PixelPaint: Make erase_selection work for non-rectangular selections

Layer::erase_selection used to erase the entire bounding box of the
selection. With the add/subtract merge modes for the selection tool it
is possible to create selections which are not rectangular. This leads
to deleting pixels that were not selected.

This change adjusts the erase behavior to walk the selection rect and
check if a pixel is selected or not before deleting.

1 files changed, 11 insertions, 2 deletions

diff --git a/Userland/Applications/PixelPaint/Layer.cpp b/Userland/Applications/PixelPaint/Layer.cpp
index ef9d500585..90b8609a44 100644
--- a/Userland/Applications/PixelPaint/Layer.cpp
+++ b/Userland/Applications/PixelPaint/Layer.cpp
@@ -135,10 +135,19 @@ RefPtr<Gfx::Bitmap> Layer::try_copy_bitmap(Selection const& selection) const
 
 void Layer::erase_selection(Selection const& selection)
 {
-    Gfx::Painter painter { content_bitmap() };
     auto const image_and_selection_intersection = m_image.rect().intersected(selection.bounding_rect());
     auto const translated_to_layer_space = image_and_selection_intersection.translated(-location());
-    painter.clear_rect(translated_to_layer_space, Color::Transparent);
+
+    for (int y = translated_to_layer_space.top(); y < translated_to_layer_space.top() + translated_to_layer_space.height(); ++y) {
+        for (int x = translated_to_layer_space.left(); x < translated_to_layer_space.left() + translated_to_layer_space.width(); ++x) {
+
+            // Selection is still in pre-translated coordinates, account for this by adding the layer's relative location
+            if (selection.is_selected(x + location().x(), y + location().y())) {
+                content_bitmap().set_pixel(x, y, Color::Transparent);
+            }
+        }
+    }
+
     did_modify_bitmap(translated_to_layer_space);
 }