From 2364d92184a2abf61ba4c49543e1e7fcead44f3d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Miguel=20Moreno?= <josemmo@pm.me>
Date: Sat, 29 Jan 2022 11:20:45 +0100
Subject: [PATCH] Added support for transparent animated GIFs

- Updated ImageFile#renderImages()

> Closes #27
---
 .../io/josemmo/bukkit/plugin/storage/ImageFile.java    | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/main/java/io/josemmo/bukkit/plugin/storage/ImageFile.java b/src/main/java/io/josemmo/bukkit/plugin/storage/ImageFile.java
index 40f038c..a0431d5 100644
--- a/src/main/java/io/josemmo/bukkit/plugin/storage/ImageFile.java
+++ b/src/main/java/io/josemmo/bukkit/plugin/storage/ImageFile.java
@@ -87,10 +87,12 @@ protected ImageFile(@NotNull String name, @NotNull String path) {
         int originalHeight = reader.getHeight(0);
         BufferedImage tmpImage = new BufferedImage(originalWidth, originalHeight, BufferedImage.TYPE_4BYTE_ABGR);
         Graphics2D tmpGraphics = tmpImage.createGraphics();
+        tmpGraphics.setBackground(new Color(0, 0, 0, 0));
 
         // Create temporary scaled canvas (for resizing)
         BufferedImage tmpScaledImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
         Graphics2D tmpScaledGraphics = tmpScaledImage.createGraphics();
+        tmpScaledGraphics.setBackground(new Color(0, 0, 0, 0));
 
         // Read images from file
         byte[][] renderedImages = new byte[numOfSteps][width*height];
@@ -99,6 +101,7 @@ protected ImageFile(@NotNull String name, @NotNull String path) {
             // Extract step metadata
             int imageLeft = 0;
             int imageTop = 0;
+            boolean disposePrevious = false;
             if (format.equalsIgnoreCase("gif")) {
                 IIOMetadata metadata = reader.getImageMetadata(step);
                 IIOMetadataNode metadataRoot = (IIOMetadataNode) metadata.getAsTree(metadata.getNativeMetadataFormatName());
@@ -112,10 +115,17 @@ protected ImageFile(@NotNull String name, @NotNull String path) {
                         IIOMetadataNode controlExtensionNode = (IIOMetadataNode) metadataRoot.item(i);
                         int delay = Integer.parseInt(controlExtensionNode.getAttribute("delayTime"));
                         delays.compute(delay, (__, count) -> (count == null) ? 1 : count+1);
+                        disposePrevious = controlExtensionNode.getAttribute("disposalMethod").startsWith("restore");
                     }
                 }
             }
 
+            // Clear temporary canvases (if needed)
+            if (disposePrevious) {
+                tmpGraphics.clearRect(0, 0, originalWidth, originalHeight);
+                tmpScaledGraphics.clearRect(0, 0, width, height);
+            }
+
             // Paint step image over temporary canvas
             BufferedImage image = reader.read(step);
             tmpGraphics.drawImage(image, imageLeft, imageTop, null);