PixelPaint: Support saving/loading masks to project file

Userland/Applications/PixelPaint/Image.cpp

@@ -92,6 +92,13 @@ ErrorOr<NonnullRefPtr<Image>> Image::try_create_from_pixel_paint_json(JsonObject
         auto bitmap = TRY(try_decode_bitmap(bitmap_data));
         auto layer = TRY(Layer::try_create_with_bitmap(*image, move(bitmap), name));
 
+        if (auto mask_object = layer_object.get("mask"); !mask_object.is_null()) {
+            auto mask_base64_encoded = mask_object.as_string();
+            auto mask_data = TRY(decode_base64(mask_base64_encoded));
+            auto mask = TRY(try_decode_bitmap(mask_data));
+            layer->set_mask_bitmap(move(mask));
+        }
+
         auto width = layer_object.get("width").to_i32();
         auto height = layer_object.get("height").to_i32();
 
@@ -126,8 +133,9 @@ void Image::serialize_as_json(JsonObjectSerializer<StringBuilder>& json) const
             MUST(json_layer.add("opacity_percent", layer.opacity_percent()));
             MUST(json_layer.add("visible", layer.is_visible()));
             MUST(json_layer.add("selected", layer.is_selected()));
-            // FIXME: Respect mask
             MUST(json_layer.add("bitmap", encode_base64(bmp_writer.dump(layer.content_bitmap()))));
+            if (layer.is_masked())
+                MUST(json_layer.add("mask", encode_base64(bmp_writer.dump(*layer.mask_bitmap()))));
             MUST(json_layer.finish());
         }
 

Userland/Applications/PixelPaint/Layer.cpp

@@ -148,6 +148,12 @@ void Layer::set_content_bitmap(NonnullRefPtr<Gfx::Bitmap> bitmap)
     update_cached_bitmap();
 }
 
+void Layer::set_mask_bitmap(NonnullRefPtr<Gfx::Bitmap> bitmap)
+{
+    m_mask_bitmap = move(bitmap);
+    update_cached_bitmap();
+}
+
 void Layer::update_cached_bitmap()
 {
     if (!is_masked()) {

Userland/Applications/PixelPaint/Layer.h

@@ -54,6 +54,7 @@ public:
     void set_name(String);
 
     void set_content_bitmap(NonnullRefPtr<Gfx::Bitmap> bitmap);
+    void set_mask_bitmap(NonnullRefPtr<Gfx::Bitmap> bitmap);
 
     void did_modify_bitmap(Gfx::IntRect const& = {});
 
@@ -72,7 +73,7 @@ public:
 
     void erase_selection(Selection const&);
 
-    bool is_masked() { return !m_mask_bitmap.is_null(); }
+    bool is_masked() const { return !m_mask_bitmap.is_null(); }
 
     enum class EditMode {
         Content,