PicoVector: Text rotation support.

Author: Gadgetoid

libraries/pico_vector/alright_fonts.cpp

@@ -41,6 +41,36 @@ namespace alright_fonts {
     }
   }
 
+  void render_character(text_metrics_t &tm, uint16_t codepoint, pretty_poly::point_t<int> origin, pretty_poly::mat3_t transform) {
+    if(tm.face.glyphs.count(codepoint) == 1) {
+      glyph_t glyph = tm.face.glyphs[codepoint];
+
+      // scale is a fixed point 16:16 value, our font data is already scaled to
+      // -128..127 so to get the pixel size we want we can just shift the
+      // users requested size up one bit
+      unsigned scale = tm.size << 9;
+
+      std::vector<pretty_poly::contour_t<int8_t>> contours;
+
+      for(auto i = 0u; i < glyph.contours.size(); i++) {
+        unsigned int count = glyph.contours[i].count;
+        point_t<int8_t> *points = (point_t<int8_t> *)malloc(sizeof(point_t<int8_t>) * count);
+        for(auto j = 0u; j < count; j++) {
+          point_t<float> point(glyph.contours[i].points[j].x, glyph.contours[i].points[j].y);
+          point *= transform;
+          points[j] = point_t<int8_t>(point.x, point.y);
+        }
+        contours.emplace_back(points, count);
+      }
+
+      pretty_poly::draw_polygon<int8_t>(contours, origin, scale);
+
+      for(auto contour : contours) {
+        free(contour.points);
+      }
+    }
+  }
+
   /*
     load functions
   */

libraries/pico_vector/alright_fonts.hpp

@@ -70,4 +70,5 @@ namespace alright_fonts {
   */
 
   void render_character(text_metrics_t &tm, uint16_t codepoint, pretty_poly::point_t<int> origin);
+  void render_character(text_metrics_t &tm, uint16_t codepoint, pretty_poly::point_t<int> origin, pretty_poly::mat3_t transform);
 }

libraries/pico_vector/pico_vector.cpp

@@ -109,4 +109,80 @@ namespace pimoroni {
 
     return Point(caret.x, caret.y);
   }
+
+  Point PicoVector::text(std::string_view text, Point origin, float angle) {
+    // TODO: Normalize types somehow, so we're not converting?
+    pretty_poly::point_t<float> caret(0, 0);
+
+    // Prepare a transformation matrix for character and offset rotation
+    angle = 2 * M_PI * (angle / 360.0f);
+    pretty_poly::mat3_t transform = pretty_poly::mat3_t::rotation(angle);
+
+    // Align text from the bottom left
+    caret.y += text_metrics.line_height;
+    caret *= transform;
+
+    pretty_poly::point_t<float> space;
+    pretty_poly::point_t<float> carriage_return(0, text_metrics.line_height);
+
+    space.x = alright_fonts::measure_character(text_metrics, ' ').w;
+    if (space.x == 0) {
+      space.x = text_metrics.word_spacing;
+    }
+
+    space *= transform;
+    carriage_return *= transform;
+
+    size_t i = 0;
+
+    while(i < text.length()) {
+      size_t next_space = text.find(' ', i + 1);
+
+      if(next_space == std::string::npos) {
+        next_space = text.length();
+      }
+
+      size_t next_linebreak = text.find('\n', i + 1);
+
+      if(next_linebreak == std::string::npos) {
+        next_linebreak = text.length();
+      }
+
+      size_t next_break = std::min(next_space, next_linebreak);
+
+      uint16_t word_width = 0;
+      for(size_t j = i; j < next_break; j++) {
+        word_width += alright_fonts::measure_character(text_metrics, text[j]).w;
+        word_width += text_metrics.letter_spacing;
+      }
+
+      if(caret.x != 0 && caret.x + word_width > graphics->clip.w) {
+        caret -= carriage_return;
+        carriage_return.x = 0;
+      }
+
+      for(size_t j = i; j < std::min(next_break + 1, text.length()); j++) {
+        if (text[j] == '\n') { // Linebreak
+          caret -= carriage_return;
+          carriage_return.x = 0;
+        } else if (text[j] == ' ') { // Space
+          caret += space;
+          carriage_return += space;
+        } else {
+          alright_fonts::render_character(text_metrics, text[j], pretty_poly::point_t<int>(origin.x + caret.x, origin.y + caret.y), transform);
+        }
+        pretty_poly::point_t<float> advance(
+          alright_fonts::measure_character(text_metrics, text[j]).w + text_metrics.letter_spacing,
+          0
+        );
+        advance *= transform;
+        caret += advance;
+        carriage_return += advance;
+      }
+
+      i = next_break + 1;
+    }
+
+    return Point(caret.x, caret.y);
+  }
 }

libraries/pico_vector/pico_vector.hpp

@@ -70,6 +70,7 @@ namespace pimoroni {
             void translate(pretty_poly::contour_t<picovector_point_type> &contour, Point translation);
 
             Point text(std::string_view text, Point origin);
+            Point text(std::string_view text, Point origin, float angle);
 
             void polygon(std::vector<pretty_poly::contour_t<picovector_point_type>> contours, Point origin = Point(0, 0), int scale=65536);
 

micropython/modules/picovector/picovector.cpp

@@ -325,12 +325,13 @@ mp_obj_t VECTOR_set_antialiasing(mp_obj_t self_in, mp_obj_t aa) {
 }
 
 mp_obj_t VECTOR_text(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
-    enum { ARG_self, ARG_text, ARG_x, ARG_y };
+    enum { ARG_self, ARG_text, ARG_x, ARG_y, ARG_angle };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_, MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_text, MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_x, MP_ARG_REQUIRED | MP_ARG_INT },
-        { MP_QSTR_y, MP_ARG_REQUIRED | MP_ARG_INT }
+        { MP_QSTR_y, MP_ARG_REQUIRED | MP_ARG_INT },
+        { MP_QSTR_angle, MP_ARG_OBJ, {.u_obj = mp_const_none} }
     };
 
     mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
@@ -349,7 +350,11 @@ mp_obj_t VECTOR_text(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args)
     int x = args[ARG_x].u_int;
     int y = args[ARG_y].u_int;
 
-    self->vector->text(t, Point(x, y));
+    if(args[ARG_angle].u_obj == mp_const_none) {
+        self->vector->text(t, Point(x, y));
+    } else {
+        self->vector->text(t, Point(x, y), mp_obj_get_float(args[ARG_angle].u_obj));
+    }
 
     return mp_const_none;
 }