ImageViewer: Disable image actions when there is no image

Previously some actions like Rotate/Flip/Set as Desktop Wallpaper would
make the application crash if no image was loaded. Now image actions are
enabled/disabled based on whether an image has been loaded or not.

Userland/Applications/ImageViewer/ViewWidget.cpp

@@ -32,6 +32,8 @@ ViewWidget::~ViewWidget()
 void ViewWidget::clear()
 {
  m_bitmap = nullptr;
+ if (on_image_change)
+ on_image_change(m_bitmap);
  m_path = {};
 
  reset_view();
@@ -255,6 +257,8 @@ void ViewWidget::load_from_file(const String& path)
 
  m_decoded_image = decoded_image_or_error.release_value();
  m_bitmap = m_decoded_image->frames[0].bitmap;
+ if (on_image_change)
+ on_image_change(m_bitmap);
 
  if (m_decoded_image->is_animated && m_decoded_image->frames.size() > 1) {
  const auto& first_frame = m_decoded_image->frames[0];

Userland/Applications/ImageViewer/ViewWidget.h

@@ -42,6 +42,7 @@ class ViewWidget final : public GUI::Frame {
  Function<void(int, Gfx::IntRect)> on_scale_change;
  Function<void()> on_doubleclick;
  Function<void(const GUI::DropEvent&)> on_drop;
+ Function<void(const Gfx::Bitmap*)> on_image_change;
 
 private:
  ViewWidget();

Userland/Applications/ImageViewer/main.cpp

@@ -205,7 +205,7 @@ int main(int argc, char** argv)
  widget.navigate(ViewWidget::Directions::Last);
  });
 
- auto full_sceen_action = GUI::CommonActions::make_fullscreen_action(
+ auto full_screen_action = GUI::CommonActions::make_fullscreen_action(
  [&](auto&) {
  widget.on_doubleclick();
  });
@@ -238,6 +238,26 @@ int main(int argc, char** argv)
  GUI::Clipboard::the().set_bitmap(*widget.bitmap());
  });
 
+ widget.on_image_change = [&](const Gfx::Bitmap* bitmap) {
+ bool should_enable_image_actions = (bitmap != nullptr);
+ delete_action->set_enabled(should_enable_image_actions);
+ rotate_left_action->set_enabled(should_enable_image_actions);
+ rotate_right_action->set_enabled(should_enable_image_actions);
+ vertical_flip_action->set_enabled(should_enable_image_actions);
+ horizontal_flip_action->set_enabled(should_enable_image_actions);
+ desktop_wallpaper_action->set_enabled(should_enable_image_actions);
+ go_first_action->set_enabled(should_enable_image_actions);
+ go_back_action->set_enabled(should_enable_image_actions);
+ go_forward_action->set_enabled(should_enable_image_actions);
+ go_last_action->set_enabled(should_enable_image_actions);
+ zoom_in_action->set_enabled(should_enable_image_actions);
+ reset_zoom_action->set_enabled(should_enable_image_actions);
+ zoom_out_action->set_enabled(should_enable_image_actions);
+ if (!should_enable_image_actions) {
+ window->set_title("Image Viewer");
+ }
+ };
+
  main_toolbar.add_action(open_action);
  main_toolbar.add_action(delete_action);
  main_toolbar.add_separator();
@@ -273,7 +293,7 @@ int main(int argc, char** argv)
  navigate_menu.add_action(go_last_action);
 
  auto& view_menu = menubar->add_menu("&View");
- view_menu.add_action(full_sceen_action);
+ view_menu.add_action(full_screen_action);
  view_menu.add_separator();
  view_menu.add_action(zoom_in_action);
  view_menu.add_action(reset_zoom_action);
@@ -291,6 +311,8 @@ int main(int argc, char** argv)
 
  if (path != nullptr) {
  widget.load_from_file(path);
+ } else {
+ widget.clear();
  }
 
  window->show();