&togif command (libvips version) (#286)

* &togif command

* use libvips not magick

* include libvips build dir in gitignore

.gitignore

@@ -25,6 +25,7 @@ build/
 # Dependency directories
 node_modules/
 jspm_packages/
+libvips/
 
 # Optional npm cache directory
 .npm

commands/image-editing/togif.js

@@ -0,0 +1,11 @@
+import ImageCommand from "../../classes/imageCommand.js";
+
+class ToGIFCommand extends ImageCommand {
+  static description = "Turns an image into a gif";
+  static aliases = ["tgif", "gifify"];
+
+  static noImage = "You need to provide an image to turn into a GIF!";
+  static command = "togif";
+}
+
+export default ToGIFCommand;

natives/image.cc

@@ -29,6 +29,7 @@
 #include "sonic.h"
 #include "spin.h"
 #include "tile.h"
+#include "togif.h"
 #include "uncaption.h"
 #include "wall.h"
 #include "watermark.h"
@@ -77,6 +78,7 @@ Napi::Object Init(Napi::Env env, Napi::Object exports)
   exports.Set(Napi::String::New(env, "spin"), Napi::Function::New(env, Spin));
   exports.Set(Napi::String::New(env, "swirl"), Napi::Function::New(env, Swirl));
   exports.Set(Napi::String::New(env, "tile"), Napi::Function::New(env, Tile));
+  exports.Set(Napi::String::New(env, "togif"), Napi::Function::New(env, ToGif));
   exports.Set(Napi::String::New(env, "uncaption"), Napi::Function::New(env, Uncaption));
   exports.Set(Napi::String::New(env, "wall"), Napi::Function::New(env, Wall));
   exports.Set(Napi::String::New(env, "watermark"), Napi::Function::New(env, Watermark));

natives/togif.cc

@@ -0,0 +1,56 @@
+#include <napi.h>
+
+#include <vips/vips8>
+
+using namespace std;
+using namespace vips;
+
+Napi::Value ToGif(const Napi::CallbackInfo &info) {
+  Napi::Env env = info.Env();
+
+  try {
+    Napi::Object obj = info[0].As<Napi::Object>();
+    Napi::Buffer<char> data = obj.Get("data").As<Napi::Buffer<char>>();
+    string type = obj.Get("type").As<Napi::String>().Utf8Value();
+
+    if (type == "gif") {
+      Napi::Object result = Napi::Object::New(env);
+      result.Set("data", data);
+      result.Set("type", "gif");
+      return result;
+    }
+
+    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 pageHeight = vips_image_get_page_height(in.get_image());
+
+    vector<VImage> img;
+
+    img.push_back(in);
+
+    VImage final = VImage::arrayjoin(img, VImage::option()->set("across", 1));
+    final.set(VIPS_META_PAGE_HEIGHT, pageHeight + in.height());
+
+    void *buf;
+    size_t length;
+    final.write_to_buffer(
+        ("." + type).c_str(), &buf, &length, VImage::option()->set("dither", 0));
+
+    vips_thread_shutdown();
+
+    Napi::Object result = Napi::Object::New(env);
+    result.Set("data", Napi::Buffer<char>::Copy(env, (char *)buf, length));
+    result.Set("type", "gif");
+    return result;
+  } catch (std::exception const &err) {
+    throw Napi::Error::New(env, err.what());
+  } catch (...) {
+    throw Napi::Error::New(env, "Unknown error");
+  }
+}

natives/togif.h

@@ -0,0 +1,5 @@
+#pragma once
+
+#include <napi.h>
+
+Napi::Value ToGif(const Napi::CallbackInfo& info);