D,
  gridSize: number,
  offsetX: number,
  offsetY: number,
  width: number,
  height: number,
) => {
  context.save();
  context.strokeStyle = "rgba(0,0,0,0.1)";
  context.beginPath();
  for (let x = offsetX; x < offsetX + width + gridSize * 2; x += gridSize) {
    context.moveTo(x, offsetY - gridSize);
    context.lineTo(x, offsetY + height + gridSize * 2);
  }
  for (let y = offsetY; y < offsetY + height + gridSize * 2; y += gridSize) {
    context.moveTo(offsetX - gridSize, y);
    context.lineTo(offsetX + width + gridSize * 2, y);
  }
  context.stroke();
  context.restore();
};

const renderLinearPointHandles = (
  context: CanvasRenderingContext2D,
  appState: AppState,
  renderConfig: RenderConfig,
  element: NonDeleted<ExcalidrawLinearElement>,
) => {
  context.save();
  context.translate(renderConfig.scrollX, renderConfig.scrollY);
  context.lineWidth = 1 / renderConfig.zoom.value;

  LinearElementEditor.getPointsGlobalCoordinates(element).forEach(
    (point, idx) => {
      context.strokeStyle = "#5e5ad8";
      context.setLineDash([]);
      context.fillStyle =
        appState.editingLinearElement?.selectedPointsIndices?.includes(idx)
          ? "rgba(134, 131, 226, 0.9)"
          : "rgba(255, 255, 255, 0.9)";
      const { POINT_HANDLE_SIZE } = LinearElementEditor;
      const radius = appState.editingLinearElement
        ? POINT_HANDLE_SIZE
        : POINT_HANDLE_SIZE / 2;
      fillCircle(context, point[0], point[1], radius / renderConfig.zoom.value);
    },
  );
  context.restore();
};

const renderLinearElementPointHighlight = (
  context: CanvasRenderingContext2D,
  appState: AppState,
  renderConfig: RenderConfig,
) => {
  const { elementId, hoverPointIndex } = appState.selectedLinearElement!;
  if (
    appState.editingLinearElement?.selectedPointsIndices?.includes(
      hoverPointIndex,
    )
  ) {
    return;
  }
  const element = LinearElementEditor.getElement(elementId);
  if (!element) {
    return;
  }
  const [x, y] = LinearElementEditor.getPointAtIndexGlobalCoordinates(
    element,
    hoverPointIndex,
  );
  context.save();
  context.translate(renderConfig.scrollX, renderConfig.scrollY);

  context.fillStyle = "rgba(105, 101, 219, 0.4)";

  fillCircle(
    context,
    x,
    y,
    LinearElementEditor.POINT_HANDLE_SIZE / renderConfig.zoom.value,
    false,
  );

  context.restore();
};
export const _renderScene = (
  elements: readonly NonDeletedExcalidrawElement[],
  appState: AppState,
  selectionElement: NonDeletedExcalidrawElement | null,
  scale: number,
  rc: RoughCanvas,
  canvas: HTMLCanvasElement,
  renderConfig: RenderConfig,
  // extra options passed to the renderer
) => {
  if (canvas === null) {
    return { atLeastOneVisibleElement: false };
  }

  const {
    renderScrollbars = true,
    renderSelection = true,
    renderGrid = true,
    isExporting,
  } = renderConfig;

  const context = canvas.getContext("2d")!;

  context.setTransform(1, 0, 0, 1, 0, 0);
  context.save();
  context.scale(scale, scale);

  // When doing calculations based on canvas width we should used normalized one
  const normalizedCanvasWidth = canvas.width / scale;
  const normalizedCanvasHeight = canvas.height / scale;

  if (isExporting && renderConfig.theme === "dark") {
    context.filter = THEME_FILTER;
  }

  // Paint background
  if (typeof renderConfig.viewBackgroundColor === "string") {
    const hasTransparence =
      renderConfig.viewBackgroundColor === "transparent" ||
      renderConfig.viewBackgroundColor.length === 5 || // #RGBA
      renderConfig.viewBackgroundColor.length === 9 || // #RRGGBBA
      /(hsla|rgba)\(/.test(renderConfig.viewBackgroundColor);
    if (hasTransparence) {
      context.clearRect(0, 0, normalizedCanvasWidth, normalizedCanvasHeight);
    }
    context.save();
    context.fillStyle = renderConfig.viewBackgroundColor;
    context.fillRect(0, 0, normalizedCanvasWidth, normalizedCanvasHeight);
    context.restore();
  } else {
    context.clearRect(0, 0, normalizedCanvasWidth, normalizedCanvasHeight);
  }

  // Apply zoom
  context.save();
  context.scale(renderConfig.zoom.value, renderConfig.zoom.value);

  // Grid
  if (renderGrid && appState.gridSize) {
    strokeGrid(
      context,
      appState.gridSize,
      -Math.ceil(renderConfig.zoom.value / appState.gridSize) *
        appState.gridSize +
        (renderConfig.scrollX % appState.gridSize),
      -Math.ceil(renderConfig.zoom.value / appState.gridSize) *
        appState.gridSize +
        (renderConfig.scrollY % appState.gridSize),
      normalizedCanvasWidth / renderConfig.zoom.value,
      normalizedCanvasHeight / renderConfig.zoom.value,
    );
  }

  // Paint visible elements
  const visibleElements = elements.filter((element) =>
    isVisibleElement(element, normalizedCanvasWidth, normalizedCanvasHeight, {
      zoom: renderConfig.zoom,
      offsetLeft: appState.offsetLeft,
      offsetTop: appState.offsetTop,
      scrollX: renderConfig.scrollX,
      scrollY: renderConfig.scrollY,
    }),
  );

  visibleElements.forEach((element) => {
    try {
      renderElement(element, rc, context, renderConfig);
      if (!isExporting) {
        renderLinkIcon(element, context, appState);
      }
    } catch (error: any) {
      console.error(error);
    }
  });

  if (appState.editingLinearElement) {
    const element = LinearElementEditor.getElement(
      appState.editingLinearElement.elementId,
    );
    if (element) {
      renderLinearPointHandles(context, appState, renderConfig, element);
    }
  }

  // Paint selection element
  if (selectionElement) {
    try {
      renderElement(selectionElement, rc, context, renderConfig);
    } catch (error: any) {
      console.error(error);
    }
  }

  if (isBindingEnabled(appState)) {
    appState.suggestedBindings
      .filter((binding) => binding != null)
      .forEach((suggestedBinding) => {
        renderBindingHighlight(context, renderConfig, suggestedBinding!);
      });
  }

  if (
    appState.selectedLinearElement &&
    appState.selectedLinearElement.hoverPointIndex !== -1
  ) {
    renderLinearElementPointHighlight(context, appState, renderConfig);
  }

  // Paint selected elements
  if (
    renderSelection &&
    !appState.multiElement &&
    !appState.editingLinearElement
  ) {
    const locallySelectedElements = getSelectedElements(elements, appState);
    const locallySelectedIds = locallySelectedElements.map(
      (element) => element.id,
    );
    const isSingleLinearElementSelected =
      locallySelectedElements.length === 1 &&
      isLinearElement(locallySelectedElements[0]);
    // render selected linear element points
    if (
      isSingleLinearElementSelected &&
      appState.selectedLinearElement?.elementId ===
        locallySelectedElements[0].id &&
      !locallySelectedElements[0].locked
    ) {
      renderLinearPointHandles(
        context,
        appState,
        renderConfig,
        locallySelectedElements[0] as ExcalidrawLinearElement,
      );
      // render bounding box
      // (unless dragging a single linear element)
    } else if (!appState.draggingElement || !isSingleLinearElementSelected) {
      const selections = elements.reduce((acc, element) => {
        const selectionColors = [];
        // local user
        if (
          locallySelectedIds.includes(element.id) &&
          !isSelectedViaGroup(appState, element)
        ) {
          selectionColors.push(oc.black);
        }
        // remote users
        if (renderConfig.remoteSelectedElementIds[element.id]) {
          selectionColors.push(
            ...renderConfig.remoteSelectedElementIds[element.id].map(
              (socketId) => {
                const { background } = getClientColors(socketId, appState);
                return background;
              },
            ),
          );
        }
        if (selectionColors.length) {
          const [elementX1, elementY1, elementX2, elementY2] =
            getElementAbsoluteCoords(element);
          acc.push({
            angle: element.angle,
            elementX1,
            elementY1,
            elementX2,
            elementY2,
            selectionColors,
          });
        }
        return acc;
      }, [] as { angle: number; elementX1: number; elementY1: number; elementX2: number; elementY2: number; selectionColors: string[] }[]);

      const addSelectionForGroupId = (groupId: GroupId) => {
        const groupElements = getElementsInGroup(elements, groupId);
        const [elementX1, elementY1, elementX2, elementY2] =
          getCommonBounds(groupElements);
        selections.push({
          angle: 0,
          elementX1,
          elementX2,
          elementY1,
          elementY2,
          selectionColors: [oc.black],
        });
      };

      for (const groupId of getSelectedGroupIds(appState)) {
        // TODO: support multiplayer selected group IDs
        addSelectionForGroupId(groupId);
      }

      if (appState.editingGroupId) {
        addSelectionForGroupId(appState.editingGroupId);
      }
      selections.forEach((selection) =>
        renderSelectionBorder(context, renderConfig, selection),
      );
    }
    // Paint resize transformHandles
    context.save();
    context.translate(renderConfig.scrollX, renderConfig.scrollY);
    if (locallySelectedElements.length === 1) {
      context.fillStyle = oc.white;
      const transformHandles = getTransformHandles(
        locallySelectedElements[0],
        renderConfig.zoom,
        "mouse", // when we render we don't know which pointer type so use mouse
      );
      if (!appState.viewModeEnabled) {
        renderTransformHandles(
          context,
          renderConfig,
          transformHandles,
          locallySelectedElements[0].angle,
        );
      }
    } else if (locallySelectedElements.length > 1 && !appState.isRotating) {
      const dashedLinePadding = 4 / renderConfig.zoom.value;
      context.fillStyle = oc.white;
      const [x1, y1, x2, y2] = getCommonBounds(locallySelectedElements);
      const initialLineDash = context.getLineDash();
      context.setLineDash([2 / renderConfig.zoom.value]);
      const lineWidth = context.lineWidth;
      context.lineWidth = 1 / renderConfig.zoom.value;
      strokeRectWithRotation(
        context,
        x1 - dashedLinePadding,
        y1 - dashedLinePadding,
        x2 - x1 + dashedLinePadding * 2,
        y2 - y1 + dashedLinePadding * 2,
        (x1 + x2) / 2,
        (y1 + y2) / 2,
        0,
      );
      context.lineWidth = lineWidth;
      context.setLineDash(initialLineDash);
      const transformHandles = getTransformHandlesFromCoords(
        [x1, y1, x2, y2],
        0,
        renderConfig.zoom,
        "mouse",
        OMIT_SIDES_FOR_MULTIPLE_ELEMENTS,
      );
      if (locallySelectedElements.some((element) => !element.locked)) {
        renderTransformHandles(context, renderConfig, transformHandles, 0);
      }
    }
    context.restore();
  }

  // Reset zoom
  context.restore();

  // Paint remote pointers
  for (const clientId in renderConfig.remotePointerViewportCoords) {
    let { x, y } = renderConfig.remotePointerViewportCoords[clientId];

    x -= appState.offsetLeft;
    y -= appState.offsetTop;

    const width = 9;
    const height = 14;

    const isOutOfBounds =
      x < 0 ||
      x > normalizedCanvasWidth - width ||
      y < 0 ||
      y > normalizedCanvasHeight - height;

    x = Math.max(x, 0);
    x = Math.min(x, normalizedCanvasWidth - width);
    y = Math.max(y, 0);
    y = Math.min(y, normalizedCanvasHeight - height);

    const { background, stroke } = getClientColors(clientId, appState);

    context.save();
    context.strokeStyle = stroke;
    context.fillStyle = background;

    const userState = renderConfig.remotePointerUserStates[clientId];
    if (isOutOfBounds || userState === UserIdleState.AWAY) {
      context.globalAlpha = 0.48;
    }

    if (
      renderConfig.remotePointerButton &&
      renderConfig.remotePointerButton[clientId] === "down"
    ) {
      context.beginPath();
      context.arc(x, y, 15, 0, 2 * Math.PI, false);
      context.lineWidth = 3;
      context.strokeStyle = "#ffffff88";
      context.stroke();
      context.closePath();

      context.beginPath();
      context.arc(x, y, 15, 0, 2 * Math.PI, false);
      context.lineWidth = 1;
      context.strokeStyle = stroke;
      context.stroke();
      context.closePath();
    }

    context.beginPath();
    context.moveTo(x, y);
    context.lineTo(x + 1, y + 14);
    context.lineTo(x + 4, y + 9);
    context.lineTo(x + 9, y + 10);
    context.lineTo(x, y);
    context.fill();
    context.stroke();

    const username = renderConfig.remotePointerUsernames[clientId];

    let idleState = "";
    if (userState === UserIdleState.AWAY) {
      idleState = hasEmojiSupport ? "⚫️" : ` (${UserIdleState.AWAY})`;
    } else if (userState === UserIdleState.IDLE) {
      idleState = hasEmojiSupport ? "💤" : ` (${UserIdleState.IDLE})`;
    } else if (userState === UserIdleState.ACTIVE) {
      idleState = hasEmojiSupport ? "🟢" : "";
    }

    const usernameAndIdleState = `${
      username ? `${username} ` : ""
    }${idleState}`;

    if (!isOutOfBounds && usernameAndIdleState) {
      const offsetX = x + width;
      const offsetY = y + height;
      const paddingHorizontal = 4;
      const paddingVertical = 4;
      const measure = context.measureText(usernameAndIdleState);
      const measureHeight =
        measure.actualBoundingBoxDescent + measure.actualBoundingBoxAscent;

      // Border
      context.fillStyle = stroke;
      context.fillRect(
        offsetX - 1,
        offsetY - 1,
        measure.width + 2 * paddingHorizontal + 2,
        measureHeight + 2 * paddingVertical + 2,
      );
      // Background
      context.fillStyle = background;
      context.fillRect(
        offsetX,
        offsetY,
        measure.width + 2 * paddingHorizontal,
        measureHeight + 2 * paddingVertical,
      );
      context.fillStyle = oc.white;

      context.fillText(
        usernameAndIdleState,
        offsetX + paddingHorizontal,
        offsetY + paddingVertical + measure.actualBoundingBoxAscent,
      );
    }

    context.restore();
    context.closePath();
  }

  // Paint scrollbars
  let scrollBars;
  if (renderScrollbars) {
    scrollBars = getScrollBars(
      elements,
      normalizedCanvasWidth,
      normalizedCanvasHeight,
      renderConfig,
    );

    context.save();
    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.restore();
  }

  context.restore();
  return { atLeastOneVisibleElement: visibleElements.length > 0, scrollBars };
};

const renderSceneThrottled = throttleRAF(
  (
    elements: readonly NonDeletedExcalidrawElement[],
    appState: AppState,
    selectionElement: NonDeletedExcalidrawElement | null,
    scale: number,
    rc: RoughCanvas,
    canvas: HTMLCanvasElement,
    renderConfig: RenderConfig,
    callback?: (data: ReturnType<typeof _renderScene>) => void,
  ) => {
    const ret = _renderScene(
      elements,
      appState,
      selectionElement,
      scale,
      rc,
      canvas,
      renderConfig,
    );
    callback?.(ret);
  },
  { trailing: true },
);

/** renderScene throttled to animation framerate */
export const renderScene = <T extends boolean = false>(
  elements: readonly NonDeletedExcalidrawElement[],
  appState: AppState,
  selectionElement: NonDeletedExcalidrawElement | null,
  scale: number,
  rc: RoughCanvas,
  canvas: HTMLCanvasElement,
  renderConfig: RenderConfig,
  callback?: (data: ReturnType<typeof _renderScene>) => void,
  /** Whether to throttle rendering. Defaults to false.
   * When throttling, no value is returned. Use the callback instead. */
  throttle?: T,
): T extends true ? void : ReturnType<typeof _renderScene> => {
  if (throttle) {
    renderSceneThrottled(
      elements,
      appState,
      selectionElement,
      scale,
      rc,
      canvas,
      renderConfig,
      callback,
    );
    return undefined as T extends true ? void : ReturnType<typeof _renderScene>;
  }
  const ret = _renderScene(
    elements,
    appState,
    selectionElement,
    scale,
    rc,
    canvas,
    renderConfig,
  );
  callback?.(ret);
  return ret as T extends true ? void : ReturnType<typeof _renderScene>;
};

const renderTransformHandles = (
  context: CanvasRenderingContext2D,
  renderConfig: RenderConfig,
  transformHandles: TransformHandles,
  angle: number,
): void => {
  Object.keys(transformHandles).forEach((key) => {
    const transformHandle = transformHandles[key as TransformHandleType];
    if (transformHandle !== undefined) {
      context.save();
      context.lineWidth = 1 / renderConfig.zoom.value;
      if (key === "rotation") {
        fillCircle(
          context,
          transformHandle[0] + transformHandle[2] / 2,
          transformHandle[1] + transformHandle[3] / 2,
          transformHandle[2] / 2,
        );
      } else {
        strokeRectWithRotation(
          context,
          transformHandle[0],
          transformHandle[1],
          transformHandle[2],
          transformHandle[3],
          transformHandle[0] + transformHandle[2] / 2,
          transformHandle[1] + transformHandle[3] / 2,
          angle,
          true, // fill before stroke
        );
      }
      context.restore();
    }
  });
};

const renderSelectionBorder = (
  context: CanvasRenderingContext2D,
  renderConfig: RenderConfig,
  elementProperties: {
    angle: number;
    elementX1: number;
    elementY1: number;
    elementX2: number;
    elementY2: number;
    selectionColors: string[];
  },
) => {
  const { angle, elementX1, elementY1, elementX2, elementY2, selectionColors } =
    elementProperties;
  const elementWidth = elementX2 - elementX1;
  const elementHeight = elementY2 - elementY1;

  const dashedLinePadding = 4 / renderConfig.zoom.value;
  const dashWidth = 8 / renderConfig.zoom.value;
  const spaceWidth = 4 / renderConfig.zoom.value;

  context.save();
  context.translate(renderConfig.scrollX, renderConfig.scrollY);
  context.lineWidth = 1 / renderConfig.zoom.value;

  const count = selectionColors.length;
  for (let index = 0; index < count; ++index) {
    context.strokeStyle = selectionColors[index];
    context.setLineDash([
      dashWidth,
      spaceWidth + (dashWidth + spaceWidth) * (count - 1),
    ]);
    context.lineDashOffset = (dashWidth + spaceWidth) * index;
    strokeRectWithRotation(
      context,
      elementX1 - dashedLinePadding,
      elementY1 - dashedLinePadding,
      elementWidth + dashedLinePadding * 2,
      elementHeight + dashedLinePadding * 2,
      elementX1 + elementWidth / 2,
      elementY1 + elementHeight / 2,
      angle,
    );
  }
  context.restore();
};

const renderBindingHighlight = (
  context: CanvasRenderingContext2D,
  renderConfig: RenderConfig,
  suggestedBinding: SuggestedBinding,
) => {
  const renderHighlight = Array.isArray(suggestedBinding)
    ? renderBindingHighlightForSuggestedPointBinding
    : renderBindingHighlightForBindableElement;

  context.save();
  context.translate(renderConfig.scrollX, renderConfig.scrollY);
  renderHighlight(context, suggestedBinding as any);

  context.restore();
};

const renderBindingHighlightForBindableElement = (
  context: CanvasRenderingContext2D,
  element: ExcalidrawBindableElement,
) => {
  const [x1, y1, x2, y2] = getElementAbsoluteCoords(element);
  const width = x2 - x1;
  const height = y2 - y1;
  const threshold = maxBindingGap(element, width, height);

  // So that we don't overlap the element itself
  const strokeOffset = 4;
  context.strokeStyle = "rgba(0,0,0,.05)";
  context.lineWidth = threshold - strokeOffset;
  const padding = strokeOffset / 2 + threshold / 2;

  switch (element.type) {
    case "rectangle":
    case "text":
    case "image":
      strokeRectWithRotation(
        context,
        x1 - padding,
        y1 - padding,
        width + padding * 2,
        height + padding * 2,
        x1 + width / 2,
        y1 + height / 2,
        element.angle,
      );
      break;
    case "diamond":
      const side = Math.hypot(width, height);
      const wPadding = (padding * side) / height;
      const hPadding = (padding * side) / width;
      strokeDiamondWithRotation(
        context,
        width + wPadding * 2,
        height + hPadding * 2,
        x1 + width / 2,
        y1 + height / 2,
        element.angle,
      );
      break;
    case "ellipse":
      strokeEllipseWithRotation(
        context,
        width + padding * 2,
        height + padding * 2,
        x1 + width / 2,
        y1 + height / 2,
        element.angle,
      );
      break;
  }
};

const renderBindingHighlightForSuggestedPointBinding = (
  context: CanvasRenderingContext2D,
  suggestedBinding: SuggestedPointBinding,
) => {
  const [element, startOrEnd, bindableElement] = suggestedBinding;

  const threshold = maxBindingGap(
    bindableElement,
    bindableElement.width,
    bindableElement.height,
  );

  context.strokeStyle = "rgba(0,0,0,0)";
  context.fillStyle = "rgba(0,0,0,.05)";

  const pointIndices =
    startOrEnd === "both" ? [0, -1] : startOrEnd === "start" ? [0] : [-1];
  pointIndices.forEach((index) => {
    const [x, y] = LinearElementEditor.getPointAtIndexGlobalCoordinates(
      element,
      index,
    );
    fillCircle(context, x, y, threshold);
  });
};

let linkCanvasCache: any;
const renderLinkIcon = (
  element: NonDeletedExcalidrawElement,
  context: CanvasRenderingContext2D,
  appState: AppState,
) => {
  if (element.link && !appState.selectedElementIds[element.id]) {
    const [x1, y1, x2, y2] = getElementAbsoluteCoords(element);
    const [x, y, width, height] = getLinkHandleFromCoords(
      [x1, y1, x2, y2],
      element.angle,
      appState,
    );
    const centerX = x + width / 2;
    const centerY = y + height / 2;
    context.save();
    context.translate(appState.scrollX + centerX, appState.scrollY + centerY);
    context.rotate(element.angle);

    if (!linkCanvasCache || linkCanvasCache.zoom !== appState.zoom.value) {
      linkCanvasCache = document.createElement("canvas");
      linkCanvasCache.zoom = appState.zoom.value;
      linkCanvasCache.width =
        width * window.devicePixelRatio * appState.zoom.value;
      linkCanvasCache.height =
        height * window.devicePixelRatio * appState.zoom.value;
      const linkCanvasCacheContext = linkCanvasCache.getContext("2d")!;
      linkCanvasCacheContext.scale(
        window.devicePixelRatio * appState.zoom.value,
        window.devicePixelRatio * appState.zoom.value,
      );
      linkCanvasCacheContext.fillStyle = "#fff";
      linkCanvasCacheContext.fillRect(0, 0, width, height);
      linkCanvasCacheContext.drawImage(EXTERNAL_LINK_IMG, 0, 0, width, height);
      linkCanvasCacheContext.restore();
      context.drawImage(
        linkCanvasCache,
        x - centerX,
        y - centerY,
        width,
        height,
      );
    } else {
      context.drawImage(
        linkCanvasCache,
        x - centerX,
        y - centerY,
        width,
        height,
      );
    }
    context.restore();
  }
};

const isVisibleElement = (
  element: ExcalidrawElement,
  canvasWidth: number,
  canvasHeight: number,
  viewTransformations: {
    zoom: Zoom;
    offsetLeft: number;
    offsetTop: number;
    scrollX: number;
    scrollY: number;
  },
) => {
  const [x1, y1, x2, y2] = getElementBounds(element); // scene coordinates
  const topLeftSceneCoords = viewportCoordsToSceneCoords(
    {
      clientX: viewTransformations.offsetLeft,
      clientY: viewTransformations.offsetTop,
    },
    viewTransformations,
  );
  const bottomRightSceneCoords = viewportCoordsToSceneCoords(
    {
      clientX: viewTransformations.offsetLeft + canvasWidth,
      clientY: viewTransformations.offsetTop + canvasHeight,
    },
    viewTransformations,
  );

  return (
    topLeftSceneCoords.x <= x2 &&
    topLeftSceneCoords.y <= y2 &&
    bottomRightSceneCoords.x >= x1 &&
    bottomRightSceneCoords.y >= y1
  );
};

// This should be only called for exporting purposes
export const renderSceneToSvg = (
  elements: readonly NonDeletedExcalidrawElement[],
  rsvg: RoughSVG,
  svgRoot: SVGElement,
  files: BinaryFiles,
  {
    offsetX = 0,
    offsetY = 0,
    exportWithDarkMode = false,
  }: {
    offsetX?: number;
    offsetY?: number;
    exportWithDarkMode?: boolean;
  } = {},
) => {
  if (!svgRoot) {
    return;
  }
  // render elements
  elements.forEach((element) => {
    if (!element.isDeleted) {
      try {
        renderElementToSvg(
          element,
          rsvg,
          svgRoot,
          files,
          element.x + offsetX,
          element.y + offsetY,
          exportWithDarkMode,
        );
      } catch (error: any) {
        console.error(error);
      }
    }
  });
};