ANDROID: Don't use compressed textures for the game screen

Some GLES drivers suck so much that uploading data to the GPU takes
ages. CLUT8 games now use a faked paletted texture, which internally
uses a RGB565 hardware texture (Android's native pixel format).
This seems to be the only way to efficiently implement constant
changing textures with GLES1 - at the cost of extra buffers.
Then again, we can now use glTexSubImage2D to only update the dirty
rects, which wasn't possible before because glCompressedTexSubImage2D
is only usable on GLES2. This commit does exactly that.
Overall, the CPU usage is massively reduced for CLUT8 games.

4 files changed, 169 insertions, 17 deletions

diff --git a/backends/platform/android/android.cpp b/backends/platform/android/android.cpp
index ca65863fc9..56e56fb3dd 100644
--- a/backends/platform/android/android.cpp
+++ b/backends/platform/android/android.cpp
@@ -330,7 +330,7 @@ void OSystem_Android::initBackend() {
 	initSurface();
 	initViewport();
 
-	_game_texture = new GLESPalette565Texture();
+	_game_texture = new GLESFakePalette565Texture();
 	_overlay_texture = new GLES4444Texture();
 	_mouse_texture_palette = new GLESPalette5551Texture();
 	_mouse_texture = _mouse_texture_palette;
diff --git a/backends/platform/android/gfx.cpp b/backends/platform/android/gfx.cpp
index 6be7a03b22..62dbe644bf 100644
--- a/backends/platform/android/gfx.cpp
+++ b/backends/platform/android/gfx.cpp
@@ -72,9 +72,9 @@ Graphics::PixelFormat OSystem_Android::getScreenFormat() const {
 
 Common::List<Graphics::PixelFormat> OSystem_Android::getSupportedFormats() const {
 	Common::List<Graphics::PixelFormat> res;
-	res.push_back(GLES565Texture::getPixelFormat());
-	res.push_back(GLES5551Texture::getPixelFormat());
-	res.push_back(GLES4444Texture::getPixelFormat());
+	res.push_back(GLES565Texture::pixelFormat());
+	res.push_back(GLES5551Texture::pixelFormat());
+	res.push_back(GLES4444Texture::pixelFormat());
 	res.push_back(Graphics::PixelFormat::createFormatCLUT8());
 
 	return res;
@@ -123,11 +123,11 @@ void OSystem_Android::initTexture(GLESTexture **texture,
 
 		delete *texture;
 
-		if (format_new == GLES565Texture::getPixelFormat())
+		if (format_new == GLES565Texture::pixelFormat())
 			*texture = new GLES565Texture();
-		else if (format_new == GLES5551Texture::getPixelFormat())
+		else if (format_new == GLES5551Texture::pixelFormat())
 			*texture = new GLES5551Texture();
-		else if (format_new == GLES4444Texture::getPixelFormat())
+		else if (format_new == GLES4444Texture::pixelFormat())
 			*texture = new GLES4444Texture();
 		else {
 			// TODO what now?
@@ -135,7 +135,7 @@ void OSystem_Android::initTexture(GLESTexture **texture,
 				LOGE("unsupported pixel format: %s",
 					getPixelFormatName(format_new).c_str());
 
-			*texture = new GLESPalette565Texture;
+			*texture = new GLESFakePalette565Texture;
 		}
 
 		LOGD("new pixel format: %s",
diff --git a/backends/platform/android/texture.cpp b/backends/platform/android/texture.cpp
index dbba275790..54479a6ab4 100644
--- a/backends/platform/android/texture.cpp
+++ b/backends/platform/android/texture.cpp
@@ -279,22 +279,26 @@ void GLESTexture::drawTexture(GLshort x, GLshort y, GLshort w, GLshort h) {
 	clearDirty();
 }
 
+const Graphics::PixelFormat &GLESTexture::getPixelFormat() const {
+	return _pixelFormat;
+}
+
 GLES4444Texture::GLES4444Texture() :
-	GLESTexture(GL_RGBA, GL_UNSIGNED_SHORT_4_4_4_4, getPixelFormat()) {
+	GLESTexture(GL_RGBA, GL_UNSIGNED_SHORT_4_4_4_4, pixelFormat()) {
 }
 
 GLES4444Texture::~GLES4444Texture() {
 }
 
 GLES5551Texture::GLES5551Texture() :
-	GLESTexture(GL_RGBA, GL_UNSIGNED_SHORT_5_5_5_1, getPixelFormat()) {
+	GLESTexture(GL_RGBA, GL_UNSIGNED_SHORT_5_5_5_1, pixelFormat()) {
 }
 
 GLES5551Texture::~GLES5551Texture() {
 }
 
 GLES565Texture::GLES565Texture() :
-	GLESTexture(GL_RGB, GL_UNSIGNED_SHORT_5_6_5, getPixelFormat()) {
+	GLESTexture(GL_RGB, GL_UNSIGNED_SHORT_5_6_5, pixelFormat()) {
 }
 
 GLES565Texture::~GLES565Texture() {
@@ -409,5 +413,112 @@ GLESPalette5551Texture::GLESPalette5551Texture() :
 GLESPalette5551Texture::~GLESPalette5551Texture() {
 }
 
+GLESFakePaletteTexture::GLESFakePaletteTexture(GLenum glFormat, GLenum glType,
+									Graphics::PixelFormat pixelFormat) :
+	GLESTexture(glFormat, glType, pixelFormat),
+	_palette(0),
+	_pixels(0),
+	_buf(0)
+{
+	_palettePixelFormat = pixelFormat;
+	_fake_format = Graphics::PixelFormat::createFormatCLUT8();
+
+	_palette = new uint16[256];
+	assert(_palette);
+}
+
+GLESFakePaletteTexture::~GLESFakePaletteTexture() {
+	delete[] _buf;
+	delete[] _pixels;
+	delete[] _palette;
+}
+
+void GLESFakePaletteTexture::allocBuffer(GLuint w, GLuint h) {
+	GLESTexture::allocBuffer(w, h);
+
+	delete[] _buf;
+	delete[] _pixels;
+
+	_pixels = new byte[w * h];
+	assert(_pixels);
+
+	// fixup surface, for the outside this is a CLUT8 surface
+	_surface.pixels = _pixels;
+	_surface.bytesPerPixel = 1;
+	_surface.pitch = w;
+
+	_buf = new uint16[w * h];
+	assert(_buf);
+}
+
+void GLESFakePaletteTexture::fillBuffer(uint32 color) {
+	assert(_surface.pixels);
+	memset(_surface.pixels, color & 0xff, _surface.pitch * _surface.h);
+	setDirty();
+}
+
+void GLESFakePaletteTexture::updateBuffer(GLuint x, GLuint y, GLuint w,
+											GLuint h, const void *buf,
+											int pitch_buf) {
+	setDirtyRect(Common::Rect(x, y, x + w, y + h));
+
+	const byte *src = (const byte *)buf;
+	byte *dst = _pixels + y * _surface.pitch + x;
+
+	do {
+		memcpy(dst, src, w);
+		dst += _surface.pitch;
+		src += pitch_buf;
+	} while (--h);
+}
+
+void GLESFakePaletteTexture::drawTexture(GLshort x, GLshort y, GLshort w,
+										GLshort h) {
+	if (_all_dirty) {
+		_dirty_rect.top = 0;
+		_dirty_rect.left = 0;
+		_dirty_rect.bottom = _surface.h;
+		_dirty_rect.right = _surface.w;
+
+		_all_dirty = false;
+	}
+
+	if (!_dirty_rect.isEmpty()) {
+		int16 dwidth = _dirty_rect.width();
+		int16 dheight = _dirty_rect.height();
+
+		byte *src = _pixels + _dirty_rect.top * _surface.pitch +
+					_dirty_rect.left;
+		uint16 *dst = _buf;
+		uint pitch_delta = _surface.pitch - dwidth;
+
+		for (uint16 j = 0; j < dheight; ++j) {
+			for (uint16 i = 0; i < dwidth; ++i)
+				*dst++ = _palette[*src++];
+			src += pitch_delta;
+		}
+
+		GLCALL(glBindTexture(GL_TEXTURE_2D, _texture_name));
+
+		GLCALL(glTexSubImage2D(GL_TEXTURE_2D, 0,
+								_dirty_rect.left, _dirty_rect.top,
+								dwidth, dheight, _glFormat, _glType, _buf));
+	}
+
+	GLESTexture::drawTexture(x, y, w, h);
+}
+
+const Graphics::PixelFormat &GLESFakePaletteTexture::getPixelFormat() const {
+	return _fake_format;
+}
+
+GLESFakePalette565Texture::GLESFakePalette565Texture() :
+	GLESFakePaletteTexture(GL_RGB, GL_UNSIGNED_SHORT_5_6_5,
+							GLES565Texture::pixelFormat()) {
+}
+
+GLESFakePalette565Texture::~GLESFakePalette565Texture() {
+}
+
 #endif
 
diff --git a/backends/platform/android/texture.h b/backends/platform/android/texture.h
index 02cb0c71fb..15ad2e78b6 100644
--- a/backends/platform/android/texture.h
+++ b/backends/platform/android/texture.h
@@ -100,9 +100,7 @@ public:
 		return _all_dirty || !_dirty_rect.isEmpty();
 	}
 
-	inline const Graphics::PixelFormat &getPixelFormat() const {
-		return _pixelFormat;
-	}
+	virtual const Graphics::PixelFormat &getPixelFormat() const;
 
 	inline const Graphics::PixelFormat &getPalettePixelFormat() const {
 		return _palettePixelFormat;
@@ -152,7 +150,7 @@ public:
 	GLES4444Texture();
 	virtual ~GLES4444Texture();
 
-	static inline Graphics::PixelFormat getPixelFormat() {
+	static Graphics::PixelFormat pixelFormat() {
 		return Graphics::PixelFormat(2, 4, 4, 4, 4, 12, 8, 4, 0);
 	}
 };
@@ -163,7 +161,7 @@ public:
 	GLES5551Texture();
 	virtual ~GLES5551Texture();
 
-	static inline Graphics::PixelFormat getPixelFormat() {
+	static inline Graphics::PixelFormat pixelFormat() {
 		return Graphics::PixelFormat(2, 5, 5, 5, 1, 11, 6, 1, 0);
 	}
 };
@@ -174,7 +172,7 @@ public:
 	GLES565Texture();
 	virtual ~GLES565Texture();
 
-	static inline Graphics::PixelFormat getPixelFormat() {
+	static inline Graphics::PixelFormat pixelFormat() {
 		return Graphics::PixelFormat(2, 5, 6, 5, 0, 11, 5, 0, 0);
 	}
 };
@@ -247,6 +245,49 @@ public:
 	virtual ~GLESPalette5551Texture();
 };
 
+class GLESFakePaletteTexture : public GLESTexture {
+protected:
+	GLESFakePaletteTexture(GLenum glFormat, GLenum glType,
+							Graphics::PixelFormat pixelFormat);
+
+public:
+	virtual ~GLESFakePaletteTexture();
+
+	virtual void allocBuffer(GLuint width, GLuint height);
+	virtual void updateBuffer(GLuint x, GLuint y, GLuint width, GLuint height,
+								const void *buf, int pitch_buf);
+	virtual void fillBuffer(uint32 color);
+
+	virtual void drawTexture(GLshort x, GLshort y, GLshort w, GLshort h);
+
+	inline void drawTexture() {
+		drawTexture(0, 0, _surface.w, _surface.h);
+	}
+
+	virtual const byte *palette_const() const {
+		return (byte *)_palette;
+	};
+
+	virtual byte *palette() {
+		setDirty();
+		return (byte *)_palette;
+	};
+
+	virtual const Graphics::PixelFormat &getPixelFormat() const;
+
+protected:
+	Graphics::PixelFormat _fake_format;
+	uint16 *_palette;
+	byte *_pixels;
+	uint16 *_buf;
+};
+
+class GLESFakePalette565Texture : public GLESFakePaletteTexture {
+public:
+	GLESFakePalette565Texture();
+	virtual ~GLESFakePalette565Texture();
+};
+
 #endif
 #endif