MAINT-6584: Streamline static LLImageJ2C implementation API.

Specifically, remove unused function pointer types CreateLLImageJ2CFunction,
DestroyLLImageJ2CFunction and EngineInfoLLImageJ2CFunction.

Also eliminate static fallbackDestroyLLImageJ2CImpl() and
fallbackEngineInfoLLImageJ2CImpl(), leaving only static
fallbackCreateLLImageJ2CImpl().

We do need a factory function to instantiate the appropriate LLImageJ2CImpl
subclass, so leave the fallbackCreateLLImageJ2CImpl() link seam in place.

However, given that every known LLImageJ2CImpl subclass is cheap to
instantiate, make getEngineInfo() a pure virtual method on that subclass: the
static LLImageJ2C::getEngineInfo() method can temporarily construct an
instance to query. While we're at it, make getEngineInfo() return std::string
like LLImageJ2C::getEngineInfo(). It's ridiculous that
fallbackEngineInfoLLImageJ2CImpl() implementations constructed a static
std::string and returned its c_str(), only to have LLImageJ2C::getEngineInfo()
construct ANOTHER std::string from the returned const char*.

fallbackDestroyLLImageJ2CImpl() never did anything useful: it merely deleted
the passed LLImageJ2CImpl subclass pointer as the specific subclass type. But
since LLImageJ2CImpl's destructor is virtual, LLImageJ2C's destructor could
simply delete the stored LLImageJ2CImpl*. In fact, make mImpl a
boost::scoped_ptr<LLImageJ2CImpl> so we don't even have to delete it manually.

indra/llimage/llimagej2c.cpp

@@ -31,18 +31,13 @@
 #include "llmath.h"
 #include "llmemory.h"
 #include "llsd.h"
+#include <boost/scoped_ptr.hpp>
 
-typedef LLImageJ2CImpl* (*CreateLLImageJ2CFunction)();
-typedef void (*DestroyLLImageJ2CFunction)(LLImageJ2CImpl*);
-typedef const char* (*EngineInfoLLImageJ2CFunction)();
-
-// Declare the prototype for theses functions here. Their functionality
-// will be implemented in other files which define a derived LLImageJ2CImpl
-// but only ONE static library which has the implementation for these
-// functions should ever be included.
+// Declare the prototype for this factory function here. It is implemented in
+// other files which define a LLImageJ2CImpl subclass, but only ONE static
+// library which has the implementation for this function should ever be
+// linked.
 LLImageJ2CImpl* fallbackCreateLLImageJ2CImpl();
-void fallbackDestroyLLImageJ2CImpl(LLImageJ2CImpl* impl);
-const char* fallbackEngineInfoLLImageJ2CImpl();
 
 // Test data gathering handle
 LLImageCompressionTester* LLImageJ2C::sTesterp = NULL ;
@@ -51,7 +46,10 @@ const std::string sTesterName("ImageCompressionTester");
 //static
 std::string LLImageJ2C::getEngineInfo()
 {
-    return fallbackEngineInfoLLImageJ2CImpl();
+	// All known LLImageJ2CImpl implementation subclasses are cheap to
+	// construct.
+	boost::scoped_ptr<LLImageJ2CImpl> impl(fallbackCreateLLImageJ2CImpl());
+	return impl->getEngineInfo();
 }
 
 LLImageJ2C::LLImageJ2C() : 	LLImageFormatted(IMG_CODEC_J2C),
@@ -61,7 +59,7 @@ LLImageJ2C::LLImageJ2C() : 	LLImageFormatted(IMG_CODEC_J2C),
 							mReversible(FALSE),
 							mAreaUsedForDataSizeCalcs(0)
 {
-	mImpl = fallbackCreateLLImageJ2CImpl();
+	mImpl.reset(fallbackCreateLLImageJ2CImpl());
 	claimMem(mImpl);
 
 	// Clear data size table
@@ -83,13 +81,7 @@ LLImageJ2C::LLImageJ2C() : 	LLImageFormatted(IMG_CODEC_J2C),
 }
 
 // virtual
-LLImageJ2C::~LLImageJ2C()
-{
-	if ( mImpl )
-	{
-        fallbackDestroyLLImageJ2CImpl(mImpl);
-	}
-}
+LLImageJ2C::~LLImageJ2C() {}
 
 // virtual
 void LLImageJ2C::resetLastError()

indra/llimage/llimagej2c.h

@@ -30,6 +30,7 @@
 #include "llimage.h"
 #include "llassettype.h"
 #include "llmetricperformancetester.h"
+#include <boost/scoped_ptr.hpp>
 
 // JPEG2000 : compression rate used in j2c conversion.
 const F32 DEFAULT_COMPRESSION_RATE = 1.f/8.f;
@@ -94,7 +95,7 @@ class LLImageJ2C : public LLImageFormatted
 	S8  mRawDiscardLevel;
 	F32 mRate;
 	BOOL mReversible;
-	LLImageJ2CImpl *mImpl;
+	boost::scoped_ptr<LLImageJ2CImpl> mImpl;
 	std::string mLastError;
 
     // Image compression/decompression tester
@@ -124,11 +125,11 @@ class LLImageJ2CImpl
 	virtual BOOL initDecode(LLImageJ2C &base, LLImageRaw &raw_image, int discard_level = -1, int* region = NULL) = 0;
 	virtual BOOL initEncode(LLImageJ2C &base, LLImageRaw &raw_image, int blocks_size = -1, int precincts_size = -1, int levels = 0) = 0;
 
+	virtual std::string getEngineInfo() const = 0;
+
 	friend class LLImageJ2C;
 };
 
-#define LINDEN_J2C_COMMENT_PREFIX "LL_"
-
 //
 // This class is used for performance data gathering only.
 // Tracks the image compression / decompression data,

indra/llimagej2coj/llimagej2coj.cpp

@@ -33,23 +33,16 @@
 #include "lltimer.h"
 //#include "llmemory.h"
 
-const char* fallbackEngineInfoLLImageJ2CImpl()
-{
-	static std::string version_string =
-		std::string("OpenJPEG: " OPENJPEG_VERSION ", Runtime: ")
-		+ opj_version();
-	return version_string.c_str();
-}
-
+// Factory function: see declaration in llimagej2c.cpp
 LLImageJ2CImpl* fallbackCreateLLImageJ2CImpl()
 {
 	return new LLImageJ2COJ();
 }
 
-void fallbackDestroyLLImageJ2CImpl(LLImageJ2CImpl* impl)
+std::string LLImageJ2COJ::getEngineInfo() const
 {
-	delete impl;
-	impl = NULL;
+	return std::string("OpenJPEG: " OPENJPEG_VERSION ", Runtime: ")
+		+ opj_version();
 }
 
 // Return string from message, eliminating final \n if present

indra/llimagej2coj/llimagej2coj.h

@@ -35,12 +35,13 @@ class LLImageJ2COJ : public LLImageJ2CImpl
 	LLImageJ2COJ();
 	virtual ~LLImageJ2COJ();
 protected:
-	/*virtual*/ BOOL getMetadata(LLImageJ2C &base);
-	/*virtual*/ BOOL decodeImpl(LLImageJ2C &base, LLImageRaw &raw_image, F32 decode_time, S32 first_channel, S32 max_channel_count);
-	/*virtual*/ BOOL encodeImpl(LLImageJ2C &base, const LLImageRaw &raw_image, const char* comment_text, F32 encode_time=0.0,
+	virtual BOOL getMetadata(LLImageJ2C &base);
+	virtual BOOL decodeImpl(LLImageJ2C &base, LLImageRaw &raw_image, F32 decode_time, S32 first_channel, S32 max_channel_count);
+	virtual BOOL encodeImpl(LLImageJ2C &base, const LLImageRaw &raw_image, const char* comment_text, F32 encode_time=0.0,
 								BOOL reversible = FALSE);
-	/*virtual*/ BOOL initDecode(LLImageJ2C &base, LLImageRaw &raw_image, int discard_level = -1, int* region = NULL);
-	/*virtual*/ BOOL initEncode(LLImageJ2C &base, LLImageRaw &raw_image, int blocks_size = -1, int precincts_size = -1, int levels = 0);
+	virtual BOOL initDecode(LLImageJ2C &base, LLImageRaw &raw_image, int discard_level = -1, int* region = NULL);
+	virtual BOOL initEncode(LLImageJ2C &base, LLImageRaw &raw_image, int blocks_size = -1, int precincts_size = -1, int levels = 0);
+    virtual std::string getEngineInfo() const;
 };
 
 #endif

indra/llkdu/llimagej2ckdu.cpp

@@ -72,21 +72,15 @@ class kdc_flow_control {
 //
 void set_default_colour_weights(kdu_params *siz);
 
+// Factory function: see declaration in llimagej2c.cpp
 LLImageJ2CImpl* fallbackCreateLLImageJ2CImpl()
 {
 	return new LLImageJ2CKDU();
 }
 
-void fallbackDestroyLLImageJ2CImpl(LLImageJ2CImpl* impl)
+std::string LLImageJ2CKDU::getEngineInfo() const
 {
-	delete impl;
-	impl = NULL;
-}
-
-const char* fallbackEngineInfoLLImageJ2CImpl()
-{
-	static std::string version = llformat("KDU %s", KDU_CORE_VERSION);
-	return version.c_str();
+	return llformat("KDU %s", KDU_CORE_VERSION);
 }
 
 class LLKDUDecodeState

indra/llkdu/llimagej2ckdu.h

@@ -65,12 +65,13 @@ class LLImageJ2CKDU : public LLImageJ2CImpl
 	virtual ~LLImageJ2CKDU();
 	
 protected:
-	/*virtual*/ BOOL getMetadata(LLImageJ2C &base);
-	/*virtual*/ BOOL decodeImpl(LLImageJ2C &base, LLImageRaw &raw_image, F32 decode_time, S32 first_channel, S32 max_channel_count);
-	/*virtual*/ BOOL encodeImpl(LLImageJ2C &base, const LLImageRaw &raw_image, const char* comment_text, F32 encode_time=0.0,
+	virtual BOOL getMetadata(LLImageJ2C &base);
+	virtual BOOL decodeImpl(LLImageJ2C &base, LLImageRaw &raw_image, F32 decode_time, S32 first_channel, S32 max_channel_count);
+	virtual BOOL encodeImpl(LLImageJ2C &base, const LLImageRaw &raw_image, const char* comment_text, F32 encode_time=0.0,
 								BOOL reversible=FALSE);
-	/*virtual*/ BOOL initDecode(LLImageJ2C &base, LLImageRaw &raw_image, int discard_level = -1, int* region = NULL);
-	/*virtual*/ BOOL initEncode(LLImageJ2C &base, LLImageRaw &raw_image, int blocks_size = -1, int precincts_size = -1, int levels = 0);
+	virtual BOOL initDecode(LLImageJ2C &base, LLImageRaw &raw_image, int discard_level = -1, int* region = NULL);
+	virtual BOOL initEncode(LLImageJ2C &base, LLImageRaw &raw_image, int blocks_size = -1, int precincts_size = -1, int levels = 0);
+	virtual std::string getEngineInfo() const;
 	void findDiscardLevelsBoundaries(LLImageJ2C &base);
 
 private: