Improve new component DND for grids and add mobile support

packages/client/src/components/Component.svelte

@@ -189,12 +189,6 @@
   // Scroll the selected element into view
   $: selected && scrollIntoView()
 
-  // When dragging and dropping, pad components to allow dropping between
-  // nested layers. Only reset this when dragging stops.
-  let pad = false
-  $: pad = pad || (interactive && hasChildren && inDndPath)
-  $: $dndIsDragging, (pad = false)
-
   // Themes
   $: currentTheme = $context?.device?.theme
   $: darkMode = !currentTheme?.includes("light")
@@ -206,8 +200,10 @@
   }
 
   // Metadata to pass into grid action to apply CSS
-  const insideGrid =
-    parent?._component.endsWith("/container") && parent?.layout === "grid"
+  const checkGrid = x =>
+    x?._component.endsWith("/container") && x?.layout === "grid"
+  $: insideGrid = checkGrid(parent)
+  $: isGrid = checkGrid(instance)
   $: gridMetadata = {
     insideGrid,
     ignoresLayout: definition?.ignoresLayout === true,
@@ -219,6 +215,12 @@
     errored: errorState,
   }
 
+  // When dragging and dropping, pad components to allow dropping between
+  // nested layers. Only reset this when dragging stops.
+  let pad = false
+  $: pad = pad || (!isGrid && interactive && hasChildren && inDndPath)
+  $: $dndIsDragging, (pad = false)
+
   // Update component context
   $: store.set({
     id,

packages/client/src/components/preview/DNDPlaceholderOverlay.svelte

@@ -6,8 +6,11 @@
   let left, top, height, width
 
   const updatePosition = () => {
-    const node =
-      document.getElementsByClassName(DNDPlaceholderID)[0]?.childNodes[0]
+    let node = document.getElementsByClassName(DNDPlaceholderID)[0]
+    const insideGrid = node?.dataset.insideGrid === "true"
+    if (!insideGrid) {
+      node = document.getElementsByClassName(`${DNDPlaceholderID}-dom`)[0]
+    }
     if (!node) {
       height = 0
       width = 0

packages/client/src/stores/dnd.js

@@ -1,5 +1,5 @@
 import { writable } from "svelte/store"
-import { computed } from "../utils/computed.js"
+import { derivedMemo } from "@budibase/frontend-core"
 
 const createDndStore = () => {
   const initialState = {
@@ -78,11 +78,11 @@ export const dndStore = createDndStore()
 // performance by deriving any state that needs to be externally observed.
 // By doing this and using primitives, we can avoid invalidating other stores
 // or components which depend on DND state unless values actually change.
-export const dndParent = computed(dndStore, x => x.drop?.parent)
-export const dndIndex = computed(dndStore, x => x.drop?.index)
-export const dndBounds = computed(dndStore, x => x.source?.bounds)
-export const dndIsDragging = computed(dndStore, x => !!x.source)
-export const dndIsNewComponent = computed(
+export const dndParent = derivedMemo(dndStore, x => x.drop?.parent)
+export const dndIndex = derivedMemo(dndStore, x => x.drop?.index)
+export const dndBounds = derivedMemo(dndStore, x => x.source?.bounds)
+export const dndIsDragging = derivedMemo(dndStore, x => !!x.source)
+export const dndIsNewComponent = derivedMemo(
   dndStore,
   x => x.source?.newComponentType != null
 )

packages/client/src/stores/screens.js

@@ -92,6 +92,8 @@ const createScreenStore = () => {
               width: `${$dndBounds?.width || 400}px`,
               height: `${$dndBounds?.height || 200}px`,
               opacity: 0,
+              "--default-width": $dndBounds?.width || 400,
+              "--default-height": $dndBounds?.height || 200,
             },
           },
           static: true,

packages/client/src/utils/computed.js

@@ -1,38 +0,0 @@
-import { writable } from "svelte/store"
-
-/**
- * Extension of Svelte's built in "derived" stores, which the addition of deep
- * comparison of non-primitives. Falls back to using shallow comparison for
- * primitive types to avoid performance penalties.
- * Useful for instances where a deep comparison is cheaper than an additional
- * store invalidation.
- * @param store the store to observer
- * @param deriveValue the derivation function
- * @returns {Writable<*>} a derived svelte store containing just the derived value
- */
-export const computed = (store, deriveValue) => {
-  const initialValue = deriveValue(store)
-  const computedStore = writable(initialValue)
-  let lastKey = getKey(initialValue)
-
-  store.subscribe(state => {
-    const value = deriveValue(state)
-    const key = getKey(value)
-    if (key !== lastKey) {
-      lastKey = key
-      computedStore.set(value)
-    }
-  })
-
-  return computedStore
-}
-
-// Helper function to serialise any value into a primitive which can be cheaply
-// and shallowly compared
-const getKey = value => {
-  if (value == null || typeof value !== "object") {
-    return value
-  } else {
-    return JSON.stringify(value)
-  }
-}

packages/client/src/utils/grid.js

@@ -92,8 +92,12 @@ export const gridLayout = (node, metadata) => {
     }
 
     // Determine default width and height of component
-    let width = errored ? 500 : definition?.size?.width || 200
-    let height = errored ? 60 : definition?.size?.height || 200
+    let width = styles["--default-width"] ?? definition?.size?.width ?? 200
+    let height = styles["--default-height"] ?? definition?.size?.height ?? 200
+    if (errored) {
+      width = 500
+      height = 60
+    }
     width += 2 * GridSpacing
     height += 2 * GridSpacing
     let vars = {