1 files changed, 250 insertions, 0 deletions
diff --git a/packages/excalidraw/scene/selection.ts b/packages/excalidraw/scene/selection.ts
new file mode 100644
index 0000000..3ca91cd
--- /dev/null
+++ b/packages/excalidraw/scene/selection.ts
@@ -0,0 +1,250 @@
+import type {
+  ElementsMap,
+  ElementsMapOrArray,
+  ExcalidrawElement,
+  NonDeletedExcalidrawElement,
+} from "../element/types";
+import { getElementAbsoluteCoords, getElementBounds } from "../element";
+import type { AppState, InteractiveCanvasAppState } from "../types";
+import { isBoundToContainer, isFrameLikeElement } from "../element/typeChecks";
+import {
+  elementOverlapsWithFrame,
+  getContainingFrame,
+  getFrameChildren,
+} from "../frame";
+import { isShallowEqual } from "../utils";
+import { isElementInViewport } from "../element/sizeHelpers";
+
+/**
+ * Frames and their containing elements are not to be selected at the same time.
+ * Given an array of selected elements, if there are frames and their containing elements
+ * we only keep the frames.
+ * @param selectedElements
+ */
+export const excludeElementsInFramesFromSelection = <
+  T extends ExcalidrawElement,
+>(
+  selectedElements: readonly T[],
+) => {
+  const framesInSelection = new Set<T["id"]>();
+
+  selectedElements.forEach((element) => {
+    if (isFrameLikeElement(element)) {
+      framesInSelection.add(element.id);
+    }
+  });
+
+  return selectedElements.filter((element) => {
+    if (element.frameId && framesInSelection.has(element.frameId)) {
+      return false;
+    }
+    return true;
+  });
+};
+
+export const getElementsWithinSelection = (
+  elements: readonly NonDeletedExcalidrawElement[],
+  selection: NonDeletedExcalidrawElement,
+  elementsMap: ElementsMap,
+  excludeElementsInFrames: boolean = true,
+) => {
+  const [selectionX1, selectionY1, selectionX2, selectionY2] =
+    getElementAbsoluteCoords(selection, elementsMap);
+
+  let elementsInSelection = elements.filter((element) => {
+    let [elementX1, elementY1, elementX2, elementY2] = getElementBounds(
+      element,
+      elementsMap,
+    );
+
+    const containingFrame = getContainingFrame(element, elementsMap);
+    if (containingFrame) {
+      const [fx1, fy1, fx2, fy2] = getElementBounds(
+        containingFrame,
+        elementsMap,
+      );
+
+      elementX1 = Math.max(fx1, elementX1);
+      elementY1 = Math.max(fy1, elementY1);
+      elementX2 = Math.min(fx2, elementX2);
+      elementY2 = Math.min(fy2, elementY2);
+    }
+
+    return (
+      element.locked === false &&
+      element.type !== "selection" &&
+      !isBoundToContainer(element) &&
+      selectionX1 <= elementX1 &&
+      selectionY1 <= elementY1 &&
+      selectionX2 >= elementX2 &&
+      selectionY2 >= elementY2
+    );
+  });
+
+  elementsInSelection = excludeElementsInFrames
+    ? excludeElementsInFramesFromSelection(elementsInSelection)
+    : elementsInSelection;
+
+  elementsInSelection = elementsInSelection.filter((element) => {
+    const containingFrame = getContainingFrame(element, elementsMap);
+
+    if (containingFrame) {
+      return elementOverlapsWithFrame(element, containingFrame, elementsMap);
+    }
+
+    return true;
+  });
+
+  return elementsInSelection;
+};
+
+export const getVisibleAndNonSelectedElements = (
+  elements: readonly NonDeletedExcalidrawElement[],
+  selectedElements: readonly NonDeletedExcalidrawElement[],
+  appState: AppState,
+  elementsMap: ElementsMap,
+) => {
+  const selectedElementsSet = new Set(
+    selectedElements.map((element) => element.id),
+  );
+  return elements.filter((element) => {
+    const isVisible = isElementInViewport(
+      element,
+      appState.width,
+      appState.height,
+      appState,
+      elementsMap,
+    );
+
+    return !selectedElementsSet.has(element.id) && isVisible;
+  });
+};
+
+// FIXME move this into the editor instance to keep utility methods stateless
+export const isSomeElementSelected = (function () {
+  let lastElements: readonly NonDeletedExcalidrawElement[] | null = null;
+  let lastSelectedElementIds: AppState["selectedElementIds"] | null = null;
+  let isSelected: boolean | null = null;
+
+  const ret = (
+    elements: readonly NonDeletedExcalidrawElement[],
+    appState: Pick<AppState, "selectedElementIds">,
+  ): boolean => {
+    if (
+      isSelected != null &&
+      elements === lastElements &&
+      appState.selectedElementIds === lastSelectedElementIds
+    ) {
+      return isSelected;
+    }
+
+    isSelected = elements.some(
+      (element) => appState.selectedElementIds[element.id],
+    );
+    lastElements = elements;
+    lastSelectedElementIds = appState.selectedElementIds;
+
+    return isSelected;
+  };
+
+  ret.clearCache = () => {
+    lastElements = null;
+    lastSelectedElementIds = null;
+    isSelected = null;
+  };
+
+  return ret;
+})();
+
+/**
+ * Returns common attribute (picked by `getAttribute` callback) of selected
+ *  elements. If elements don't share the same value, returns `null`.
+ */
+export const getCommonAttributeOfSelectedElements = <T>(
+  elements: readonly NonDeletedExcalidrawElement[],
+  appState: Pick<AppState, "selectedElementIds">,
+  getAttribute: (element: ExcalidrawElement) => T,
+): T | null => {
+  const attributes = Array.from(
+    new Set(
+      getSelectedElements(elements, appState).map((element) =>
+        getAttribute(element),
+      ),
+    ),
+  );
+  return attributes.length === 1 ? attributes[0] : null;
+};
+
+export const getSelectedElements = (
+  elements: ElementsMapOrArray,
+  appState: Pick<InteractiveCanvasAppState, "selectedElementIds">,
+  opts?: {
+    includeBoundTextElement?: boolean;
+    includeElementsInFrames?: boolean;
+  },
+) => {
+  const addedElements = new Set<ExcalidrawElement["id"]>();
+  const selectedElements: ExcalidrawElement[] = [];
+  for (const element of elements.values()) {
+    if (appState.selectedElementIds[element.id]) {
+      selectedElements.push(element);
+      addedElements.add(element.id);
+      continue;
+    }
+    if (
+      opts?.includeBoundTextElement &&
+      isBoundToContainer(element) &&
+      appState.selectedElementIds[element?.containerId]
+    ) {
+      selectedElements.push(element);
+      addedElements.add(element.id);
+      continue;
+    }
+  }
+
+  if (opts?.includeElementsInFrames) {
+    const elementsToInclude: ExcalidrawElement[] = [];
+    selectedElements.forEach((element) => {
+      if (isFrameLikeElement(element)) {
+        getFrameChildren(elements, element.id).forEach(
+          (e) => !addedElements.has(e.id) && elementsToInclude.push(e),
+        );
+      }
+      elementsToInclude.push(element);
+    });
+
+    return elementsToInclude;
+  }
+
+  return selectedElements;
+};
+
+export const getTargetElements = (
+  elements: ElementsMapOrArray,
+  appState: Pick<
+    AppState,
+    "selectedElementIds" | "editingTextElement" | "newElement"
+  >,
+) =>
+  appState.editingTextElement
+    ? [appState.editingTextElement]
+    : appState.newElement
+    ? [appState.newElement]
+    : getSelectedElements(elements, appState, {
+        includeBoundTextElement: true,
+      });
+
+/**
+ * returns prevState's selectedElementids if no change from previous, so as to
+ * retain reference identity for memoization
+ */
+export const makeNextSelectedElementIds = (
+  nextSelectedElementIds: AppState["selectedElementIds"],
+  prevState: Pick<AppState, "selectedElementIds">,
+) => {
+  if (isShallowEqual(prevState.selectedElementIds, nextSelectedElementIds)) {
+    return prevState.selectedElementIds;
+  }
+
+  return nextSelectedElementIds;
+};