feat(viewport): add fit artboard command

commands/viewport.ts

@@ -1,3 +1,4 @@
+import type { ArtboardId } from "@core/id";
 import type { Vec2D } from "@core/geometry";
 import type { Command } from "./command";
 import { commandIds } from "./ids";
@@ -20,6 +21,11 @@ export type ViewportSetSizePayload = {
   h: number;
 };
 
+export type ViewportFitArtboardPayload = {
+  artboardId?: ArtboardId;
+  padding?: number;
+};
+
 export const viewportPanCommand: Command<ViewportPanPayload> = {
   id: commandIds.viewportPan,
   name: "Pan viewport",
@@ -111,6 +117,40 @@ export const viewportSetSizeCommand: Command<ViewportSetSizePayload> = {
   },
 };
 
+export const viewportFitArtboardCommand: Command<ViewportFitArtboardPayload | undefined> = {
+  id: commandIds.viewportFitArtboard,
+  name: "Fit artboard in viewport",
+  execute({ state }, payload) {
+    const artboardId = payload?.artboardId ?? state.editor.selection.artboardId;
+    const artboard = artboardId
+      ? state.document.artboards.find((candidate) => candidate.id === artboardId)
+      : state.document.artboards[0];
+
+    if (!artboard) return state;
+
+    const padding = Math.max(0, payload?.padding ?? 48);
+    const availableWidth = Math.max(0, state.editor.viewport.size.w - padding * 2);
+    const availableHeight = Math.max(0, state.editor.viewport.size.h - padding * 2);
+    const canFitZoom = availableWidth > 0 && availableHeight > 0 && artboard.bounds.w > 0 && artboard.bounds.h > 0;
+    const zoom = canFitZoom ? Math.max(0.01, Math.min(availableWidth / artboard.bounds.w, availableHeight / artboard.bounds.h)) : state.editor.viewport.zoom;
+
+    return {
+      ...state,
+      editor: {
+        ...state.editor,
+        viewport: {
+          ...state.editor.viewport,
+          center: {
+            x: artboard.bounds.x + artboard.bounds.w / 2,
+            y: artboard.bounds.y + artboard.bounds.h / 2,
+          },
+          zoom,
+        },
+      },
+    };
+  },
+};
+
 export const viewportResetCommand: Command = {
   id: commandIds.viewportReset,
   name: "Reset viewport",
@@ -135,5 +175,6 @@ export const viewportCommands = [
   viewportSetZoomCommand,
   viewportZoomAroundPointCommand,
   viewportSetSizeCommand,
+  viewportFitArtboardCommand,
   viewportResetCommand,
 ] satisfies Command<unknown>[];