XY flip is implemented, works only for portrait LCD.

src/libslic3r/PrintExport.hpp

@@ -31,8 +31,6 @@ template<FilePrinterFormat format>
 class FilePrinter {
 public:
 
-    void print_config(const Print&);
-
     // Draw an ExPolygon which is a polygon inside a slice on the specified layer.
     void draw_polygon(const ExPolygon& p, unsigned lyr);
 
@@ -147,8 +145,8 @@ template<> class FilePrinter<FilePrinterFormat::SLA_PNGZIP>
                   +layerh_str+"+printer=DWARF3\n";
     }
 
-    // Change this to TOP_LEFT if you want correct PNG orientation
+    // The PNG format has its origin in the top left corner.
-    static const Raster::Origin ORIGIN = Raster::Origin::BOTTOM_LEFT;
+    static const Raster::Origin ORIGIN = Raster::Origin::TOP_LEFT;
 
 public:
     inline FilePrinter(double width_mm, double height_mm,

src/libslic3r/Rasterizer/Rasterizer.cpp

@@ -45,15 +45,20 @@ private:
     TRawRenderer m_raw_renderer;
     TRendererAA m_renderer;
     Origin m_o;
-    std::function<void(agg::path_storage&)> m_flipy = [](agg::path_storage&) {};
+
+    inline void flipy(agg::path_storage& path) const {
+        path.flip_y(0, m_resolution.height_px);
+    }
+
 public:
+
     inline Impl(const Raster::Resolution& res, const Raster::PixelDim &pd,
                 Origin o):
         m_resolution(res), m_pxdim(pd),
         m_buf(res.pixels()),
         m_rbuf(reinterpret_cast<TPixelRenderer::value_type*>(m_buf.data()),
               res.width_px, res.height_px,
-              res.width_px*TPixelRenderer::num_components),
+              int(res.width_px*TPixelRenderer::num_components)),
         m_pixfmt(m_rbuf),
         m_raw_renderer(m_pixfmt),
         m_renderer(m_raw_renderer),
@@ -65,10 +70,6 @@ public:
         // ras.gamma(agg::gamma_power(1.0));
 
         clear();
-
-        if(m_o == Origin::TOP_LEFT) m_flipy = [this](agg::path_storage& path) {
-            path.flip_y(0, m_resolution.height_px);
-        };
     }
 
     void draw(const ExPolygon &poly) {
@@ -76,12 +77,14 @@ public:
         agg::scanline_p8 scanlines;
 
         auto&& path = to_path(poly.contour);
-        m_flipy(path);
+
+        if(m_o == Origin::TOP_LEFT) flipy(path);
+
         ras.add_path(path);
 
         for(auto h : poly.holes) {
             auto&& holepath = to_path(h);
-            m_flipy(holepath);
+            if(m_o == Origin::TOP_LEFT) flipy(holepath);
             ras.add_path(holepath);
         }
 
@@ -205,8 +208,9 @@ void Raster::save(std::ostream& stream, Compression comp)
                << m_impl->resolution().height_px << " "
                << "255 ";
 
+        auto sz = m_impl->buffer().size()*sizeof(Impl::TBuffer::value_type);
         stream.write(reinterpret_cast<const char*>(m_impl->buffer().data()),
-                     m_impl->buffer().size()*sizeof(Impl::TBuffer::value_type));
+                     std::streamsize(sz));
     }
     }
 }

src/libslic3r/Rasterizer/Rasterizer.hpp

@@ -27,6 +27,13 @@ public:
         PNG     //!> PNG compression
     };
 
+    /// The Rasterizer expects the input polygons to have their coordinate
+    /// system origin in the bottom left corner. If the raster is then
+    /// configured with the TOP_LEFT origin parameter (in the constructor) than
+    /// it will flip the Y axis in output to maintain the correct orientation.
+    /// This is the default case with PNG images. They have the origin in the
+    /// top left corner. Without the flipping, the image would be upside down
+    /// with the scaled (clipper) coordinate system of the input polygons.
     enum class Origin {
         TOP_LEFT,
         BOTTOM_LEFT

src/libslic3r/SLAPrint.cpp

@@ -715,6 +715,8 @@ void SLAPrint::process()
         std::vector<long long> keys; keys.reserve(levels.size());
         for(auto& e : levels) keys.emplace_back(e.first);
 
+        bool flpXY = m_printer_config.display_flip_xy.getBool();
+
         { // create a raster printer for the current print parameters
             // I don't know any better
             auto& ocfg = m_objects.front()->m_config;
@@ -729,6 +731,8 @@ void SLAPrint::process()
             double exp_t = matcfg.exposure_time.getFloat();
             double iexp_t = matcfg.initial_exposure_time.getFloat();
 
+            if(flpXY) { std::swap(w, h); std::swap(pw, ph); }
+
             m_printer.reset(new SLAPrinter(w, h, pw, ph, lh, exp_t, iexp_t));
         }
 
@@ -744,7 +748,7 @@ void SLAPrint::process()
 
         // procedure to process one height level. This will run in parallel
         auto lvlfn =
-        [this, &slck, &keys, &levels, &printer, slot, sd, ist, &pst]
+        [this, &slck, &keys, &levels, &printer, slot, sd, ist, &pst, flpXY]
             (unsigned level_id)
         {
             if(canceled()) return;
@@ -764,8 +768,12 @@ void SLAPrint::process()
                     for(ExPolygon slice : sl) {
                         // The order is important here:
                         // apply rotation before translation...
-                        slice.rotate(cp.rotation);
+                        slice.rotate(double(cp.rotation));
                         slice.translate(cp.shift(X), cp.shift(Y));
+                        if(flpXY) {
+                            for(auto& p : slice.contour.points) std::swap(p(X), p(Y));
+                            for(auto& h : slice.holes) for(auto& p : h.points) std::swap(p(X), p(Y));
+                        }
                         printer.draw_polygon(slice, level_id);
                     }
                 }