updated StreamBuffer with features used by TIFFTranslator, updated TGATranslator to use new version of this class

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@3058 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/translators/tgatranslator/StreamBuffer.cpp

@@ -9,7 +9,7 @@
 // read from a BPositionIO object.
 //
 //
-// Copyright (c) 2002 OpenBeOS Project
+// Copyright (c) 2003 OpenBeOS Project
 //
 // Permission is hereby granted, free of charge, to any person obtaining a
 // copy of this software and associated documentation files (the "Software"),
@@ -30,6 +30,7 @@
 // DEALINGS IN THE SOFTWARE.
 /*****************************************************************************/
 
+#include <stdio.h>
 #include <string.h>
 #include "StreamBuffer.h"
 
@@ -55,7 +56,8 @@
 //
 // Returns:
 // ---------------------------------------------------------------
-StreamBuffer::StreamBuffer(BPositionIO *pstream, size_t nbuffersize)
+StreamBuffer::StreamBuffer(BPositionIO *pstream, size_t nbuffersize,
+	bool binitialread)
 {
 	fpStream = pstream;
 	fpBuffer = NULL;
@@ -68,7 +70,7 @@ StreamBuffer::StreamBuffer(BPositionIO *pstream, size_t nbuffersize)
 
 	fnBufferSize = max(nbuffersize, MIN_BUFFER_SIZE);
 	fpBuffer = new uint8[fnBufferSize];
-	if (fpBuffer)
+	if (fpBuffer && binitialread)
 		ReadStream();
 			// Fill the buffer with data so that
 			// object is prepared for first call to
@@ -113,7 +115,8 @@ StreamBuffer::~StreamBuffer()
 // Returns: B_OK if object has been initialized successfully,
 // B_ERROR if not
 // ---------------------------------------------------------------
-status_t StreamBuffer::InitCheck()
+status_t
+StreamBuffer::InitCheck()
 {
 	if (fpStream && fpBuffer)
 		return B_OK;
@@ -138,7 +141,8 @@ status_t StreamBuffer::InitCheck()
 // Returns: the number of bytes successfully read or an
 // error code returned by BPositionIO::Read()
 // ---------------------------------------------------------------
-ssize_t StreamBuffer::Read(uint8 *pinto, size_t nbytes)
+ssize_t
+StreamBuffer::Read(uint8 *pinto, size_t nbytes)
 {
 	ssize_t result = B_ERROR;
 	size_t rd1 = 0, rd2 = 0;
@@ -162,6 +166,37 @@ ssize_t StreamBuffer::Read(uint8 *pinto, size_t nbytes)
 	return rd1 + rd2;
 }
 
+// ---------------------------------------------------------------
+// Seek
+//
+// Seeks the stream to the given position and refreshes the
+// read buffer.  If the seek operation fails, the read buffer
+// will be reset.
+//
+// Preconditions: fpBuffer must be allocated and fnBufferSize
+// must be valid
+//
+// Parameters:	
+//
+// Postconditions:
+//
+// Returns: true if the seek was successful,
+// false if the seek operation failed
+// ---------------------------------------------------------------
+bool
+StreamBuffer::Seek(off_t position)
+{
+	fnLen = 0;
+	fnPos = 0;
+	
+	if (fpStream->Seek(position, SEEK_SET) == position) {
+		ReadStream();
+		return true;
+	}
+	
+	return false;
+}
+
 // ---------------------------------------------------------------
 // ReadStream
 //
@@ -177,7 +212,8 @@ ssize_t StreamBuffer::Read(uint8 *pinto, size_t nbytes)
 // Returns: the number of bytes successfully read or an
 // error code returned by BPositionIO::Read()
 // ---------------------------------------------------------------
-ssize_t StreamBuffer::ReadStream()
+ssize_t
+StreamBuffer::ReadStream()
 {
 	ssize_t rd;
 	rd = fpStream->Read(fpBuffer, fnBufferSize);
@@ -187,5 +223,3 @@ ssize_t StreamBuffer::ReadStream()
 	}
 	return rd;
 }
-
-

src/add-ons/translators/tgatranslator/StreamBuffer.h

@@ -9,7 +9,7 @@
 // read from a BPositionIO object.
 //
 //
-// Copyright (c) 2002 OpenBeOS Project
+// Copyright (c) 2003 OpenBeOS Project
 //
 // Permission is hereby granted, free of charge, to any person obtaining a
 // copy of this software and associated documentation files (the "Software"),
@@ -39,7 +39,7 @@
 
 class StreamBuffer {
 public:
-	StreamBuffer(BPositionIO *pstream, size_t nbuffersize);
+	StreamBuffer(BPositionIO *pstream, size_t nbuffersize, bool binitialread);
 	~StreamBuffer();
 	
 	status_t InitCheck();
@@ -48,6 +48,9 @@ public:
 	ssize_t Read(uint8 *pinto, size_t nbytes);
 		// copy nbytes from the stream into pinto
 		
+	bool Seek(off_t position);
+		// seek the stream to the given position
+	
 private:
 	ssize_t ReadStream();
 		// Load the stream buffer from the stream

src/add-ons/translators/tgatranslator/TGATranslator.cpp

@@ -1887,7 +1887,7 @@ translate_from_tganmrle_to_bits(BPositionIO *inSource,
 	memset(bitsRowData, 0xff, bitsRowBytes);
 	uint8 *pbitspixel = bitsRowData;
 	uint8 packethead;
-	StreamBuffer sbuf(inSource, TGA_STREAM_BUFFER_SIZE);
+	StreamBuffer sbuf(inSource, TGA_STREAM_BUFFER_SIZE, true);
 	ssize_t rd = 0;
 	if (sbuf.InitCheck() == B_OK)
 		rd = sbuf.Read(&packethead, 1);
@@ -2198,7 +2198,7 @@ translate_from_tgamrle_to_bits(BPositionIO *inSource,
 	memset(bitsRowData, 0xff, bitsRowBytes);
 	uint8 *pbitspixel = bitsRowData;
 	uint8 packethead;
-	StreamBuffer sbuf(inSource, TGA_STREAM_BUFFER_SIZE);
+	StreamBuffer sbuf(inSource, TGA_STREAM_BUFFER_SIZE, true);
 	ssize_t rd = 0;
 	if (sbuf.InitCheck() == B_OK)
 		rd = sbuf.Read(&packethead, 1);