IMAGE: Add a paletted transparency mode flag to PNGDecoder

Previously, the PNGDecoder would always convert images that
have a palette with a transparent color(s) to a full RGBA
surface automatically. There needed to be a way to diable
this and keep the image paletted for the Glk engine, since
some Infocom V6 game Blorb files reuse the palettes from
previous images, so I couldn't have the decoder using the
dummy palette that comes with the image

1 files changed, 6 insertions, 1 deletions

diff --git a/image/png.h b/image/png.h
index adbc6d7a68..f983da467e 100644
--- a/image/png.h
+++ b/image/png.h
@@ -57,8 +57,9 @@ public:
 	const Graphics::Surface *getSurface() const { return _outputSurface; }
 	const byte *getPalette() const { return _palette; }
 	uint16 getPaletteColorCount() const { return _paletteColorCount; }
+	int getTransparentColor() const { return _transparentColor; }
 	void setSkipSignature(bool skip) { _skipSignature = skip; }
-
+	void setKeepTransparencyPaletted(bool keep) { _keepTransparencyPaletted = keep; }
 private:
 	Graphics::PixelFormat getByteOrderRgbaPixelFormat() const;
 
@@ -68,6 +69,10 @@ private:
 	// flag to skip the png signature check for headless png files
 	bool _skipSignature;
 
+	// Flag to keep paletted images paletted, even when the image has transparency
+	bool _keepTransparencyPaletted;
+	int _transparentColor;
+
 	Graphics::Surface *_outputSurface;
 };