mrmBot-Matrix/natives/mirror.cc

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#include <napi.h>
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#include <vips/vips8>
using namespace std;
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using namespace vips;
Napi::Value Mirror(const Napi::CallbackInfo &info) {
Napi::Env env = info.Env();
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Napi::Object result = Napi::Object::New(env);
try {
Napi::Object obj = info[0].As<Napi::Object>();
Napi::Buffer<char> data = obj.Get("data").As<Napi::Buffer<char>>();
bool vertical = obj.Has("vertical")
? obj.Get("vertical").As<Napi::Boolean>().Value()
: false;
bool first =
obj.Has("first") ? obj.Get("first").As<Napi::Boolean>().Value() : false;
string type = obj.Get("type").As<Napi::String>().Utf8Value();
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VOption *options = VImage::option()->set("access", "sequential");
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VImage in =
VImage::new_from_buffer(data.Data(), data.Length(), "",
type == "gif" ? options->set("n", -1) : options)
.colourspace(VIPS_INTERPRETATION_sRGB);
if (!in.has_alpha()) in = in.bandjoin(255);
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VImage out;
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if (vertical) {
if (type == "gif") {
// once again, libvips gif handling is both a blessing and a curse
vector<VImage> img;
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int pageHeight = vips_image_get_page_height(in.get_image());
int nPages = vips_image_get_n_pages(in.get_image());
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bool isOdd = pageHeight % 2;
for (int i = 0; i < nPages; i++) {
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int x = (i * pageHeight) + (first ? 0 : (pageHeight / 2));
VImage cropped = in.crop(0, x, in.width(), pageHeight / 2);
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VImage flipped = cropped.flip(VIPS_DIRECTION_VERTICAL);
VImage final = VImage::arrayjoin(
{first ? cropped : flipped, first ? flipped : cropped},
VImage::option()->set("across", 1));
img.push_back(final);
}
out = VImage::arrayjoin(img, VImage::option()->set("across", 1));
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out.set(VIPS_META_PAGE_HEIGHT, pageHeight - (isOdd ? 1 : 0));
} else {
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VImage cropped = in.extract_area(0, 0, in.width(), in.height() / 2);
VImage flipped = cropped.flip(VIPS_DIRECTION_VERTICAL);
out = VImage::arrayjoin({cropped, flipped},
VImage::option()->set("across", 1));
}
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} else {
if (first) {
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VImage cropped = in.extract_area(0, 0, in.width() / 2, in.height());
VImage flipped = cropped.flip(VIPS_DIRECTION_HORIZONTAL);
out = VImage::arrayjoin({cropped, flipped});
} else {
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int size = in.width() / 2;
VImage cropped = in.extract_area(size, 0, size, in.height());
VImage flipped = cropped.flip(VIPS_DIRECTION_HORIZONTAL);
out = VImage::arrayjoin({flipped, cropped});
}
}
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void *buf;
size_t length;
out.write_to_buffer(("." + type).c_str(), &buf, &length);
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result.Set("data", Napi::Buffer<char>::Copy(env, (char *)buf, length));
result.Set("type", type);
} catch (std::exception const &err) {
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Napi::Error::New(env, err.what()).ThrowAsJavaScriptException();
} catch (...) {
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Napi::Error::New(env, "Unknown error").ThrowAsJavaScriptException();
}
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vips_error_clear();
vips_thread_shutdown();
return result;
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}