Add paint renderer compositor tests

tests/CMakeLists.txt

@@ -76,6 +76,16 @@ add_test(NAME pp_renderer_api_tests COMMAND pp_renderer_api_tests)
 set_tests_properties(pp_renderer_api_tests PROPERTIES
     LABELS "renderer;desktop-fast")
 
+add_executable(pp_paint_renderer_compositor_tests
+    paint_renderer/compositor_tests.cpp)
+target_link_libraries(pp_paint_renderer_compositor_tests PRIVATE
+    pp_paint_renderer
+    pp_test_harness)
+
+add_test(NAME pp_paint_renderer_compositor_tests COMMAND pp_paint_renderer_compositor_tests)
+set_tests_properties(pp_paint_renderer_compositor_tests PROPERTIES
+    LABELS "renderer;paint;desktop-fast")
+
 add_executable(pp_ui_core_layout_value_tests
     ui_core/layout_value_tests.cpp)
 target_link_libraries(pp_ui_core_layout_value_tests PRIVATE

tests/paint_renderer/compositor_tests.cpp

@@ -0,0 +1,109 @@
+#include "paint_renderer/compositor.h"
+#include "test_harness.h"
+
+#include <cmath>
+#include <vector>
+
+using pp::foundation::StatusCode;
+using pp::paint::BlendMode;
+using pp::paint::Rgba;
+using pp::paint_renderer::LayerCompositeView;
+using pp::paint_renderer::composite_layer;
+using pp::renderer::Extent2D;
+
+namespace {
+
+bool near(float a, float b)
+{
+    return std::fabs(a - b) < 0.0001F;
+}
+
+void composites_visible_layer_with_opacity(pp::tests::Harness& h)
+{
+    std::vector<Rgba> destination {
+        Rgba { .r = 0.2F, .g = 0.4F, .b = 0.6F, .a = 0.5F },
+    };
+    const std::vector<Rgba> foreground {
+        Rgba { .r = 0.8F, .g = 0.2F, .b = 0.1F, .a = 0.5F },
+    };
+
+    const auto status = composite_layer(
+        destination,
+        Extent2D { .width = 1, .height = 1 },
+        LayerCompositeView {
+            .pixels = foreground,
+            .opacity = 0.5F,
+            .visible = true,
+            .blend_mode = BlendMode::normal,
+        });
+
+    PP_EXPECT(h, status.ok());
+    PP_EXPECT(h, near(destination[0].a, 0.625F));
+    PP_EXPECT(h, near(destination[0].r, 0.44F));
+    PP_EXPECT(h, near(destination[0].g, 0.32F));
+    PP_EXPECT(h, near(destination[0].b, 0.4F));
+}
+
+void invisible_and_zero_opacity_layers_are_noops(pp::tests::Harness& h)
+{
+    const Rgba original { .r = 0.1F, .g = 0.2F, .b = 0.3F, .a = 0.4F };
+    std::vector<Rgba> destination { original };
+    const std::vector<Rgba> foreground {
+        Rgba { .r = 1.0F, .g = 1.0F, .b = 1.0F, .a = 1.0F },
+    };
+
+    PP_EXPECT(h, composite_layer(
+        destination,
+        Extent2D { .width = 1, .height = 1 },
+        LayerCompositeView { .pixels = foreground, .opacity = 1.0F, .visible = false }).ok());
+    PP_EXPECT(h, near(destination[0].r, original.r));
+    PP_EXPECT(h, near(destination[0].g, original.g));
+    PP_EXPECT(h, near(destination[0].b, original.b));
+    PP_EXPECT(h, near(destination[0].a, original.a));
+
+    PP_EXPECT(h, composite_layer(
+        destination,
+        Extent2D { .width = 1, .height = 1 },
+        LayerCompositeView { .pixels = foreground, .opacity = 0.0F, .visible = true }).ok());
+    PP_EXPECT(h, near(destination[0].r, original.r));
+    PP_EXPECT(h, near(destination[0].g, original.g));
+    PP_EXPECT(h, near(destination[0].b, original.b));
+    PP_EXPECT(h, near(destination[0].a, original.a));
+}
+
+void rejects_invalid_sizes_and_opacity(pp::tests::Harness& h)
+{
+    std::vector<Rgba> destination(2);
+    const std::vector<Rgba> foreground(1);
+
+    const auto mismatched = composite_layer(
+        destination,
+        Extent2D { .width = 2, .height = 1 },
+        LayerCompositeView { .pixels = foreground });
+    const auto bad_opacity = composite_layer(
+        destination,
+        Extent2D { .width = 2, .height = 1 },
+        LayerCompositeView { .pixels = destination, .opacity = 1.5F });
+    const auto bad_extent = composite_layer(
+        destination,
+        Extent2D { .width = 0, .height = 1 },
+        LayerCompositeView { .pixels = destination });
+
+    PP_EXPECT(h, !mismatched.ok());
+    PP_EXPECT(h, mismatched.code == StatusCode::invalid_argument);
+    PP_EXPECT(h, !bad_opacity.ok());
+    PP_EXPECT(h, bad_opacity.code == StatusCode::out_of_range);
+    PP_EXPECT(h, !bad_extent.ok());
+    PP_EXPECT(h, bad_extent.code == StatusCode::invalid_argument);
+}
+
+}
+
+int main()
+{
+    pp::tests::Harness harness;
+    harness.run("composites_visible_layer_with_opacity", composites_visible_layer_with_opacity);
+    harness.run("invisible_and_zero_opacity_layers_are_noops", invisible_and_zero_opacity_layers_are_noops);
+    harness.run("rejects_invalid_sizes_and_opacity", rejects_invalid_sizes_and_opacity);
+    return harness.finish();
+}