From 22585e2845c0b9a3ea7799f576239a5478a18050 Mon Sep 17 00:00:00 2001
From: Davipb <daviparca@gmail.com>
Date: Sun, 20 Jun 2021 10:53:41 -0300
Subject: [PATCH] PixelPaint: Expose more complex selection operations

Now that we use RectMask internally to store the selection, we can
expose more powerful APIs to allow for better control over the image
selection.
---
 .../PixelPaint/RectangleSelectTool.cpp        |  2 +-
 .../Applications/PixelPaint/Selection.cpp     | 20 +++++++++++++++++++
 Userland/Applications/PixelPaint/Selection.h  | 17 +++++++++++++++-
 Userland/Applications/PixelPaint/main.cpp     |  2 +-
 4 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/Userland/Applications/PixelPaint/RectangleSelectTool.cpp b/Userland/Applications/PixelPaint/RectangleSelectTool.cpp
index 66b541405f5..70d0c366a76 100644
--- a/Userland/Applications/PixelPaint/RectangleSelectTool.cpp
+++ b/Userland/Applications/PixelPaint/RectangleSelectTool.cpp
@@ -60,7 +60,7 @@ void RectangleSelectTool::on_mouseup(Layer&, GUI::MouseEvent&, GUI::MouseEvent&
     m_editor->update();
 
     auto rect_in_image = Gfx::IntRect::from_two_points(m_selection_start, m_selection_end);
-    m_editor->selection().set(rect_in_image);
+    m_editor->selection().merge(rect_in_image, Selection::MergeMode::Set);
 }
 
 void RectangleSelectTool::on_keydown(GUI::KeyEvent& key_event)
diff --git a/Userland/Applications/PixelPaint/Selection.cpp b/Userland/Applications/PixelPaint/Selection.cpp
index 776999069c2..dc1e9e08387 100644
--- a/Userland/Applications/PixelPaint/Selection.cpp
+++ b/Userland/Applications/PixelPaint/Selection.cpp
@@ -107,6 +107,26 @@ void Selection::clear()
     m_editor.update();
 }
 
+void Selection::merge(Mask const& mask, MergeMode mode)
+{
+    switch (mode) {
+    case MergeMode::Set:
+        m_mask = mask;
+        break;
+    case MergeMode::Add:
+        m_mask.add(mask);
+        break;
+    case MergeMode::Subtract:
+        m_mask.subtract(mask);
+        break;
+    case MergeMode::Intersect:
+        m_mask.intersect(mask);
+        break;
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
 void Selection::draw_marching_ants_pixel(Gfx::Painter& painter, int x, int y) const
 {
     int pattern_index = x + y + m_marching_ants_offset;
diff --git a/Userland/Applications/PixelPaint/Selection.h b/Userland/Applications/PixelPaint/Selection.h
index f521421f7fe..4080b9c09ea 100644
--- a/Userland/Applications/PixelPaint/Selection.h
+++ b/Userland/Applications/PixelPaint/Selection.h
@@ -18,13 +18,28 @@ class ImageEditor;
 // Coordinates are image-relative.
 class Selection {
 public:
+    enum class MergeMode {
+        Set,
+        Add,
+        Subtract,
+        Intersect,
+        __Count,
+    };
+
     explicit Selection(ImageEditor&);
 
     bool is_empty() const { return m_mask.is_null(); }
     void clear();
-    void set(Gfx::IntRect const& rect) { m_mask = Mask::full(rect); }
+    void merge(Mask const&, MergeMode);
+    void merge(Gfx::IntRect const& rect, MergeMode mode) { merge(Mask::full(rect), mode); }
     Gfx::IntRect bounding_rect() const { return m_mask.bounding_rect(); }
 
+    [[nodiscard]] bool is_selected(int x, int y) const { return m_mask.get(x, y) > 0; }
+    [[nodiscard]] bool is_selected(Gfx::IntPoint const& point) const { return is_selected(point.x(), point.y()); }
+
+    [[nodiscard]] u8 get_selection_alpha(int x, int y) const { return m_mask.get(x, y); }
+    [[nodiscard]] u8 get_selection_alpha(Gfx::IntPoint const& point) const { return get_selection_alpha(point.x(), point.y()); }
+
     void paint(Gfx::Painter&);
 
     void draw_marching_ants(Gfx::Painter&, Gfx::IntRect const&) const;
diff --git a/Userland/Applications/PixelPaint/main.cpp b/Userland/Applications/PixelPaint/main.cpp
index 76d413fa429..bbce9285220 100644
--- a/Userland/Applications/PixelPaint/main.cpp
+++ b/Userland/Applications/PixelPaint/main.cpp
@@ -237,7 +237,7 @@ int main(int argc, char** argv)
         auto* editor = current_image_editor();
         if (!editor->active_layer())
             return;
-        editor->selection().set(editor->active_layer()->relative_rect());
+        editor->selection().merge(editor->active_layer()->relative_rect(), PixelPaint::Selection::MergeMode::Set);
     }));
     edit_menu.add_action(GUI::Action::create(
         "Clear &Selection", { Mod_Ctrl | Mod_Shift, Key_A }, [&](auto&) {