fix: show bounding box for 3 or more linear point elements (#5554)

* fix: show bounding box for 3+ linear point elements

* refactor

* show bounding box for 3 points as well

* fix dragging bounding box for linear elements

* Increase margin/padding for linear elements

* fix cursor and keep bounding box same but offset resize handles

* introduce slight padding for selection border

* better

* add constant for spacing

src/element/collision.ts

@@ -35,6 +35,7 @@ import { getShapeForElement } from "../renderer/renderElement";
 import { hasBoundTextElement, isImageElement } from "./typeChecks";
 import { isTextElement } from ".";
 import { isTransparent } from "../utils";
+import { shouldShowBoundingBox } from "./transformHandles";
 
 const isElementDraggableFromInside = (
   element: NonDeletedExcalidrawElement,
@@ -64,7 +65,10 @@ export const hitTest = (
   const threshold = 10 / appState.zoom.value;
   const point: Point = [x, y];
 
-  if (isElementSelected(appState, element) && !appState.selectedLinearElement) {
+  if (
+    isElementSelected(appState, element) &&
+    shouldShowBoundingBox([element])
+  ) {
     return isPointHittingElementBoundingBox(element, point, threshold);
   }
 

src/element/transformHandles.ts

@@ -1,10 +1,15 @@
-import { ExcalidrawElement, PointerType } from "./types";
+import {
+  ExcalidrawElement,
+  NonDeletedExcalidrawElement,
+  PointerType,
+} from "./types";
 
 import { getElementAbsoluteCoords, Bounds } from "./bounds";
 import { rotate } from "../math";
 import { Zoom } from "../types";
 import { isTextElement } from ".";
 import { isLinearElement } from "./typeChecks";
+import { DEFAULT_SPACING } from "../renderer/renderScene";
 
 export type TransformHandleDirection =
   | "n"
@@ -81,6 +86,7 @@ export const getTransformHandlesFromCoords = (
   zoom: Zoom,
   pointerType: PointerType,
   omitSides: { [T in TransformHandleType]?: boolean } = {},
+  margin = 4,
 ): TransformHandles => {
   const size = transformHandleSizes[pointerType];
   const handleWidth = size / zoom.value;
@@ -93,9 +99,7 @@ export const getTransformHandlesFromCoords = (
   const height = y2 - y1;
   const cx = (x1 + x2) / 2;
   const cy = (y1 + y2) / 2;
-
-  const dashedLineMargin = 4 / zoom.value;
-
+  const dashedLineMargin = margin / zoom.value;
   const centeringOffset = (size - 8) / (2 * zoom.value);
 
   const transformHandles: TransformHandles = {
@@ -248,12 +252,29 @@ export const getTransformHandles = (
   } else if (isTextElement(element)) {
     omitSides = OMIT_SIDES_FOR_TEXT_ELEMENT;
   }
-
+  const dashedLineMargin = isLinearElement(element)
+    ? DEFAULT_SPACING * 3
+    : DEFAULT_SPACING;
   return getTransformHandlesFromCoords(
     getElementAbsoluteCoords(element),
     element.angle,
     zoom,
     pointerType,
     omitSides,
+    dashedLineMargin,
   );
 };
+
+export const shouldShowBoundingBox = (
+  elements: NonDeletedExcalidrawElement[],
+) => {
+  if (elements.length > 1) {
+    return true;
+  }
+  const element = elements[0];
+  if (!isLinearElement(element)) {
+    return true;
+  }
+
+  return element.points.length > 2;
+};