mrmBot-Matrix/natives/flag.cc

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#include <napi.h>
#include <vips/vips8>
using namespace std;
using namespace vips;
Napi::Value Flag(const Napi::CallbackInfo &info) {
Napi::Env env = info.Env();
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try {
Napi::Object obj = info[0].As<Napi::Object>();
Napi::Buffer<char> data = obj.Get("data").As<Napi::Buffer<char>>();
string overlay = obj.Get("overlay").As<Napi::String>().Utf8Value();
string type = obj.Get("type").As<Napi::String>().Utf8Value();
string basePath = obj.Get("basePath").As<Napi::String>().Utf8Value();
VOption *options = VImage::option()->set("access", "sequential");
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);
int width = in.width();
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int pageHeight = vips_image_get_page_height(in.get_image());
int nPages = vips_image_get_n_pages(in.get_image());
string assetPath = basePath + overlay;
VImage overlayInput = VImage::new_from_file(assetPath.c_str());
VImage overlayImage = overlayInput.resize(
(double)width / (double)overlayInput.width(),
VImage::option()->set(
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"vscale", (double)pageHeight / (double)overlayInput.height()));
if (!overlayImage.has_alpha()) {
overlayImage = overlayImage.bandjoin(127);
} else {
// this is a pretty cool line, just saying
overlayImage = overlayImage * vector<double>{1, 1, 1, 0.5};
}
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;
VImage composited =
img_frame.composite2(overlayImage, VIPS_BLEND_MODE_OVER);
img.push_back(composited);
}
VImage final = VImage::arrayjoin(img, VImage::option()->set("across", 1));
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final.set(VIPS_META_PAGE_HEIGHT, pageHeight);
void *buf;
size_t length;
final.write_to_buffer(
("." + type).c_str(), &buf, &length,
type == "gif" ? VImage::option()->set("dither", 0) : 0);
Napi::Object result = Napi::Object::New(env);
result.Set("data", Napi::Buffer<char>::Copy(env, (char *)buf, length));
result.Set("type", type);
return result;
} catch (std::exception const &err) {
throw Napi::Error::New(env, err.what());
} catch (...) {
throw Napi::Error::New(env, "Unknown error");
}
}