Creating a text near the center of a shape should put it in the center (#270)

* Snap to element center

* Fixed typo

* Added comment

* Reduced threshold to 30

* Skip snapping if alt key is pressed

* Fixed creating text with shape tool

src/scene/comparisons.ts

@@ -1,5 +1,6 @@
 import { ExcalidrawElement } from "../element/types";
 import { hitTest } from "../element/collision";
+import { getElementAbsoluteCoords } from "../element";
 
 export const hasBackground = (elements: ExcalidrawElement[]) =>
   elements.some(
@@ -36,3 +37,20 @@ export function getElementAtPosition(
 
   return hitElement;
 }
+
+export function getElementContainingPosition(
+  elements: ExcalidrawElement[],
+  x: number,
+  y: number
+) {
+  let hitElement = null;
+  // We need to to hit testing from front (end of the array) to back (beginning of the array)
+  for (let i = elements.length - 1; i >= 0; --i) {
+    const [x1, y1, x2, y2] = getElementAbsoluteCoords(elements[i]);
+    if (x1 < x && x < x2 && y1 < y && y < y2) {
+      hitElement = elements[i];
+      break;
+    }
+  }
+  return hitElement;
+}

src/scene/index.ts

@@ -14,5 +14,10 @@ export {
   restoreFromLocalStorage,
   saveToLocalStorage
 } from "./data";
-export { hasBackground, hasStroke, getElementAtPosition } from "./comparisons";
+export {
+  hasBackground,
+  hasStroke,
+  getElementAtPosition,
+  getElementContainingPosition
+} from "./comparisons";
 export { createScene } from "./createScene";