Version 1.2.0pre

1 files changed, 97 insertions, 0 deletions

diff --git a/imagescaler.h b/imagescaler.h
new file mode 100644
index 0000000..f2de6ba
--- /dev/null
+++ b/imagescaler.h
@@ -0,0 +1,97 @@
+#ifndef _ImageScaler_h
+#define _ImageScaler_h
+
+/*!
+ * this class scales images consisting of 4 components (RGBA)
+ * to an arbitrary size using a 4-tap filter
+ */
+class ImageScaler {
+public:
+
+	struct Filter {
+		unsigned  m_offset;
+		short     m_coeff[4];
+	};
+
+	ImageScaler();
+	~ImageScaler();
+
+	//! set destination image and source image size
+	void SetImageParameters( unsigned *dst_image, unsigned dst_stride, unsigned dst_width, unsigned dst_height, unsigned src_width, unsigned src_height );
+
+	/*! process one pixel of source image; destination image is written while input is processed
+	 * SetImageParameters() must be called first
+	 */
+	void PutSourcePixel( unsigned char c0, unsigned char c1, unsigned char c2, unsigned char c3 ) {
+		m_hbuf[ (m_src_x++) & 3 ].Set( c0, c1, c2, c3 );
+
+		TmpPixel      *bp = m_buffer + 4 * m_dst_x + (m_src_y & 3);
+		const Filter  *fh;
+
+		while ( (fh=m_hor_filters+m_dst_x)->m_offset == m_src_x ) {
+			*bp = m_hbuf[0]*fh->m_coeff[0] + m_hbuf[1]*fh->m_coeff[1] + m_hbuf[2]*fh->m_coeff[2] + m_hbuf[3]*fh->m_coeff[3];
+			m_dst_x++;
+			bp += 4;
+		}
+
+		if ( m_src_x == m_src_width ) NextSourceLine();
+	}
+
+private:
+
+	//! temporary image pixel class - a 4-element integer vector
+	class TmpPixel {
+	public:
+		TmpPixel() {
+		}
+
+		TmpPixel( int c0, int c1, int c2, int c3 ) {
+			Set(c0,c1,c2,c3);
+		}
+
+		void Set( int c0, int c1, int c2, int c3 ) {
+			m_comp[0] = c0;
+			m_comp[1] = c1;
+			m_comp[2] = c2;
+			m_comp[3] = c3;
+		}
+
+		TmpPixel operator*( int s ) const {
+			return TmpPixel( m_comp[0]*s, m_comp[1]*s, m_comp[2]*s, m_comp[3]*s );
+		}
+
+		TmpPixel operator+( const TmpPixel &x ) const {
+			return TmpPixel( m_comp[0] + x[0], m_comp[1] + x[1], m_comp[2] + x[2], m_comp[3] + x[3] );
+		}
+
+		// return component i=[0..3] - No range check!
+		int operator[](unsigned i) const {
+			return m_comp[i];
+		}
+
+	private:
+		int  m_comp[4];
+	};
+
+	//! this is called whenever one input line is processed completely
+	void NextSourceLine();
+
+	TmpPixel   m_hbuf[4];      //! ring buffer for 4 input pixels
+	char      *m_memory;       //! buffer container
+	Filter    *m_hor_filters;  //! buffer for horizontal filters (one for each output image column)
+	Filter    *m_ver_filters;  //! buffer for vertical   filters (one for each output image row)
+	TmpPixel  *m_buffer;       //! buffer contains 4 horizontally filtered input lines, multiplexed
+	unsigned  *m_dst_image;    //! pointer to destination image
+	unsigned   m_dst_stride;   //! destination image stride
+	unsigned   m_dst_width;    //! destination image width
+	unsigned   m_dst_height;   //! destination image height
+	unsigned   m_src_width;    //! source image width
+	unsigned   m_src_height;   //! source image height
+	unsigned   m_src_x;        //! x position of next source image pixel
+	unsigned   m_src_y;        //! y position of source image line currently beeing processed
+	unsigned   m_dst_x;        //! x position of next destination image pixel
+	unsigned   m_dst_y;        //! x position of next destination image line
+};
+
+#endif  // _ImageScaler_h
+