feat: add flipping multiple elements with a command

src/actions/actionFlip.ts

@@ -1,41 +1,26 @@
 import { register } from "./register";
 import { getSelectedElements } from "../scene";
 import { getNonDeletedElements } from "../element";
-import { mutateElement } from "../element/mutateElement";
 import { ExcalidrawElement, NonDeleted } from "../element/types";
-import { normalizeAngle, resizeSingleElement } from "../element/resizeElements";
-import { AppState } from "../types";
-import { getTransformHandles } from "../element/transformHandles";
+import { resizeMultipleElements } from "../element/resizeElements";
+import { AppState, PointerDownState } from "../types";
 import { updateBoundElements } from "../element/binding";
 import { arrayToMap } from "../utils";
-import {
-  getElementAbsoluteCoords,
-  getElementPointsCoords,
-} from "../element/bounds";
-import { isLinearElement } from "../element/typeChecks";
-import { LinearElementEditor } from "../element/linearElementEditor";
 import { KEYS } from "../keys";
+import { getCommonBoundingBox } from "../element/bounds";
 
 const enableActionFlipHorizontal = (
   elements: readonly ExcalidrawElement[],
   appState: AppState,
 ) => {
-  const eligibleElements = getSelectedElements(
-    getNonDeletedElements(elements),
-    appState,
-  );
-  return eligibleElements.length === 1 && eligibleElements[0].type !== "text";
+  return true;
 };
 
 const enableActionFlipVertical = (
   elements: readonly ExcalidrawElement[],
   appState: AppState,
 ) => {
-  const eligibleElements = getSelectedElements(
-    getNonDeletedElements(elements),
-    appState,
-  );
-  return eligibleElements.length === 1;
+  return true;
 };
 
 export const actionFlipHorizontal = register({
@@ -81,11 +66,6 @@ const flipSelectedElements = (
     appState,
   );
 
-  // remove once we allow for groups of elements to be flipped
-  if (selectedElements.length > 1) {
-    return elements;
-  }
-
   const updatedElements = flipElements(
     selectedElements,
     appState,
@@ -104,144 +84,18 @@ const flipElements = (
   appState: AppState,
   flipDirection: "horizontal" | "vertical",
 ): ExcalidrawElement[] => {
-  elements.forEach((element) => {
-    flipElement(element, appState);
-    // If vertical flip, rotate an extra 180
-    if (flipDirection === "vertical") {
-      rotateElement(element, Math.PI);
-    }
-  });
+  const { minX, minY, maxX, maxY } = getCommonBoundingBox(elements);
+
+  resizeMultipleElements(
+    { originalElements: arrayToMap(elements) } as PointerDownState,
+    elements,
+    "nw",
+    true,
+    flipDirection === "horizontal" ? maxX : minX,
+    flipDirection === "horizontal" ? minY : maxY,
+  );
+
+  elements.forEach((element) => updateBoundElements(element));
+
   return elements;
 };
-
-const flipElement = (
-  element: NonDeleted<ExcalidrawElement>,
-  appState: AppState,
-) => {
-  const originalX = element.x;
-  const originalY = element.y;
-  const width = element.width;
-  const height = element.height;
-  const originalAngle = normalizeAngle(element.angle);
-
-  // Rotate back to zero, if necessary
-  mutateElement(element, {
-    angle: normalizeAngle(0),
-  });
-  // Flip unrotated by pulling TransformHandle to opposite side
-  const transformHandles = getTransformHandles(element, appState.zoom);
-  let usingNWHandle = true;
-  let nHandle = transformHandles.nw;
-  if (!nHandle) {
-    // Use ne handle instead
-    usingNWHandle = false;
-    nHandle = transformHandles.ne;
-    if (!nHandle) {
-      mutateElement(element, {
-        angle: originalAngle,
-      });
-      return;
-    }
-  }
-
-  let finalOffsetX = 0;
-  if (isLinearElement(element) && element.points.length < 3) {
-    finalOffsetX =
-      element.points.reduce((max, point) => Math.max(max, point[0]), 0) * 2 -
-      element.width;
-  }
-
-  let initialPointsCoords;
-  if (isLinearElement(element)) {
-    initialPointsCoords = getElementPointsCoords(element, element.points);
-  }
-  const initialElementAbsoluteCoords = getElementAbsoluteCoords(element);
-
-  if (isLinearElement(element) && element.points.length < 3) {
-    for (let index = 1; index < element.points.length; index++) {
-      LinearElementEditor.movePoints(element, [
-        {
-          index,
-          point: [-element.points[index][0], element.points[index][1]],
-        },
-      ]);
-    }
-    LinearElementEditor.normalizePoints(element);
-  } else {
-    const elWidth = initialPointsCoords
-      ? initialPointsCoords[2] - initialPointsCoords[0]
-      : initialElementAbsoluteCoords[2] - initialElementAbsoluteCoords[0];
-
-    const startPoint = initialPointsCoords
-      ? [initialPointsCoords[0], initialPointsCoords[1]]
-      : [initialElementAbsoluteCoords[0], initialElementAbsoluteCoords[1]];
-
-    resizeSingleElement(
-      new Map().set(element.id, element),
-      false,
-      element,
-      usingNWHandle ? "nw" : "ne",
-      true,
-      usingNWHandle ? startPoint[0] + elWidth : startPoint[0] - elWidth,
-      startPoint[1],
-    );
-  }
-
-  // Rotate by (360 degrees - original angle)
-  let angle = normalizeAngle(2 * Math.PI - originalAngle);
-  if (angle < 0) {
-    // check, probably unnecessary
-    angle = normalizeAngle(angle + 2 * Math.PI);
-  }
-  mutateElement(element, {
-    angle,
-  });
-
-  // Move back to original spot to appear "flipped in place"
-  mutateElement(element, {
-    x: originalX + finalOffsetX,
-    y: originalY,
-    width,
-    height,
-  });
-
-  updateBoundElements(element);
-
-  if (initialPointsCoords && isLinearElement(element)) {
-    // Adjusting origin because when a beizer curve path exceeds min/max points it offsets the origin.
-    // There's still room for improvement since when the line roughness is > 1
-    // we still have a small offset of the origin when fliipping the element.
-    const finalPointsCoords = getElementPointsCoords(element, element.points);
-
-    const topLeftCoordsDiff = initialPointsCoords[0] - finalPointsCoords[0];
-    const topRightCoordDiff = initialPointsCoords[2] - finalPointsCoords[2];
-
-    const coordsDiff = topLeftCoordsDiff + topRightCoordDiff;
-
-    mutateElement(element, {
-      x: element.x + coordsDiff * 0.5,
-      y: element.y,
-      width,
-      height,
-    });
-  }
-};
-
-const rotateElement = (element: ExcalidrawElement, rotationAngle: number) => {
-  const originalX = element.x;
-  const originalY = element.y;
-  let angle = normalizeAngle(element.angle + rotationAngle);
-  if (angle < 0) {
-    // check, probably unnecessary
-    angle = normalizeAngle(2 * Math.PI + angle);
-  }
-  mutateElement(element, {
-    angle,
-  });
-
-  // Move back to original spot
-  mutateElement(element, {
-    x: originalX,
-    y: originalY,
-  });
-};

src/element/resizeElements.ts

@@ -587,7 +587,7 @@ export const resizeSingleElement = (
   }
 };
 
-const resizeMultipleElements = (
+export const resizeMultipleElements = (
   pointerDownState: PointerDownState,
   selectedElements: readonly NonDeletedExcalidrawElement[],
   transformHandleType: "nw" | "ne" | "sw" | "se",
@@ -684,6 +684,7 @@ const resizeMultipleElements = (
     const x = anchorX + flipFactorX * (offsetX * scale + flipAdjustX);
     const y = anchorY + flipFactorY * (offsetY * scale + flipAdjustY);
 
+    // TODO curved lines adjustment
     // readjust points for linear & free draw elements
     const rescaledPoints = rescalePointsInElement(
       element.orig,