libui: Allow not filling the window with a background color every time

libui/include/ui/Window.h

@@ -62,7 +62,7 @@ namespace ui
         int m_id;
         Canvas m_canvas;
         Widget* m_main_widget { nullptr };
-        Color m_background { ui::BLACK };
+        Option<Color> m_background {};
         Option<int> m_old_mouse_buttons;
     };
 }

libui/src/Window.cpp

@@ -74,7 +74,7 @@ namespace ui
 
     Result<void> Window::draw()
     {
-        m_canvas.fill(m_background);
+        if (m_background.has_value()) m_canvas.fill(*m_background);
         if (m_main_widget) TRY(m_main_widget->draw(m_canvas));
         update();
         return {};

terminal/TerminalWidget.cpp

@@ -46,10 +46,8 @@ Result<void> TerminalWidget::init(char* const* args)
     m_font = ui::Font::default_font();
     m_bold_font = ui::Font::default_bold_font();
 
-    m_terminal_canvas = ui::Canvas { .width = m_rect.width,
-                                     .height = m_rect.height,
-                                     .stride = m_rect.width,
-                                     .ptr = (u8*)TRY(calloc_impl(m_rect.width, m_rect.height * sizeof(u32), false)) };
+    m_terminal_canvas = ui::App::the().main_window()->canvas();
+    m_terminal_canvas.fill(ui::BLACK);
 
     signal(SIGCHLD, sigchld_handler);
 
@@ -213,13 +211,12 @@ Result<ui::EventResult> TerminalWidget::handle_key_event(const ui::KeyEventReque
     return ui::EventResult::DidHandle;
 }
 
-Result<void> TerminalWidget::draw(ui::Canvas& canvas)
+Result<void> TerminalWidget::draw(ui::Canvas&)
 {
-    canvas.fill((u32*)m_terminal_canvas.ptr, m_terminal_canvas.stride);
     return {};
 }
 
-Result<void> TerminalWidget::process()
+Result<bool> TerminalWidget::process()
 {
     char buffer[BUFSIZ];
     ssize_t nread = read(m_pty, buffer, BUFSIZ);
@@ -238,7 +235,7 @@ Result<void> TerminalWidget::process()
 
     if (should_update_cursor || nread > 0) ui::App::the().main_window()->draw();
 
-    return {};
+    return nread == 0;
 }
 
 bool TerminalWidget::tick_cursor()

terminal/TerminalWidget.h

@@ -16,7 +16,7 @@ class TerminalWidget : public ui::Widget
 
     Result<void> draw(ui::Canvas& canvas) override;
 
-    Result<void> process();
+    Result<bool> process();
 
     void quit();
 

terminal/main.cpp

@@ -11,7 +11,6 @@ Result<int> luna_main(int argc, char** argv)
 
     auto* window = TRY(ui::Window::create(ui::Rect { 150, 150, 640, 400 }));
     app.set_main_window(window);
-    window->set_background(ui::BLACK);
     window->set_title("Terminal");
 
     TerminalWidget terminal;
@@ -24,8 +23,8 @@ Result<int> luna_main(int argc, char** argv)
 
     while (app.process_events())
     {
-        TRY(terminal.process());
-        usleep(10000);
+        bool should_sleep = TRY(terminal.process());
+        if (should_sleep) usleep(10000);
     }
 
     terminal.quit();