Fixed text alignment to be visible based rather than surface based

Widgets/WidgetText.cpp

@@ -15,6 +15,72 @@ static SDL_Surface* render_text(bool should_wrap, TTF_Font* font, const string&
 	return txt_surface;
 }
 
+static SDL_Rect find_visible_area(const SDL_Surface* txt_surface)
+{
+	int x_start = -1;
+	int x_end = -1;
+	int y_start = -1;
+	int y_end = -1;
+
+	for (int y = 0; y < txt_surface->h; ++y)
+	{
+		bool found = false;
+		for (int x = 0; x < txt_surface->w; ++x)
+		{
+			if (1 == (static_cast<Uint8*>(txt_surface->pixels)[y * txt_surface->pitch + x]))
+			{
+				if (-1 == x_start)
+				{
+					x_start = x;
+				}
+				else
+				{
+					if (x < x_start)
+					{
+						x_start = x;
+					}
+				}
+
+				if (-1 == x_end)
+				{
+					x_end = x;
+				}
+				else
+				{
+					if (x > x_end)
+					{
+						x_end = x;
+					}
+				}
+				found = true;
+			}
+		}
+
+		if (found)
+		{
+			if (-1 == y_start)
+			{
+				y_start = y;
+			}
+			y_end = y;
+		}
+	}
+	SDL_Rect result = {.x = 0, .y = 0, .w = 0, .h = 0};
+	if ((-1 != x_start) && (-1 != x_end))
+	{
+		result.x = x_start;
+		result.w = x_end - x_start + 1;
+	}
+
+	if ((-1 != y_start) && (-1 != y_end))
+	{
+		result.y = y_start;
+		result.h = y_end - y_start + 1;
+	}
+
+	return result;
+}
+
 WidgetText::WidgetText(int x, int y, int width, int height, string text,
 	TextFit fit, bool should_wrap,
 	HorizontalAlign halign, VerticalAlign valign,
@@ -171,7 +237,8 @@ void WidgetText::draw()
 	}
 
 	// Now we have the final rendered text surface
-	SDL_Rect align = surface_align(m_surface, txt_surface, m_halign, m_valign);
+	SDL_Rect hint = find_visible_area(txt_surface);
+	SDL_Rect align = surface_align(m_surface, txt_surface, m_halign, m_valign, &hint);
 	SDL_BlitSurface(txt_surface, NULL, m_surface, &align);
 	SDL_FreeSurface(txt_surface);
 }

sdl_helpers.cpp

@@ -77,42 +77,52 @@ TTF_Font* get_font(int size, const string& filename)
 }
 
 SDL_Rect surface_align(const SDL_Surface* base, const SDL_Surface* applied,
-	HorizontalAlign halign, VerticalAlign valign)
+	HorizontalAlign halign, VerticalAlign valign, const SDL_Rect* hint_external)
 {
 	SDL_Rect align = {.x = 0, .y = 0, .w = 0, .h = 0};
+	SDL_Rect hint;
 
 	if ((nullptr == base) || (nullptr == applied))
 	{
 		return align;
 	}
 
+	if (nullptr == hint_external)
+	{
+		hint = SDL_Rect{.x = 0, .y = 0, .w = applied->w, .h = applied->h};
+	}
+	else
+	{
+		hint = *hint_external;
+	}
+
 	switch (halign)
 	{
 	case HALIGN_LEFT:
-		align.x = 0;
+		align.x = -hint.x;
 		break;
 
 	case HALIGN_CENTER:
-		align.x = base->w / 2 - applied->w / 2;
+		align.x = base->w / 2 - hint.x - hint.w / 2;
 		break;
 
 	case HALIGN_RIGHT:
-		align.x = base->w - applied->w;
+		align.x = base->w - (hint.x + hint.w);
 		break;
 	}
 
 	switch (valign)
 	{
 	case VALIGN_TOP:
-		align.y = 0;
+		align.y = -hint.y;
 		break;
 
 	case VALIGN_CENTER:
-		align.y = base->h / 2 - applied->h / 2;
+		align.y = base->h / 2 - hint.y - hint.h / 2;
 		break;
 
 	case VALIGN_BOTTOM:
-		align.y = base->h - applied->h;
+		align.y = base->h - (hint.y + hint.h);
 		break;
 	}
 

sdl_helpers.h

@@ -66,8 +66,9 @@ TTF_Font* get_font(int size, const std::string& filename = default_font_name);
 // Returns a rect to use during bliting of 2 surfaces
 // base - surface on which the other is applied to
 // applied - the surface which will be applied to the other
+// hint - rect to hint visible area from applied - can be NULL
 SDL_Rect surface_align(const SDL_Surface* base, const SDL_Surface* applied,
-	HorizontalAlign halign, VerticalAlign valign);
+	HorizontalAlign halign, VerticalAlign valign, const SDL_Rect* hint = nullptr);
 
 // Reads the file and tries to parse a JSON file with comments
 // cfg - output json struct