6 files changed, 44 insertions, 14 deletions

diff --git a/engines/glk/frotz/pics_decoder.cpp b/engines/glk/frotz/pics_decoder.cpp
index 73032df0d8..375abf20a2 100644
--- a/engines/glk/frotz/pics_decoder.cpp
+++ b/engines/glk/frotz/pics_decoder.cpp
@@ -114,7 +114,7 @@ Common::SeekableReadStream *PictureDecoder::decode(Common::ReadStream &src, uint
 	// Write out palette
 	out.writeUint16LE(palette.size() / 3 + 2);
 	for (int idx = 0; idx < 6; ++idx)
-		out.writeByte(0);
+		out.writeByte((idx < 3) ? 0x77 : 0);
 	if (!palette.empty())
 		out.write(&palette[0], palette.size());
 
diff --git a/engines/glk/picture.cpp b/engines/glk/picture.cpp
index 2cebcb2780..59ee50c835 100644
--- a/engines/glk/picture.cpp
+++ b/engines/glk/picture.cpp
@@ -110,6 +110,7 @@ Picture *Pictures::load(uint32 id) {
 	const Graphics::Surface *img;
 	const byte *palette = nullptr;
 	uint palCount = 0;
+	int transColor = -1;
 	Picture *pic;
 
 	// Check if the picture is already in the store
@@ -131,6 +132,7 @@ Picture *Pictures::load(uint32 id) {
 		img = raw.getSurface();
 		palette = raw.getPalette();
 		palCount = raw.getPaletteColorCount();
+		transColor = raw.getTransparentColor();
 	} else if (f.open(Common::String::format("pic%u.rect", id))) {
 		rectImg.w = f.readUint16LE();
 		rectImg.h = f.readUint16LE();
@@ -144,6 +146,8 @@ Picture *Pictures::load(uint32 id) {
 	pic->_refCount = 1;
     pic->_id = id;
     pic->_scaled = false;
+	if (transColor != -1)
+		pic->clear(pic->getTransparentColor());
 
 	if (!img->getPixels()) {
 		// Area definition without any content
@@ -158,11 +162,13 @@ Picture *Pictures::load(uint32 id) {
 		const byte *srcP = (const byte *)img->getPixels();
 		byte *destP = (byte *)pic->getPixels();
 		for (int idx = 0; idx < img->w * img->h; ++idx, srcP++, destP += pic->format.bytesPerPixel) {
-			uint val = (*srcP >= palCount) ? 0 : pal[*srcP];
-			if (pic->format.bytesPerPixel == 2)
-				WRITE_LE_UINT16(destP, val);
-			else
-				WRITE_LE_UINT32(destP, val);
+			if ((int)*srcP != transColor) {
+				uint val = (*srcP >= palCount) ? 0 : pal[*srcP];
+				if (pic->format.bytesPerPixel == 2)
+					WRITE_LE_UINT16(destP, val);
+				else
+					WRITE_LE_UINT32(destP, val);
+			}
 		}
 	}
 
@@ -188,6 +194,13 @@ Picture *Pictures::scale(Picture *src, size_t sx, size_t sy) {
 
 /*--------------------------------------------------------------------------*/
 
+Picture::Picture(int width, int height, const Graphics::PixelFormat &fmt) :
+		Graphics::ManagedSurface(width, height, fmt), _refCount(0), _id(0), _scaled(false) {
+
+	// Default transparent color chosen at random
+	_transColor = format.RGBToColor(0x77, 0x77, 0x77);
+}
+
 void Picture::increment() {
 	++_refCount;
 }
diff --git a/engines/glk/picture.h b/engines/glk/picture.h
index 7c9bcc67d7..e3b65602a2 100644
--- a/engines/glk/picture.h
+++ b/engines/glk/picture.h
@@ -32,6 +32,8 @@ namespace Glk {
  * Picture/image class
  */
 struct Picture : Graphics::ManagedSurface {
+private:
+	int _transColor;
 public:
 	int _refCount;
 	uint _id;
@@ -40,14 +42,12 @@ public:
 	/**
 	 * Constructor
 	 */
-	Picture() : Graphics::ManagedSurface(), _refCount(0), _id(0), _scaled(false) {}
+	Picture() : Graphics::ManagedSurface(), _refCount(0), _id(0), _scaled(false), _transColor(0x7777) {}
 
 	/**
 	 * Constructor
 	 */
-	Picture(int width, int height, const Graphics::PixelFormat &fmt) :
-		Graphics::ManagedSurface(width, height, fmt), _refCount(0), _id(0), _scaled(false) {}
-
+	Picture(int width, int height, const Graphics::PixelFormat &fmt);
 	/**
 	 * Increment reference counter
 	 */
@@ -62,6 +62,16 @@ public:
 	 * Draw the picture
 	 */
 	void drawPicture(const Common::Point &destPos, const Common::Rect &box);
+
+	/**
+	 * Get the transparency color
+	 */
+	uint getTransparentColor() const { return _transColor; }
+
+	/**
+	 * Set the transparency color
+	 */
+	void setTransparentColor(uint color) { _transColor = color; }
 };
 
 /**
diff --git a/engines/glk/raw_decoder.cpp b/engines/glk/raw_decoder.cpp
index 659b333cac..cf3700371b 100644
--- a/engines/glk/raw_decoder.cpp
+++ b/engines/glk/raw_decoder.cpp
@@ -26,7 +26,8 @@
 
 namespace Glk {
 
-RawDecoder::RawDecoder() : Image::ImageDecoder(), _palette(nullptr), _paletteColorCount(0) {
+RawDecoder::RawDecoder() : Image::ImageDecoder(), _palette(nullptr), _paletteColorCount(0),
+	_transColor(0) {
 }
 
 RawDecoder::~RawDecoder() {
@@ -52,11 +53,15 @@ bool RawDecoder::loadStream(Common::SeekableReadStream &stream) {
 	_palette = new byte[_paletteColorCount * 3];
 	stream.read(_palette, _paletteColorCount * 3);
 
+	// Get the transparent color
+	byte transColor = stream.readByte();
+	if (transColor < _paletteColorCount)
+		_transColor = transColor;
+
 	// Set up the surface and read it in
-	stream.readByte();
 	_surface.create(width, height, Graphics::PixelFormat::createFormatCLUT8());
 
-	assert((stream.size() - stream.pos()) <= (int)(width * height));
+	assert((stream.size() - stream.pos()) == (int)(width * height));
 	byte *pixels = (byte *)_surface.getPixels();
 	stream.read(pixels, width * height);
 
diff --git a/engines/glk/raw_decoder.h b/engines/glk/raw_decoder.h
index 96f25c2512..086cf2555f 100644
--- a/engines/glk/raw_decoder.h
+++ b/engines/glk/raw_decoder.h
@@ -45,6 +45,7 @@ private:
 	Graphics::Surface _surface;
 	byte *_palette;
 	uint16 _paletteColorCount;
+	int _transColor;
 public:
 	RawDecoder();
 	~RawDecoder();
@@ -54,6 +55,7 @@ public:
 	virtual const Graphics::Surface *getSurface() const override { return &_surface; }
 	virtual const byte *getPalette() const override { return _palette; }
 	virtual uint16 getPaletteColorCount() const override { return _paletteColorCount; }
+	int getTransparentColor() const { return _transColor; }
 };
 
 } // End of namespace Glk
diff --git a/engines/glk/window_graphics.cpp b/engines/glk/window_graphics.cpp
index bc762f5ce1..063a590dc6 100644
--- a/engines/glk/window_graphics.cpp
+++ b/engines/glk/window_graphics.cpp
@@ -230,7 +230,7 @@ void GraphicsWindow::drawPicture(Picture *src,  int x0, int y0, int width, int h
 	w = sx1 - sx0;
 	h = sy1 - sy0;
 
-	_surface->blitFrom(*src, Rect(sx0, sy0, sx0 + w, sy0 + h), Point(0, 0));
+	_surface->transBlitFrom(*src, Rect(sx0, sy0, sx0 + w, sy0 + h), Point(0, 0), src->getTransparentColor());
 }
 
 void GraphicsWindow::getSize(uint *width, uint *height) const {