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DSTexCompress/FreeImage/Examples/Generic/LoadFromMemory-classified.cpp

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+// ==========================================================
+// Classified FreeImageIO handler
+//
+// Design and implementation by
+// - schickb (schickb@hotmail.com)
+//
+// This file is part of FreeImage 3
+//
+// COVERED CODE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTY
+// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES
+// THAT THE COVERED CODE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE
+// OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE COVERED
+// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT
+// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY
+// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL
+// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER
+// THIS DISCLAIMER.
+//
+// Use at your own risk!
+// ==========================================================
+
+class MemIO : public FreeImageIO {
+public :
+    MemIO( BYTE *data ) : _start(data), _cp(data) {
+        read_proc  = _ReadProc;
+        write_proc = _WriteProc;
+        tell_proc  = _TellProc;
+        seek_proc  = _SeekProc;
+    }
+
+    void Reset() {
+		_cp = _start;
+	}
+
+    static unsigned _ReadProc(void *buffer, unsigned size, unsigned count, fi_handle handle);
+    static unsigned _WriteProc(void *buffer, unsigned size, unsigned count, fi_handle handle);
+    static int _SeekProc(fi_handle handle, long offset, int origin);
+	static long _TellProc(fi_handle handle);
+
+private:
+    BYTE * const _start;
+    BYTE *_cp;
+};
+
+
+unsigned
+MemIO::_ReadProc(void *buffer, unsigned size, unsigned count, fi_handle handle) {
+    MemIO *memIO = (MemIO*)handle;
+    
+    BYTE *tmp = (BYTE *)buffer;
+
+    for (unsigned c = 0; c < count; c++) {
+        memcpy(tmp, memIO->_cp, size);
+
+        memIO->_cp = memIO->_cp + size;
+
+        tmp += size;
+    }
+
+    return count;
+}
+
+unsigned
+MemIO::_WriteProc(void *buffer, unsigned size, unsigned count, fi_handle handle) {
+    ASSERT( false );
+    return size;
+}
+
+int
+MemIO::_SeekProc(fi_handle handle, long offset, int origin) {
+    ASSERT(origin != SEEK_END);
+
+    MemIO *memIO = (MemIO*)handle;
+
+    if (origin == SEEK_SET) 
+        memIO->_cp = memIO->_start + offset;
+    else
+        memIO->_cp = memIO->_cp + offset;
+
+    return 0;
+}
+
+long
+MemIO::_TellProc(fi_handle handle) {
+    MemIO *memIO = (MemIO*)handle;
+
+    return memIO->_cp - memIO->_start;
+}
+
+// ----------------------------------------------------------
+// PSEUDOCODE... HELPS TO UNDERSTAND HOW THE MEMIO CLASS WORKS
+// ----------------------------------------------------------
+
+int
+main(int argc, char *argv[]) {
+	BYTE *data = loadimagesomehow();
+
+	MemIO memIO(data);
+
+	FIBITMAP *fbmp = FreeImage_LoadFromHandle( fif, &memIO, (fi_handle)&memIO );
+}