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Dropped imagescaler source files

This commit is contained in:
Manuel Reimer 2014-10-30 21:12:03 +01:00
parent f17af1f713
commit 052bc50408
2 changed files with 0 additions and 246 deletions
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149
libcore/imagescaler.c
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#include "imagescaler.h"
#include <cstdlib>
#include <cmath>
ImageScaler::ImageScaler() :
m_memory(NULL),
m_hor_filters(NULL),
m_ver_filters(NULL),
m_buffer(NULL),
m_dst_image(NULL),
m_dst_stride(0),
m_dst_width(0),
m_dst_height(0),
m_src_width(0),
m_src_height(0),
m_src_x(0),
m_src_y(0),
m_dst_x(0),
m_dst_y(0) {
}
ImageScaler::~ImageScaler() {
if ( m_memory ) free( m_memory );
}
// sin(x)/(x)
static float sincf( float x ) {
if ( fabsf(x) < 0.05f ) return 1.0f - (1.0f/6.0f)*x*x; // taylor series approximation to avoid 0/0
return sin(x)/x;
}
static void CalculateFilters( ImageScaler::Filter *filters, int dst_size, int src_size ) {
const float fc = dst_size >= src_size ? 1.0f : ((float) dst_size)/((float) src_size);
for (int i = 0; i < dst_size; i++) {
const int d = 2*dst_size; // sample position denominator
const int e = (2*i+1) * src_size - dst_size; // sample position enumerator
int offset = e / d; // truncated sample position
const float sub_offset = ((float) (e - offset*d)) / ((float) d); // exact sample position is (float) e/d = offset + sub_offset
// calculate filter coefficients
float h[4];
for (int j=0; j<4; j++) {
const float t = 3.14159265359f * (sub_offset+(1-j));
h[j] = sincf( fc * t ) * cosf( 0.25f * t ); // sinc-lowpass and cos-window
}
// ensure that filter does not reach out off image bounds:
while ( offset < 1 ) {
h[0] += h[1];
h[1] = h[2];
h[2] = h[3];
h[3] = 0.0f;
offset++;
}
while ( offset+3 > src_size ) {
h[3] += h[2];
h[2] = h[1];
h[1] = h[0];
h[0] = 0.0f;
offset--;
}
// coefficients are normalized to sum up to 2048
const float norm = 2048.0f / ( h[0] + h[1] + h[2] + h[3] );
offset--; // offset of fist used pixel
filters[i].m_offset = offset + 4; // store offset of first unused pixel
for (int j=0; j<4; j++) {
const float t = norm * h[j];
filters[i].m_coeff[(offset+j) & 3] = (int) ((t > 0.0f) ? (t+0.5f) : (t-0.5f)); // consider ring buffer index permutations
}
}
// set end marker
filters[dst_size].m_offset = (unsigned) -1;
}
void ImageScaler::SetImageParameters( unsigned *dst_image, unsigned dst_stride, unsigned dst_width, unsigned dst_height, unsigned src_width, unsigned src_height ) {
m_src_x = 0;
m_src_y = 0;
m_dst_x = 0;
m_dst_y = 0;
m_dst_image = dst_image;
m_dst_stride = dst_stride;
// if image dimensions do not change we can keep the old filter coefficients
if ( (src_width == m_src_width) && (src_height == m_src_height) && (dst_width == m_dst_width) && (dst_height == m_dst_height) ) return;
m_dst_width = dst_width;
m_dst_height = dst_height;
m_src_width = src_width;
m_src_height = src_height;
if ( m_memory ) free( m_memory );
const unsigned hor_filters_size = (m_dst_width + 1) * sizeof(Filter); // reserve one extra position for end marker
const unsigned ver_filters_size = (m_dst_height + 1) * sizeof(Filter);
const unsigned buffer_size = 4 * m_dst_width * sizeof(TmpPixel);
char *p = (char *) malloc( hor_filters_size + ver_filters_size + buffer_size );
m_memory = p;
m_hor_filters = (Filter *) p; p += hor_filters_size;
m_ver_filters = (Filter *) p; p += ver_filters_size;
m_buffer = (TmpPixel *) p;
CalculateFilters( m_hor_filters, m_dst_width , m_src_width );
CalculateFilters( m_ver_filters, m_dst_height, m_src_height );
}
// shift range to 0..255 and clamp overflows
static unsigned shift_clamp( int x ) {
x = ( x + (1<<21) ) >> 22;
if ( x < 0 ) return 0;
if ( x > 255 ) return 255;
return x;
}
void ImageScaler::NextSourceLine() {
m_dst_x = 0;
m_src_x = 0;
m_src_y++;
while ( m_ver_filters[m_dst_y].m_offset == m_src_y ) {
const int h0 = m_ver_filters[m_dst_y].m_coeff[0];
const int h1 = m_ver_filters[m_dst_y].m_coeff[1];
const int h2 = m_ver_filters[m_dst_y].m_coeff[2];
const int h3 = m_ver_filters[m_dst_y].m_coeff[3];
const TmpPixel *src = m_buffer;
unsigned *dst = m_dst_image + m_dst_stride * m_dst_y;
for (unsigned i=0; i<m_dst_width; i++) {
const ImageScaler::TmpPixel t( src[0]*h0 + src[1]*h1 + src[2]*h2 + src[3]*h3 );
src += 4;
dst[i] = shift_clamp(t[0]) | (shift_clamp(t[1])<<8) | (shift_clamp(t[2])<<16) | (shift_clamp(t[3])<<24);
}
m_dst_y++;
}
}

97
libcore/imagescaler.h
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#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