nr-filter-pixops.h revision d0bb68525547101b5c938b246ff897a5de413cff
#ifndef __NR_FILTER_PIXOPS_H__
#define __NR_FILTER_PIXOPS_H__
/*
* Per-pixel image manipulation functions.
* These can be used by all filter primitives, which combine two images on
* per-pixel basis. These are at least feBlend, feComposite and feMerge.
*
* Authors:
* Niko Kiirala <niko@kiirala.com>
*
* Copyright (C) 2007 authors
*
* Released under GNU GPL, read the file 'COPYING' for more information
*/
namespace NR {
/**
* Mixes the two input images using the function given as template.
* The result is placed in out.
* The mixing function should have the following type:
* void mix(unsigned char *result, unsigned char const *in1,
* unsigned char const *in2);
* Each of the parameters for mix-function is a pointer to four bytes of data,
* giving the RGBA values for that pixel. The mix function must only access
* the four bytes beginning at a pointer given as parameter.
*/
/*
* The implementation is in a header file because of the template. It has to
* be in the same compilation unit as the code using it. Otherwise, linking
* the program will not succeed.
*/
template <void(*blend)(unsigned char *cr, unsigned char const *ca, unsigned char const *cb)>
void pixops_mix(NRPixBlock &out, NRPixBlock &in1, NRPixBlock &in2) {
unsigned char *in1_data = NR_PIXBLOCK_PX(&in1);
unsigned char *in2_data = NR_PIXBLOCK_PX(&in2);
unsigned char *out_data = NR_PIXBLOCK_PX(&out);
unsigned char zero_rgba[4] = {0, 0, 0, 0};
if (in1.area.y0 < in2.area.y0) {
// in1 begins before in2 on y-axis
for (int y = in1.area.y0 ; y < in2.area.y0 ; y++) {
int out_line = (y - out.area.y0) * out.rs;
int in_line = (y - in1.area.y0) * in1.rs;
for (int x = in1.area.x0 ; x < in1.area.x1 ; x++) {
blend(out_data + out_line + 4 * (x - out.area.x0),
in1_data + in_line + 4 * (x - in1.area.x0),
zero_rgba);
}
}
} else if (in1.area.y0 > in2.area.y0) {
// in2 begins before in1 on y-axis
for (int y = in2.area.y0 ; y < in1.area.y0 ; y++) {
int out_line = (y - out.area.y0) * out.rs;
int in_line = (y - in2.area.y0) * in2.rs;
for (int x = in2.area.x0 ; x < in2.area.x1 ; x++) {
blend(out_data + out_line + 4 * (x - out.area.x0),
zero_rgba,
in2_data + in_line + 4 * (x - in2.area.x0));
}
}
}
for (int y = std::max(in1.area.y0, in2.area.y0) ;
y < std::min(in1.area.y1, in2.area.y1) ; ++y) {
int out_line = (y - out.area.y0) * out.rs;
int in1_line = (y - in1.area.y0) * in1.rs;
int in2_line = (y - in2.area.y0) * in2.rs;
if (in1.area.x0 < in2.area.x0) {
// in1 begins before in2 on x-axis
for (int x = in1.area.x0 ; x < in2.area.x0 ; ++x) {
blend(out_data + out_line + 4 * (x - out.area.x0),
in1_data + in1_line + 4 * (x - in1.area.x0),
zero_rgba);
}
} else if (in1.area.x0 > in2.area.x0) {
// in2 begins before in1 on x-axis
for (int x = in2.area.x0 ; x < in1.area.x0 ; ++x) {
blend(out_data + out_line + 4 * (x - out.area.x0),
zero_rgba,
in2_data + in2_line + 4 * (x - in2.area.x0));
}
}
for (int x = std::max(in1.area.x0, in2.area.x0) ;
x < std::min(in1.area.x1, in2.area.x1) ; ++x) {
blend(out_data + out_line + 4 * (x - out.area.x0),
in1_data + in1_line + 4 * (x - in1.area.x0),
in2_data + in2_line + 4 * (x - in2.area.x0));
}
if (in1.area.x1 > in2.area.x1) {
// in1 ends after in2 on x-axis
for (int x = in2.area.x1 ; x < in1.area.x1 ; ++x) {
blend(out_data + out_line + 4 * (x - out.area.x0),
in1_data + in1_line + 4 * (x - in1.area.x0),
zero_rgba);
}
} else if (in1.area.x1 < in2.area.x1) {
// in2 ends after in1 on x-axis
for (int x = in1.area.x1 ; x < in2.area.x1 ; ++x) {
blend(out_data + out_line + 4 * (x - out.area.x0),
zero_rgba,
in2_data + in2_line + 4 * (x - in2.area.x0));
}
}
}
if (in1.area.y1 > in2.area.y1) {
// in1 ends after in2 on y-axis
for (int y = in2.area.y1 ; y < in1.area.y1 ; y++) {
int out_line = (y - out.area.y0) * out.rs;
int in_line = (y - in1.area.y0) * in1.rs;
for (int x = in1.area.x0 ; x < in1.area.x1 ; x++) {
blend(out_data + out_line + 4 * (x - out.area.x0),
in1_data + in_line + 4 * (x - in1.area.x0),
zero_rgba);
}
}
} else if (in1.area.y1 < in2.area.y1) {
// in2 ends after in1 on y-axis
for (int y = in1.area.y1 ; y < in2.area.y1 ; y++) {
int out_line = (y - out.area.y0) * out.rs;
int in_line = (y - in2.area.y0) * in2.rs;
for (int x = in2.area.x0 ; x < in2.area.x1 ; x++) {
blend(out_data + out_line + 4 * (x - out.area.x0),
zero_rgba,
in2_data + in_line + 4 * (x - in2.area.x0));
}
}
}
}
} // namespace NR
#endif // __NR_FILTER_PIXOPS_H_
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :