using drag and drop to create nested Grids

fix gridstack#1009 remaining issues
* dragging out last item will nuke empty nested grid
* dragging over item to create nested grid, will revert back to normal item if you continue to drag out
* fixed CSS issues dragging nested in/out couple times

TODO: fix test cases, doc, more testing

demo/nested_advanced.html

@@ -13,7 +13,7 @@
   <div class="container-fluid">
     <h1>Advanced Nested grids demo</h1>
     <p>Create sub-grids (darker background) on the fly, by dragging items completely over others (nest) vs partially (push) using
-      the new v7 API <code>GridStackOptions.subGrid.createDynamic=true</code></p>
+      the new v7 API <code>GridStackOptions.subGridDynamic=true</code></p>
     <p>This will use the new delay drag&drop option <code>DDDragOpt.pause</code> to tell the gesture difference</p>
     <p>Note: <code>gridstack-extra.min.css</code> is required for [2-11] column of sub-grids</p>
     <a class="btn btn-primary" onClick="addNested()" href="#">Add Widget</a>
@@ -34,28 +34,28 @@ <h1>Advanced Nested grids demo</h1>
   </div>
 
   <script type="text/javascript">
-    let main = [{x:0, y:0}, {x:0, y:1}, {x:0, y:2}]
-    let sub0 = [{x:0, y:0}];
+    let main = [{x:0, y:0}, {x:0, y:1}, {x:1, y:0}]
+    // let sub0 = [{x:0, y:0}];
     let sub1 = [{x:0, y:0}, {x:1, y:0}];
     let count = 0;
-    [...main, ...sub0, ...sub1].forEach(d => d.content = String(count++));
+    [...main, ...sub1].forEach(d => d.content = String(count++));
     let subOptions = {
       cellHeight: 50, // should be 50 - top/bottom
       column: 'auto', // size to match container. make sure to include gridstack-extra.min.css
       acceptWidgets: true, // will accept .grid-stack-item by default
-      createDynamic: true, // NEW v7 api to create sub-grids on the fly
       margin: 5,
+      subGridDynamic: true, // make it recursive for all future sub-grids
     };
     let options = { // main grid options
       cellHeight: 50,
       margin: 5,
       minRow: 2, // don't collapse when empty
       acceptWidgets: true,
-      id: 'main',
       subGrid: subOptions,
+      subGridDynamic: true, // NEW v7 api to create sub-grids on the fly
       children: [
         ...main,
-        {x:1, y:2, h:2, subGrid: {children: sub0, ...subOptions}},
+        // {x:1, y:0, h:2, subGrid: {children: sub0, ...subOptions}},
         {x:2, y:0, w:2, h:3, subGrid: {children: sub1, ...subOptions}},
         // {x:2, y:0, w:2, h:3, subGrid: {children: [...sub1, {x:0, y:1, subGrid: subOptions}], ...subOptions}/*,content: "<div>nested grid here</div>"*/},
       ]

doc/CHANGES.md

@@ -74,7 +74,7 @@ Change log
 
 ## 7-dev (TBD)
 * add [#1009](https://github.com/gridstack/gridstack.js/issues/1009) Create sub-grids on the fly,
-by dragging items completely over others (nest) vs partially (push) using new flag `GridStackOptions.subGrid.createDynamic=true`.
+by dragging items completely over others (nest) vs partially (push) using new flag `GridStackOptions.subGridDynamic=true`.
 Thank you [StephanP] for sponsoring it.<br>
 See [advance Nested](https://github.com/gridstack/gridstack.js/blob/master/demo/nested_advanced.html)
 * add - ability to pause drag&drop collision until the user stops moving - see `DDDragOpt.pause` (used for creating nested grids on the fly based on gesture).

src/dd-droppable.ts

@@ -9,7 +9,6 @@ import { DDBaseImplement, HTMLElementExtendOpt } from './dd-base-impl';
 import { Utils } from './utils';
 import { DDElementHost } from './dd-element';
 import { isTouch, pointerenter, pointerleave } from './dd-touch';
-import { GridHTMLElement } from './gridstack';
 
 export interface DDDroppableOpt {
   accept?: string | ((el: HTMLElement) => boolean);

src/dd-gridstack.ts

@@ -1,10 +1,10 @@
 /**
  * dd-gridstack.ts 6.0.2-dev
- * Copyright (c) 2021 Alain Dumesny - see GridStack root license
+ * Copyright (c) 2021-2022 Alain Dumesny - see GridStack root license
  */
 
 /* eslint-disable @typescript-eslint/no-unused-vars */
-import { GridItemHTMLElement, GridStackNode, GridStackElement, DDUIData, DDDragInOpt, GridStackPosition, dragInDefaultOptions } from './types';
+import { GridItemHTMLElement, GridStackNode, GridStackElement, DDUIData, DDDragInOpt, GridStackPosition, dragInDefaultOptions, GridStackOptions } from './types';
 import { GridStack } from './gridstack';
 import { Utils } from './utils';
 import { DDManager } from './dd-manager';
@@ -311,6 +311,10 @@ GridStack.prototype._setupAcceptWidget = function(this: GridStack): GridStack {
       // so skip this one if we're not the active grid really..
       if (!node.grid || node.grid === this) {
         this._leave(el, helper);
+        // if we were created as temporary nested grid, go back to before state
+        if (this._isTemp) {
+          this.removeAsSubGrid(node);
+        }
       }
       return false; // prevent parent from receiving msg (which may be grid as well)
     })
@@ -333,6 +337,10 @@ GridStack.prototype._setupAcceptWidget = function(this: GridStack): GridStack {
         let oGrid = origNode.grid;
         oGrid.engine.removedNodes.push(origNode);
         oGrid._triggerRemoveEvent();
+        // if it's an empty sub-grid, nuke it
+        if (oGrid._isNested && !oGrid.engine.nodes.length) {
+          oGrid.removeAsSubGrid();
+        }
       }
 
       if (!node) return false;
@@ -358,13 +366,13 @@ GridStack.prototype._setupAcceptWidget = function(this: GridStack): GridStack {
       if (!wasAdded) return false;
       el.gridstackNode = node;
       node.el = el;
+      let subGrid = (node.subGrid as GridStack)?.el?.gridstack; // set when actual sub-grid present
       // @ts-ignore
       Utils.copyPos(node, this._readAttr(this.placeholder)); // placeholder values as moving VERY fast can throw things off #1578
       Utils.removePositioningStyles(el);// @ts-ignore
       this._writeAttr(el, node);
       this.el.appendChild(el);// @ts-ignore // TODO: now would be ideal time to _removeHelperStyle() overriding floating styles (native only)
-      let subGrid: GridStack = node.subGrid;
-      if (subGrid?.el && !subGrid.opts.styleInHead) subGrid._updateStyles(true); // re-create sub-grid styles now that we've moved
+      if (subGrid && !subGrid.opts.styleInHead) subGrid._updateStyles(true); // re-create sub-grid styles now that we've moved
       this._updateContainerHeight();
       this.engine.addedNodes.push(node);// @ts-ignore
       this._triggerAddEvent();// @ts-ignore
@@ -383,6 +391,7 @@ GridStack.prototype._setupAcceptWidget = function(this: GridStack): GridStack {
         } else {
           this.engine.removeNode(node);
         }
+        delete node.grid._isTemp;
       });
 
       return false; // prevent parent from receiving msg (which may be grid as well)

src/dd-manager.ts

@@ -1,6 +1,6 @@
 /**
  * dd-manager.ts 6.0.2-dev
- * Copyright (c) 2021 Alain Dumesny - see GridStack root license
+ * Copyright (c) 2021-2022 Alain Dumesny - see GridStack root license
  */
 
 import { DDDraggable } from './dd-draggable';

src/gridstack-engine.ts

@@ -4,7 +4,7 @@
  */
 
 import { Utils } from './utils';
-import { GridStackNode, ColumnOptions, GridStackPosition, GridStackMoveOpts } from './types';
+import { GridStackNode, ColumnOptions, GridStackPosition, GridStackMoveOpts, GridStackOptions } from './types';
 
 /** callback to update the DOM attributes since this class is generic (no HTML or other info) for items that changed - see _notify() */
 type OnChangeCB = (nodes: GridStackNode[]) => void;
@@ -44,7 +44,7 @@ export class GridStackEngine {
   /** @internal true if we have some items locked */
   protected _hasLocked: boolean;
   /** @internal unique global internal _id counter NOT starting at 0 */
-  protected static _idSeq = 1;
+  public static _idSeq = 1;
 
   public constructor(opts: GridStackEngineOptions = {}) {
     this.column = opts.column || 12;
@@ -648,8 +648,8 @@ export class GridStackEngine {
       // check to make sure we actually collided over 50% surface area while dragging
       let collide = activeDrag ? this.directionCollideCoverage(node, o, collides) : collides[0];
       // if we're enabling creation of sub-grids on the fly, see if we're covering 80% of either one, if we didn't already do that
-      let subOpt = node.grid.opts.subGrid;
-      if (activeDrag && collide && subOpt?.createDynamic && !subOpt.isTemp) {
+      let opts = node.grid.opts;
+      if (activeDrag && collide && opts.subGridDynamic && !node.grid._isTemp) {
         let over = Utils.areaIntercept(o.rect, collide._rect);
         let a1 = Utils.area(o.rect);
         let a2 = Utils.area(collide._rect);

src/gridstack.scss

@@ -1,6 +1,6 @@
 /**
  * gridstack SASS styles 6.0.2-dev
- * Copyright (c) 2021 Alain Dumesny - see GridStack root license
+ * Copyright (c) 2021-2022 Alain Dumesny - see GridStack root license
  */
 
 @use "sass:math";

src/gridstack.ts

@@ -8,7 +8,7 @@
 import { GridStackEngine } from './gridstack-engine';
 import { Utils, HeightData, obsolete } from './utils';
 import { gridDefaults, ColumnOptions, GridItemHTMLElement, GridStackElement, GridStackEventHandlerCallback,
-  GridStackNode, GridStackOptions, GridStackWidget, numberOrString, DDUIData, DDDragInOpt, GridStackPosition, GridStackSubOptions } from './types';
+  GridStackNode, GridStackWidget, numberOrString, DDUIData, DDDragInOpt, GridStackPosition, GridStackOptions } from './types';
 
 // export all dependent file as well to make it easier for users to just import the main file
 export * from './types';
@@ -35,8 +35,7 @@ export interface CellPosition {
 }
 
 interface GridCSSStyleSheet extends CSSStyleSheet {
-  _id?: string; // random id we will use to style us
-  _max?: number; // internal tracker of the max # of rows we created\
+  _max?: number; // internal tracker of the max # of rows we created
 }
 
 /**
@@ -164,6 +163,9 @@ export class GridStack {
   protected _isNested?: GridStackNode;
   /** @internal unique class name for our generated CSS style sheet */
   protected _styleSheetClass?: string;
+  /** @internal true if we got created by drag over gesture, so we can removed on drag out (temporary) */
+  public _isTemp?: boolean;
+
 
   /** @internal create placeholder DIV as needed */
   public get placeholder(): HTMLElement {
@@ -295,7 +297,7 @@ export class GridStack {
       this.opts.alwaysShowResizeHandle = isTouch;
     }
 
-    this._styleSheetClass = 'grid-stack-instance-' + (Math.random() * 10000).toFixed(0)
+    this._styleSheetClass = 'grid-stack-instance-' + GridStackEngine._idSeq++;
     this.el.classList.add(this._styleSheetClass);
 
     this._setStaticClass();
@@ -351,7 +353,7 @@ export class GridStack {
     delete this.opts.dragInOptions;
 
     // dynamic grids require pausing during drag to detect over to nest vs push
-    if (this.opts.subGrid?.createDynamic && !DDManager.pauseDrag) DDManager.pauseDrag = true;
+    if (this.opts.subGridDynamic && !DDManager.pauseDrag) DDManager.pauseDrag = true;
     if (this.opts.draggable?.pause !== undefined) DDManager.pauseDrag = this.opts.draggable.pause;
 
     this._setupRemoveDrop();
@@ -440,15 +442,17 @@ export class GridStack {
    * @param el gridItem element to convert
    * @param ops (optional) sub-grid options, else default to node, then parent settings, else defaults
    * @param nodeToAdd (optional) node to add to the newly created sub grid (used when dragging over existing regular item)
+   * @returns newly created grid
    */
-  public makeSubGrid(el: GridItemHTMLElement, ops?: GridStackSubOptions, nodeToAdd?: GridStackNode, saveContent = true): GridStack {
+  public makeSubGrid(el: GridItemHTMLElement, ops?: GridStackOptions, nodeToAdd?: GridStackNode, saveContent = true): GridStack {
     let node = el.gridstackNode;
     if (!node) {
       node = this.makeWidget(el).gridstackNode;
     }
     if ((node.subGrid as GridStack)?.el) return node.subGrid as GridStack; // already done
 
-    ops = Utils.cloneDeep(ops || node.subGrid as GridStackOptions || this.opts.subGrid || this.opts);
+    ops = Utils.cloneDeep(ops || node.subGrid as GridStackOptions || {...this.opts.subGrid, children: undefined});
+    ops.subGrid = Utils.cloneDeep(ops); // carry nesting settings to next one down
     node.subGrid = ops;
 
     // if column special case it set, remember that flag and set default
@@ -486,27 +490,51 @@ export class GridStack {
       style.transition = 'none'; // show up instantly so we don't see scrollbar with nodeToAdd
       this.update(node.el, {w, h});
       setTimeout(() =>  style.transition = null); // recover animation
-      ops.isTemp = true; // prevent re-nesting as we add over
     }
 
-    let grid = node.subGrid = GridStack.addGrid(content, ops);
-    if (autoColumn) node.subGrid._autoColumn = true;
+    let subGrid = node.subGrid = GridStack.addGrid(content, ops);
+    if (nodeToAdd?._moving) subGrid._isTemp = true; // prevent re-nesting as we add over
+    if (autoColumn) subGrid._autoColumn = true;
 
     // add the original content back as a child of hte newly created grid
     if (saveContent) {
-      grid.addWidget(newItem, newItemOpt);
+      subGrid.addWidget(newItem, newItemOpt);
     }
 
     // now add any additional node
     if (nodeToAdd) {
       if (nodeToAdd._moving) {
         // create an artificial event even for the just created grid to receive this item
-        window.setTimeout(() => Utils.simulateMouseEvent(nodeToAdd._event, 'mouseenter', grid.el), 0);
+        window.setTimeout(() => Utils.simulateMouseEvent(nodeToAdd._event, 'mouseenter', subGrid.el), 0);
       } else {
-        grid.addWidget(node.el, node);
+        subGrid.addWidget(node.el, node);
       }
     }
-    return grid;
+    return subGrid;
+  }
+
+  /**
+   * called when an item was converted into a nested grid to accommodate a dragged over item, but then item leaves - return back
+   * to the original grid-item. Also called to remove empty sub-grids when last item is dragged out (since re-creating is simple)
+   */
+  public removeAsSubGrid(nodeThatRemoved?: GridStackNode): void {
+    let parentGrid = this._isNested?.grid;
+    if (!parentGrid) return;
+
+    parentGrid.batchUpdate();
+    parentGrid.removeWidget(this._isNested.el, true, true);
+    this.engine.nodes.forEach(n => {
+      // migrate any children over and offsetting by our location
+      n.x += this._isNested.x;
+      n.y += this._isNested.y;
+      parentGrid.addWidget(n.el, n);
+    });
+    parentGrid.batchUpdate(false);
+
+    // create an artificial event for the original grid now that this one is gone (got a leave, but won't get enter)
+    if (nodeThatRemoved) {
+      window.setTimeout(() => Utils.simulateMouseEvent(nodeThatRemoved._event, 'mouseenter', parentGrid.el), 0);
+    }
   }
 
   /**
@@ -712,7 +740,7 @@ export class GridStack {
     this.opts.cellHeight = data.h;
 
     if (update) {
-      this._updateStyles(true, this.getRow()); // true = force re-create, for that # of rows
+      this._updateStyles(true); // true = force re-create for current # of rows
     }
     return this;
   }
@@ -1218,7 +1246,7 @@ export class GridStack {
   protected _removeStylesheet(): GridStack {
 
     if (this._styles) {
-      Utils.removeStylesheet(this._styles._id);
+      Utils.removeStylesheet(this._styleSheetClass);
       delete this._styles;
     }
     return this;
@@ -1231,6 +1259,7 @@ export class GridStack {
       this._removeStylesheet();
     }
 
+    if (!maxH) maxH = this.getRow();
     this._updateContainerHeight();
 
     // if user is telling us they will handle the CSS themselves by setting heights to 0. Do we need this opts really ??
@@ -1244,12 +1273,10 @@ export class GridStack {
 
     // create one as needed
     if (!this._styles) {
-      let id = 'gridstack-style-' + (Math.random() * 100000).toFixed();
       // insert style to parent (instead of 'head' by default) to support WebComponent
       let styleLocation = this.opts.styleInHead ? undefined : this.el.parentNode as HTMLElement;
-      this._styles = Utils.createStylesheet(id, styleLocation);
+      this._styles = Utils.createStylesheet(this._styleSheetClass, styleLocation);
       if (!this._styles) return this;
-      this._styles._id = id;
       this._styles._max = 0;
 
       // these are done once only

src/types.ts

@@ -1,6 +1,6 @@
 /**
  * types.ts 6.0.2-dev
- * Copyright (c) 2021 Alain Dumesny - see GridStack root license
+ * Copyright (c) 2021-2022 Alain Dumesny - see GridStack root license
  */
 
 import { GridStack } from './gridstack';
@@ -239,15 +239,10 @@ export interface GridStackOptions {
   styleInHead?: boolean;
 
   /** list of differences in options for automatically created sub-grids under us */
-  subGrid?: GridStackSubOptions;
-}
+  subGrid?: GridStackOptions;
 
-/** additional prop that only apply to sub-grids */
-export interface GridStackSubOptions extends GridStackOptions {
   /** enable/disable the creation of sub-grids on the fly (drop over other items) */
-  createDynamic?: boolean;
-  /** true if we got created by drag over gesture, so we can removed on drag out (temporary) */
-  isTemp?: boolean;
+  subGridDynamic?: boolean;
 }
 
 /** options used during GridStackEngine.moveNode() */
@@ -311,7 +306,7 @@ export interface GridStackWidget extends GridStackPosition {
   /** html to append inside as content */
   content?: string;
   /** optional nested grid options and list of children, which then turns into actual instance at runtime */
-  subGrid?: GridStackSubOptions | GridStack;
+  subGrid?: GridStackOptions | GridStack;
 }
 
 /** Drag&Drop resize options */

src/utils.ts

@@ -1,6 +1,6 @@
 /**
  * utils.ts 6.0.2-dev
- * Copyright (c) 2021 Alain Dumesny - see GridStack root license
+ * Copyright (c) 2021-2022 Alain Dumesny - see GridStack root license
  */
 
 import { GridStackElement, GridStackNode, GridStackOptions, numberOrString, GridStackPosition, GridStackWidget } from './types';