feat: add tab drop preview indicator for split pane drag-and-drop

2026-03-18 20:09:28 +07:00
parent b763d4358e
commit ed9a15c0bd
7 changed files with 329 additions and 38 deletions
@@ -0,0 +1,55 @@
+import type { WorkspaceTabDescriptor } from "@/screens/workspace/workspace-tabs-types";
+
+export interface TabDropPreview {
+  paneId: string;
+  insertionIndex: number;
+  indicatorIndex: number;
+}
+
+interface ComputeTabDropPreviewInput {
+  activePaneId: string;
+  activeTabId: string;
+  overPaneId: string;
+  overTabId: string;
+  targetTabs: WorkspaceTabDescriptor[];
+  activeRect: {
+    left: number;
+    width: number;
+  };
+  overRect: {
+    left: number;
+    width: number;
+  };
+}
+
+export function computeTabDropPreview(
+  input: ComputeTabDropPreviewInput
+): TabDropPreview | null {
+  const targetIndex = input.targetTabs.findIndex((tab) => tab.tabId === input.overTabId);
+  if (targetIndex < 0 || input.overRect.width <= 0) {
+    return null;
+  }
+
+  const activeCenterX = input.activeRect.left + input.activeRect.width / 2;
+  const overCenterX = input.overRect.left + input.overRect.width / 2;
+  const insertAfterTarget = activeCenterX >= overCenterX;
+
+  const indicatorIndex = targetIndex + (insertAfterTarget ? 1 : 0);
+  let insertionIndex = indicatorIndex;
+  if (input.activePaneId === input.overPaneId) {
+    const sourceIndex = input.targetTabs.findIndex((tab) => tab.tabId === input.activeTabId);
+    if (sourceIndex < 0) {
+      return null;
+    }
+    if (sourceIndex < insertionIndex) {
+      insertionIndex -= 1;
+    }
+    insertionIndex = Math.max(0, Math.min(input.targetTabs.length - 1, insertionIndex));
+  }
+
+  return {
+    paneId: input.overPaneId,
+    insertionIndex,
+    indicatorIndex,
+  };
+}