Add paint brush parameter tests

src/paint/brush.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include "foundation/result.h"
+
+#include <cstdint>
+
+namespace pp::paint {
+
+constexpr float min_brush_size = 0.1F;
+constexpr float max_brush_size = 4096.0F;
+constexpr float min_brush_spacing = 0.01F;
+constexpr float max_brush_spacing = 16.0F;
+constexpr float max_brush_angle_degrees = 360.0F;
+
+struct BrushParams {
+    float size = 32.0F;
+    float spacing = 0.25F;
+    float opacity = 1.0F;
+    float flow = 1.0F;
+    float angle_degrees = 0.0F;
+    float size_jitter = 0.0F;
+    float opacity_jitter = 0.0F;
+    bool pressure_controls_size = true;
+    bool pressure_controls_opacity = false;
+};
+
+struct BrushStamp {
+    float size = 0.0F;
+    float opacity = 0.0F;
+    float flow = 0.0F;
+    float angle_degrees = 0.0F;
+};
+
+[[nodiscard]] pp::foundation::Status validate_brush_params(const BrushParams& params) noexcept;
+[[nodiscard]] BrushStamp evaluate_brush_stamp(const BrushParams& params, float pressure) noexcept;
+
+}