stuff

src/rasterimage/image_span.hpp

@@ -26,6 +26,8 @@ SOFTWARE.
 
 #pragma once
 
+#include <r4/rectangle.hpp>
+
 #include "dimensioned.hpp"
 #include "operations.hpp"
 
@@ -218,6 +220,12 @@ class image_span : public dimensioned
 		}
 	};
 
+	image_span(dimensions_type dimsensions, utki::span<pixel_type> span, size_t stride) :
+		dimensioned(dimensions),
+		span(span),
+		stride(stride)
+	{}
+
 public:
 	using iterator = iterator_internal<false>;
 	using const_iterator = iterator_internal<true>;
@@ -289,6 +297,13 @@ class image_span : public dimensioned
 		return *utki::next(this->begin(), line_index);
 	}
 
+	image_span subspan(r4::rectangle<uint32_t> rect)
+	{
+		rect.intersect(r4::rectangle<uint32_t>({0, 0}, this->dims()));
+
+		return image_span(rect.d, this->span.subspan(rect.p.y() * this->stride + rect.p.x()), this->stride);
+	}
+
 	void clear(pixel_type val)
 	{
 		for (auto l : *this) {

tests/unit/src/image_span.cpp

@@ -296,5 +296,18 @@ const tst::set set("image_span", [](tst::suite& suite) {
 
 		tst::check(b == e, SL);
 	});
+
+	suite.add("subspan__rectangle", []() {
+		rasterimage::image<uint8_t, 4> img(rasterimage::dimensioned::dimensions_type{100, 200});
+
+		auto im = img.span();
+
+		decltype(im)::pixel_type expected = {10, 20, 30, 40};
+		im.clear(expected);
+
+		auto subim = im.subspan({1, 2, 2, 3});
+
+		subim.clear(0);
+	});
 });
 } // namespace