OutfitImageRenderer: Handle different layer sizes

Example: http://localhost:3000/outfits/new.png?species=18&color=40&pose=HAPPY_MASC&objects%5B%5D=78994

Before this change, the cape renders too big. Now, it renders correctly.

lib/outfit_image_renderer.rb

@@ -31,12 +31,19 @@ class OutfitImageRenderer
       begin
         layer_image = Vips::Image.new_from_buffer(image_data, "")
 
-        # Center the layer on the canvas
+        # Resize the layer to fit the canvas size
-        x_offset = (CANVAS_SIZE - layer_image.width) / 2
+        # All layer images are square, but may not be CANVAS_SIZE x CANVAS_SIZE
-        y_offset = (CANVAS_SIZE - layer_image.height) / 2
+        # We need to resize them to exactly CANVAS_SIZE x CANVAS_SIZE
+        if layer_image.width != CANVAS_SIZE || layer_image.height != CANVAS_SIZE
+          layer_image = layer_image.resize(
+            CANVAS_SIZE.to_f / layer_image.width,
+            vscale: CANVAS_SIZE.to_f / layer_image.height
+          )
+        end
 
-        # Composite this layer onto the canvas
+        # Composite this layer onto the canvas at (0, 0)
-        canvas = canvas.composite([layer_image], :over, x: x_offset, y: y_offset)
+        # No offset needed since the layer is now exactly canvas-sized
+        canvas = canvas.composite([layer_image], :over)
       rescue Vips::Error => e
         # Log and skip layers that fail to load/composite
         Rails.logger.warn "Failed to composite layer #{layer.id} (#{layer.image_url}): #{e.message}"

spec/lib/outfit_image_renderer_spec.rb

@@ -182,5 +182,59 @@ RSpec.describe OutfitImageRenderer do
         expect(result).to be_nil
       end
     end
+
+    it "resizes all layers to 600x600 before compositing" do
+      # Load a 1200x1200 item layer (real-world case from Neopets)
+      item_1200_png = load_fixture_image('Cape.png')
+      acara_600_png = load_fixture_image('Blue Acara.png')
+      expected_composite_png = load_fixture_image('Blue Acara With Cape.png')
+
+      # Create assets
+      biology_asset = build_biology_asset(zones(:head), body_id: 1)
+      item_asset = build_item_asset(zones(:hat1), body_id: 1)
+
+      # Stub HTTP requests
+      stub_request(:get, biology_asset.image_url).
+        to_return(body: acara_600_png, status: 200)
+      stub_request(:get, item_asset.image_url).
+        to_return(body: item_1200_png, status: 200)
+
+      # Build outfit
+      pet_state = build_pet_state(@pet_type, swf_assets: [biology_asset])
+      item = build_item("Test Item", swf_assets: [item_asset])
+      outfit = Outfit.new(
+        pet_state: pet_state,
+        worn_items: [item]
+      )
+
+      # Render
+      renderer = OutfitImageRenderer.new(outfit)
+      result = renderer.render
+
+      # Verify we got valid PNG data
+      expect(result).not_to be_nil
+      expect(result).to be_a(String)
+      expect(result[0..7]).to eq("\x89PNG\r\n\x1A\n".b)
+
+      # Verify the result is exactly 600x600
+      result_image = Vips::Image.new_from_buffer(result, "")
+      expect(result_image.width).to eq(600)
+      expect(result_image.height).to eq(600)
+
+      # Verify the composite matches the expected image pixel-perfectly
+      expected_image = Vips::Image.new_from_buffer(expected_composite_png, "")
+
+      # Calculate the absolute difference between images
+      diff = (result_image - expected_image).abs
+      max_diff = diff.max
+
+      # Allow a small tolerance for minor encoding/compositing differences
+      tolerance = 2
+      if max_diff > tolerance
+        debug_path = Rails.root.join('tmp', 'test_render_1200_result.png')
+        result_image.write_to_file(debug_path.to_s)
+        fail "Images should match within tolerance of #{tolerance}, but found max difference of #{max_diff}. Actual output saved to #{debug_path}"
+      end
+    end
   end
 end