mrmBot-Matrix/natives/swirl.cc

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#include <vips/vips8>
#include "common.h"
using namespace std;
using namespace vips;
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char *Swirl(string type, string *outType, char *BufferData, size_t BufferLength,
[[maybe_unused]] ArgumentMap Arguments, size_t *DataSize) {
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VOption *options = VImage::option()->set("access", "sequential");
VImage in =
VImage::new_from_buffer(BufferData, BufferLength, "",
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type == "gif" ? options->set("n", -1) : options)
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.colourspace(VIPS_INTERPRETATION_sRGB);
if (!in.has_alpha()) in = in.bandjoin(255);
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int pageHeight = vips_image_get_page_height(in.get_image());
int nPages = vips_image_get_n_pages(in.get_image());
int width = in.width();
double newWidth = width * 3;
double newHeight = pageHeight * 3;
vector<double> divSize = {newWidth / 2, newHeight / 2};
VImage index = VImage::xyz(newWidth, newHeight);
VImage center = index - divSize;
VImage polar = center
.copy(VImage::option()
->set("format", VIPS_FORMAT_COMPLEX)
->set("bands", 1))
.polar()
.copy(VImage::option()
->set("format", VIPS_FORMAT_FLOAT)
->set("bands", 2));
int size = min(width, pageHeight) / 2;
VImage test = (1 - polar.extract_band(0) / size);
VImage degrees = test.cast(VIPS_FORMAT_FLOAT).pow(2);
VImage angle = polar.extract_band(1) + degrees * 180;
VImage distortion = polar.extract_band(0)
.bandjoin(angle)
.copy(VImage::option()
->set("format", VIPS_FORMAT_COMPLEX)
->set("bands", 1))
.rect()
.copy(VImage::option()
->set("format", VIPS_FORMAT_FLOAT)
->set("bands", 2)) +
divSize;
vector<VImage> img;
for (int i = 0; i < nPages; i++) {
VImage img_frame =
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type == "gif" ? in.crop(0, i * pageHeight, width, pageHeight) : in;
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VImage distort =
img_frame
.gravity(VIPS_COMPASS_DIRECTION_CENTRE, newWidth, newHeight,
VImage::option()->set("extend", VIPS_EXTEND_COPY))
.mapim(distortion,
VImage::option()->set(
"interpolate", VInterpolate::new_from_name("bicubic")));
VImage frame = distort.crop(width, pageHeight, width, pageHeight);
img.push_back(frame);
}
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VImage final = VImage::arrayjoin(img, VImage::option()->set("across", 1));
final.set(VIPS_META_PAGE_HEIGHT, pageHeight);
void *buf;
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final.write_to_buffer(("." + *outType).c_str(), &buf, DataSize);
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return (char *)buf;
}