Using unit per em instead of ascent

src/libslic3r/Emboss.cpp

@@ -38,7 +38,7 @@ public:
     /// <returns>ExPolygons with only unique points</returns>
     static ExPolygons dilate_to_unique_points(ExPolygons &expolygons);
 
-    // scale and convert flota to int coordinate
+    // scale and convert float to int coordinate
     static Point to_point(const stbtt__point &point);
 };
 
@@ -118,6 +118,9 @@ std::optional<Emboss::Glyph> Private::get_glyph(stbtt_fontinfo &font_info, int u
     }
     // fix for bad defined fonts
     glyph.shape = Slic3r::union_ex(glyph_polygons);
+
+    BoundingBox bb(glyph.shape.front().contour.points);
+
     // inner cw - hole
     // outer ccw - contour
     return glyph;
@@ -481,8 +484,12 @@ std::unique_ptr<Emboss::FontFile> Emboss::load_font(
     // load information about line gap
     int ascent, descent, linegap;
     stbtt_GetFontVMetrics(info, &ascent, &descent, &linegap);
+
+    float pixels = 1000.; // value is irelevant
+    float em_pixels = stbtt_ScaleForMappingEmToPixels(info, pixels);
+    int   units_per_em = static_cast<int>(std::round(pixels / em_pixels));
     return std::make_unique<Emboss::FontFile>(
-        std::move(data), collection_size, ascent, descent, linegap);
+        std::move(data), collection_size, ascent, descent, linegap, units_per_em);
 }
 
 std::unique_ptr<Emboss::FontFile> Emboss::load_font(const char *file_path)

src/libslic3r/Emboss.hpp

@@ -45,7 +45,11 @@ public:
     // description of one letter
     struct Glyph
     {
+        // NOTE: shape is scaled by SHAPE_SCALE 
+        // to be able store points without floating points
         ExPolygons shape;
+
+        // values are in font points
         int advance_width=0, left_side_bearing=0;
     };
     // cache for glyph by unicode
@@ -68,19 +72,25 @@ public:
         // vertical position is "scale*(ascent - descent + lineGap)"
         const int ascent, descent, linegap;
 
+        // for convert font units to pixel
+        int unit_per_em;
+
         Emboss::Glyphs cache; // cache of glyphs
 
         FontFile(std::vector<unsigned char> &&buffer,
                  unsigned int                 count,
                  int                          ascent,
                  int                          descent,
-                 int                          linegap)
+                 int                          linegap,
+                 int unit_per_em
+            )
             : buffer(std::move(buffer))
             , index(0) // select default font on index 0
             , count(count)
             , ascent(ascent)
             , descent(descent)
             , linegap(linegap)
+            , unit_per_em(unit_per_em)
         {}
         bool operator==(const FontFile &other) const {
             return index == other.index &&

src/slic3r/GUI/Gizmos/GLGizmoEmboss.cpp

@@ -41,7 +41,8 @@
 #ifdef ALLOW_DEBUG_MODE
 #define ALLOW_ADD_FONT_BY_FILE
 #define ALLOW_ADD_FONT_BY_OS_SELECTOR
-#define SHOW_WX_FONT_DESCRIPTOR
+#define SHOW_WX_FONT_DESCRIPTOR // OS specific descriptor | file path
+#define SHOW_FONT_FILE_PROPERTY // ascent, descent, line gap, cache
 #define SHOW_IMGUI_ATLAS
 #define SHOW_ICONS_TEXTURE
 #define SHOW_FINE_POSITION
@@ -51,6 +52,7 @@
 #endif // ALLOW_DEBUG_MODE
 
 #define SHOW_WX_FONT_DESCRIPTOR
+#define SHOW_FONT_FILE_PROPERTY
 #define ALLOW_ADD_FONT_BY_FILE
 #define ALLOW_ADD_FONT_BY_OS_SELECTOR
 #define ALLOW_REVERT_ALL_STYLES
@@ -200,10 +202,9 @@ bool GLGizmoEmboss::on_mouse_for_rotation(const wxMouseEvent &mouse_event)
         // propagate angle into property
         angle_opt = static_cast<float>(*start_angle + angle);
         // move to range <-M_PI, M_PI>
-        if (*angle_opt > M_PI) {
+        if (*angle_opt > M_PI || *angle_opt < -M_PI) {
-            *angle_opt -= 2 * M_PI;
+            int count = static_cast<int>(std::round(*angle_opt / (2 * M_PI)));
-        } else if (*angle_opt < -M_PI) {
+            *angle_opt -= static_cast<float>(count * 2 * M_PI);
-            *angle_opt += 2 * M_PI;
         }
         // do not store zero
         if (std::fabs(*angle_opt) < std::numeric_limits<float>::epsilon())
@@ -1341,6 +1342,19 @@ void GLGizmoEmboss::draw_advanced()
         return;
     }
     
+#ifdef SHOW_FONT_FILE_PROPERTY
+    ImGui::SameLine();
+    std::string ff_property = 
+        "ascent=" + std::to_string(font_file->ascent) +
+        ", descent=" + std::to_string(font_file->descent) +
+        ", lineGap=" + std::to_string(font_file->linegap) +
+        ", unitPerEm=" + std::to_string(font_file->unit_per_em) +
+        ", cache(" + std::to_string(font_file->cache.size()) + " glyphs)";
+    if (font_file->count > 1) ff_property += 
+        ", collect=" + std::to_string(font_file->index + 1) + "/" + std::to_string(font_file->count);
+    m_imgui->text_colored(ImGuiWrapper::COL_GREY_DARK, ff_property);
+#endif // SHOW_FONT_FILE_PROPERTY
+
     FontProp &font_prop = m_font_manager.get_font_item().prop;
     bool   exist_change = false;    
     

src/slic3r/GUI/Jobs/EmbossJob.cpp

@@ -242,7 +242,7 @@ TriangleMesh EmbossCreateJob::create_mesh(const char *      text,
     if (shapes.empty()) return {};
     if (ctl.was_canceled()) return {};
 
-    float scale    = font_prop.size_in_mm / font.ascent;
+    float scale    = font_prop.size_in_mm / font.unit_per_em;
     float depth    = font_prop.emboss / scale;
     auto  projectZ = std::make_unique<Emboss::ProjectZ>(depth);
     Emboss::ProjectScale project(std::move(projectZ), scale);

src/slic3r/Utils/FontManager.cpp

@@ -437,7 +437,7 @@ void FontManager::init_style_images(int max_width) {
         // dot per inch for monitor
         int    dpi = get_dpi_for_window(mf);
         double ppm = dpi / 25.4; // pixel per milimeter
-        double scale = font_prop.size_in_mm / font_file->ascent * Emboss::SHAPE_SCALE * ppm;
+        double scale = font_prop.size_in_mm / font_file->unit_per_em * Emboss::SHAPE_SCALE * ppm;
         scales[index] = scale;
 
         //double scale = font_prop.size_in_mm * SCALING_FACTOR;
@@ -494,9 +494,6 @@ void FontManager::init_style_images(int max_width) {
         sla::Resolution resolution(image.tex_size.x, image.tex_size.y);
 
         size_t index = &item - &m_font_list.front();
-        //double scale = item.font_item.prop.size_in_mm / SCALING_FACTOR / item.font_file->ascent;
-        //double scale = item.font_item.prop.size_in_mm;
-        //sla::PixelDim dim(1 / scale, 1 / scale);
         double pixel_dim = SCALING_FACTOR / scales[index];
         sla::PixelDim dim(pixel_dim, pixel_dim);
         double gamma = 1.;
@@ -567,7 +564,9 @@ ImFont * FontManager::load_imgui_font(size_t index, const std::string &text)
 
     const FontProp &font_prop = item.font_item.prop;
 
-    float c1 = (font_file.ascent - font_file.descent + font_file.linegap) / (float)font_file.ascent;
+    // coeficient for convert line height to font size
+    float c1 = (font_file.ascent - font_file.descent + font_file.linegap) / (float) font_file.unit_per_em;
+
     // The point size is defined as 1/72 of the Anglo-Saxon inch (25.4 mm): 
     // it is approximately 0.0139 inch or 352.8 um.
     // But it is too small, so I decide use point size as mm for emboss
@@ -581,11 +580,11 @@ ImFont * FontManager::load_imgui_font(size_t index, const std::string &text)
     // TODO: start using merge mode
     //font_config.MergeMode = true;
     if (font_prop.char_gap.has_value()) {
-        float coef = font_size / (double) font_file.ascent;
+        float coef = font_size / (double) font_file.unit_per_em;
         font_config.GlyphExtraSpacing.x = coef * (*font_prop.char_gap);
     }
     if (font_prop.line_gap.has_value()) {
-        float coef = font_size / (double) font_file.ascent;
+        float coef = font_size / (double) font_file.unit_per_em;
         font_config.GlyphExtraSpacing.y = coef * (*font_prop.line_gap);
     }