PixelPaint: Add "Clear Guides" to remove all Guides

This patch adds a "Clear Guides" option to the "View"-menu.

Userland/Applications/PixelPaint/ImageEditor.h

@@ -45,6 +45,7 @@ public:
     {
         m_guides.remove_first_matching([&](auto& entry) { return &guide == entry.ptr(); });
     }
+    void clear_guides() { m_guides.clear(); }
 
     void layers_did_change();
 

Userland/Applications/PixelPaint/MainWidget.cpp

@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
  * Copyright (c) 2021, Mustafa Quraish <mustafa@cs.toronto.edu>
+ * Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -351,6 +352,12 @@ void MainWidget::initialize_menubar(GUI::Window& window)
     view_menu.add_action(*m_add_guide_action);
     view_menu.add_action(*m_show_guides_action);
 
+    view_menu.add_action(GUI::Action::create(
+        "Clear Guides", [&](auto&) {
+            if (auto* editor = current_image_editor())
+                editor->clear_guides();
+        }));
+
     auto& tool_menu = window.add_menu("&Tool");
     m_toolbox->for_each_tool([&](auto& tool) {
         if (tool.action())
@@ -818,5 +825,4 @@ void MainWidget::drop_event(GUI::DropEvent& event)
         open_image_fd(*result.fd, *result.chosen_file);
     }
 }
-
 }