Initial source commit

minorGems/graphics/converters/BMPImageConverter.h

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+/*
+ * Modification History
+ *
+ * 2001-February-19		Jason Rohrer
+ * Created.
+ *
+ * 2001-February-19		Jason Rohrer
+ * Fixed some bugs in the raster formatting code.
+ *
+ * 2001-May-19   Jason Rohrer
+ * Fixed a bug in zero padding for each line.
+ *
+ * 2001-May-21   Jason Rohrer
+ * Fixed another bug in zero padding for each line.
+ *
+ * 2001-September-22   Jason Rohrer
+ * Changed to subclass LittleEndianImageConverter.
+ */
+ 
+ 
+#ifndef BMP_IMAGE_CONVERTER_INCLUDED
+#define BMP_IMAGE_CONVERTER_INCLUDED 
+
+
+#include "LittleEndianImageConverter.h"
+
+
+/**
+ * Windows BMP implementation of the image conversion interface.
+ *
+ * Note that it only supports 24-bit BMP files (and thus only 3-channel
+ * Images).
+ *
+ * BMP format information taken from:
+ * http://www.daubnet.com/formats/BMP.html
+ * Some information from this site is incorrect:
+ *   24-bit pixels are _not_ stored in 32-bit blocks.
+ *
+ * @author Jason Rohrer
+ */
+class BMPImageConverter : public LittleEndianImageConverter {
+	
+	public:
+		
+		// implement the ImageConverter interface
+		virtual void formatImage( Image *inImage, 
+			OutputStream *inStream );
+			
+		virtual Image *deformatImage( InputStream *inStream );		
+
+
+	};
+
+
+
+inline void BMPImageConverter::formatImage( Image *inImage, 
+	OutputStream *inStream ) {
+	
+	// make sure the image is in the right format
+	if( inImage->getNumChannels() != 3 ) {
+		printf(
+			"Only 3-channel images can be converted to the BMP format.\n" );
+		return;
+		}
+
+	long width = inImage->getWidth();
+	long height = inImage->getHeight();
+	
+	long numPixels = width * height;
+
+	// each line should be padded with zeros to
+	// end on a 4-byte boundary
+	int numZeroPaddingBytes = ( 4 - ( width * 3 ) % 4 ) % 4;
+	
+	short bitCount = 24;
+	long rasterSize = numPixels * 3;
+	// zero padding bytes for each row
+	rasterSize += numZeroPaddingBytes * height;
+	
+	// offset past two headers
+	long offsetToRaster = 14 + 40;
+	
+	long fileSize = offsetToRaster + rasterSize;
+	
+	long compressionType = 0;
+	
+	
+	long pixelsPerMeter = 2834;
+	
+	// both are 0 since we have no color map
+	long colorsUsed = 0;
+	long colorsImportant = 0;
+	
+	// write the header
+	unsigned char *signature = new unsigned char[2];
+	signature[0] = 'B';
+	signature[1] = 'M';
+	inStream->write( signature, 2 );
+	delete [] signature;
+	writeLittleEndianLong( fileSize, inStream );
+	writeLittleEndianLong( 0, inStream );
+	writeLittleEndianLong( offsetToRaster, inStream );
+	
+	// write the info header
+	// header size
+	writeLittleEndianLong( 40, inStream );
+	writeLittleEndianLong( width, inStream );
+	writeLittleEndianLong( height, inStream );
+	// numPlanes
+	writeLittleEndianShort( 1, inStream );
+	writeLittleEndianShort( bitCount, inStream );
+	writeLittleEndianLong( compressionType, inStream );
+	writeLittleEndianLong( rasterSize, inStream );
+	writeLittleEndianLong( pixelsPerMeter, inStream );
+	writeLittleEndianLong( pixelsPerMeter, inStream );
+	writeLittleEndianLong( colorsUsed, inStream );
+	writeLittleEndianLong( colorsImportant, inStream );
+	
+	// no color table...
+	
+	// now write the raster
+	
+	unsigned char *raster = new unsigned char[ rasterSize ];
+	double *red = inImage->getChannel( 0 );
+	double *green = inImage->getChannel( 1 );
+	double *blue = inImage->getChannel( 2 );
+	
+	// pixels are stored bottom-up, left to right
+	// (row major order)
+	
+	long rasterIndex = 0;
+	for( int y=height-1; y>=0; y-- ) {
+		for( int x=0; x<width; x++ ) {
+			int imageIndex = y * width + x;
+			
+			raster[rasterIndex] = 
+				(unsigned char)( 255 * blue[imageIndex] );
+			raster[rasterIndex + 1] = 
+				(unsigned char)( 255 * green[imageIndex] );
+			raster[rasterIndex + 2] = 
+				(unsigned char)( 255 * red[imageIndex] );
+			
+			rasterIndex += 3;
+			}
+
+		for( int p=0; p<numZeroPaddingBytes; p++ ) {
+			// insert at the end of this line
+			raster[ rasterIndex ] = 0;
+			rasterIndex++;
+			}
+		}
+	
+	inStream->write( raster, rasterSize );
+	
+	delete [] raster;
+	}
+
+
+
+inline Image *BMPImageConverter::deformatImage( InputStream *inStream ) {
+	// temp buffer used to skip data in the stream
+	unsigned char *temp = new unsigned char[ 100 ];
+	
+	// skip signature
+	inStream->read( temp, 2 );
+	
+	long fileSize = readLittleEndianLong( inStream );
+	
+	// skip unused
+	inStream->read( temp, 4 );
+	
+	long rasterOffset = readLittleEndianLong( inStream );
+	long rasterSize = fileSize - rasterOffset;
+	
+	// skip size of header
+	inStream->read( temp, 4 );
+	
+	long width = readLittleEndianLong( inStream );
+	long height = readLittleEndianLong( inStream );
+	
+	// skip planes
+	inStream->read( temp, 2 );
+	
+	short bitCount = readLittleEndianShort( inStream );
+	
+	char failing = false;
+	if( bitCount != 24 ) {
+		printf( "Only 24-bit BMP file formats supported.\n" );
+		failing = true;
+		}
+	long compression = readLittleEndianLong( inStream );
+	if( compression != 0 ) {
+		printf( "Only uncompressed BMP file formats supported.\n" );
+		failing = true;
+		}
+	
+	// skip imageSize, resolution, and color usage information
+	inStream->read( temp, 20 );
+	
+	// now we're at the raster.
+
+	// each line should be padded with zeros to
+	// end on a 4-byte boundary
+	int numZeroPaddingBytes = ( 4 - ( width * 3 ) % 4 ) % 4;
+	
+	unsigned char *raster = new unsigned char[ rasterSize ];
+	inStream->read( raster, rasterSize );
+	Image *returnImage;
+	if( failing ) {
+		return NULL;
+		}
+	else {
+		
+		returnImage = new Image( width, height, 3 );
+		
+		double *red = returnImage->getChannel( 0 );
+		double *green = returnImage->getChannel( 1 );
+		double *blue = returnImage->getChannel( 2 );
+
+		// pixels are stored bottom-up, left to right
+		// (row major order)
+
+		long rasterIndex = 0;
+		for( int y=height-1; y>=0; y-- ) {
+			for( int x=0; x<width; x++ ) {
+				int imageIndex = y * width + x;
+
+				blue[imageIndex] = 
+					(double)( raster[rasterIndex] ) / 255.0;
+				green[imageIndex] = 
+					(double)( raster[rasterIndex + 1] ) / 255.0;
+				red[imageIndex] = 
+					(double)( raster[rasterIndex + 2] ) / 255.0;
+
+				rasterIndex += 3;
+				}
+			
+			// skip the zero padding bytes at the end of this line
+			rasterIndex += numZeroPaddingBytes;
+			}
+		}
+	
+	delete [] raster;	
+	delete [] temp;
+	
+	return returnImage;
+	}
+
+
+		
+#endif