Extract brush UI operation planning

src/app_core/brush_ui.h

@@ -0,0 +1,122 @@
+#pragma once
+
+#include "foundation/result.h"
+
+#include <cmath>
+#include <string>
+#include <string_view>
+
+namespace pp::app {
+
+enum class BrushUiTextureSlot {
+    tip,
+    pattern,
+    dual,
+};
+
+enum class BrushUiOperation {
+    set_tip_color,
+    set_texture,
+    replace_brush_from_preset,
+    stroke_settings_changed,
+};
+
+struct BrushUiPlan {
+    BrushUiOperation operation = BrushUiOperation::stroke_settings_changed;
+    BrushUiTextureSlot texture_slot = BrushUiTextureSlot::tip;
+    std::string path;
+    std::string thumbnail_path;
+    float r = 0.0F;
+    float g = 0.0F;
+    float b = 0.0F;
+    float a = 1.0F;
+    bool mutates_brush = false;
+    bool preserves_existing_color = false;
+    bool loads_brush_resources = false;
+    bool update_color_ui = false;
+    bool update_brush_ui = false;
+};
+
+[[nodiscard]] inline pp::foundation::Status validate_brush_ui_color_channel(float value) noexcept
+{
+    if (!std::isfinite(value) || value < 0.0F || value > 1.0F) {
+        return pp::foundation::Status::out_of_range("brush color channels must be finite and within 0..1");
+    }
+
+    return pp::foundation::Status::success();
+}
+
+[[nodiscard]] inline pp::foundation::Result<BrushUiPlan> plan_brush_ui_color(
+    float r,
+    float g,
+    float b,
+    float a)
+{
+    for (const auto value : { r, g, b, a }) {
+        const auto channel_status = validate_brush_ui_color_channel(value);
+        if (!channel_status.ok()) {
+            return pp::foundation::Result<BrushUiPlan>::failure(channel_status);
+        }
+    }
+
+    BrushUiPlan plan;
+    plan.operation = BrushUiOperation::set_tip_color;
+    plan.r = r;
+    plan.g = g;
+    plan.b = b;
+    plan.a = a;
+    plan.mutates_brush = true;
+    plan.update_color_ui = true;
+    return pp::foundation::Result<BrushUiPlan>::success(plan);
+}
+
+[[nodiscard]] inline pp::foundation::Result<BrushUiPlan> plan_brush_ui_texture(
+    BrushUiTextureSlot slot,
+    std::string_view path,
+    std::string_view thumbnail_path)
+{
+    if (path.empty()) {
+        return pp::foundation::Result<BrushUiPlan>::failure(
+            pp::foundation::Status::invalid_argument("brush texture path must not be empty"));
+    }
+
+    BrushUiPlan plan;
+    plan.operation = BrushUiOperation::set_texture;
+    plan.texture_slot = slot;
+    plan.path = std::string(path);
+    plan.thumbnail_path = std::string(thumbnail_path);
+    plan.mutates_brush = true;
+    plan.loads_brush_resources = true;
+    plan.update_color_ui = true;
+    plan.update_brush_ui = true;
+    return pp::foundation::Result<BrushUiPlan>::success(std::move(plan));
+}
+
+[[nodiscard]] inline pp::foundation::Result<BrushUiPlan> plan_brush_ui_preset_replace(bool has_preset_brush)
+{
+    if (!has_preset_brush) {
+        return pp::foundation::Result<BrushUiPlan>::failure(
+            pp::foundation::Status::invalid_argument("preset brush must be available"));
+    }
+
+    BrushUiPlan plan;
+    plan.operation = BrushUiOperation::replace_brush_from_preset;
+    plan.mutates_brush = true;
+    plan.preserves_existing_color = true;
+    plan.loads_brush_resources = true;
+    plan.update_color_ui = true;
+    plan.update_brush_ui = true;
+    return pp::foundation::Result<BrushUiPlan>::success(plan);
+}
+
+[[nodiscard]] inline constexpr BrushUiPlan plan_brush_ui_stroke_settings_changed() noexcept
+{
+    BrushUiPlan plan;
+    plan.operation = BrushUiOperation::stroke_settings_changed;
+    plan.mutates_brush = true;
+    plan.update_color_ui = true;
+    plan.update_brush_ui = true;
+    return plan;
+}
+
+} // namespace pp::app