Clipboard sync on new connections

Summary: Timestamp on changes to clipboards so that when a new device connects it can sync both clipboards to the most recent updated clipboard.

Reviewers: #kde_connect, albertvaka

Reviewed By: #kde_connect, albertvaka

Subscribers: albertvaka, sredman, kdeconnect

Tags: #kde_connect

Differential Revision: https://phabricator.kde.org/D22585

src/org/kde/kdeconnect/Plugins/ClibpoardPlugin/ClipboardListener.java

@@ -41,6 +41,7 @@ public class ClipboardListener {
 
     private final Context context;
     private String currentContent;
+    private long updateTimestamp;
 
     private ClipboardManager cm = null;
     private ClipboardManager.OnPrimaryClipChangedListener listener;
@@ -76,7 +77,7 @@ public class ClipboardListener {
                     if (content.equals(currentContent)) {
                         return;
                     }
-
+                    updateTimestamp = System.currentTimeMillis();
                     currentContent = content;
 
                     for (ClipboardObserver observer : observers) {
@@ -91,8 +92,17 @@ public class ClipboardListener {
         });
     }
 
+    public String getCurrentContent() {
+        return currentContent;
+    }
+
+    public long getUpdateTimestamp() {
+        return updateTimestamp;
+    }
+
     @SuppressWarnings("deprecation")
     public void setText(String text) {
+        updateTimestamp = System.currentTimeMillis();
         currentContent = text;
         cm.setText(text);
     }

src/org/kde/kdeconnect/Plugins/ClibpoardPlugin/ClipboardPlugin.java

@@ -28,8 +28,31 @@ import org.kde.kdeconnect_tp.R;
 @PluginFactory.LoadablePlugin
 public class ClipboardPlugin extends Plugin {
 
+    /**
+     * Packet containing just clipboard contents, sent when a device updates its clipboard.
+     * <p>
+     * The body should look like so:
+     * {
+     * "content": "password"
+     * }
+     */
     private final static String PACKET_TYPE_CLIPBOARD = "kdeconnect.clipboard";
 
+    /**
+     * Packet containing clipboard contents and a timestamp that the contents were last updated, sent
+     * on first connection
+     * <p>
+     * The timestamp is milliseconds since epoch. It can be 0, which indicates that the clipboard
+     * update time is currently unknown.
+     * <p>
+     * The body should look like so:
+     * {
+     * "timestamp": 542904563213,
+     * "content": "password"
+     * }
+     */
+    private final static String PACKET_TYPE_CLIPBOARD_CONNECT = "kdeconnect.clipboard.connect";
+
     @Override
     public String getDisplayName() {
         return context.getResources().getString(R.string.pref_plugin_clipboard);
@@ -43,19 +66,44 @@ public class ClipboardPlugin extends Plugin {
     @Override
     public boolean onPacketReceived(NetworkPacket np) {
         String content = np.getString("content");
-        ClipboardListener.instance(context).setText(content);
+        switch (np.getType()) {
-        return true;
+            case (PACKET_TYPE_CLIPBOARD):
+                ClipboardListener.instance(context).setText(content);
+                return true;
+            case(PACKET_TYPE_CLIPBOARD_CONNECT):
+                long packetTime = np.getLong("timestamp");
+                // If the packetTime is 0, it means the timestamp is unknown (so do nothing).
+                if (packetTime == 0 || packetTime < ClipboardListener.instance(context).getUpdateTimestamp()) {
+                    return false;
+                }
+
+                ClipboardListener.instance(context).setText(content);
+                return true;
+        }
+        throw new UnsupportedOperationException("Unknown packet type: " + np.getType());
     }
 
-    private final ClipboardListener.ClipboardObserver observer = content -> {
+    private final ClipboardListener.ClipboardObserver observer = this::propagateClipboard;
+
+    private void propagateClipboard(String content) {
         NetworkPacket np = new NetworkPacket(ClipboardPlugin.PACKET_TYPE_CLIPBOARD);
         np.set("content", content);
         device.sendPacket(np);
-    };
+    }
+
+    private void sendConnectPacket() {
+        String content = ClipboardListener.instance(context).getCurrentContent();
+        NetworkPacket np = new NetworkPacket(ClipboardPlugin.PACKET_TYPE_CLIPBOARD_CONNECT);
+        long timestamp = ClipboardListener.instance(context).getUpdateTimestamp();
+        np.set("timestamp", timestamp);
+        np.set("content", content);
+        device.sendPacket(np);
+    }
 
     @Override
     public boolean onCreate() {
         ClipboardListener.instance(context).registerObserver(observer);
+        sendConnectPacket();
         return true;
     }
 
@@ -66,12 +114,12 @@ public class ClipboardPlugin extends Plugin {
 
     @Override
     public String[] getSupportedPacketTypes() {
-        return new String[]{PACKET_TYPE_CLIPBOARD};
+        return new String[]{PACKET_TYPE_CLIPBOARD, PACKET_TYPE_CLIPBOARD_CONNECT};
     }
 
     @Override
     public String[] getOutgoingPacketTypes() {
-        return new String[]{PACKET_TYPE_CLIPBOARD};
+        return new String[]{PACKET_TYPE_CLIPBOARD, PACKET_TYPE_CLIPBOARD_CONNECT};
     }