feat(dees-dashboardgrid): enhance drag-and-drop functionality with preview state and previous position tracking

ts_web/elements/dees-dashboardgrid/dees-dashboardgrid.demo.ts

@@ -89,10 +89,12 @@ export const demoFunc = () => {
         grid.applyBreakpointLayout(target);
         updateStatus();
       };
-      if ('addEventListener' in mediaQuery) {
+      if (typeof mediaQuery.addEventListener === 'function') {
         mediaQuery.addEventListener('change', handleBreakpoint);
       } else {
-        mediaQuery.addListener(handleBreakpoint);
+        (mediaQuery as MediaQueryList & {
+          addListener?: (listener: (this: MediaQueryList, ev: MediaQueryListEvent) => void) => void;
+        }).addListener?.(handleBreakpoint);
       }
       handleBreakpoint();
 

ts_web/elements/dees-dashboardgrid/dees-dashboardgrid.ts

@@ -49,6 +49,7 @@ type DragState = {
   offsetX: number;
   offsetY: number;
   start: DashboardLayoutItem;
+  previousPosition: DashboardLayoutItem;
   currentPointer: PointerPosition;
   lastPlacement: PlacementResult | null;
 };
@@ -111,20 +112,23 @@ export class DeesDashboardgrid extends DeesElement {
   @state()
   private resolvedMargins: DashboardResolvedMargins | null = null;
 
+  @state()
+  private previewWidgets: DashboardWidget[] | null = null;
+
   private containerBounds: DOMRect | null = null;
   private dragState: DragState | null = null;
   private resizeState: ResizeState | null = null;
   private resizeObserver?: ResizeObserver;
   private interactionActive = false;
 
-  connectedCallback(): void {
-    super.connectedCallback();
+  public override async connectedCallback(): Promise<void> {
+    await super.connectedCallback();
     this.computeMetrics();
     this.observeResize();
   }
 
-  disconnectedCallback(): void {
-    super.disconnectedCallback();
+  public override async disconnectedCallback(): Promise<void> {
+    await super.disconnectedCallback();
     this.disconnectResizeObserver();
     this.releasePointerEvents();
   }
@@ -145,7 +149,8 @@ export class DeesDashboardgrid extends DeesElement {
   }
 
   public render(): TemplateResult {
-    if (this.widgets.length === 0) {
+    const baseWidgets = this.widgets;
+    if (baseWidgets.length === 0) {
       return html`
         <div class="empty-state">
           <dees-icon .icon=${'lucide:layoutGrid'}></dees-icon>
@@ -158,12 +163,14 @@ export class DeesDashboardgrid extends DeesElement {
     const metrics = this.ensureMetrics();
     const margins = this.resolvedMargins ?? resolveMargins(this.margin);
     const cellHeight = metrics.cellHeightPx;
-    const gridHeight = calculateGridHeight(this.widgets, margins, cellHeight);
+    const layoutForHeight = this.previewWidgets ?? this.widgets;
+    const gridHeight = calculateGridHeight(layoutForHeight, margins, cellHeight);
+    const previewMap = this.previewWidgets ? new Map(this.previewWidgets.map(widget => [widget.id, widget])) : null;
 
     return html`
       <div class="grid-container" style="height: ${gridHeight}px;">
         ${this.showGridLines ? this.renderGridLines(metrics, gridHeight) : null}
-        ${this.widgets.map(widget => this.renderWidget(widget, metrics, margins))}
+        ${baseWidgets.map(widget => this.renderWidget(widget, metrics, margins, previewMap))}
         ${this.placeholderPosition ? this.renderPlaceholder(metrics, margins) : null}
       </div>
     `;
@@ -199,11 +206,14 @@ export class DeesDashboardgrid extends DeesElement {
     widget: DashboardWidget,
     metrics: GridCellMetrics,
     margins: DashboardResolvedMargins,
+    previewMap: Map<string, DashboardWidget> | null,
   ): TemplateResult {
     const isDragging = this.dragState?.widgetId === widget.id;
     const isResizing = this.resizeState?.widgetId === widget.id;
     const isLocked = widget.locked || !this.editable;
-    const rect = this.computeWidgetRect(widget, metrics, margins);
+    const previewWidget = previewMap?.get(widget.id) ?? null;
+    const layoutForRender = isDragging ? widget : previewWidget ?? widget;
+    const rect = this.computeWidgetRect(layoutForRender, metrics, margins);
 
     const sideProperty = this.rtl ? 'right' : 'left';
     const sideValue = this.pxToPercent(rect.left, metrics.containerWidth);
@@ -322,6 +332,7 @@ export class DeesDashboardgrid extends DeesElement {
       offsetX: event.clientX - widgetRect.left,
       offsetY: event.clientY - widgetRect.top,
       start: { id: widget.id, x: widget.x, y: widget.y, w: widget.w, h: widget.h },
+      previousPosition: { id: widget.id, x: widget.x, y: widget.y, w: widget.w, h: widget.h },
       currentPointer: { clientX: event.clientX, clientY: event.clientY },
       lastPlacement: null,
     };
@@ -337,11 +348,14 @@ export class DeesDashboardgrid extends DeesElement {
   private handleDragMove = (event: PointerEvent): void => {
     if (!this.dragState) return;
     const metrics = this.ensureMetrics();
-    const widget = this.widgets.find(item => item.id === this.dragState!.widgetId);
+    const activeWidgets = this.widgets;
+    const widget = activeWidgets.find(item => item.id === this.dragState!.widgetId);
     if (!widget) return;
 
     event.preventDefault();
 
+    const previousPosition = this.dragState.previousPosition;
+
     const coords = computeGridCoordinates({
       pointer: { clientX: event.clientX, clientY: event.clientY },
       containerRect: this.containerBounds ?? this.getBoundingClientRect(),
@@ -353,14 +367,39 @@ export class DeesDashboardgrid extends DeesElement {
       dragOffsetY: this.dragState.offsetY,
     });
 
-    const placement = resolveWidgetPlacement(this.widgets, widget.id, { x: coords.x, y: coords.y }, this.columns);
+    const placement = resolveWidgetPlacement(
+      activeWidgets,
+      widget.id,
+      { x: coords.x, y: coords.y },
+      this.columns,
+      previousPosition,
+    );
     if (placement) {
+      const updatedWidget = placement.widgets.find(item => item.id === widget.id);
       this.dragState = {
         ...this.dragState,
         currentPointer: { clientX: event.clientX, clientY: event.clientY },
         lastPlacement: placement,
+        previousPosition: updatedWidget
+          ? { id: updatedWidget.id, x: updatedWidget.x, y: updatedWidget.y, w: updatedWidget.w, h: updatedWidget.h }
+          : { id: widget.id, x: coords.x, y: coords.y, w: widget.w, h: widget.h },
       };
-      this.placeholderPosition = { id: widget.id, x: coords.x, y: coords.y, w: widget.w, h: widget.h };
+      this.previewWidgets = placement.widgets;
+      const previewWidget = placement.widgets.find(item => item.id === widget.id);
+      if (previewWidget) {
+        this.placeholderPosition = {
+          id: previewWidget.id,
+          x: previewWidget.x,
+          y: previewWidget.y,
+          w: previewWidget.w,
+          h: previewWidget.h,
+        };
+      } else {
+        this.placeholderPosition = { id: widget.id, x: coords.x, y: coords.y, w: widget.w, h: widget.h };
+      }
+    } else {
+      this.previewWidgets = null;
+      this.placeholderPosition = null;
     }
 
     this.requestUpdate();
@@ -372,10 +411,18 @@ export class DeesDashboardgrid extends DeesElement {
       return;
     }
 
+    const layoutSource = this.widgets;
+    this.previewWidgets = null;
     const target = this.placeholderPosition ?? dragState.start;
     const placement =
       dragState.lastPlacement ??
-      resolveWidgetPlacement(this.widgets, dragState.widgetId, { x: target.x, y: target.y }, this.columns);
+      resolveWidgetPlacement(
+        layoutSource,
+        dragState.widgetId,
+        { x: target.x, y: target.y },
+        this.columns,
+        dragState.previousPosition,
+      );
 
     if (placement) {
       this.commitPlacement(placement, dragState.widgetId, 'widget-move');
@@ -423,7 +470,8 @@ export class DeesDashboardgrid extends DeesElement {
   private handleResizeMove = (event: PointerEvent): void => {
     if (!this.resizeState) return;
     const metrics = this.ensureMetrics();
-    const widget = this.widgets.find(item => item.id === this.resizeState!.widgetId);
+    const activeWidgets = this.widgets;
+    const widget = activeWidgets.find(item => item.id === this.resizeState!.widgetId);
     if (!widget) return;
 
     event.preventDefault();
@@ -441,15 +489,37 @@ export class DeesDashboardgrid extends DeesElement {
     });
 
     const placement = resolveWidgetPlacement(
-      this.widgets,
+      activeWidgets,
       widget.id,
       { x: widget.x, y: widget.y, w: nextSize.width, h: nextSize.height },
       this.columns,
+      this.resizeState.start,
     );
 
     if (placement) {
       this.resizeState = { ...this.resizeState, lastPlacement: placement };
-      this.placeholderPosition = { id: widget.id, x: widget.x, y: widget.y, w: nextSize.width, h: nextSize.height };
+      this.previewWidgets = placement.widgets;
+      const previewWidget = placement.widgets.find(item => item.id === widget.id);
+      if (previewWidget) {
+        this.placeholderPosition = {
+          id: previewWidget.id,
+          x: previewWidget.x,
+          y: previewWidget.y,
+          w: previewWidget.w,
+          h: previewWidget.h,
+        };
+      } else {
+        this.placeholderPosition = {
+          id: widget.id,
+          x: widget.x,
+          y: widget.y,
+          w: nextSize.width,
+          h: nextSize.height,
+        };
+      }
+    } else {
+      this.previewWidgets = null;
+      this.placeholderPosition = null;
     }
 
     this.requestUpdate();
@@ -461,7 +531,22 @@ export class DeesDashboardgrid extends DeesElement {
       return;
     }
 
-    const placement = resizeState.lastPlacement;
+    const layoutSource = this.widgets;
+    this.previewWidgets = null;
+    const placement =
+      resizeState.lastPlacement ??
+      resolveWidgetPlacement(
+        layoutSource,
+        resizeState.widgetId,
+        {
+          x: this.placeholderPosition?.x ?? resizeState.start.x,
+          y: this.placeholderPosition?.y ?? resizeState.start.y,
+          w: this.placeholderPosition?.w ?? resizeState.start.w,
+          h: this.placeholderPosition?.h ?? resizeState.start.h,
+        },
+        this.columns,
+        resizeState.start,
+      );
 
     if (placement) {
       this.commitPlacement(placement, resizeState.widgetId, 'widget-resize');
@@ -545,6 +630,7 @@ export class DeesDashboardgrid extends DeesElement {
   }
 
   private commitPlacement(result: PlacementResult, widgetId: string, type: 'widget-move' | 'widget-resize'): void {
+    this.previewWidgets = null;
     this.widgets = result.widgets;
     const subject = this.widgets.find(item => item.id === widgetId);
     if (subject) {

ts_web/elements/dees-dashboardgrid/layout.ts

@@ -129,6 +129,7 @@ export const resolveWidgetPlacement = (
   widgetId: string,
   next: { x: number; y: number; w?: number; h?: number },
   columns: number,
+  previousPosition?: DashboardLayoutItem,
 ): PlacementResult | null => {
   const sourceWidgets = cloneWidgets(widgets);
   const moving = sourceWidgets.find(widget => widget.id === widgetId);
@@ -160,8 +161,9 @@ export const resolveWidgetPlacement = (
     if (!other.locked && !other.noMove && other.w === moving.w && other.h === moving.h) {
       const otherClone = sourceWidgets.find(widget => widget.id === other.id);
       if (otherClone) {
-        otherClone.x = original.x;
-        otherClone.y = original.y;
+        const swapTarget = previousPosition ?? original;
+        otherClone.x = swapTarget.x;
+        otherClone.y = swapTarget.y;
         return { widgets: sourceWidgets, movedWidgets: [moving.id, otherClone.id], swappedWith: otherClone.id };
       }
     }