handle transparent images when importing symbols

data/ch-s.mse-locale/locale

@@ -1094,6 +1094,8 @@ error:
 	negative image height:				Image with zero or negative height created in function '%s'
 	#TODO: Localize
 	can't load image:					Failed to load image. Ensure the image's actual format matches its saved extension.
+	#TODO: Localize
+	symbol image has alpha:				For best results, image should be black and white with no transparency.
 
 	# error from files
 	#TODO: Localize

data/ch-t.mse-locale/locale

@@ -1092,6 +1092,8 @@ error:
 	negative image height:				Image with zero or negative height created in function '%s'
 	#TODO: Localize
 	can't load image:					Failed to load image. Ensure the image's actual format matches its saved extension.
+	#TODO: Localize
+	symbol image has alpha:				For best results, image should be black and white with no transparency.
 
 	# error from files
 	#TODO: Localize

data/da.mse-locale/locale

@@ -1119,6 +1119,8 @@ error:
 	negative image height:				Image with zero or negative height created in function '%s'
 	#TODO: Localize
 	can't load image:					Failed to load image. Ensure the image's actual format matches its saved extension.
+	#TODO: Localize
+	symbol image has alpha:				For best results, image should be black and white with no transparency.
 
 	# error from files
 	#TODO: Localize Section

data/de.mse-locale/locale

@@ -1021,6 +1021,7 @@ error:
 	negative image width:				Bild mit Breite Null oder negativer Breite, erstellt in der Funktion '%s'
 	negative image height:				Bild mit Höhe Null oder negativer Höhe, erstellt in der Funktion '%s'
 	can't load image:					Bild konnte nicht geladen werden. Stelle sicher, dass das tatsächliche Format des Bildes mit der gespeicherten Dateiendung übereinstimmt.
+	symbol image has alpha:				Für optimale Ergebnisse sollte das Bild schwarzweiß und ohne Transparenz sein.
 
 	# error from files
 	no card fields:						Das Spiel '%s' hat keine Kartenfelder. Definieren Sie mindestens ein Kartenfeld.

data/en.mse-locale/locale

@@ -1023,6 +1023,7 @@ error:
 	negative image width:				Image with zero or negative width created in function '%s'
 	negative image height:				Image with zero or negative height created in function '%s'
 	can't load image:					Failed to load image. Ensure the image's actual format matches its saved extension.
+	symbol image has alpha:				For best results, image should be black and white with no transparency.
 
 	# error from files
 	no card fields:						Game '%s' does not have any card fields. Define at least one card field.

data/es.mse-locale/locale

@@ -1095,6 +1095,8 @@ error:
 	negative image height:				Image with zero or negative height created in function '%s'
 	#TODO: Localize
 	can't load image:					Failed to load image. Ensure the image's actual format matches its saved extension.
+	#TODO: Localize
+	symbol image has alpha:				For best results, image should be black and white with no transparency.
 
 	# error from files
 	#TODO: Localize

data/fr.mse-locale/locale

@@ -1022,6 +1022,7 @@ error:
 	negative image width:				Image de largeur nulle ou négative créée par la fonction '%s'
 	negative image height:				Image de hauteur nulle ou négative créée par la fonction '%s'
 	can't load image:					Échec du chargement de l'image. Assurez-vous que le format réel de l'image corresponde à son extension enregistrée.
+	symbol image has alpha:				Pour un résultat optimal, l'image doit être en noir et blanc sans transparence.
 
 	# error from files
 	no card fields:						Le jeu '%s' ne contient aucun champ de carte. Définissez au moins un champ de carte.

data/it.mse-locale/locale

@@ -1022,6 +1022,7 @@ error:
 	negative image width:				Immagine con larghezza zero o negativa creata nella funzione '%s'
 	negative image height:				Immagine con altezza zero o negativa creata nella funzione '%s'
 	can't load image:					Impossibile caricare l'immagine. Assicurarsi che il formato effettivo dell'immagine corrisponda all'estensione salvata.
+	symbol image has alpha:				Per ottenere risultati ottimali, l'immagine dovrebbe essere in bianco e nero, senza trasparenza.
 
 	# error from files
 	no card fields:						Il gioco '%s' non ha campi carta. Definisci almeno un campo carta.

data/jp.mse-locale/locale

@@ -1095,6 +1095,8 @@ error:
 	negative image height:				Image with zero or negative height created in function '%s'
 	#TODO: Localize
 	can't load image:					Failed to load image. Ensure the image's actual format matches its saved extension.
+	#TODO: Localize
+	symbol image has alpha:				For best results, image should be black and white with no transparency.
 
 	# error from files
 	#TODO: Localize

data/ko.mse-locale/locale

@@ -1101,6 +1101,8 @@ error:
 	negative image height:				Image with zero or negative height created in function '%s'
 	#TODO: Localize
 	can't load image:					Failed to load image. Ensure the image's actual format matches its saved extension.
+	#TODO: Localize
+	symbol image has alpha:				For best results, image should be black and white with no transparency.
 
 	# error from files
 	#TODO: Localize

data/pl.mse-locale/locale

@@ -1151,6 +1151,8 @@ error:
 	negative image height:				Image with zero or negative height created in function '%s'
 	#TODO: Localize
 	can't load image:					Failed to load image. Ensure the image's actual format matches its saved extension.
+	#TODO: Localize
+	symbol image has alpha:				For best results, image should be black and white with no transparency.
 
 	# error from files
 	#TODO: Localize

data/pt-br.mse-locale/locale

@@ -1023,6 +1023,7 @@ error:
 	negative image width:				Imagem com largura zero ou negativa criada na função '%s'
 	negative image height:				Imagem com altura zero ou negativa criada na função '%s'
 	can't load image:					Falha ao carregar a imagem. Verifique se o formato real da imagem corresponde à extensão salva.
+	symbol image has alpha:				Para obter melhores resultados, a imagem deve ser em preto e branco, sem transparência.
 
 	# error from files
 	no card fields:						O jogo '%s' não possui campos de Card. Defina pelo menos um campo de Card.

data/ru.mse-locale/locale

@@ -1147,6 +1147,8 @@ error:
 	negative image height:				Image with zero or negative height created in function '%s'
 	#TODO: Localize
 	can't load image:					Failed to load image. Ensure the image's actual format matches its saved extension.
+	#TODO: Localize
+	symbol image has alpha:				For best results, image should be black and white with no transparency.
 
 	# error from files
 	#TODO: Localize Section

src/data/action/value.cpp

@@ -194,10 +194,11 @@ String compute_new_variable_value(const String& str, const String& tag, size_t s
   }
   while (end_i < str.size() &&
          is_formatting_tag(str, end_i)) {
-    end_i = str.find_first_of(">", end_i) + 1;
+    end_i = str.find_first_of(">", end_i);
+    if (end_i != String::npos) end_i++;
   }
   String prefix(substr(str, 0, start_i));
-  String suffix(substr(str, end_i));
+  String suffix = end_i == String::npos ? String() : substr(str, end_i);
   String selection(substr(str, start_i, end_i - start_i));
 
   // tally open tags that are variants of this tag

src/data/format/image_to_symbol.cpp

@@ -15,6 +15,7 @@
 
 #include <util/prec.hpp>
 #include <data/format/image_to_symbol.hpp>
+#include <gfx/gfx.hpp>
 #include <gfx/bezier.hpp>
 #include <util/error.hpp>
 #include <util/platform.hpp>
@@ -205,11 +206,13 @@ SymbolShapeP read_symbol_shape(const ImageData& data) {
 
 
 SymbolP image_to_symbol(Image& img) {
-  int w = img.GetWidth(), h = img.GetHeight();
+  int w = img.GetWidth(), h = img.GetHeight();
-  // 1. threshold the image
+  // get rid of alpha channel
+  fill_alpha(img, w, h);
+  // threshold the image
   greyscale(img);
   threshold(img.GetData(), w, h);
-  // 2. read as many symbol shapes as we can
+  // read as many symbol shapes as we can
   ImageData data = {w,h,img.GetData()};
   SymbolP symbol(new Symbol);
   while (true) {
@@ -221,6 +224,30 @@ SymbolP image_to_symbol(Image& img) {
   return symbol;
 }
 
+void fill_alpha(Image& img, int w, int h) {
+  if (!img.HasAlpha() || w <= 0 || h <= 0) return;
+  Byte* alpha = img.GetAlpha();
+  for (int i = 0; i < w*h ; ++i) {
+    if (alpha[i] < 255) {
+      Byte* pixels = img.GetData();
+      Byte first_pixel = pixels[0];
+      for (int j = 1; j < 3 * w * h; ++j) {
+        if (pixels[j] != first_pixel) {
+          wxMessageDialog dial = wxMessageDialog(nullptr, _ERROR_("symbol image has alpha"));
+          dial.ShowModal();
+          break;
+        }
+      }
+      Image copy = img.Copy();
+      memset(copy.GetData(), 255, 3 * w * h);
+      memset(pixels,         0,   3 * w * h);
+      memset(alpha,          255,     w * h);
+      img.Paste(copy, 0, 0, wxIMAGE_ALPHA_BLEND_COMPOSE);
+      return;
+    }
+  }
+}
+
 SymbolP import_symbol(Image& img) {
   SymbolP symbol;
   if (is_mse1_symbol(img)) {

src/data/format/image_to_symbol.hpp

@@ -23,6 +23,9 @@ bool is_mse1_symbol(const Image& img);
 
 /// Convert an image to a symbol, destroys the image in the process
 SymbolP image_to_symbol(Image& img);
+
+/// If an image has alpha, try to save it if it has only one color
+void fill_alpha(Image& img, int w, int h);
 
 // ----------------------------------------------------------------------------- : Simplify symbol