fix(context-menu): render submenu based on viewport constraints #577

src/ContextMenu/ContextMenu.svelte

@@ -26,6 +26,7 @@
   const position = writable([x, y]);
   const currentIndex = writable(-1);
   const hasPopup = writable(false);
+  const menuOffsetX = writable(0);
   const ctx = getContext("ContextMenu");
 
   let options = [];
@@ -44,6 +45,7 @@
   }
 
   setContext("ContextMenu", {
+    menuOffsetX,
     currentIndex,
     position,
     close,
@@ -77,9 +79,19 @@
 <svelte:window
   on:contextmenu|preventDefault="{(e) => {
     if (level > 1) return;
-    if (open || x === 0) x = e.x;
+
+    const { height, width } = ref.getBoundingClientRect();
+
+    if (open || x === 0) {
+      if (window.innerWidth - width < e.x) {
+        x = e.x - width;
+      } else {
+        x = e.x;
+      }
+    }
+
     if (open || y === 0) {
-      const { height } = ref.getBoundingClientRect();
+      menuOffsetX.set(e.x);
 
       if (window.innerHeight - height < e.y) {
         y = e.y - height;

src/ContextMenu/ContextMenuOption.svelte

@@ -70,11 +70,16 @@
   let role = "menuitem";
   let submenuOpen = false;
   let submenuPosition = [0, 0];
+  let menuOffsetX = 0;
 
   const unsubPosition = ctx.position.subscribe((position) => {
     rootMenuPosition = position;
   });
 
+  const unsubMenuOffsetX = ctx.menuOffsetX.subscribe((_menuOffsetX) => {
+    menuOffsetX = _menuOffsetX;
+  });
+
   function handleClick(opts = {}) {
     if (disabled) return ctx.close();
     if (subOptions) return;
@@ -112,6 +117,7 @@
 
     return () => {
       unsubPosition();
+      unsubMenuOffsetX();
       if (unsubCurrentIds) unsubCurrentIds();
       if (unsubCurrentId) unsubCurrentId();
       if (typeof timeoutHover === "number") clearTimeout(timeoutHover);
@@ -124,7 +130,13 @@
   $: ctx.setPopup(submenuOpen);
   $: if (submenuOpen) {
     const { width, y } = ref.getBoundingClientRect();
-    submenuPosition = [rootMenuPosition[0] + width, y];
+    let x = rootMenuPosition[0] + width;
+
+    if (window.innerWidth - menuOffsetX < width) {
+      x = rootMenuPosition[0] - width;
+    }
+
+    submenuPosition = [x, y];
   }
   $: {
     if (isSelectable) {