Fixed 'scale to fit' functionality of WidgetImage

Widgets/WidgetImage.cpp

@@ -16,7 +16,6 @@ m_valign(valign),
 m_bg_color(bg_color)
 {
 	m_image_surface = IMG_Load(m_filename.c_str());
-
 	if (nullptr == m_image_surface)
 	{
 		// TODO: Print errors
@@ -39,16 +38,23 @@ void WidgetImage::draw()
 		return;
 	}
 
-	SDL_Rect align = surface_align(m_surface, m_image_surface, m_halign, m_valign);
+	SDL_Rect align;
+	SDL_Surface* scaled_image = nullptr;
 	switch (m_resize_type)
 	{
 	case RESIZE_NONE:
+		align = surface_align(m_surface, m_image_surface, m_halign, m_valign);
 		SDL_BlitSurface(m_image_surface, nullptr, m_surface, &align);
 		break;
 
 	case RESIZE_FIT:
-		// TODO: This currently stretches
+		scaled_image = image_scale_fit();
-		SDL_BlitScaled(m_image_surface, nullptr, m_surface, nullptr);
+		if (nullptr != scaled_image)
+		{
+			align = surface_align(m_surface, scaled_image, m_halign, m_valign);
+			SDL_BlitScaled(scaled_image, nullptr, m_surface, &align);
+			SDL_FreeSurface(scaled_image);
+		}
 		break;
 
 	case RESIZE_STRETCH:
@@ -82,3 +88,41 @@ std::unique_ptr<Widget> WidgetImage::builder(const nlohmann::json& j)
 	return std::make_unique<WidgetImage>(x, y, width, height, filename,
 		resize_type, halign, valign, bg_color);
 }
+
+SDL_Surface* WidgetImage::image_scale_fit()
+{
+	SDL_Rect align = {.x = 0, .y = 0, .w = 0, .h = 0};
+
+	if ((nullptr == m_surface) || (nullptr == m_image_surface))
+	{
+		return nullptr;
+	}
+
+	double x_scale = m_surface->w;
+	x_scale /= m_image_surface->w;
+
+	double y_scale = m_surface->h;
+	y_scale /= m_image_surface->h;
+
+	// Find smallest scale factor
+	double min_scale = x_scale;
+	if (y_scale < min_scale)
+	{
+		min_scale = y_scale;
+	}
+
+	// Scale with double in the front and then clamp to int via SDL_Rect
+	align.w = min_scale * m_image_surface->w;
+	align.h = min_scale * m_image_surface->h;
+
+	SDL_Surface* scaled_image_surface =
+		SDL_CreateRGBSurfaceWithFormat(0, align.w, align.h, 32, SDL_PIXELFORMAT_RGBA8888);
+	if (nullptr == scaled_image_surface)
+	{
+		// TODO: Print Error
+		return nullptr;
+	}
+
+	SDL_BlitScaled(m_image_surface, nullptr, scaled_image_surface, nullptr);
+	return scaled_image_surface;
+}

Widgets/WidgetImage.h

@@ -42,6 +42,11 @@ public:
 	virtual void draw() override;
 
 	static std::unique_ptr<Widget> builder(const nlohmann::json& j);
+
+protected:
+	// Create a new surface of the image_surface that is scaled via RESIZE_FIT method
+	// NOTE: The user MUST free the surface when done with it
+	SDL_Surface* image_scale_fit();
 };
 
 #endif // WIDGET_IMAGE_H_

sdl_helpers.cpp

@@ -87,6 +87,10 @@ SDL_Rect surface_align(const SDL_Surface* base, const SDL_Surface* applied,
 		return align;
 	}
 
+	// These are set in order to handle scaled blits
+	align.w = applied->w;
+	align.h = applied->h;
+
 	if (nullptr == hint_external)
 	{
 		hint = SDL_Rect{.x = 0, .y = 0, .w = applied->w, .h = applied->h};