Multi-selection

src/lib/Canvas.svelte

@@ -30,7 +30,7 @@
 
 	function handleMouseUp(e: MouseEvent) {
 		if (isPanning && !hasPanned && e.target === container) {
-			state.select(null);
+			state.clearSelection();
 			state.focus(null);
 		}
 		isPanning = false;
@@ -142,38 +142,50 @@
 		const centerX = (rect.width / 2 - state.viewport.x) / state.viewport.zoom;
 		const centerY = (rect.height / 2 - state.viewport.y) / state.viewport.zoom;
 
-		if (mod && e.key === 'c' && state.selectedId) {
+		const hasSelection = state.selectedIds.size > 0;
+		const singleSelection = state.selectedIds.size === 1;
+		const firstSelectedId = singleSelection ? [...state.selectedIds][0] : null;
+
+		if (mod && e.key === 'c' && hasSelection) {
 			e.preventDefault();
-			state.copyItem(state.selectedId);
+			state.copySelected();
 		} else if (mod && e.key === 'v') {
 			e.preventDefault();
-			const newId = state.pasteItem(centerX, centerY);
+			const newIds = state.pasteItems(centerX, centerY);
-			if (newId) state.select(newId);
+			if (newIds.length > 0) state.select(newIds[0]);
-		} else if (mod && e.key === 'd' && state.selectedId) {
+			for (let i = 1; i < newIds.length; i++) {
+				state.toggleSelection(newIds[i]);
+			}
+		} else if (mod && e.key === 'd' && hasSelection) {
 			e.preventDefault();
-			const newId = state.duplicateItem(state.selectedId, centerX, centerY);
+			const newIds = state.duplicateSelected(centerX, centerY);
-			if (newId) state.select(newId);
+			if (newIds.length > 0) state.select(newIds[0]);
+			for (let i = 1; i < newIds.length; i++) {
+				state.toggleSelection(newIds[i]);
+			}
 		} else if (e.key === 'Escape') {
-			state.select(null);
+			state.clearSelection();
 			state.focus(null);
-		} else if (e.key === '[' && state.selectedId) {
+		} else if (e.key === '[' && hasSelection) {
 			e.preventDefault();
-			state.sendBackward(state.selectedId);
+			for (const id of state.selectedIds) {
-		} else if (e.key === ']' && state.selectedId) {
+				state.sendBackward(id);
+			}
+		} else if (e.key === ']' && hasSelection) {
 			e.preventDefault();
-			state.bringForward(state.selectedId);
+			for (const id of state.selectedIds) {
-		} else if (e.key.startsWith('Arrow') && state.selectedId) {
+				state.bringForward(id);
+			}
+		} else if (e.key.startsWith('Arrow') && hasSelection) {
 			e.preventDefault();
 			const step = e.shiftKey ? 10 : 1;
-			const item = state.getItem(state.selectedId);
-			if (!item) return;
 			const dx = e.key === 'ArrowLeft' ? -step : e.key === 'ArrowRight' ? step : 0;
 			const dy = e.key === 'ArrowUp' ? -step : e.key === 'ArrowDown' ? step : 0;
-			state.updateItem(state.selectedId, { x: item.x + dx, y: item.y + dy });
+			state.moveSelected(dx, dy);
-		} else if (e.key === 'e' && state.selectedId && !mod) {
+		} else if (e.key === 'e' && singleSelection && !mod) {
 			e.preventDefault();
-			state.focus(state.selectedId);
+			state.focus(firstSelectedId!);
-			state.edit(state.selectedId);
+			state.edit(firstSelectedId!);
 		}
 	}
 </script>

src/lib/Item.svelte

@@ -5,12 +5,13 @@
 
 	let { item }: { item: Item } = $props();
 
-	let isSelected = $derived(appState.selectedId === item.id);
+	let isSelected = $derived(appState.selectedIds.has(item.id));
 	let isFocused = $derived(appState.focusedId === item.id);
 	let isDragging = $state(false);
 	let isResizing = $state(false);
 	let isRotating = $state(false);
 	let dragStart = { x: 0, y: 0, itemX: 0, itemY: 0 };
+	let dragStartPositions: Map<string, { x: number; y: number }> = new Map();
 	let resizeStart = { x: 0, y: 0, width: 0, height: 0, itemX: 0, itemY: 0, corner: '', aspectRatio: 1 };
 	let rotateStart = { angle: 0, startAngle: 0 };
 
@@ -39,8 +40,13 @@
 		if (e.button !== 0) return;
 		if (isFocused) return;
 		e.stopPropagation();
+
+		if (e.shiftKey) {
+			appState.toggleSelection(item.id);
+		} else if (!isSelected) {
 			appState.select(item.id);
 			appState.bringToFront(item.id);
+		}
 
 		isDragging = true;
 		dragStart = {
@@ -49,6 +55,13 @@
 			itemX: item.x,
 			itemY: item.y
 		};
+		dragStartPositions = new Map();
+		for (const id of appState.selectedIds) {
+			const selectedItem = appState.getItem(id);
+			if (selectedItem) {
+				dragStartPositions.set(id, { x: selectedItem.x, y: selectedItem.y });
+			}
+		}
 	}
 
 	function handleResizeStart(e: MouseEvent, corner: string) {
@@ -84,10 +97,12 @@
 		if (isDragging) {
 			const dx = (e.clientX - dragStart.x) / appState.viewport.zoom;
 			const dy = (e.clientY - dragStart.y) / appState.viewport.zoom;
-			appState.updateItem(item.id, {
+			for (const [id, startPos] of dragStartPositions) {
-				x: dragStart.itemX + dx,
+				appState.updateItem(id, {
-				y: dragStart.itemY + dy
+					x: startPos.x + dx,
+					y: startPos.y + dy
 				});
+			}
 		} else if (isResizing) {
 			const dx = (e.clientX - resizeStart.x) / appState.viewport.zoom;
 			const dy = (e.clientY - resizeStart.y) / appState.viewport.zoom;
@@ -147,7 +162,7 @@
 		if (tag === 'INPUT' || tag === 'TEXTAREA') return;
 		if ((e.target as HTMLElement)?.isContentEditable) return;
 		if (e.key === 'Delete' || e.key === 'Backspace') {
-			appState.removeItem(item.id);
+			appState.removeSelected();
 		}
 	}
 

src/lib/state.svelte.ts

@@ -72,11 +72,11 @@ function createState() {
 	});
 	let assets = $state<AssetStore>({});
 	let viewport = $state<Viewport>({ x: 0, y: 0, zoom: 1 });
-	let selectedId = $state<string | null>(null);
+	let selectedIds = $state<Set<string>>(new Set());
 	let editingId = $state<string | null>(null);
 	let editingGlobal = $state<boolean>(false);
 	let focusedId = $state<string | null>(null);
-	let clipboard = $state<Omit<Item, 'id'> | null>(null);
+	let clipboard = $state<Omit<Item, 'id'>[]>([]);
 
 	let saveTimeout: ReturnType<typeof setTimeout> | null = null;
 	let animationId: number | null = null;
@@ -153,7 +153,7 @@ function createState() {
 			delete assets[item.assetId];
 		}
 		manifest.items.splice(idx, 1);
-		if (selectedId === id) selectedId = null;
+		selectedIds.delete(id);
 		if (editingId === id) editingId = null;
 		save();
 	}
@@ -168,7 +168,21 @@ function createState() {
 	}
 
 	function select(id: string | null) {
-		selectedId = id;
+		selectedIds = new Set(id ? [id] : []);
+	}
+
+	function toggleSelection(id: string) {
+		const newSet = new Set(selectedIds);
+		if (newSet.has(id)) {
+			newSet.delete(id);
+		} else {
+			newSet.add(id);
+		}
+		selectedIds = newSet;
+	}
+
+	function clearSelection() {
+		selectedIds = new Set();
 	}
 
 	function edit(id: string | null) {
@@ -202,24 +216,48 @@ function createState() {
 		save();
 	}
 
-	function copyItem(id: string) {
+	function copySelected() {
-		const item = manifest.items.find((i) => i.id === id);
+		if (selectedIds.size === 0) return;
-		if (!item) return;
+		const items = manifest.items.filter((i) => selectedIds.has(i.id));
-		const { id: _, ...rest } = item;
+		clipboard = items.map(({ id, ...rest }) => rest);
-		clipboard = rest;
 	}
 
-	function pasteItem(x: number, y: number): string | null {
+	function pasteItems(x: number, y: number): string[] {
-		if (!clipboard) return null;
+		if (clipboard.length === 0) return [];
+		const newIds: string[] = [];
+		const centerX = clipboard.reduce((sum, i) => sum + i.x, 0) / clipboard.length;
+		const centerY = clipboard.reduce((sum, i) => sum + i.y, 0) / clipboard.length;
+		for (const item of clipboard) {
 			const id = crypto.randomUUID();
-		const newItem = { ...clipboard, id, x, y, zIndex: maxZIndex + 1 };
+			const offsetX = item.x - centerX;
-		addItem(newItem);
+			const offsetY = item.y - centerY;
-		return id;
+			addItem({ ...item, id, x: x + offsetX, y: y + offsetY, zIndex: maxZIndex + 1 });
+			newIds.push(id);
+		}
+		return newIds;
 	}
 
-	function duplicateItem(id: string, x: number, y: number): string | null {
+	function duplicateSelected(x: number, y: number): string[] {
-		copyItem(id);
+		copySelected();
-		return pasteItem(x, y);
+		return pasteItems(x, y);
+	}
+
+	function removeSelected() {
+		const ids = [...selectedIds];
+		for (const id of ids) {
+			removeItem(id);
+		}
+	}
+
+	function moveSelected(dx: number, dy: number) {
+		for (const id of selectedIds) {
+			const item = manifest.items.find((i) => i.id === id);
+			if (item) {
+				item.x += dx;
+				item.y += dy;
+			}
+		}
+		save();
 	}
 
 	function sendBackward(id: string) {
@@ -324,7 +362,7 @@ function createState() {
 		};
 		assets = {};
 		viewport = { x: 0, y: 0, zoom: 1 };
-		selectedId = null;
+		selectedIds = new Set();
 		editingId = null;
 		editingGlobal = false;
 		focusedId = null;
@@ -336,7 +374,7 @@ function createState() {
 		manifest = newManifest;
 		assets = newAssets;
 		viewport = { x: 0, y: 0, zoom: 1 };
-		selectedId = null;
+		selectedIds = new Set();
 		editingId = null;
 		editingGlobal = false;
 		focusedId = null;
@@ -355,8 +393,8 @@ function createState() {
 		get viewport() {
 			return viewport;
 		},
-		get selectedId() {
+		get selectedIds() {
-			return selectedId;
+			return selectedIds;
 		},
 		get editingId() {
 			return editingId;
@@ -376,15 +414,19 @@ function createState() {
 		addAsset,
 		getItem,
 		select,
+		toggleSelection,
+		clearSelection,
 		edit,
 		editGlobal,
 		focus,
 		updateSharedCss,
 		updateAppCss,
 		bringToFront,
-		copyItem,
+		copySelected,
-		pasteItem,
+		pasteItems,
-		duplicateItem,
+		duplicateSelected,
+		removeSelected,
+		moveSelected,
 		sendBackward,
 		bringForward,
 		pan,