Normalize dimensions (#527)

* normalize dimensions of non-linear elements

* fix element type check regression

src/element/resizeTest.ts

@@ -91,3 +91,61 @@ export function getCursorForResizingElement(resizingElement: {
 
   return cursor ? `${cursor}-resize` : "";
 }
+
+export function normalizeResizeHandle(
+  element: ExcalidrawElement,
+  resizeHandle: HandlerRectanglesRet,
+): HandlerRectanglesRet {
+  if (
+    (element.width >= 0 && element.height >= 0) ||
+    element.type === "line" ||
+    element.type === "arrow"
+  ) {
+    return resizeHandle;
+  }
+
+  if (element.width < 0 && element.height < 0) {
+    switch (resizeHandle) {
+      case "nw":
+        return "se";
+      case "ne":
+        return "sw";
+      case "se":
+        return "nw";
+      case "sw":
+        return "ne";
+    }
+  } else if (element.width < 0) {
+    switch (resizeHandle) {
+      case "nw":
+        return "ne";
+      case "ne":
+        return "nw";
+      case "se":
+        return "sw";
+      case "sw":
+        return "se";
+      case "e":
+        return "w";
+      case "w":
+        return "e";
+    }
+  } else {
+    switch (resizeHandle) {
+      case "nw":
+        return "sw";
+      case "ne":
+        return "se";
+      case "se":
+        return "ne";
+      case "sw":
+        return "nw";
+      case "n":
+        return "s";
+      case "s":
+        return "n";
+    }
+  }
+
+  return resizeHandle;
+}