DownloadableImage.java

    public void download(final ImageType type) {
        if (locations.get(type) == MISSING_TEXTURE) {
            TextureManager texturemanager = Minecraft.getMinecraft().getTextureManager();
            final String filepath = "creations/" + owner.user_id + "/" + type.name() + "/" + owner.id;
            final ResourceLocation res = new ResourceLocation(CTBMod.DOMAIN, filepath);
            ITextureObject texture = texturemanager.getTexture(res);

            if (texture == null) {

                downloadExecutor.execute(new Runnable() {

                    @Override
                    @SneakyThrows
                    public void run() {
                        String url = parent.links.get(type);
                        File cacheJPG = new File(DataCache.cacheFolder, filepath + ".jpg");
                        File cachePNG = new File(DataCache.cacheFolder, filepath + ".png");

                        if (!(cacheJPG.exists() || cachePNG.exists())) {
                            File outputFile = cacheJPG;
                            try {
                                InputStream in = new URL(url).openStream();
                                try {
                                    byte[] buf = new byte[4096];
                                    int n = 0;
                                    while (n < buf.length) {
                                        int read = in.read(buf, n, buf.length - n);
                                        if (read <= 0)
                                            break;
                                        n += read;
                                    }
                                    if (n < 8) {
                                        throw new IOException("File too small for an image");
                                    }
                                    if (PNGDecoder.checkSignature(buf)) {
                                        outputFile = cachePNG;
                                    }
                                    outputFile.getParentFile().mkdirs();
                                    outputFile.createNewFile();
                                    FileOutputStream fos = new FileOutputStream(outputFile);
                                    try {
                                        do {
                                            fos.write(buf, 0, n);
                                            n = in.read(buf);
                                        } while (n > 0);
                                    } finally {
                                        fos.close();
                                    }
                                } finally {
                                    in.close();
                                }
                            } catch (IOException e) {
                                throw new RuntimeException(String.format("Could not save image %s to %s.", outputFile.getName(), outputFile.getAbsolutePath()), e);
                            }
                        }

                        final File cache = cacheJPG.exists() ? cacheJPG : cachePNG;

                        // Do this on the main thread with GL context
                        Minecraft.getMinecraft().addScheduledTask(new Runnable() {

                            @Override
                            @SneakyThrows
                            public void run() {
                                Texture image = Texture.loadTexture(cache.toURI().toURL());
                                RescaledTexture texture = new RescaledTexture(image);
                                Minecraft.getMinecraft().getTextureManager().loadTexture(res, texture);

                                // Don't populate size and location data until after the texture is loaded
                                sizes.put(type, Size.create(image));
                                locations.put(type, res);
                            }
                        });
                    }
                });
            } else if (texture instanceof RescaledTexture) {
                // Grab cached size data
                sizes.put(type, ((RescaledTexture) texture).getSize());
                locations.put(type, res);
            }
        }
    }