add the 'gradient' and 'step' color maps (97b7cc81) · Commits · github_fork / Clip

core/color_map.cc

+103 −0

Original line number	Diff line number	Diff line
		@@ -15,5 +15,108 @@

		namespace fviz {

		ColorMap color_map_gradient(std::vector<std::pair<double, Color>> gradient) {
		std::sort(
		gradient.begin(),
		gradient.end(),
		[] (const auto& a, const auto& b) {
		return a.first < b.first;
		});

		return [gradient] (const auto& value, Color* color) -> ReturnCode {
		if (gradient.empty()) {
		*color = Color{};
		return OK;
		}

		double value_num = 0.0;
		try {
		value_num = std::clamp(std::stod(value), 0.0, 1.0);
		} catch (...) {
		return errorf(
		ERROR,
		"invalid data; can't map '{}' to a color",
		value);
		}

		auto step = std::lower_bound(
		gradient.begin(),
		gradient.end(),
		value_num,
		[] (const auto& a, auto b) {
		return a.first < b;
		});

		double limit0 = 0.0;
		auto limit1 = step->first;
		Color color0;
		auto color1 = step->second;

		if (step != gradient.end() && step != gradient.begin()) {
		limit0 = (step - 1)->first;
		color0 = (step - 1)->second;
		}

		auto weight1 = (value_num - limit0) / (limit1 - limit0);
		auto weight0 = 1.0 - weight1;

		if (value_num >= limit1) {
		weight1 = 1.0;
		weight0 = 0.0;
		}

		*color = Color::fromRGBA(
		color0[0] * weight0 + color1[0] * weight1,
		color0[1] * weight0 + color1[1] * weight1,
		color0[2] * weight0 + color1[2] * weight1,
		color0[3] * weight0 + color1[3] * weight1);

		return OK;
		};
		}


		ColorMap color_map_steps(std::vector<std::pair<double, Color>> steps) {
		std::sort(
		steps.begin(),
		steps.end(),
		[] (const auto& a, const auto& b) {
		return a.first < b.first;
		});

		return [steps] (const auto& value, Color* color) -> ReturnCode {
		if (steps.empty()) {
		*color = Color{};
		return OK;
		}

		double value_num = 0.0;
		try {
		value_num = std::clamp(std::stod(value), 0.0, 1.0);
		} catch (...) {
		return errorf(
		ERROR,
		"invalid data; can't map '{}' to a color",
		value);
		}

		auto step = std::upper_bound(
		steps.begin(),
		steps.end(),
		value_num,
		[] (const auto& a, const auto& b) {
		return a < b.first;
		});

		if (step == steps.begin()) {
		*color = {};
		} else {
		*color = (step - 1)->second;
		}

		return OK;
		};
		}

		} // namespace fviz

core/color_map.h

+4 −2

Original line number	Diff line number	Diff line
		@@ -17,9 +17,11 @@

		namespace fviz {

		using ColorMap = std::function<ReturnCode (double v, Color* c)>;
		using ColorMap = std::function<ReturnCode (const std::string& v, Color* c)>;

		ColorMap color_map_raw(std::vector<Color> colors);
		ColorMap color_map_gradient(std::vector<std::pair<double, Color>> gradient);

		ColorMap color_map_steps(std::vector<std::pair<double, Color>> steps);

		} // namespace fviz

core/color_reader.cc

+86 −0

Original line number	Diff line number	Diff line
		@@ -125,6 +125,84 @@ ReturnCode color_read_opt(
		return OK;
		}

		ReturnCode color_map_read_gradient(
		const Environment& env,
		const Expr* expr,
		ColorMap* color_map) {
		std::vector<std::pair<double, Color>> gradient;

		for (; expr; expr = expr_next(expr)) {
		if (!expr_is_list(expr)) {
		return errorf(
		ERROR,
		"invalid argument to 'gradient'; expected a 2-tuple, but got: '{}'",
		expr_inspect(expr));
		}

		auto args = expr_collect(expr_get_list(expr));
		if (args.size() != 2) {
		return errorf(
		ERROR,
		"invalid argument to 'gradient'; expected a 2-tuple, but got: '{}'",
		expr_inspect(expr));
		}

		double step;
		if (auto rc = expr_to_ratio(args[0], &step); !rc) {
		return rc;
		}

		Color color;
		if (auto rc = color_read(env, args[1], &color); !rc) {
		return rc;
		}

		gradient.emplace_back(step, color);
		}

		*color_map = color_map_gradient(gradient);
		return OK;
		}

		ReturnCode color_map_read_steps(
		const Environment& env,
		const Expr* expr,
		ColorMap* color_map) {
		std::vector<std::pair<double, Color>> steps;

		for (; expr; expr = expr_next(expr)) {
		if (!expr_is_list(expr)) {
		return errorf(
		ERROR,
		"invalid argument to 'steps'; expected a 2-tuple, but got: '{}'",
		expr_inspect(expr));
		}

		auto args = expr_collect(expr_get_list(expr));
		if (args.size() != 2) {
		return errorf(
		ERROR,
		"invalid argument to 'steps'; expected a 2-tuple, but got: '{}'",
		expr_inspect(expr));
		}

		double step;
		if (auto rc = expr_to_ratio(args[0], &step); !rc) {
		return rc;
		}

		Color color;
		if (auto rc = color_read(env, args[1], &color); !rc) {
		return rc;
		}

		steps.emplace_back(step, color);
		}

		*color_map = color_map_steps(steps);
		return OK;
		}

		ReturnCode color_map_read(
		const Environment& env,
		const Expr* expr,
		@@ -138,6 +216,14 @@ ReturnCode color_map_read(

		expr = expr_get_list(expr);

		if (expr_is_value(expr, "gradient")) {
		return color_map_read_gradient(env, expr_next(expr), color_map);
		}

		if (expr_is_value(expr, "steps")) {
		return color_map_read_steps(env, expr_next(expr), color_map);
		}

		return errorf(
		ERROR,
		"invalid value to <color-map>; got '{}', but expected one of: \n"

core/sexpr_conv.cc

+6 −0

Original line number	Diff line number	Diff line
		@@ -125,6 +125,12 @@ ReturnCode expr_to_float64_opt_pair(
		return OK;
		}

		ReturnCode expr_to_ratio(
		const Expr* expr,
		double* value) {
		return expr_to_float64(expr, value);
		}

		ReturnCode expr_to_switch(
		const Expr* expr,
		bool* value) {

core/sexpr_conv.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -52,6 +52,10 @@ ReturnCode expr_to_float64_opt_pair(
		std::optional<double>* v1,
		std::optional<double>* v2);

		ReturnCode expr_to_ratio(
		const Expr* expr,
		double* value);

		ReturnCode expr_to_switch(
		const Expr* expr,
		bool* value);

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