Add paint brush parameter tests

CMakeLists.txt

@@ -98,6 +98,7 @@ target_link_libraries(pp_assets
         pp_project_warnings)
 
 add_library(pp_paint STATIC
+    src/paint/brush.cpp
     src/paint/blend.cpp
     src/paint/stroke.cpp)
 target_include_directories(pp_paint

docs/modernization/build-inventory.md

@@ -81,8 +81,8 @@ Known local toolchain state:
   `pp_paint`, `pp_document`, `pp_renderer_api`, `pp_paint_renderer`,
   `pp_ui_core`, `pano_cli`, and their current headless test binaries,
   including foundation event/logging/task queue coverage, PPI header, settings
-  document, paint stroke sampling, UI color parsing, and layout XML parse
+  document, paint brush/stroke coverage, UI color parsing, and layout XML
-  coverage.
+  parse coverage.
 - `panopainter_validate_shaders` validates the current combined GLSL shader
   files for one vertex stage marker, one fragment stage marker, valid marker
   order, and existing relative includes.

docs/modernization/roadmap.md

@@ -310,8 +310,9 @@ component/name/thread/frame/stroke metadata with filtering, capacity, and
 invalid-end tests. `pp_assets` has started with PNG/JPEG signature detection,
 PPI header recognition, and a pure typed settings document model, with
 corrupt/truncated/unsupported and key/value limit tests.
-`pp_paint` has started with CPU reference math for the five current shader
+`pp_paint` has started with pure brush parameter validation/stamp evaluation,
-blend modes plus deterministic stroke spacing/interpolation. `pp_document` has
+CPU reference math for the five current shader blend modes, and deterministic
+stroke spacing/interpolation. `pp_document` has
 started with a pure canvas/layer/frame model, layer metadata operations, and
 layer/frame/undo-redo history invariant tests. `pp_renderer_api` has started with renderer-neutral
 texture/readback descriptors and validation tests. `pp_paint_renderer` has
@@ -526,7 +527,7 @@ Last verified on 2026-06-01:
 
 ```powershell
 cmake --preset windows-msvc-default
-cmake --build --preset windows-msvc-default --config Debug --target pp_foundation_binary_stream_tests pp_foundation_event_tests pp_foundation_log_tests pp_foundation_parse_tests pp_foundation_task_queue_tests pp_foundation_trace_tests pp_assets_image_format_tests pp_assets_ppi_header_tests pp_assets_settings_document_tests pp_paint_blend_tests pp_paint_stroke_tests pp_document_tests pp_renderer_api_tests pp_paint_renderer_compositor_tests pp_ui_core_color_tests pp_ui_core_layout_value_tests pp_ui_core_layout_xml_tests pano_cli PanoPainter
+cmake --build --preset windows-msvc-default --config Debug --target pp_foundation_binary_stream_tests pp_foundation_event_tests pp_foundation_log_tests pp_foundation_parse_tests pp_foundation_task_queue_tests pp_foundation_trace_tests pp_assets_image_format_tests pp_assets_ppi_header_tests pp_assets_settings_document_tests pp_paint_brush_tests pp_paint_blend_tests pp_paint_stroke_tests pp_document_tests pp_renderer_api_tests pp_paint_renderer_compositor_tests pp_ui_core_color_tests pp_ui_core_layout_value_tests pp_ui_core_layout_xml_tests pano_cli PanoPainter
 ctest --preset desktop-fast --build-config Debug
 powershell -ExecutionPolicy Bypass -File scripts\automation\test.ps1 -Preset desktop-fast -Configuration Debug
 powershell -ExecutionPolicy Bypass -File scripts\automation\build.ps1 -Preset windows-msvc-default -Configuration Debug -Target pano_cli
@@ -548,6 +549,7 @@ Results:
 - `pp_assets_image_format_tests` passed.
 - `pp_assets_ppi_header_tests` passed.
 - `pp_assets_settings_document_tests` passed.
+- `pp_paint_brush_tests` passed.
 - `pp_paint_blend_tests` passed.
 - `pp_paint_stroke_tests` passed.
 - `pp_document_tests` passed.

scripts/automation/platform-build.ps1

@@ -1,7 +1,7 @@
 [CmdletBinding()]
 param(
     [string[]]$Presets = @("android-arm64"),
-    [string[]]$Targets = @("pp_foundation", "pp_assets", "pp_paint", "pp_document", "pp_renderer_api", "pp_paint_renderer", "pp_ui_core", "pano_cli", "pp_foundation_binary_stream_tests", "pp_foundation_event_tests", "pp_foundation_log_tests", "pp_foundation_parse_tests", "pp_foundation_task_queue_tests", "pp_foundation_trace_tests", "pp_assets_image_format_tests", "pp_assets_ppi_header_tests", "pp_assets_settings_document_tests", "pp_paint_blend_tests", "pp_paint_stroke_tests", "pp_document_tests", "pp_renderer_api_tests", "pp_paint_renderer_compositor_tests", "pp_ui_core_color_tests", "pp_ui_core_layout_value_tests", "pp_ui_core_layout_xml_tests")
+    [string[]]$Targets = @("pp_foundation", "pp_assets", "pp_paint", "pp_document", "pp_renderer_api", "pp_paint_renderer", "pp_ui_core", "pano_cli", "pp_foundation_binary_stream_tests", "pp_foundation_event_tests", "pp_foundation_log_tests", "pp_foundation_parse_tests", "pp_foundation_task_queue_tests", "pp_foundation_trace_tests", "pp_assets_image_format_tests", "pp_assets_ppi_header_tests", "pp_assets_settings_document_tests", "pp_paint_brush_tests", "pp_paint_blend_tests", "pp_paint_stroke_tests", "pp_document_tests", "pp_renderer_api_tests", "pp_paint_renderer_compositor_tests", "pp_ui_core_color_tests", "pp_ui_core_layout_value_tests", "pp_ui_core_layout_xml_tests")
 )
 
 $ErrorActionPreference = "Stop"

scripts/automation/platform-build.sh

@@ -3,7 +3,7 @@ set -u
 
 preset="${1:-android-arm64}"
 shift || true
-targets="${*:-pp_foundation pp_assets pp_paint pp_document pp_renderer_api pp_paint_renderer pp_ui_core pano_cli pp_foundation_binary_stream_tests pp_foundation_event_tests pp_foundation_log_tests pp_foundation_parse_tests pp_foundation_task_queue_tests pp_foundation_trace_tests pp_assets_image_format_tests pp_assets_ppi_header_tests pp_assets_settings_document_tests pp_paint_blend_tests pp_paint_stroke_tests pp_document_tests pp_renderer_api_tests pp_paint_renderer_compositor_tests pp_ui_core_color_tests pp_ui_core_layout_value_tests pp_ui_core_layout_xml_tests}"
+targets="${*:-pp_foundation pp_assets pp_paint pp_document pp_renderer_api pp_paint_renderer pp_ui_core pano_cli pp_foundation_binary_stream_tests pp_foundation_event_tests pp_foundation_log_tests pp_foundation_parse_tests pp_foundation_task_queue_tests pp_foundation_trace_tests pp_assets_image_format_tests pp_assets_ppi_header_tests pp_assets_settings_document_tests pp_paint_brush_tests pp_paint_blend_tests pp_paint_stroke_tests pp_document_tests pp_renderer_api_tests pp_paint_renderer_compositor_tests pp_ui_core_color_tests pp_ui_core_layout_value_tests pp_ui_core_layout_xml_tests}"
 start="$(date +%s)"
 
 cmake --preset "$preset"

src/paint/brush.cpp

@@ -0,0 +1,72 @@
+#include "paint/brush.h"
+
+#include <algorithm>
+#include <cmath>
+
+namespace pp::paint {
+
+namespace {
+
+[[nodiscard]] bool finite_in_range(float value, float min, float max) noexcept
+{
+    return std::isfinite(value) && value >= min && value <= max;
+}
+
+[[nodiscard]] float clamp01(float value) noexcept
+{
+    return std::clamp(value, 0.0F, 1.0F);
+}
+
+}
+
+pp::foundation::Status validate_brush_params(const BrushParams& params) noexcept
+{
+    if (!finite_in_range(params.size, min_brush_size, max_brush_size)) {
+        return pp::foundation::Status::out_of_range("brush size is outside the configured range");
+    }
+
+    if (!finite_in_range(params.spacing, min_brush_spacing, max_brush_spacing)) {
+        return pp::foundation::Status::out_of_range("brush spacing is outside the configured range");
+    }
+
+    if (!finite_in_range(params.opacity, 0.0F, 1.0F)) {
+        return pp::foundation::Status::out_of_range("brush opacity must be finite and within 0..1");
+    }
+
+    if (!finite_in_range(params.flow, 0.0F, 1.0F)) {
+        return pp::foundation::Status::out_of_range("brush flow must be finite and within 0..1");
+    }
+
+    if (!finite_in_range(params.angle_degrees, -max_brush_angle_degrees, max_brush_angle_degrees)) {
+        return pp::foundation::Status::out_of_range("brush angle is outside the configured range");
+    }
+
+    if (!finite_in_range(params.size_jitter, 0.0F, 1.0F)) {
+        return pp::foundation::Status::out_of_range("brush size jitter must be finite and within 0..1");
+    }
+
+    if (!finite_in_range(params.opacity_jitter, 0.0F, 1.0F)) {
+        return pp::foundation::Status::out_of_range("brush opacity jitter must be finite and within 0..1");
+    }
+
+    return pp::foundation::Status::success();
+}
+
+BrushStamp evaluate_brush_stamp(const BrushParams& params, float pressure) noexcept
+{
+    const auto clamped_pressure = clamp01(std::isfinite(pressure) ? pressure : 0.0F);
+    const auto size_pressure = params.pressure_controls_size ? clamped_pressure : 1.0F;
+    const auto opacity_pressure = params.pressure_controls_opacity ? clamped_pressure : 1.0F;
+
+    const auto jitter_size_scale = 1.0F - (params.size_jitter * 0.5F);
+    const auto jitter_opacity_scale = 1.0F - (params.opacity_jitter * 0.5F);
+
+    return BrushStamp {
+        .size = std::max(min_brush_size, params.size * size_pressure * jitter_size_scale),
+        .opacity = clamp01(params.opacity * opacity_pressure * jitter_opacity_scale),
+        .flow = clamp01(params.flow),
+        .angle_degrees = params.angle_degrees,
+    };
+}
+
+}

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;
+
+}

tests/CMakeLists.txt

@@ -96,6 +96,16 @@ add_test(NAME pp_assets_settings_document_tests COMMAND pp_assets_settings_docum
 set_tests_properties(pp_assets_settings_document_tests PROPERTIES
     LABELS "assets;desktop-fast")
 
+add_executable(pp_paint_brush_tests
+    paint/brush_tests.cpp)
+target_link_libraries(pp_paint_brush_tests PRIVATE
+    pp_paint
+    pp_test_harness)
+
+add_test(NAME pp_paint_brush_tests COMMAND pp_paint_brush_tests)
+set_tests_properties(pp_paint_brush_tests PROPERTIES
+    LABELS "paint;desktop-fast")
+
 add_executable(pp_paint_blend_tests
     paint/blend_tests.cpp)
 target_link_libraries(pp_paint_blend_tests PRIVATE

tests/paint/brush_tests.cpp

@@ -0,0 +1,127 @@
+#include "paint/brush.h"
+#include "test_harness.h"
+
+#include <cmath>
+
+using pp::foundation::StatusCode;
+using pp::paint::BrushParams;
+using pp::paint::evaluate_brush_stamp;
+using pp::paint::max_brush_size;
+using pp::paint::min_brush_size;
+using pp::paint::validate_brush_params;
+
+namespace {
+
+bool near(float a, float b)
+{
+    return std::fabs(a - b) < 0.0001F;
+}
+
+void accepts_default_and_boundary_params(pp::tests::Harness& h)
+{
+    BrushParams defaults;
+    BrushParams minimums {
+        .size = min_brush_size,
+        .spacing = 0.01F,
+        .opacity = 0.0F,
+        .flow = 0.0F,
+        .angle_degrees = -360.0F,
+        .size_jitter = 0.0F,
+        .opacity_jitter = 0.0F,
+    };
+    BrushParams maximums {
+        .size = max_brush_size,
+        .spacing = 16.0F,
+        .opacity = 1.0F,
+        .flow = 1.0F,
+        .angle_degrees = 360.0F,
+        .size_jitter = 1.0F,
+        .opacity_jitter = 1.0F,
+    };
+
+    PP_EXPECT(h, validate_brush_params(defaults).ok());
+    PP_EXPECT(h, validate_brush_params(minimums).ok());
+    PP_EXPECT(h, validate_brush_params(maximums).ok());
+}
+
+void rejects_invalid_params(pp::tests::Harness& h)
+{
+    BrushParams params;
+
+    params.size = 0.0F;
+    PP_EXPECT(h, validate_brush_params(params).code == StatusCode::out_of_range);
+    params = BrushParams {};
+    params.spacing = 0.0F;
+    PP_EXPECT(h, validate_brush_params(params).code == StatusCode::out_of_range);
+    params = BrushParams {};
+    params.opacity = -0.1F;
+    PP_EXPECT(h, validate_brush_params(params).code == StatusCode::out_of_range);
+    params = BrushParams {};
+    params.flow = 1.1F;
+    PP_EXPECT(h, validate_brush_params(params).code == StatusCode::out_of_range);
+    params = BrushParams {};
+    params.angle_degrees = 361.0F;
+    PP_EXPECT(h, validate_brush_params(params).code == StatusCode::out_of_range);
+    params = BrushParams {};
+    params.size_jitter = std::nanf("");
+    PP_EXPECT(h, validate_brush_params(params).code == StatusCode::out_of_range);
+    params = BrushParams {};
+    params.opacity_jitter = 2.0F;
+    PP_EXPECT(h, validate_brush_params(params).code == StatusCode::out_of_range);
+}
+
+void evaluates_pressure_controlled_stamp(pp::tests::Harness& h)
+{
+    const BrushParams params {
+        .size = 20.0F,
+        .spacing = 0.5F,
+        .opacity = 0.8F,
+        .flow = 0.6F,
+        .angle_degrees = 45.0F,
+        .size_jitter = 0.0F,
+        .opacity_jitter = 0.0F,
+        .pressure_controls_size = true,
+        .pressure_controls_opacity = true,
+    };
+
+    const auto stamp = evaluate_brush_stamp(params, 0.5F);
+    PP_EXPECT(h, near(stamp.size, 10.0F));
+    PP_EXPECT(h, near(stamp.opacity, 0.4F));
+    PP_EXPECT(h, near(stamp.flow, 0.6F));
+    PP_EXPECT(h, near(stamp.angle_degrees, 45.0F));
+}
+
+void clamps_bad_pressure_and_applies_deterministic_jitter_scale(pp::tests::Harness& h)
+{
+    const BrushParams params {
+        .size = 20.0F,
+        .spacing = 0.5F,
+        .opacity = 0.8F,
+        .flow = 0.6F,
+        .angle_degrees = 0.0F,
+        .size_jitter = 0.5F,
+        .opacity_jitter = 1.0F,
+        .pressure_controls_size = false,
+        .pressure_controls_opacity = false,
+    };
+
+    const auto nan_pressure = evaluate_brush_stamp(params, std::nanf(""));
+    const auto high_pressure = evaluate_brush_stamp(params, 2.0F);
+
+    PP_EXPECT(h, near(nan_pressure.size, 15.0F));
+    PP_EXPECT(h, near(nan_pressure.opacity, 0.4F));
+    PP_EXPECT(h, near(high_pressure.size, 15.0F));
+    PP_EXPECT(h, near(high_pressure.opacity, 0.4F));
+}
+
+}
+
+int main()
+{
+    pp::tests::Harness harness;
+    harness.run("accepts_default_and_boundary_params", accepts_default_and_boundary_params);
+    harness.run("rejects_invalid_params", rejects_invalid_params);
+    harness.run("evaluates_pressure_controlled_stamp", evaluates_pressure_controlled_stamp);
+    harness.run("clamps_bad_pressure_and_applies_deterministic_jitter_scale", clamps_bad_pressure_and_applies_deterministic_jitter_scale);
+    return harness.finish();
+}