Fix parameter order in case of right-to-left lines, formatting

client/gui/SDL_Extensions.cpp

@@ -362,9 +362,10 @@ void CSDL_Ext::update(SDL_Surface * what)
 		logGlobal->error("%s SDL_UpdateTexture %s", __FUNCTION__, SDL_GetError());
 }
 
-uint8_t lerp(uint8_t a, uint8_t b, float f)
+template<typename Int>
+Int lerp(Int a, Int b, float f)
 {
-	return a + std::round((b-a)*f);
+	return a + std::round((b - a) * f);
 }
 
 static void drawLineX(SDL_Surface * sur, int x1, int y1, int x2, int y2, const SDL_Color & color1, const SDL_Color & color2)
@@ -372,7 +373,7 @@ static void drawLineX(SDL_Surface * sur, int x1, int y1, int x2, int y2, const S
 	for(int x = x1; x <= x2; x++)
 	{
 		float f = float(x - x1) / float(x2 - x1);
-		int y = y1 + std::round((y2-y1)*f);
+		int y = lerp(y1, y2, f);
 
 		uint8_t r = lerp(color1.r, color2.r, f);
 		uint8_t g = lerp(color1.g, color2.g, f);
@@ -389,7 +390,7 @@ static void drawLineY(SDL_Surface * sur, int x1, int y1, int x2, int y2, const S
 	for(int y = y1; y <= y2; y++)
 	{
 		float f = float(y - y1) / float(y2 - y1);
-		int x = x1 + std::round((x2-x1)*f);
+		int x = lerp(x1, x2, f);
 
 		uint8_t r = lerp(color1.r, color2.r, f);
 		uint8_t g = lerp(color1.g, color2.g, f);
@@ -418,14 +419,14 @@ void CSDL_Ext::drawLine(SDL_Surface * sur, int x1, int y1, int x2, int y2, const
 		if ( x1 < x2)
 			drawLineX(sur, x1,y1,x2,y2, color1, color2);
 		else
-			drawLineX(sur, x2,y2,x1,y1, color1, color2);
+			drawLineX(sur, x2,y2,x1,y1, color2, color1);
 	}
 	else
 	{
 		if ( y1 < y2)
 			drawLineY(sur, x1,y1,x2,y2, color1, color2);
 		else
-			drawLineY(sur, x2,y2,x1,y1, color1, color2);
+			drawLineY(sur, x2,y2,x1,y1, color2, color1);
 	}
 }