1 files changed, 204 insertions, 0 deletions
diff --git a/packages/excalidraw/actions/actionFlip.ts b/packages/excalidraw/actions/actionFlip.ts
new file mode 100644
index 0000000..80149b8
--- /dev/null
+++ b/packages/excalidraw/actions/actionFlip.ts
@@ -0,0 +1,204 @@
+import { register } from "./register";
+import { getSelectedElements } from "../scene";
+import { getNonDeletedElements } from "../element";
+import type {
+  ExcalidrawArrowElement,
+  ExcalidrawElbowArrowElement,
+  ExcalidrawElement,
+  NonDeleted,
+  NonDeletedSceneElementsMap,
+} from "../element/types";
+import { resizeMultipleElements } from "../element/resizeElements";
+import type { AppClassProperties, AppState } from "../types";
+import { arrayToMap } from "../utils";
+import { CODES, KEYS } from "../keys";
+import {
+  bindOrUnbindLinearElements,
+  isBindingEnabled,
+} from "../element/binding";
+import { updateFrameMembershipOfSelectedElements } from "../frame";
+import { flipHorizontal, flipVertical } from "../components/icons";
+import { CaptureUpdateAction } from "../store";
+import {
+  isArrowElement,
+  isElbowArrow,
+  isLinearElement,
+} from "../element/typeChecks";
+import { mutateElement, newElementWith } from "../element/mutateElement";
+import { deepCopyElement } from "../element/newElement";
+import { getCommonBoundingBox } from "../element/bounds";
+
+export const actionFlipHorizontal = register({
+  name: "flipHorizontal",
+  label: "labels.flipHorizontal",
+  icon: flipHorizontal,
+  trackEvent: { category: "element" },
+  perform: (elements, appState, _, app) => {
+    return {
+      elements: updateFrameMembershipOfSelectedElements(
+        flipSelectedElements(
+          elements,
+          app.scene.getNonDeletedElementsMap(),
+          appState,
+          "horizontal",
+          app,
+        ),
+        appState,
+        app,
+      ),
+      appState,
+      captureUpdate: CaptureUpdateAction.IMMEDIATELY,
+    };
+  },
+  keyTest: (event) => event.shiftKey && event.code === CODES.H,
+});
+
+export const actionFlipVertical = register({
+  name: "flipVertical",
+  label: "labels.flipVertical",
+  icon: flipVertical,
+  trackEvent: { category: "element" },
+  perform: (elements, appState, _, app) => {
+    return {
+      elements: updateFrameMembershipOfSelectedElements(
+        flipSelectedElements(
+          elements,
+          app.scene.getNonDeletedElementsMap(),
+          appState,
+          "vertical",
+          app,
+        ),
+        appState,
+        app,
+      ),
+      appState,
+      captureUpdate: CaptureUpdateAction.IMMEDIATELY,
+    };
+  },
+  keyTest: (event) =>
+    event.shiftKey && event.code === CODES.V && !event[KEYS.CTRL_OR_CMD],
+});
+
+const flipSelectedElements = (
+  elements: readonly ExcalidrawElement[],
+  elementsMap: NonDeletedSceneElementsMap,
+  appState: Readonly<AppState>,
+  flipDirection: "horizontal" | "vertical",
+  app: AppClassProperties,
+) => {
+  const selectedElements = getSelectedElements(
+    getNonDeletedElements(elements),
+    appState,
+    {
+      includeBoundTextElement: true,
+      includeElementsInFrames: true,
+    },
+  );
+
+  const updatedElements = flipElements(
+    selectedElements,
+    elementsMap,
+    appState,
+    flipDirection,
+    app,
+  );
+
+  const updatedElementsMap = arrayToMap(updatedElements);
+
+  return elements.map(
+    (element) => updatedElementsMap.get(element.id) || element,
+  );
+};
+
+const flipElements = (
+  selectedElements: NonDeleted<ExcalidrawElement>[],
+  elementsMap: NonDeletedSceneElementsMap,
+  appState: AppState,
+  flipDirection: "horizontal" | "vertical",
+  app: AppClassProperties,
+): ExcalidrawElement[] => {
+  if (
+    selectedElements.every(
+      (element) =>
+        isArrowElement(element) && (element.startBinding || element.endBinding),
+    )
+  ) {
+    return selectedElements.map((element) => {
+      const _element = element as ExcalidrawArrowElement;
+      return newElementWith(_element, {
+        startArrowhead: _element.endArrowhead,
+        endArrowhead: _element.startArrowhead,
+      });
+    });
+  }
+
+  const { midX, midY } = getCommonBoundingBox(selectedElements);
+
+  resizeMultipleElements(
+    selectedElements,
+    elementsMap,
+    "nw",
+    app.scene,
+    new Map(
+      Array.from(elementsMap.values()).map((element) => [
+        element.id,
+        deepCopyElement(element),
+      ]),
+    ),
+    {
+      flipByX: flipDirection === "horizontal",
+      flipByY: flipDirection === "vertical",
+      shouldResizeFromCenter: true,
+      shouldMaintainAspectRatio: true,
+    },
+  );
+
+  bindOrUnbindLinearElements(
+    selectedElements.filter(isLinearElement),
+    elementsMap,
+    app.scene.getNonDeletedElements(),
+    app.scene,
+    isBindingEnabled(appState),
+    [],
+    appState.zoom,
+  );
+
+  // ---------------------------------------------------------------------------
+  // flipping arrow elements (and potentially other) makes the selection group
+  // "move" across the canvas because of how arrows can bump against the "wall"
+  // of the selection, so we need to center the group back to the original
+  // position so that repeated flips don't accumulate the offset
+
+  const { elbowArrows, otherElements } = selectedElements.reduce(
+    (
+      acc: {
+        elbowArrows: ExcalidrawElbowArrowElement[];
+        otherElements: ExcalidrawElement[];
+      },
+      element,
+    ) =>
+      isElbowArrow(element)
+        ? { ...acc, elbowArrows: acc.elbowArrows.concat(element) }
+        : { ...acc, otherElements: acc.otherElements.concat(element) },
+    { elbowArrows: [], otherElements: [] },
+  );
+
+  const { midX: newMidX, midY: newMidY } =
+    getCommonBoundingBox(selectedElements);
+  const [diffX, diffY] = [midX - newMidX, midY - newMidY];
+  otherElements.forEach((element) =>
+    mutateElement(element, {
+      x: element.x + diffX,
+      y: element.y + diffY,
+    }),
+  );
+  elbowArrows.forEach((element) =>
+    mutateElement(element, {
+      x: element.x + diffX,
+      y: element.y + diffY,
+    }),
+  );
+  // ---------------------------------------------------------------------------
+
+  return selectedElements;
+};