PNG image read with libpng

src/libslic3r/CMakeLists.txt

@@ -161,6 +161,8 @@ add_library(libslic3r STATIC
     PrintConfig.hpp
     PrintObject.cpp
     PrintRegion.cpp
+    PNGRead.hpp
+    PNGRead.cpp
     Semver.cpp
     ShortestPath.cpp
     ShortestPath.hpp
@@ -308,6 +310,8 @@ target_link_libraries(libslic3r
     TBB::tbb
     libslic3r_cgal
     ${CMAKE_DL_LIBS}
+    PNG::PNG
+    ZLIB::ZLIB
     )
 
 if (TARGET OpenVDB::openvdb)

src/libslic3r/PNGRead.cpp

@@ -0,0 +1,59 @@
+#include "PNGRead.hpp"
+
+#include <memory>
+
+#include <cstdio>
+#include <png.h>
+
+namespace Slic3r { namespace png {
+
+struct png_deleter { void operator()(png_struct *p) {
+    png_destroy_read_struct( &p, nullptr, nullptr); }
+};
+
+using png_ptr_t = std::unique_ptr<png_struct_def, png_deleter>;
+
+bool is_png(const ReadBuf &rb)
+{
+    static const constexpr int PNG_SIG_BYTES = 8;
+
+    return rb.sz >= PNG_SIG_BYTES &&
+           !png_sig_cmp(static_cast<png_const_bytep>(rb.buf), 0, PNG_SIG_BYTES);
+}
+
+bool decode_png(const ReadBuf &rb, ImageGreyscale &img)
+{
+    if (!is_png(rb)) return false;
+
+    png_ptr_t png{png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr)};
+
+    if(!png) return false;
+
+    png_infop info = png_create_info_struct(png.get());
+    if(!info) return {};
+
+    FILE *io = ::fmemopen(const_cast<void *>(rb.buf), rb.sz, "rb");
+    png_init_io(png.get(), io);
+
+    png_read_info(png.get(), info);
+
+    img.cols = png_get_image_width(png.get(), info);
+    img.rows = png_get_image_height(png.get(), info);
+    size_t color_type = png_get_color_type(png.get(), info);
+    size_t bit_depth  = png_get_bit_depth(png.get(), info);
+
+    if (color_type != PNG_COLOR_TYPE_GRAY || bit_depth != 8)
+        return false;
+
+    img.buf.resize(img.rows * img.cols);
+
+    auto readbuf = static_cast<png_bytep>(img.buf.data());
+    for (size_t r = 0; r < img.rows; ++r)
+        png_read_row(png.get(), readbuf + r * img.cols, nullptr);
+
+    fclose(io);
+
+    return true;
+}
+
+}}

src/libslic3r/PNGRead.hpp

@@ -0,0 +1,30 @@
+#ifndef PNGREAD_HPP
+#define PNGREAD_HPP
+
+#include <vector>
+#include <string>
+
+namespace Slic3r { namespace png {
+
+struct ReadBuf { const void *buf = nullptr; const size_t sz = 0; };
+
+template<class PxT> struct Image {
+    std::vector<PxT> buf;
+    size_t rows, cols;
+    PxT get(size_t row, size_t col) const { return buf[row * cols + col]; }
+};
+
+struct RGB { uint8_t r, g, b; };
+
+using ImageRGB = Image<RGB>;
+using ImageGreyscale = Image<uint8_t>;
+
+// TODO
+// bool decode_png(Buffer &&pngbuf, ImageRGB &img);
+
+bool is_png(const ReadBuf &pngbuf);
+
+bool decode_png(const ReadBuf &pngbuf, ImageGreyscale &img);
+
+}}
+#endif // PNGREAD_HPP

src/slic3r/Utils/SLAImport.cpp

@@ -9,32 +9,31 @@
 #include "libslic3r/PrintConfig.hpp"
 #include "libslic3r/SLA/RasterBase.hpp"
 #include "libslic3r/miniz_extension.hpp"
+#include "libslic3r/PNGRead.hpp"
 
 #include <boost/property_tree/ini_parser.hpp>
 #include <boost/filesystem/path.hpp>
 #include <boost/algorithm/string.hpp>
 
-#include <wx/image.h>
 #include <wx/mstream.h>
 
 namespace marchsq {
 
-// Specialize this struct to register a raster type for the Marching squares alg
-template<> struct _RasterTraits<wxImage> {
-    using Rst = wxImage;
-    
+template<> struct _RasterTraits<Slic3r::png::ImageGreyscale> {
+    using Rst = Slic3r::png::ImageGreyscale;
+
     // The type of pixel cell in the raster
     using ValueType = uint8_t;
-    
+
     // Value at a given position
     static uint8_t get(const Rst &rst, size_t row, size_t col)
     {
-        return rst.GetRed(col, row);
+        return rst.get(row, col);
     }
 
     // Number of rows and cols of the raster
-    static size_t rows(const Rst &rst) { return rst.GetHeight(); }
-    static size_t cols(const Rst &rst) { return rst.GetWidth(); }
+    static size_t rows(const Rst &rst) { return rst.rows; }
+    static size_t cols(const Rst &rst) { return rst.cols; }
 };
 
 } // namespace marchsq
@@ -44,7 +43,6 @@ namespace Slic3r {
 namespace {
 
 struct PNGBuffer { std::vector<uint8_t> buf; std::string fname; };
-
 struct ArchiveData {
     boost::property_tree::ptree profile, config;
     std::vector<PNGBuffer> images;
@@ -69,8 +67,8 @@ boost::property_tree::ptree read_ini(const mz_zip_archive_file_stat &entry,
 }
 
 PNGBuffer read_png(const mz_zip_archive_file_stat &entry,
-                            MZ_Archive &                    zip,
-                            const std::string &             name)
+                   MZ_Archive &                    zip,
+                   const std::string &             name)
 {
     std::vector<uint8_t> buf(entry.m_uncomp_size);
 
@@ -259,9 +257,13 @@ std::vector<ExPolygons> extract_slices_from_sla_archive(
             }
         }
         
-        PNGBuffer &png = arch.images[i];
-        wxMemoryInputStream   stream{png.buf.data(), png.buf.size()};
-        wxImage               img{stream};
+//        PNGBuffer &png = arch.images[i];
+//        wxMemoryInputStream   stream{png.buf.data(), png.buf.size()};
+//        wxImage               img{stream};
+
+        png::ImageGreyscale img;
+        png::ReadBuf rb{arch.images[i].buf.data(), arch.images[i].buf.size()};
+        png::decode_png(rb, img);
     
         auto rings = marchsq::execute(img, 128, rstp.win);
         ExPolygons expolys = rings_to_expolygons(rings, rstp.px_w, rstp.px_h);

tests/libslic3r/CMakeLists.txt

@@ -17,6 +17,8 @@ add_executable(${_TEST_NAME}_tests
 	test_marchingsquares.cpp
 	test_timeutils.cpp
 	test_voronoi.cpp
+    test_png_io.cpp
+    test_timeutils.cpp
 	)
 
 if (TARGET OpenVDB::openvdb)

tests/libslic3r/test_png_io.cpp

@@ -0,0 +1,52 @@
+#define NOMINMAX
+#include <catch2/catch.hpp>
+
+#include "libslic3r/PNGRead.hpp"
+#include "libslic3r/SLA/AGGRaster.hpp"
+
+using namespace Slic3r;
+
+static sla::RasterGrayscaleAA create_raster(const sla::RasterBase::Resolution &res)
+{
+    sla::RasterBase::PixelDim pixdim{1., 1.};
+
+    auto bb = BoundingBox({0, 0}, {scaled(1.), scaled(1.)});
+    sla::RasterBase::Trafo trafo;
+    trafo.center_x = bb.center().x();
+    trafo.center_y = bb.center().y();
+
+    return sla::RasterGrayscaleAA{res, pixdim, trafo, agg::gamma_threshold(.5)};
+}
+
+TEST_CASE("PNG read", "[PNG]") {
+    auto rst = create_raster({100, 100});
+
+    size_t rstsum = 0;
+    for (size_t r = 0; r < rst.resolution().height_px; ++r)
+        for (size_t c = 0; c < rst.resolution().width_px; ++c)
+            rstsum += rst.read_pixel(c, r);
+
+    SECTION("Correct png buffer should be recognized as such.") {
+        auto enc_rst = rst.encode(sla::PNGRasterEncoder{});
+        REQUIRE(Slic3r::png::is_png({enc_rst.data(), enc_rst.size()}));
+    }
+
+    SECTION("Fake png buffer should be recognized as such.") {
+        std::vector<uint8_t> fake(10, '\0');
+        REQUIRE(!Slic3r::png::is_png({fake.data(), fake.size()}));
+    }
+
+    SECTION("Decoded PNG buffer resolution should match the original") {
+        auto enc_rst = rst.encode(sla::PNGRasterEncoder{});
+
+        png::ImageGreyscale img;
+        png::decode_png({enc_rst.data(), enc_rst.size()}, img);
+
+        REQUIRE(img.rows == rst.resolution().height_px);
+        REQUIRE(img.cols == rst.resolution().width_px);
+
+        size_t sum = std::accumulate(img.buf.begin(), img.buf.end(), size_t(0));
+
+        REQUIRE(sum == rstsum);
+    }
+}