Update README.md

Author: woshimajintao

annotation_tool/ui/common/README.md

@@ -1,45 +1,59 @@
 # 🛠️ Common UI Components
 
-This directory contains **shared interface widgets** that are used across multiple modes of the application (both Classification and Localization). 
+This directory contains **shared interface widgets and layout containers** used across the application. 
 
-The goal of this module is to adhere to the **DRY (Don't Repeat Yourself)** principle and ensure a consistent user experience regardless of the active task.
+The goal of this module is to adhere to the **DRY (Don't Repeat Yourself)** principle, ensuring a consistent user experience and architecture for both **Classification** and **Localization** tasks.
 
-## 📂 Files
+## 📂 Structural Components
 
-### 1. `dialogs.py`
+### 1. `main_window.py`
+* **Purpose:** The top-level UI container for the application.
+* **Key Class:** **`MainWindowUI`**
+    * Uses a `QStackedLayout` to manage the high-level views.
+    * **View 0:** `WelcomeWidget` (Entry screen).
+    * **View 1:** `Classification` Interface (assembled via `UnifiedTaskPanel`).
+    * **View 2:** `Localization` Interface (assembled via `UnifiedTaskPanel`).
 
-* **Purpose:** Contains modal dialog windows used during project initialization and configuration.
-* **Key Classes:**
-    * **`ProjectTypeDialog`**: A simple selection window asking the user to choose between "Classification" or "Localization" modes.
-    * **`CreateProjectDialog`**: A comprehensive wizard for setting up new projects. It handles:
-        * Task Name and Description input.
-        * Modality selection (Video/Image/Audio).
-        * **Dynamic Schema Creation**: Allows users to define Categories (Heads) and Labels interactively.
-    * **`FolderPickerDialog`**: A specialized file tree widget that allows selecting multiple folders via checkboxes (solving the UX issue of requiring `Ctrl+Click` in standard dialogs).
+### 2. `workspace.py`
+* **Purpose:** Defines the generic layout skeleton used by specific tasks.
+* **Key Class:** **`UnifiedTaskPanel`**
+    * Implements the standard **3-Column Layout** strategy:
+        * **Left (Fixed):** `CommonProjectTreePanel` (Shared resource list).
+        * **Center (Expandable):** Task-specific visualizer (e.g., Media Player).
+        * **Right (Fixed):** Task-specific editor (e.g., Annotation Editor).
+    * This ensures both modes look visually consistent while hosting different logic.
 
 ---
 
-### 2. `project_controls.py`
-
-This file contains widgets responsible for the control and navigation of the project workspace.
-
-#### **Class: `UnifiedProjectControls`**
-* **Purpose:** Provides a standardized **Project Management Panel** to handle the application lifecycle.
-* **Layout:** A 3x2 Grid Layout containing the following essential buttons:
-    * **Row 1:** `New Project`, `Load Project`
-    * **Row 2:** `Add Data`, `Close Project`
-    * **Row 3:** `Save`, `Export`
-* **Signal Interface:**
-    * `createRequested`, `loadRequested`, `addVideoRequested`
-    * `closeRequested`, `saveRequested`, `exportRequested`
-
-#### **Class: `UnifiedClipExplorer`**
-* **Purpose:** A unified widget to display and manage the list of imported video clips/actions.
-* **Components:**
-    * **Clip Tree:** Displays the file list with status icons (Done/Not Done).
-    * **Filter:** A ComboBox to filter the list by status.
-    * **Clear Button:** Allows removing all items from the workspace.
-* **Signal Interface:**
-    * `requestRemoveItem(QTreeWidgetItem)`: Triggered via right-click context menu.
-    * `filterChanged(int)`: Triggered when the filter combo box is changed.
-    * `clearRequested()`: Triggered when the "Clear List" button is clicked.
+## 📂 Widget Components
+
+### 3. `clip_explorer.py`
+* **Purpose:** The standardized **Left Sidebar** for resource management.
+* **Key Class:** **`CommonProjectTreePanel`**
+    * **Composition:**
+        * Embeds `UnifiedProjectControls` at the top.
+        * Contains a `QTreeWidget` to display videos/clips.
+        * Contains a bottom row with a **Filter ComboBox** and a **Clear Button**.
+    * **Customization:** Accepts parameters for `tree_title` and `filter_items` to adapt text for Classification ("Actions") vs. Localization ("Clips").
+    * **Signals:**
+        * `request_remove_item(QTreeWidgetItem)`: Emitted via context menu.
+
+### 4. `project_controls.py`
+* **Purpose:** A reusable button grid for project lifecycle management.
+* **Key Class:** **`UnifiedProjectControls`**
+    * **Layout:** A 3x2 Grid containing 6 essential buttons:
+        * `New Project`, `Load Project`
+        * `Add Data`, `Close Project`
+        * `Save`, `Export`
+    * **Signals:** `createRequested`, `loadRequested`, `addVideoRequested`, `closeRequested`, `saveRequested`, `exportRequested`.
+
+### 5. `dialogs.py`
+* **Purpose:** Modal dialogs for configuration and initialization.
+* **Key Classes:**
+    * **`ProjectTypeDialog`**: Selection window for choosing between Classification/Localization modes.
+    * **`CreateProjectDialog`**: A wizard for setting up new projects (Task Name, Modality, Description, and **Dynamic Schema Editor**).
+    * **`FolderPickerDialog`**: A custom file tree allowing multi-folder selection via checkboxes (optimizing UX over standard OS dialogs).
+
+### 6. `welcome_widget.py`
+* **Purpose:** The landing screen displayed when no project is open.
+* **Features:** Provides large, clear entry points to **"Create New Project"** or **"Import Existing Project"**.