Add favicon support

api/src/main/java/com/velocitypowered/api/server/Favicon.java

@@ -0,0 +1,88 @@
+package com.velocitypowered.api.server;
+
+import com.google.common.base.Preconditions;
+
+import javax.annotation.Nonnull;
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Base64;
+import java.util.Objects;
+
+/**
+ * Represents a Minecraft server favicon. A Minecraft server favicon is a 64x64 image that can be displayed to a remote
+ * client that sends a Server List Ping packet, and is automatically displayed in the Minecraft client.
+ */
+public final class Favicon {
+    private final String base64Url;
+
+    /**
+     * Directly create a favicon using its Base64 URL directly. You are generally better served by the create() series
+     * of functions.
+     * @param base64Url the url for use with this favicon
+     */
+    public Favicon(@Nonnull String base64Url) {
+        this.base64Url = Preconditions.checkNotNull(base64Url, "base64Url");
+    }
+
+    /**
+     * Returns the Base64-encoded URI for this image.
+     * @return a URL representing this favicon
+     */
+    public String getBase64Url() {
+        return base64Url;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Favicon favicon = (Favicon) o;
+        return Objects.equals(base64Url, favicon.base64Url);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(base64Url);
+    }
+
+    @Override
+    public String toString() {
+        return "Favicon{" +
+                "base64Url='" + base64Url + '\'' +
+                '}';
+    }
+
+    /**
+     * Creates a new {@code Favicon} from the specified {@code image}.
+     * @param image the image to use for the favicon
+     * @return the created {@link Favicon} instance
+     */
+    public static Favicon create(@Nonnull BufferedImage image) {
+        Preconditions.checkNotNull(image, "image");
+        Preconditions.checkArgument(image.getWidth() == 64 && image.getHeight() == 64, "Image does not have" +
+                " 64x64 dimensions (found %sx%s)", image.getWidth(), image.getHeight());
+        ByteArrayOutputStream os = new ByteArrayOutputStream();
+        try {
+            ImageIO.write(image, "PNG", os);
+        } catch (IOException e) {
+            throw new AssertionError(e);
+        }
+        return new Favicon("data:image/png;base64," + Base64.getEncoder().encodeToString(os.toByteArray()));
+    }
+
+    /**
+     * Creates a new {@code Favicon} by reading the image from the specified {@code path}.
+     * @param path the path to the image to create a favicon for
+     * @return the created {@link Favicon} instance
+     */
+    public static Favicon create(@Nonnull Path path) throws IOException {
+        try (InputStream stream = Files.newInputStream(path)) {
+            return create(ImageIO.read(stream));
+        }
+    }
+}