Fix some rare PNG tRNS chunk cases

- For grayscale images drawn with the paletted renderer, the value here
  was treated as always full range [0,65535]. The max value is actually
  determined by the bit depth.
- For RGB images drawn with the paletted renderer, the tRNS chunk was
  ignored.
- For grayscale images drawn with the RGB renderer, having a tRNS chunk
  present resulted in undefined behavior.
- For RGB images drawn with the RGB renderer, the tRNS chunk was ignored.

src/textures/bitmap.cpp

@@ -46,7 +46,8 @@
 //
 //===========================================================================
 template<class TSrc, class TDest, class TBlend>
-void iCopyColors(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *inf)
+void iCopyColors(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *inf,
+	BYTE tr, BYTE tg, BYTE tb)
 {
 	int i;
 	int fac;
@@ -59,7 +60,7 @@ void iCopyColors(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *in
 	case BLEND_NONE:
 		for(i=0;i<count;i++)
 		{
-			a = TSrc::A(pin);
+			a = TSrc::A(pin, tr, tg, tb);
 			if (TBlend::ProcessAlpha0() || a)
 			{
 				TBlend::OpC(pout[TDest::RED], TSrc::R(pin), a, inf);
@@ -77,7 +78,7 @@ void iCopyColors(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *in
 		// Since this is done in True Color the purplish tint is fully preserved - even in Doom!
 		for(i=0;i<count;i++)
 		{
-			a = TSrc::A(pin);
+			a = TSrc::A(pin, tr, tg, tb);
 			if (TBlend::ProcessAlpha0() || a)
 			{
 				int gray = TSrc::Gray(pin)>>4;
@@ -99,7 +100,7 @@ void iCopyColors(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *in
 			FSpecialColormap *cm = &SpecialColormaps[inf->blend - BLEND_SPECIALCOLORMAP1];
 			for(i=0;i<count;i++)
 			{
-				a = TSrc::A(pin);
+				a = TSrc::A(pin, tr, tg, tb);
 				if (TBlend::ProcessAlpha0() || a)
 				{
 					gray = clamp<int>(TSrc::Gray(pin),0,255);
@@ -120,7 +121,7 @@ void iCopyColors(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *in
 			fac=inf->blend-BLEND_DESATURATE1+1;
 			for(i=0;i<count;i++)
 			{
-			a = TSrc::A(pin);
+			a = TSrc::A(pin, tr, tg, tb);
 			if (TBlend::ProcessAlpha0() || a)
 				{
 					gray = TSrc::Gray(pin);
@@ -142,7 +143,7 @@ void iCopyColors(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *in
 	case BLEND_MODULATE:
 		for(i=0;i<count;i++)
 		{
-			a = TSrc::A(pin);
+			a = TSrc::A(pin, tr, tg, tb);
 			if (TBlend::ProcessAlpha0() || a)
 			{
 				r = (TSrc::R(pin)*inf->blendcolor[0])>>FRACBITS;
@@ -163,7 +164,7 @@ void iCopyColors(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *in
 		for(i=0;i<count;i++)
 		{
 			// color blend
-			a = TSrc::A(pin);
+			a = TSrc::A(pin, tr, tg, tb);
 			if (TBlend::ProcessAlpha0() || a)
 			{
 				r = (TSrc::R(pin)*inf->blendcolor[3] + inf->blendcolor[0]) >> FRACBITS;
@@ -183,11 +184,12 @@ void iCopyColors(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *in
 	}
 }
 
-typedef void (*CopyFunc)(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *inf);
+typedef void (*CopyFunc)(BYTE *pout, const BYTE *pin, int count, int step, FCopyInfo *inf, BYTE r, BYTE g, BYTE b);
 
 #define COPY_FUNCS(op) \
 	{ \
 		iCopyColors<cRGB, cBGRA, op>, \
+		iCopyColors<cRGBT, cBGRA, op>, \
 		iCopyColors<cRGBA, cBGRA, op>, \
 		iCopyColors<cIA, cBGRA, op>, \
 		iCopyColors<cCMYK, cBGRA, op>, \
@@ -197,7 +199,7 @@ typedef void (*CopyFunc)(BYTE *pout, const BYTE *pin, int count, int step, FCopy
 		iCopyColors<cRGB555, cBGRA, op>, \
 		iCopyColors<cPalEntry, cBGRA, op> \
 	}
-static const CopyFunc copyfuncs[][9]={
+static const CopyFunc copyfuncs[][10]={
 	COPY_FUNCS(bCopy),
 	COPY_FUNCS(bBlend),
 	COPY_FUNCS(bAdd),
@@ -370,7 +372,8 @@ bool FClipRect::Intersect(int ix, int iy, int iw, int ih)
 //
 //===========================================================================
 void FBitmap::CopyPixelDataRGB(int originx, int originy, const BYTE *patch, int srcwidth, 
-							   int srcheight, int step_x, int step_y, int rotate, int ct, FCopyInfo *inf)
+							   int srcheight, int step_x, int step_y, int rotate, int ct, FCopyInfo *inf,
+							   int r, int g, int b)
 {
 	if (ClipCopyPixelRect(&ClipRect, originx, originy, patch, srcwidth, srcheight, step_x, step_y, rotate))
 	{
@@ -378,7 +381,7 @@ void FBitmap::CopyPixelDataRGB(int originx, int originy, const BYTE *patch, int
 		int op = inf==NULL? OP_COPY : inf->op;
 		for (int y=0;y<srcheight;y++)
 		{
-			copyfuncs[op][ct](&buffer[y*Pitch], &patch[y*step_y], srcwidth, step_x, inf);
+			copyfuncs[op][ct](&buffer[y*Pitch], &patch[y*step_y], srcwidth, step_x, inf, r, g, b);
 		}
 	}
 }
@@ -443,7 +446,7 @@ void FBitmap::CopyPixelData(int originx, int originy, const BYTE * patch, int sr
 		memset(penew, 0, sizeof(penew));
 		if (inf && inf->blend)
 		{
-			iCopyColors<cPalEntry, cBGRA, bCopy>((BYTE*)penew, (const BYTE*)palette, 256, 4, inf);
+			iCopyColors<cPalEntry, cBGRA, bCopy>((BYTE*)penew, (const BYTE*)palette, 256, 4, inf, 0, 0, 0);
 			palette = penew;
 		}
 

src/textures/bitmap.h

@@ -157,7 +157,8 @@ public:
 
 
 	virtual void CopyPixelDataRGB(int originx, int originy, const BYTE *patch, int srcwidth, 
-								int srcheight, int step_x, int step_y, int rotate, int ct, FCopyInfo *inf = NULL);
+								int srcheight, int step_x, int step_y, int rotate, int ct, FCopyInfo *inf = NULL,
+		/* for PNG tRNS */		int r=0, int g=0, int b=0);
 	virtual void CopyPixelData(int originx, int originy, const BYTE * patch, int srcwidth, int srcheight, 
 								int step_x, int step_y, int rotate, PalEntry * palette, FCopyInfo *inf = NULL);
 
@@ -179,7 +180,16 @@ struct cRGB
 	static __forceinline unsigned char R(const unsigned char * p) { return p[0]; }
 	static __forceinline unsigned char G(const unsigned char * p) { return p[1]; }
 	static __forceinline unsigned char B(const unsigned char * p) { return p[2]; }
-	static __forceinline unsigned char A(const unsigned char * p) { return 255; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return 255; }
+	static __forceinline int Gray(const unsigned char * p) { return (p[0]*77 + p[1]*143 + p[2]*36)>>8; }
+};
+
+struct cRGBT
+{
+	static __forceinline unsigned char R(const unsigned char * p) { return p[0]; }
+	static __forceinline unsigned char G(const unsigned char * p) { return p[1]; }
+	static __forceinline unsigned char B(const unsigned char * p) { return p[2]; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE r, BYTE g, BYTE b) { return p[0] != r || p[1] != g || p[2] != b; }
 	static __forceinline int Gray(const unsigned char * p) { return (p[0]*77 + p[1]*143 + p[2]*36)>>8; }
 };
 
@@ -195,7 +205,7 @@ struct cRGBA
 	static __forceinline unsigned char R(const unsigned char * p) { return p[0]; }
 	static __forceinline unsigned char G(const unsigned char * p) { return p[1]; }
 	static __forceinline unsigned char B(const unsigned char * p) { return p[2]; }
-	static __forceinline unsigned char A(const unsigned char * p) { return p[3]; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return p[3]; }
 	static __forceinline int Gray(const unsigned char * p) { return (p[0]*77 + p[1]*143 + p[2]*36)>>8; }
 };
 
@@ -204,7 +214,7 @@ struct cIA
 	static __forceinline unsigned char R(const unsigned char * p) { return p[0]; }
 	static __forceinline unsigned char G(const unsigned char * p) { return p[0]; }
 	static __forceinline unsigned char B(const unsigned char * p) { return p[0]; }
-	static __forceinline unsigned char A(const unsigned char * p) { return p[1]; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return p[1]; }
 	static __forceinline int Gray(const unsigned char * p) { return p[0]; }
 };
 
@@ -213,7 +223,7 @@ struct cCMYK
 	static __forceinline unsigned char R(const unsigned char * p) { return p[3] - (((256-p[0])*p[3]) >> 8); }
 	static __forceinline unsigned char G(const unsigned char * p) { return p[3] - (((256-p[1])*p[3]) >> 8); }
 	static __forceinline unsigned char B(const unsigned char * p) { return p[3] - (((256-p[2])*p[3]) >> 8); }
-	static __forceinline unsigned char A(const unsigned char * p) { return 255; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return 255; }
 	static __forceinline int Gray(const unsigned char * p) { return (R(p)*77 + G(p)*143 + B(p)*36)>>8; }
 };
 
@@ -222,7 +232,7 @@ struct cBGR
 	static __forceinline unsigned char R(const unsigned char * p) { return p[2]; }
 	static __forceinline unsigned char G(const unsigned char * p) { return p[1]; }
 	static __forceinline unsigned char B(const unsigned char * p) { return p[0]; }
-	static __forceinline unsigned char A(const unsigned char * p) { return 255; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return 255; }
 	static __forceinline int Gray(const unsigned char * p) { return (p[2]*77 + p[1]*143 + p[0]*36)>>8; }
 };
 
@@ -238,7 +248,7 @@ struct cBGRA
 	static __forceinline unsigned char R(const unsigned char * p) { return p[2]; }
 	static __forceinline unsigned char G(const unsigned char * p) { return p[1]; }
 	static __forceinline unsigned char B(const unsigned char * p) { return p[0]; }
-	static __forceinline unsigned char A(const unsigned char * p) { return p[3]; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return p[3]; }
 	static __forceinline int Gray(const unsigned char * p) { return (p[2]*77 + p[1]*143 + p[0]*36)>>8; }
 };
 
@@ -254,7 +264,7 @@ struct cARGB
 	static __forceinline unsigned char R(const unsigned char * p) { return p[1]; }
 	static __forceinline unsigned char G(const unsigned char * p) { return p[2]; }
 	static __forceinline unsigned char B(const unsigned char * p) { return p[3]; }
-	static __forceinline unsigned char A(const unsigned char * p) { return p[0]; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return p[0]; }
 	static __forceinline int Gray(const unsigned char * p) { return (p[1]*77 + p[2]*143 + p[3]*36)>>8; }
 };
 
@@ -263,7 +273,7 @@ struct cI16
 	static __forceinline unsigned char R(const unsigned char * p) { return p[1]; }
 	static __forceinline unsigned char G(const unsigned char * p) { return p[1]; }
 	static __forceinline unsigned char B(const unsigned char * p) { return p[1]; }
-	static __forceinline unsigned char A(const unsigned char * p) { return 255; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return 255; }
 	static __forceinline int Gray(const unsigned char * p) { return p[1]; }
 };
 
@@ -272,7 +282,7 @@ struct cRGB555
 	static __forceinline unsigned char R(const unsigned char * p) { return (((*(WORD*)p)&0x1f)<<3); }
 	static __forceinline unsigned char G(const unsigned char * p) { return (((*(WORD*)p)&0x3e0)>>2); }
 	static __forceinline unsigned char B(const unsigned char * p) { return (((*(WORD*)p)&0x7c00)>>7); }
-	static __forceinline unsigned char A(const unsigned char * p) { return 255; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return 255; }
 	static __forceinline int Gray(const unsigned char * p) { return (R(p)*77 + G(p)*143 + B(p)*36)>>8; }
 };
 
@@ -281,13 +291,14 @@ struct cPalEntry
 	static __forceinline unsigned char R(const unsigned char * p) { return ((PalEntry*)p)->r; }
 	static __forceinline unsigned char G(const unsigned char * p) { return ((PalEntry*)p)->g; }
 	static __forceinline unsigned char B(const unsigned char * p) { return ((PalEntry*)p)->b; }
-	static __forceinline unsigned char A(const unsigned char * p) { return ((PalEntry*)p)->a; }
+	static __forceinline unsigned char A(const unsigned char * p, BYTE x, BYTE y, BYTE z) { return ((PalEntry*)p)->a; }
 	static __forceinline int Gray(const unsigned char * p) { return (R(p)*77 + G(p)*143 + B(p)*36)>>8; }
 };
 
 enum ColorType
 {
 	CF_RGB,
+	CF_RGBT,
 	CF_RGBA,
 	CF_IA,
 	CF_CMYK,

src/textures/pngtexture.cpp

@@ -70,6 +70,8 @@ protected:
 	BYTE BitDepth;
 	BYTE ColorType;
 	BYTE Interlace;
+	bool HaveTrans;
+	WORD NonPaletteTrans[3];
 
 	BYTE *PaletteMap;
 	int PaletteSize;
@@ -195,7 +197,7 @@ FTexture *PNGTexture_CreateFromFile(PNGHandle *png, const FString &filename)
 FPNGTexture::FPNGTexture (FileReader &lump, int lumpnum, const FString &filename, int width, int height,
 						  BYTE depth, BYTE colortype, BYTE interlace)
 : FTexture(NULL, lumpnum), SourceFile(filename), Pixels(0), Spans(0),
-  BitDepth(depth), ColorType(colortype), Interlace(interlace),
+  BitDepth(depth), ColorType(colortype), Interlace(interlace), HaveTrans(false),
   PaletteMap(0), PaletteSize(0), StartOfIDAT(0)
 {
 	union
@@ -204,7 +206,6 @@ FPNGTexture::FPNGTexture (FileReader &lump, int lumpnum, const FString &filename
 		BYTE pngpal[256][3];
 	} p;
 	BYTE trans[256];
-	bool havetRNS = false;
 	DWORD len, id;
 	int i;
 
@@ -273,7 +274,11 @@ FPNGTexture::FPNGTexture (FileReader &lump, int lumpnum, const FString &filename
 
 		case MAKE_ID('t','R','N','S'):
 			lump.Read (trans, len);
-			havetRNS = true;
+			HaveTrans = true;
+			// Save for colortype 2
+			NonPaletteTrans[0] = BigShort(((WORD *)trans)[0]);
+			NonPaletteTrans[1] = BigShort(((WORD *)trans)[1]);
+			NonPaletteTrans[2] = BigShort(((WORD *)trans)[2]);
 			break;
 
 		case MAKE_ID('a','l','P','h'):
@@ -297,13 +302,13 @@ FPNGTexture::FPNGTexture (FileReader &lump, int lumpnum, const FString &filename
 	case 0:		// Grayscale
 		if (!bAlphaTexture)
 		{
-			if (colortype == 0 && havetRNS && trans[0] != 0)
+			if (colortype == 0 && HaveTrans && NonPaletteTrans[0] != 0 && NonPaletteTrans[0] < 256)
 			{
 				bMasked = true;
 				PaletteSize = 256;
 				PaletteMap = new BYTE[256];
 				memcpy (PaletteMap, GrayMap, 256);
-				PaletteMap[trans[0]] = 0;
+				PaletteMap[NonPaletteTrans[0]] = 0;
 			}
 			else
 			{
@@ -328,6 +333,10 @@ FPNGTexture::FPNGTexture (FileReader &lump, int lumpnum, const FString &filename
 	case 6:		// RGB + Alpha
 		bMasked = true;
 		break;
+
+	case 2:		// RGB
+		bMasked = HaveTrans;
+		break;
 	}
 }
 
@@ -520,8 +529,24 @@ void FPNGTexture::MakeTexture ()
 				for (x = Width; x > 0; --x)
 				{
 					for (y = Height; y > 0; --y)
+					{
+						if (!HaveTrans)
 						{
 							*out++ = RGB32k.RGB[in[0]>>3][in[1]>>3][in[2]>>3];
+						}
+						else
+						{
+							if (in[0] == NonPaletteTrans[0] &&
+								in[1] == NonPaletteTrans[1] &&
+								in[2] == NonPaletteTrans[2])
+							{
+								*out++ = 0;
+							}
+							else
+							{
+								*out++ = RGB32k.RGB[in[0]>>3][in[1]>>3][in[2]>>3];
+							}
+						}
 						in += pitch;
 					}
 					in -= backstep;
@@ -625,12 +650,15 @@ int FPNGTexture::CopyTrueColorPixels(FBitmap *bmp, int x, int y, int rotate, FCo
 			break;
 
 		case MAKE_ID('t','R','N','S'):
+			if (ColorType == 3)
+			{
 				for(DWORD i = 0; i < len; i++)
 				{
 					(*lump) >> pe[i].a;
 					if (pe[i].a != 0 && pe[i].a != 255)
 						transpal = true;
 				}
+			}
 			break;
 		}
 		lump->Seek(4, SEEK_CUR);		// Skip CRC
@@ -639,6 +667,12 @@ int FPNGTexture::CopyTrueColorPixels(FBitmap *bmp, int x, int y, int rotate, FCo
 		lump->Read(&id, 4);
 	}
 
+	if (ColorType == 0 && HaveTrans && NonPaletteTrans[0] < 256)
+	{
+		pe[NonPaletteTrans[0]].a = 0;
+		transpal = true;
+	}
+
 	BYTE * Pixels = new BYTE[pixwidth * Height];
 
 	lump->Seek (StartOfIDAT, SEEK_SET);
@@ -655,7 +689,15 @@ int FPNGTexture::CopyTrueColorPixels(FBitmap *bmp, int x, int y, int rotate, FCo
 		break;
 
 	case 2:
+		if (!HaveTrans)
+		{
 			bmp->CopyPixelDataRGB(x, y, Pixels, Width, Height, 3, pixwidth, rotate, CF_RGB, inf);
+		}
+		else
+		{
+			bmp->CopyPixelDataRGB(x, y, Pixels, Width, Height, 3, pixwidth, rotate, CF_RGBT, inf,
+				NonPaletteTrans[0], NonPaletteTrans[1], NonPaletteTrans[2]);
+		}
 		break;
 
 	case 4: