From cda5c37a4a4463a8abc4e5035dd0a734e597f188 Mon Sep 17 00:00:00 2001
From: DieGurke <55625494+DieGurke@users.noreply.github.com>
Date: Sun, 15 Dec 2019 12:48:40 +0100
Subject: [PATCH] Autoscroll

* Implemented functionality to automatically scroll down when user is on
the bottom of the chat and then there are new messages added.
* When chat is opened, the vertical scroll bar starts at the bottom.
* When rereading messages, the chat doesn't scroll down if new messages
are added. (Besides see first point)
---
 src/main/java/envoy/client/ui/ChatWindow.java | 34 ++++++++++++++-----
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/src/main/java/envoy/client/ui/ChatWindow.java b/src/main/java/envoy/client/ui/ChatWindow.java
index 6968f5c..134734f 100644
--- a/src/main/java/envoy/client/ui/ChatWindow.java
+++ b/src/main/java/envoy/client/ui/ChatWindow.java
@@ -63,6 +63,8 @@ public class ChatWindow extends JFrame {
 	// private JCheckBox jCbChangeMode;
 	private PrimaryButton	postButton		= new PrimaryButton("Post");
 	private PrimaryButton	settingsButton	= new PrimaryButton("Settings");
+	private int				verticalScrollBarMaximumValue	= scrollPane.getVerticalScrollBar().getMaximum();
+	private boolean			chatOpened						= false;
 
 	private static int space = 4;
 
@@ -208,6 +210,7 @@ public class ChatWindow extends JFrame {
 				textPane.setText(currentChat.getRecipient().getName());
 
 				messageList.setModel(currentChat.getModel());
+				chatOpened = true;
 				contentPane.revalidate();
 			}
 		});
@@ -253,11 +256,8 @@ public class ChatWindow extends JFrame {
 		// scrollPane
 		scrollPane.setForeground(theme.getBackgroundColor());
 		scrollPane.setBackground(theme.getCellColor());
-		// scrollPane.getVerticalScrollBar()
-		// .setBackground(
-		// new Color(theme.getBackgroundColor().getRed() + 50,
-		// theme.getBackgroundColor().getGreen() + 50,
-		// theme.getBackgroundColor().getBlue() + 50));
+
+		// Scroll Bar Styling
 		scrollPane.getVerticalScrollBar().setBackground(theme.getCellColor());
 		scrollPane.getVerticalScrollBar()
 			.setUI(new PrimaryScrollBar(5, theme.getInteractableBackgroundColor(),
@@ -267,10 +267,26 @@ public class ChatWindow extends JFrame {
 		scrollPane.getHorizontalScrollBar()
 			.setUI(new PrimaryScrollBar(5, theme.getInteractableBackgroundColor(), new Color(theme.getInteractableBackgroundColor().getRGB() - 50),
 					new Color(theme.getInteractableBackgroundColor().getRGB() + 170), false));
-		// int currentVerticalScrollBarValue =
-		// scrollPane.getVerticalScrollBar().getValue() +
-		// scrollPane.getVerticalScrollBar().getVisibleAmount(); Work in Progress for
-		// autoscroll
+
+		// Autoscroll
+		scrollPane.getVerticalScrollBar().addAdjustmentListener(e -> {
+			if ((verticalScrollBarMaximumValue - e.getAdjustable().getMaximum()) == 0) {
+				return;
+			}
+
+			if (chatOpened == true) {
+				e.getAdjustable().setValue(e.getAdjustable().getMaximum());
+				verticalScrollBarMaximumValue	= scrollPane.getVerticalScrollBar().getMaximum();
+				chatOpened						= false;
+				return;
+			}
+			if (scrollPane.getVerticalScrollBar().getValue()
+					+ scrollPane.getVerticalScrollBar().getVisibleAmount() + 100 >= scrollPane.getVerticalScrollBar().getMaximum()) {
+				e.getAdjustable().setValue(e.getAdjustable().getMaximum());
+				verticalScrollBarMaximumValue = scrollPane.getVerticalScrollBar().getMaximum();
+			}
+		});
+
 		// messageEnterTextArea
 		messageEnterTextArea.setCaretColor(theme.getTypingMessageColor());
 		messageEnterTextArea.setForeground(theme.getTypingMessageColor());