Added support for ETC1 and PVR1 compressed textures contained in KTX, PKM, and PVR files.

Most desktop graphics drivers don't support those formats.

--HG--
branch : minor

src/modules/image/magpie/PKMHandler.cpp

@@ -0,0 +1,156 @@
+/**
+ * Copyright (c) 2006-2014 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+// LOVE
+#include "PKMHandler.h"
+#include "common/int.h"
+
+namespace love
+{
+namespace image
+{
+namespace magpie
+{
+
+namespace
+{
+
+// Big endian to host (and vice versa.)
+inline uint16 swap16big(uint16 x)
+{
+#ifdef LOVE_BIG_ENDIAN
+	return x;
+#else
+	return swap16(x);
+#endif
+}
+
+static const uint8 pkmIdentifier[] = {'P','K','M',' '};
+
+struct PKMHeader
+{
+	uint8 identifier[4];
+	uint8 version[2];
+	uint16 textureFormatBig;
+	uint16 extendedWidthBig;
+	uint16 extendedHeightBig;
+	uint16 widthBig;
+	uint16 heightBig;
+};
+
+enum PKMTextureFormat
+{
+	ETC1_RGB_NO_MIPMAPS = 0,
+	ETC2PACKAGE_RGB_NO_MIPMAPS,
+	ETC2PACKAGE_RGBA_NO_MIPMAPS_OLD,
+	ETC2PACKAGE_RGBA_NO_MIPMAPS,
+	ETC2PACKAGE_RGBA1_NO_MIPMAPS,
+	ETC2PACKAGE_R_NO_MIPMAPS,
+	ETC2PACKAGE_RG_NO_MIPMAPS,
+	ETC2PACKAGE_R_SIGNED_NO_MIPMAPS,
+	ETC2PACKAGE_RG_SIGNED_NO_MIPMAPS
+};
+
+CompressedData::Format convertFormat(uint16 texformat)
+{
+	switch (texformat)
+	{
+	case ETC1_RGB_NO_MIPMAPS:
+		return CompressedData::FORMAT_ETC1;
+	default:
+		return CompressedData::FORMAT_UNKNOWN;
+	}
+}
+
+} // Anonymous namespace.
+
+bool PKMHandler::canParse(const filesystem::FileData *data)
+{
+	if (data->getSize() <= sizeof(PKMHeader))
+		return false;
+
+	const PKMHeader *header = (const PKMHeader *) data->getData();
+
+	if (memcmp(header->identifier, pkmIdentifier, 4) != 0)
+		return false;
+
+	// At the time of this writing, only v1.0 and v2.0 exist.
+	if ((header->version[0] != '2' && header->version[0] != '1') || header->version[1] != '0')
+		return false;
+
+	return true;
+}
+
+uint8 *PKMHandler::parse(filesystem::FileData *filedata, std::vector<CompressedData::SubImage> &images, size_t &dataSize, CompressedData::Format &format)
+{
+	if (!canParse(filedata))
+		throw love::Exception("Could not decode compressed data (not a PKM file?)");
+
+	PKMHeader header = *(const PKMHeader *) filedata->getData();
+
+	header.textureFormatBig = swap16big(header.textureFormatBig);
+	header.extendedWidthBig = swap16big(header.extendedWidthBig);
+	header.extendedHeightBig = swap16big(header.extendedHeightBig);
+	header.widthBig = swap16big(header.widthBig);
+	header.heightBig = swap16big(header.heightBig);
+
+	CompressedData::Format cformat = convertFormat(header.textureFormatBig);
+
+	if (cformat == CompressedData::FORMAT_UNKNOWN)
+		throw love::Exception("Could not parse PKM file: unsupported texture format.");
+
+	// The rest of the file after the header is all texture data.
+	size_t totalsize = filedata->getSize() - sizeof(PKMHeader);
+	uint8 *data = nullptr;
+
+	try
+	{
+		data = new uint8[totalsize];
+	}
+	catch (std::bad_alloc &)
+	{
+		throw love::Exception("Out of memory.");
+	}
+
+	// PKM files only store a single mipmap level.
+	memcpy(data, (uint8 *) filedata->getData() + sizeof(PKMHeader), totalsize);
+
+	CompressedData::SubImage mip;
+
+	// TODO: verify whether glCompressedTexImage works properly with the unpadded
+	// width and height values (extended == padded.)
+	mip.width = header.widthBig;
+	mip.height = header.heightBig;
+
+	mip.size = totalsize;
+	mip.data = data;
+
+	images.push_back(mip);
+
+	dataSize = totalsize;
+	format = cformat;
+
+	return data;
+}
+
+} // magpie
+} // image
+} // love
+