add 'add_stroke_effect' script function

doc/function/index.txt

@@ -91,6 +91,7 @@ These functions are built into the program, other [[type:function]]s can be defi
 | [[fun:recolor_image]]		Change the colors of an image to match the font color.
 | [[fun:resize_image]]		Stretch or squeeze an image to a given height and width.
 | [[fun:enlarge]]		Enlarge an image by putting a border around it.
+| [[fun:add_stroke_effect]]		Add a stroke effect around an image.
 | [[fun:add_bleed_edge]]		Add a crude print bleed edge around an image.
 | [[fun:crop]]			Crop an image, giving only a small subset of it.
 | [[fun:flip_horizontal]]	Flip an image horizontally.

doc/function/stroke_image.txt

@@ -0,0 +1,15 @@
+Function: add_stroke_effect
+
+--Usage--
+> add_stroke_effect(input: image, radius: number, blur: number, color: color)
+
+Add a stroke effect around an image.
+
+--Parameters--
+! Parameter				Type				Description
+| @input@				[[type:image]]		Image that needs a stroke effect
+| @radius@		[[type:int]]		Size of the stroke, in pixels
+| @blur@		[[type:int]]		Size of the blur of the stroke, in pixels. Optional, defaults to 0
+| @color@	[[type:color]]		Color of the stroke
+| @include_image@	[[type:boolean]]		Draw the original image in the middle of the stroke effect. Optional, defaults to true
+

src/data/symbol_font.cpp

@@ -301,96 +301,20 @@ void SymbolFont::draw(RotatedDC& dc, RealRect rect, double scale, const SymbolFo
     RealPoint bmp_pos  = align_in_rect(font.alignment(), bmp_size, sym_rect);
     // 2. draw potential stroke or shadow
     if (font.hasStroke()) {
-      // add margin
-      Image img = bmp.ConvertToImage();
-      if (!img.HasAlpha()) set_alpha(img, 0);
       int blur_radius = lround(font.stroke_blur() * s_scale);
       int stroke_radius = lround(font.stroke_radius() * s_scale);
-      int margin = blur_radius + stroke_radius;
-      int s_width = img.GetWidth() + 2 * margin, s_height = img.GetHeight() + 2 * margin;
-      int x_end = s_width - margin;
-      int y_end = s_height - margin;
-      wxImage s_img(s_width, s_height, false);
-      s_img.InitAlpha();
-      // convert to stroke color
-      Byte* s_data = s_img.GetData();
-      Byte* s_alpha = s_img.GetAlpha(), *alpha = img.GetAlpha();
-      Color color = font.stroke_color();
-      unsigned char r = color.Red();
-      unsigned char g = color.Green();
-      unsigned char b = color.Blue();
-      unsigned char a = color.Alpha();
-      for (int y = 0 ; y < s_height ; ++y) {
-        for (int x = 0 ; x < s_width ; ++x) {
-          s_data[0] = r;
-          s_data[1] = g;
-          s_data[2] = b;
-          s_data += 3;
-          if (margin <= x && x < x_end && margin <= y && y < y_end) {
-            s_alpha[0] = alpha[0] * a / 255;
-            alpha += 1;
-          }
-          else {
-            s_alpha[0] = 0;
-          }
-          s_alpha += 1;
-        }
-      }
-      // add stroke effect
-      for (int i = 0 ; i < stroke_radius ; ++i) {
-        thicken_image_alpha(s_img, 1);
-      }
-      // add blur
-      for (int i = 0 ; i < blur_radius ; ++i) {
-        blur_image_alpha(s_img, 3);
-      }
-      // draw
+      Image s_img = make_stroke_image(bmp.ConvertToImage(), font.stroke_color(), stroke_radius, blur_radius);
       RealSize  s_size = dc.trInvS(RealSize(s_img));
       RealPoint s_pos(bmp_pos.x - (s_size.width - bmp_size.width)/2, bmp_pos.y - (s_size.height - bmp_size.height)/2);
       dc.DrawImage(s_img, s_pos);
     }
     else if (font.hasShadow()) {
-      // add margin
-      Image img = bmp.ConvertToImage();
-      if (!img.HasAlpha()) set_alpha(img, 0);
-      int margin = lround(font.shadow_blur() * s_scale);
-      int s_width = img.GetWidth() + 2 * margin, s_height = img.GetHeight() + 2 * margin;
-      int x_end = s_width - margin;
-      int y_end = s_height - margin;
-      wxImage s_img(s_width, s_height, false);
-      s_img.InitAlpha();
-      // convert to shadow color
-      Byte* s_data = s_img.GetData();
-      Byte* s_alpha = s_img.GetAlpha(), *alpha = img.GetAlpha();
-      Color color = font.shadow_color();
-      unsigned char r = color.Red();
-      unsigned char g = color.Green();
-      unsigned char b = color.Blue();
-      unsigned char a = color.Alpha();
-      for (int y = 0 ; y < s_height ; ++y) {
-        for (int x = 0 ; x < s_width ; ++x) {
-          s_data[0] = r;
-          s_data[1] = g;
-          s_data[2] = b;
-          s_data += 3;
-          if (margin <= x && x < x_end && margin <= y && y < y_end) {
-            s_alpha[0] = alpha[0] * a / 255;
-            alpha += 1;
-          }
-          else {
-            s_alpha[0] = 0;
-          }
-          s_alpha += 1;
-        }
-      }
-      // add blur
-      for (int i = 0 ; i < margin ; ++i) {
-        blur_image_alpha(s_img, 3);
-      }
-      // draw
+      int blur_radius = lround(font.shadow_blur() * s_scale);
+      Image s_img = make_stroke_image(bmp.ConvertToImage(), font.shadow_color(), 0, blur_radius);
       RealSize  s_size = dc.trInvS(RealSize(s_img));
       RealPoint s_pos(bmp_pos.x - (s_size.width - bmp_size.width)/2, bmp_pos.y - (s_size.height - bmp_size.height)/2);
-      dc.DrawImage(s_img, s_pos + RealPoint(font.shadow_displacement_x(), font.shadow_displacement_y()) * scale);
+      RealSize s_displacement = dc.trInvS(RealSize(font.shadow_displacement_x, font.shadow_displacement_y) * s_scale);
+      dc.DrawImage(s_img, s_pos + s_displacement);
     }
     bmps.push_back(std::move(bmp));
     bmp_sizes.push_back(bmp_size);

src/gfx/generated_image.cpp

@@ -320,6 +320,26 @@ bool ResizeImage::operator == (const GeneratedImage& that) const {
     && height == that2->height;
 }
 
+// ----------------------------------------------------------------------------- : StrokeImage
+
+Image StrokeImage::generate(const Options& opt) {
+  // create enlarged image
+  Image base_img = base_image->generate(opt);
+  Image s_img = make_stroke_image(base_img, color, radius, blur);
+  if (include_image) {
+    int offset = radius + blur;
+    s_img.Paste(base_img, offset, offset, wxIMAGE_ALPHA_BLEND_COMPOSE);
+  }
+  return s_img;
+}
+bool StrokeImage::operator == (const GeneratedImage& that) const {
+  const StrokeImage* that2 = dynamic_cast<const StrokeImage*>(&that);
+  return that2 && *base_image == *that2->base_image
+    && radius == that2->radius
+    && blur == that2->blur
+    && color == that2->color;
+}
+
 // ----------------------------------------------------------------------------- : BleedEdgedImage
 
 Image BleedEdgedImage::generate(const Options& opt) {

src/gfx/generated_image.hpp

@@ -318,6 +318,23 @@ private:
   double offset_x, offset_y;
 };
 
+// ----------------------------------------------------------------------------- : StrokeImage
+
+/// Create a stroke effect that goes around an image
+class StrokeImage : public GeneratedImage {
+public:
+  inline StrokeImage(const GeneratedImageP& base_image, int radius, int blur, Color color, bool include_image)
+    : base_image(base_image), radius(radius), blur(blur), color(color), include_image(include_image)
+  {}
+  Image generate(const Options& opt) override;
+  bool operator == (const GeneratedImage& that) const override;
+private:
+  GeneratedImageP base_image;
+  int radius, blur;
+  Color color;
+  bool include_image;
+};
+
 // ----------------------------------------------------------------------------- : BleedEdgedImage
 
 /// Add a crude bleed edge to an image

src/gfx/gfx.hpp

@@ -107,6 +107,9 @@ Byte thicken_pixel_alpha_5x5(std::vector<Byte> in, int i, int x, int y, int widt
 Byte thicken_pixel_alpha_7x7(std::vector<Byte> in, int i, int x, int y, int width, int height);
 // Thicken the alpha channel of an image
 void thicken_image_alpha(Image& img, int radius);
+
+// Create a stroke effect that goes around an image
+Image make_stroke_image(Image& img, Color stroke_color, int stroke_radius, int blur_radius = 0);
 
 // ----------------------------------------------------------------------------- : Combining
 

src/gfx/image_effects.cpp

@@ -360,7 +360,51 @@ void downsample_to_alpha(Bitmap& bmp_in, Image& img_out) {
   }
 
   delete[] temp;
-}
+}
+
+Image make_stroke_image(Image& img, Color stroke_color, int stroke_radius, int blur_radius) {
+  stroke_radius = max(0,min(100,stroke_radius));
+  blur_radius   = max(0,min(100,blur_radius));
+  if (!img.HasAlpha()) set_alpha(img, 255);
+  int margin = blur_radius + stroke_radius;
+  int s_width = img.GetWidth() + 2 * margin, s_height = img.GetHeight() + 2 * margin;
+  int x_end = s_width - margin;
+  int y_end = s_height - margin;
+  wxImage s_img(s_width, s_height, false);
+  s_img.InitAlpha();
+  // convert to stroke color
+  Byte* s_data = s_img.GetData();
+  Byte* s_alpha = s_img.GetAlpha(), *alpha = img.GetAlpha();
+  unsigned char r = stroke_color.Red();
+  unsigned char g = stroke_color.Green();
+  unsigned char b = stroke_color.Blue();
+  unsigned char a = stroke_color.Alpha();
+  for (int y = 0 ; y < s_height ; ++y) {
+    for (int x = 0 ; x < s_width ; ++x) {
+      s_data[0] = r;
+      s_data[1] = g;
+      s_data[2] = b;
+      s_data += 3;
+      if (margin <= x && x < x_end && margin <= y && y < y_end) {
+        s_alpha[0] = alpha[0] * a / 255;
+        alpha += 1;
+      }
+      else {
+        s_alpha[0] = 0;
+      }
+      s_alpha += 1;
+    }
+  }
+  // add stroke effect
+  for (int i = 0 ; i < stroke_radius ; ++i) {
+    thicken_image_alpha(s_img, 1);
+  }
+  // add blur
+  for (int i = 0 ; i < blur_radius ; ++i) {
+    blur_image_alpha(s_img, 3);
+  }
+  return s_img;
+}
 
 // ----------------------------------------------------------------------------- : Coloring symbol images
 

src/gfx/resample_text.cpp

@@ -47,40 +47,22 @@ void draw_resampled_text(DC& dc, const String& text, const RealPoint& pos, const
   downsample_to_alpha(buffer, img);
   // if there is no stroke effect, just add blur and draw
   if (stroke_radius == 0) {
-    if (color.Alpha() != 255) {
-      set_alpha(img, color.Alpha() / 255.);
-    }
-    if (blur_radius > 0) {
-      Image s_img(w + 2*blur_radius, h + 2*blur_radius, false);
-      set_alpha(s_img, 0);
-      s_img.Paste(img, blur_radius, blur_radius, wxIMAGE_ALPHA_BLEND_COMPOSE);
-      for (int i = 0 ; i < blur_radius ; ++i) {
-        blur_image_alpha(s_img, 3);
+    if (blur_radius == 0) {
+      if (color.Alpha() != 255) {
+        set_alpha(img, color.Alpha() / 255.);
       }
-      fill_image(s_img, color);
-      dc.DrawBitmap(s_img, xi-blur_radius, yi-blur_radius);
+      fill_image(img, color);
+      dc.DrawBitmap(img, xi, yi);
     }
     else {
-      fill_image(img, color);
-      dc.DrawBitmap(img, xi, yi);
+      Image s_img = make_stroke_image(img, color, 0, blur_radius);
+      dc.DrawBitmap(s_img, xi-blur_radius, yi-blur_radius);
     }
   }
-  // otherwise add stroke effect
+  // otherwise add stroke effect, add copy of text on top, draw
   else {
     int radius = blur_radius + stroke_radius;
-    Image s_img(w + 2*radius, h + 2*radius, false);
-    set_alpha(s_img, 0);
-    s_img.Paste(img, radius, radius, wxIMAGE_ALPHA_BLEND_COMPOSE);
-    for (int i = 0 ; i < stroke_radius ; ++i) {
-      thicken_image_alpha(s_img, 1);
-    }
-    for (int i = 0 ; i < blur_radius ; ++i) {
-      blur_image_alpha(s_img, 3);
-    }
-    if (stroke_color.Alpha() != 255) {
-      set_alpha(s_img, stroke_color.Alpha() / 255.);
-    }
-    fill_image(s_img, stroke_color);
+    Image s_img = make_stroke_image(img, stroke_color, stroke_radius, blur_radius);
     if (stroke_color != color) {
       fill_image(img, color);
       if (color.Alpha() != 255) {

src/script/functions/image.cpp

@@ -172,6 +172,15 @@ SCRIPT_FUNCTION(enlarge) {
   return make_intrusive<EnlargeImage>(input, border_size);
 }
 
+SCRIPT_FUNCTION(add_stroke_effect) {
+  SCRIPT_PARAM_C(GeneratedImageP, input);
+  SCRIPT_PARAM(Color, color);
+  SCRIPT_PARAM(int, radius);
+  SCRIPT_PARAM_DEFAULT(int, blur, 0);
+  SCRIPT_PARAM_DEFAULT(bool, include_image, true);
+  return make_intrusive<StrokeImage>(input, radius, blur, color, include_image);
+}
+
 SCRIPT_FUNCTION(add_bleed_edge) {
   SCRIPT_PARAM_C(GeneratedImageP, input);
   SCRIPT_PARAM_DEFAULT(double, horizontal_size, -1.0);
@@ -308,6 +317,7 @@ void init_script_image_functions(Context& ctx) {
   ctx.setVariable(_("invert_image"),     script_invert_image);
   ctx.setVariable(_("recolor_image"),    script_recolor_image);
   ctx.setVariable(_("enlarge"),          script_enlarge);
+  ctx.setVariable(_("add_stroke_effect"),script_add_stroke_effect);
   ctx.setVariable(_("add_bleed_edge"),   script_add_bleed_edge);
   ctx.setVariable(_("resize_image"),     script_resize_image);
   ctx.setVariable(_("crop"),             script_crop);

src/util/rotation.cpp

@@ -220,8 +220,9 @@ void RotatedDC::DrawText(const String& text, const RealPoint& pos, Color color,
 
 void RotatedDC::DrawTextWithShadowOrStroke(const String& text, const Font& font, const RealPoint& pos, double scale, double stretch) {
   double s_scale = scale * dc.GetFont().GetPointSize() / text_scaling / 15.;
-  if (font.hasShadow() && !font.hasStroke()) {
-    DrawText(text, pos + RealSize(font.shadow_displacement_x, font.shadow_displacement_y) * scale, font.shadow_color, lround(font.shadow_blur * s_scale), Color(0,0,0), 0, stretch);
+  if (font.hasShadow() && !font.hasStroke()) {
+    RealSize shadow_displacement = trInvS(RealSize(font.shadow_displacement_x, font.shadow_displacement_y) * s_scale);
+    DrawText(text, pos + shadow_displacement, font.shadow_color, lround(font.shadow_blur * s_scale), Color(0,0,0), 0, stretch);
   }
   DrawText(text, pos, font.color, lround(font.stroke_blur * s_scale), font.stroke_color, lround(font.stroke_radius * s_scale), stretch);
 }