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