mapnik/test/unit/imaging/image_premultiply.cpp

#include "catch.hpp"

// mapnik
#include <mapnik/image_any.hpp>
#include <mapnik/color.hpp>
#include <mapnik/image_util.hpp>

TEST_CASE("image premultiply")
{
    SECTION("test rgba8")
    {
        mapnik::image_rgba8 im(4, 4);
        mapnik::image_rgba8 im2(4, 4, true, true); // Initialize as already premultiplied
        mapnik::image_any im_any(mapnik::image_rgba8(4, 4));
        mapnik::image_any im2_any(mapnik::image_rgba8(4, 4, true, true));

        // First test that the default state is correct for each
        CHECK_FALSE(im.get_premultiplied());
        CHECK_FALSE(im_any.get_premultiplied());
        CHECK(im2.get_premultiplied());
        CHECK(im2_any.get_premultiplied());

        // Set the image to premultiplied
        im.set_premultiplied(true);
        CHECK(im.get_premultiplied());
        // Set back to not premultiplied
        im.set_premultiplied(false);
        CHECK_FALSE(im.get_premultiplied());

        mapnik::set_premultiplied_alpha(im, true);
        CHECK(im.get_premultiplied());
        mapnik::set_premultiplied_alpha(im, false);
        CHECK_FALSE(im.get_premultiplied());

        // Fill the images with meaningfull values
        mapnik::color c1(57, 70, 128, 128);       // This color is not premultiplied
        mapnik::color c2(57, 70, 128, 128, true); // This color is premultiplied
        mapnik::fill(im, c2);                     // Because c2 is premultiplied it will make the image premultiplied
        mapnik::fill(im_any, c2);                 // Because c2 is premultiplied it will make the image premultiplied
        mapnik::fill(im2, c1);     // Because c1 is not premultiplied it will make the image not premultiplied
        mapnik::fill(im2_any, c1); // Because c1 is not premultiplied it will make the image not premultiplied

        // Demultipled via image_util
        CHECK(mapnik::demultiply_alpha(im));            // Should return true as was premultiplied
        CHECK(mapnik::demultiply_alpha(im_any));        // Should return true as was premultiplied
        CHECK_FALSE(mapnik::demultiply_alpha(im2));     // Should return false as was demultiplied
        CHECK_FALSE(mapnik::demultiply_alpha(im2_any)); // Should return false as was demultiplied

        mapnik::color out;
        // This will be higher because it became demultiplied!
        out = mapnik::get_pixel<mapnik::color>(im, 0, 0);
        CHECK(static_cast<int>(out.red()) == 113);
        CHECK(static_cast<int>(out.green()) == 139);
        CHECK(static_cast<int>(out.blue()) == 255);
        CHECK(static_cast<int>(out.alpha()) == 128);
        out = mapnik::get_pixel<mapnik::color>(im_any, 0, 0);
        CHECK(static_cast<int>(out.red()) == 113);
        CHECK(static_cast<int>(out.green()) == 139);
        CHECK(static_cast<int>(out.blue()) == 255);
        CHECK(static_cast<int>(out.alpha()) == 128);
        // This will be the same because it was already demultiplied
        out = mapnik::get_pixel<mapnik::color>(im2, 0, 0);
        CHECK(static_cast<int>(out.red()) == 57);
        CHECK(static_cast<int>(out.green()) == 70);
        CHECK(static_cast<int>(out.blue()) == 128);
        CHECK(static_cast<int>(out.alpha()) == 128);
        out = mapnik::get_pixel<mapnik::color>(im2_any, 0, 0);
        CHECK(static_cast<int>(out.red()) == 57);
        CHECK(static_cast<int>(out.green()) == 70);
        CHECK(static_cast<int>(out.blue()) == 128);
        CHECK(static_cast<int>(out.alpha()) == 128);

        // Set back to im2s to "premultiplied" with out changing underlying values
        mapnik::set_premultiplied_alpha(im2, true);
        mapnik::set_premultiplied_alpha(im2_any, true);

        // Demultipled via image_util
        CHECK(mapnik::premultiply_alpha(im));            // Should return true as was demultiplied
        CHECK(mapnik::premultiply_alpha(im_any));        // Should return true as was demultiplied
        CHECK_FALSE(mapnik::premultiply_alpha(im2));     // Should return false as was premultiplied
        CHECK_FALSE(mapnik::premultiply_alpha(im2_any)); // Should return false as was premultiplied

        // This will be the same because it was already demultiplied
        out = mapnik::get_pixel<mapnik::color>(im, 0, 0);
        CHECK(static_cast<int>(out.red()) == 57);
        CHECK(static_cast<int>(out.green()) == 70);
        CHECK(static_cast<int>(out.blue()) == 128);
        CHECK(static_cast<int>(out.alpha()) == 128);
        out = mapnik::get_pixel<mapnik::color>(im_any, 0, 0);
        CHECK(static_cast<int>(out.red()) == 57);
        CHECK(static_cast<int>(out.green()) == 70);
        CHECK(static_cast<int>(out.blue()) == 128);
        CHECK(static_cast<int>(out.alpha()) == 128);
        // This will be the same because it was already demultiplied
        out = mapnik::get_pixel<mapnik::color>(im2, 0, 0);
        CHECK(static_cast<int>(out.red()) == 57);
        CHECK(static_cast<int>(out.green()) == 70);
        CHECK(static_cast<int>(out.blue()) == 128);
        CHECK(static_cast<int>(out.alpha()) == 128);
        out = mapnik::get_pixel<mapnik::color>(im2_any, 0, 0);
        CHECK(static_cast<int>(out.red()) == 57);
        CHECK(static_cast<int>(out.green()) == 70);
        CHECK(static_cast<int>(out.blue()) == 128);
        CHECK(static_cast<int>(out.alpha()) == 128);

    } // END SECTION

    SECTION("test gray8")
    {
        mapnik::image_gray8 im(4, 4);
        mapnik::image_gray8 im2(4, 4, true, true); // Initialize as already premultiplied
        mapnik::image_any im_any(mapnik::image_gray8(4, 4));
        mapnik::image_any im2_any(mapnik::image_gray8(4, 4, true, true));

        // First test that the default state is correct for each
        CHECK_FALSE(im.get_premultiplied());
        CHECK_FALSE(im_any.get_premultiplied());
        CHECK(im2.get_premultiplied());
        CHECK(im2_any.get_premultiplied());

        // Set the image to premultiplied
        im.set_premultiplied(true);
        CHECK(im.get_premultiplied());
        // Set back to not premultiplied
        im.set_premultiplied(false);
        CHECK_FALSE(im.get_premultiplied());

        mapnik::set_premultiplied_alpha(im, true);
        CHECK(im.get_premultiplied());
        mapnik::set_premultiplied_alpha(im, false);
        CHECK_FALSE(im.get_premultiplied());

        // Always fails on demultiply since its gray8
        CHECK_FALSE(mapnik::demultiply_alpha(im));
        CHECK_FALSE(mapnik::demultiply_alpha(im_any));
        CHECK_FALSE(mapnik::demultiply_alpha(im2));
        CHECK_FALSE(mapnik::demultiply_alpha(im2_any));

        // Always fails on premultiply since its gray8
        CHECK_FALSE(mapnik::premultiply_alpha(im));
        CHECK_FALSE(mapnik::premultiply_alpha(im_any));
        CHECK_FALSE(mapnik::premultiply_alpha(im2));
        CHECK_FALSE(mapnik::premultiply_alpha(im2_any));

    } // END SECTION
} // END TEST_CASE