Implement basic focus.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/1929cb6b714

Widgets/Widget.cpp

@@ -120,3 +120,16 @@ void Widget::setWindow(Window* window)
         return;
     m_window = window;
 }
+
+bool Widget::isFocused() const
+{
+    return m_window && m_window->focusedWidget() == this;
+}
+
+void Widget::setFocus(bool focus)
+{
+    if (focus == isFocused())
+        return;
+    if (m_window)
+        m_window->setFocusedWidget(this);
+}

Widgets/Widget.h

@@ -36,6 +36,9 @@ public:
     void update();
     void repaint(const Rect&);
 
+    bool isFocused() const;
+    void setFocus(bool);
+
     struct HitTestResult {
         Widget* widget { nullptr };
         int localX { 0 };

Widgets/Window.cpp

@@ -83,6 +83,12 @@ void Window::event(Event& event)
         return Object::event(event);
     }
 
+    if (event.isKeyEvent()) {
+        if (m_focusedWidget)
+            return m_focusedWidget->event(event);
+        return Object::event(event);
+    }
+
     return Object::event(event);
 }
 
@@ -91,3 +97,14 @@ bool Window::isActive() const
     return WindowManager::the().activeWindow() == this;
 }
 
+void Window::setFocusedWidget(Widget* widget)
+{
+    if (m_focusedWidget.ptr() == widget)
+        return;
+    if (!widget) {
+        m_focusedWidget = nullptr;
+        return;
+    }
+    m_focusedWidget = widget->makeWeakPtr();
+}
+

Widgets/Window.h

@@ -1,8 +1,9 @@
 #pragma once
 
-#include <AK/String.h>
 #include "Object.h"
 #include "Rect.h"
+#include <AK/String.h>
+#include <AK/WeakPtr.h>
 
 class Widget;
 
@@ -39,10 +40,15 @@ public:
 
     bool isActive() const;
 
+    Widget* focusedWidget() { return m_focusedWidget.ptr(); }
+    void setFocusedWidget(Widget*);
+
 private:
     String m_title;
     Rect m_rect;
     Widget* m_mainWidget { nullptr };
     bool m_isBeingDragged { false };
+
+    WeakPtr<Widget> m_focusedWidget;
 };
 

Widgets/WindowManager.cpp

@@ -254,9 +254,10 @@ void WindowManager::event(Event& event)
         return processMouseEvent(static_cast<MouseEvent&>(event));
 
     if (event.isKeyEvent()) {
-        // FIXME: Implement proper focus.
-        Widget* focusedWidget = g_tw;
-        return focusedWidget->event(event);
+        // FIXME: This is a good place to hook key events globally. :)
+        if (m_activeWindow)
+            return m_activeWindow->event(event);
+        return Object::event(event);
     }
 
     if (event.isPaintEvent())

Widgets/test.cpp

@@ -80,6 +80,7 @@ int main(int argc, char** argv)
 
     auto* t = new TerminalWidget(nullptr);
     win->setMainWidget(t);
+    t->setFocus(true);
 
     auto* clockWin = new Window;
     clockWin->setTitle("Clock");