Paste on "set clipboard" if possible

Ctrl+Shift+v synchronizes the computer clipboard to the Android device
clipboard. This feature had been added to provide a way to copy UTF-8
text from the computer to the device.

To make such a paste more straightforward, if the device runs at least
Android 7, also send a PASTE keycode to paste immediately.

<https://developer.android.com/reference/android/view/KeyEvent.html#KEYCODE_PASTE>

Fixes #786 <https://github.com/Genymobile/scrcpy/issues/786>

server/src/main/java/com/genymobile/scrcpy/ControlMessage.java

@@ -17,6 +17,8 @@ public final class ControlMessage {
     public static final int TYPE_SET_SCREEN_POWER_MODE = 9;
     public static final int TYPE_ROTATE_DEVICE = 10;
 
+    public static final int FLAGS_PASTE = 1;
+
     private int type;
     private String text;
     private int metaState; // KeyEvent.META_*
@@ -28,6 +30,7 @@ public final class ControlMessage {
     private Position position;
     private int hScroll;
     private int vScroll;
+    private int flags;
 
     private ControlMessage() {
     }
@@ -68,10 +71,13 @@ public final class ControlMessage {
         return msg;
     }
 
-    public static ControlMessage createSetClipboard(String text) {
+    public static ControlMessage createSetClipboard(String text, boolean paste) {
         ControlMessage msg = new ControlMessage();
         msg.type = TYPE_SET_CLIPBOARD;
         msg.text = text;
+        if (paste) {
+            msg.flags = FLAGS_PASTE;
+        }
         return msg;
     }
 
@@ -134,4 +140,8 @@ public final class ControlMessage {
     public int getVScroll() {
         return vScroll;
     }
+
+    public int getFlags() {
+        return flags;
+    }
 }

server/src/main/java/com/genymobile/scrcpy/ControlMessageReader.java

@@ -12,8 +12,9 @@ public class ControlMessageReader {
     static final int INJECT_TOUCH_EVENT_PAYLOAD_LENGTH = 27;
     static final int INJECT_SCROLL_EVENT_PAYLOAD_LENGTH = 20;
     static final int SET_SCREEN_POWER_MODE_PAYLOAD_LENGTH = 1;
+    static final int SET_CLIPBOARD_FIXED_PAYLOAD_LENGTH = 1;
 
-    public static final int CLIPBOARD_TEXT_MAX_LENGTH = 4093;
+    public static final int CLIPBOARD_TEXT_MAX_LENGTH = 4092; // 4096 - 1 (type) - 1 (parse flag) - 2 (length)
     public static final int INJECT_TEXT_MAX_LENGTH = 300;
 
     private static final int RAW_BUFFER_SIZE = 4096;
@@ -148,11 +149,15 @@ public class ControlMessageReader {
     }
 
     private ControlMessage parseSetClipboard() {
+        if (buffer.remaining() < SET_CLIPBOARD_FIXED_PAYLOAD_LENGTH) {
+            return null;
+        }
+        boolean parse = buffer.get() != 0;
         String text = parseString();
         if (text == null) {
             return null;
         }
-        return ControlMessage.createSetClipboard(text);
+        return ControlMessage.createSetClipboard(text, parse);
     }
 
     private ControlMessage parseSetScreenPowerMode() {

server/src/main/java/com/genymobile/scrcpy/Controller.java

@@ -1,5 +1,6 @@
 package com.genymobile.scrcpy;
 
+import android.os.Build;
 import android.os.SystemClock;
 import android.view.InputDevice;
 import android.view.KeyCharacterMap;
@@ -107,10 +108,8 @@ public class Controller {
                 sender.pushClipboardText(clipboardText);
                 break;
             case ControlMessage.TYPE_SET_CLIPBOARD:
-                boolean setClipboardOk = device.setClipboardText(msg.getText());
-                if (setClipboardOk) {
-                    Ln.i("Device clipboard set");
-                }
+                boolean paste = (msg.getFlags() & ControlMessage.FLAGS_PASTE) != 0;
+                setClipboard(msg.getText(), paste);
                 break;
             case ControlMessage.TYPE_SET_SCREEN_POWER_MODE:
                 if (device.supportsInputEvents()) {
@@ -227,4 +226,18 @@ public class Controller {
         int keycode = device.isScreenOn() ? KeyEvent.KEYCODE_BACK : KeyEvent.KEYCODE_POWER;
         return device.injectKeycode(keycode);
     }
+
+    private boolean setClipboard(String text, boolean paste) {
+        boolean ok = device.setClipboardText(text);
+        if (ok) {
+            Ln.i("Device clipboard set");
+        }
+
+        // On Android >= 7, also press the PASTE key if requested
+        if (paste && Build.VERSION.SDK_INT >= Build.VERSION_CODES.N && device.supportsInputEvents()) {
+            device.injectKeycode(KeyEvent.KEYCODE_PASTE);
+        }
+
+        return ok;
+    }
 }

server/src/test/java/com/genymobile/scrcpy/ControlMessageReaderTest.java

@@ -216,6 +216,7 @@ public class ControlMessageReaderTest {
         ByteArrayOutputStream bos = new ByteArrayOutputStream();
         DataOutputStream dos = new DataOutputStream(bos);
         dos.writeByte(ControlMessage.TYPE_SET_CLIPBOARD);
+        dos.writeByte(1); // paste
         byte[] text = "testé".getBytes(StandardCharsets.UTF_8);
         dos.writeShort(text.length);
         dos.write(text);
@@ -227,6 +228,9 @@ public class ControlMessageReaderTest {
 
         Assert.assertEquals(ControlMessage.TYPE_SET_CLIPBOARD, event.getType());
         Assert.assertEquals("testé", event.getText());
+
+        boolean parse = (event.getFlags() & ControlMessage.FLAGS_PASTE) != 0;
+        Assert.assertTrue(parse);
     }
 
     @Test
@@ -238,6 +242,7 @@ public class ControlMessageReaderTest {
         dos.writeByte(ControlMessage.TYPE_SET_CLIPBOARD);
 
         byte[] rawText = new byte[ControlMessageReader.CLIPBOARD_TEXT_MAX_LENGTH];
+        dos.writeByte(1); // paste
         Arrays.fill(rawText, (byte) 'a');
         String text = new String(rawText, 0, rawText.length);
 
@@ -251,6 +256,9 @@ public class ControlMessageReaderTest {
 
         Assert.assertEquals(ControlMessage.TYPE_SET_CLIPBOARD, event.getType());
         Assert.assertEquals(text, event.getText());
+
+        boolean parse = (event.getFlags() & ControlMessage.FLAGS_PASTE) != 0;
+        Assert.assertTrue(parse);
     }
 
     @Test