The WidgetManager is responsible for maintaining a collection of widgets, handling their input events, rendering them in the correct order, and managing their lifecycle. It provides centralized widget management with proper Z-order handling and responsive layout support.
Key Features
- Automatic widget lifecycle management
- Proper Z-order input handling (top widgets receive input first)
- Responsive layout support with window resize handling
- Singleton pattern for global access
- Memory management with shared_ptr
Widgets are rendered in the order they were added (first added = bottom layer). Input is handled in reverse order (last added = top layer receives input first).
Static Methods
getInstance()
static WidgetManager& getInstance()
Reference to the singleton instance
void addWidget(std::shared_ptr<Widget> widget)
widget
std::shared_ptr<Widget>
required
Shared pointer to the widget to add
auto button = Button(ButtonConfig(0, 0, 100, 30, "Click"));
WidgetManager::getInstance().addWidget(button);
void removeWidget(std::shared_ptr<Widget> widget)
widget
std::shared_ptr<Widget>
required
Shared pointer to the widget to remove
If the widget is not found, this method does nothing.
clear()
Clears the entire widget collection. All widgets will be removed and will no longer be rendered or receive input events.
This is useful for scene transitions or cleanup. The widgets themselves are not destroyed if other references exist.
updateAll()
void updateAll(const InputState& input)
input
const InputState&
required
Current input state containing mouse and keyboard info
Call this every frame before rendering to handle user interaction. Input propagation stops at the first widget that handles the event.
renderAll()
Renders all widgets in the order they were added (first added = bottom layer). This creates the proper visual layering where newer widgets appear on top.
Call this every frame after updating to draw all widgets. Widgets are responsible for their own rendering logic.
Responsive Layout
onWindowResize()
void onWindowResize(int newWidth, int newHeight)
New window width in pixels
New window height in pixels
Only widgets that inherit from ResponsiveWidget will be notified.
refreshLayout()
Triggers a layout refresh using the current canvas dimensions. This is useful when you need to force a layout update without an actual window resize event.
getCanvasWidth()
int getCanvasWidth() const
Current canvas width in pixels
Deprecated: Use Fern::getWidth() instead for accurate dimensions.
getCanvasHeight()
int getCanvasHeight() const
Current canvas height in pixels
Deprecated: Use Fern::getHeight() instead for accurate dimensions.
Helper Functions
void addWidget(std::shared_ptr<Widget> widget)
widget
std::shared_ptr<Widget>
required
Shared pointer to the widget to add
auto button = Button(ButtonConfig(0, 0, 100, 30, "Click"));
addWidget(button); // Equivalent to WidgetManager::getInstance().addWidget(button)
void removeWidget(std::shared_ptr<Widget> widget)
widget
std::shared_ptr<Widget>
required
Shared pointer to the widget to remove
Example Usage
auto button = Button(ButtonConfig(100, 100, 120, 40, "Click Me"));
WidgetManager::getInstance().addWidget(button);
// In your main loop:
WidgetManager::getInstance().updateAll(inputState);
WidgetManager::getInstance().renderAll();
// Clean up when transitioning scenes:
WidgetManager::getInstance().clear();
Z-Order Example
// Background widget (rendered first, receives input last)
auto background = Container(0, 0, 800, 600, Colors::Gray);
addWidget(background);
// Button widget (rendered second, receives input first)
auto button = Button(ButtonConfig(100, 100, 120, 40, "Click"));
addWidget(button);
// The button will receive input events before the background
// and will be rendered on top of the background