Support specifying the Blend Mode as part of the filename

This is supported e.g. by a DynRPG plugin but we are not feature compatible to this.

Works for everything that is processed as a Sprite which is almost everything except scrolling backgrounds (e.g. Panorama) and the Tilemap.

Fix EasyRPG#2628

src/bitmap.cpp

@@ -130,6 +130,8 @@ Bitmap::Bitmap(Filesystem_Stream::InputStream stream, bool transparent, uint32_t
 	ConvertImage(w, h, pixels, transparent);
 
 	CheckPixels(flags);
+
+	filename = ToString(stream.GetName());
 }
 
 Bitmap::Bitmap(const uint8_t* data, unsigned bytes, bool transparent, uint32_t flags) {

src/bitmap.h

@@ -215,6 +215,14 @@ class Bitmap {
 	 */
 	Color GetShadowColor() const;
 
+	/**
+	 * Gets the filename this bitmap was loaded from.
+	 * This will be empty when the origin was not a file.
+	 *
+	 * @return filename
+	 */
+	StringView GetFilename() const;
+
 	void CheckPixels(uint32_t flags);
 
 	/**
@@ -578,6 +586,8 @@ class Bitmap {
 	TileOpacity tile_opacity;
 	Color bg_color, sh_color;
 
+	std::string filename;
+
 	/** Bitmap data. */
 	PixmanImagePtr bitmap;
 	pixman_format_code_t pixman_format;
@@ -647,4 +657,8 @@ inline bool Bitmap::GetTransparent() const {
 	return format.alpha_type != PF::NoAlpha;
 }
 
+inline StringView Bitmap::GetFilename() const {
+	return filename;
+}
+
 #endif

src/sprite.cpp

@@ -114,11 +114,43 @@ BitmapRef Sprite::Refresh(Rect& rect) {
 }
 
 void Sprite::SetBitmap(BitmapRef const& nbitmap) {
+	if (nbitmap == bitmap) {
+		return;
+	}
+
 	bitmap = nbitmap;
 	if (!bitmap) {
 		src_rect = Rect();
 	} else {
 		src_rect = bitmap->GetRect();
+
+		// EasyRPG Extension: Set the Blend Mode based on the filename, e.g. ".add.png" for "Additive"
+		SetBlendType(0);
+		StringView filename = bitmap->GetFilename();
+		if (filename.size() >= 8 && filename[filename.size() - 4] == '.' && filename[filename.size() - 8] == '.') {
+			filename = filename.substr(filename.size() - 7, 3);
+			constexpr std::array<std::pair<StringView, Bitmap::BlendMode>, 13> exts = {{
+				{"add", Bitmap::BlendMode::Additive},
+				{"clb", Bitmap::BlendMode::ColorBurn},
+				{"cld", Bitmap::BlendMode::ColorDodge},
+				{"dif", Bitmap::BlendMode::Difference},
+				{"drk", Bitmap::BlendMode::Darken},
+				{"exc", Bitmap::BlendMode::Exclusion},
+				{"hlg", Bitmap::BlendMode::HardLight},
+				{"lgh", Bitmap::BlendMode::Lighten},
+				{"mul", Bitmap::BlendMode::Multiply},
+				{"ove", Bitmap::BlendMode::Overlay},
+				{"sat", Bitmap::BlendMode::Saturate},
+				{"slg", Bitmap::BlendMode::SoftLight},
+				{"xor", Bitmap::BlendMode::XOR}
+			}};
+			auto it = std::lower_bound(exts.begin(), exts.end(), filename, [](const auto& e, const auto& fname) {
+				return e.first < fname;
+			});
+			if (it != exts.end() && it->first == filename) {
+				SetBlendType((int)it->second);
+			}
+		}
 	}
 
 	src_rect_effect = src_rect;

src/sprite_picture.cpp

@@ -144,7 +144,9 @@ void Sprite_Picture::Draw(Bitmap& dst) {
 
 	SetFlipX(data.easyrpg_flip_horizontal);
 	SetFlipY(data.easyrpg_flip_vertical);
-	SetBlendType(data.easyrpg_blend_mode);
+	if (static_cast<Bitmap::BlendMode>(data.easyrpg_blend_mode) != Bitmap::BlendMode::Default) {
+		SetBlendType(data.easyrpg_blend_mode);
+	}
 
 	Sprite::Draw(dst);
 }