Fix clipboard paste condition

To avoid possible copy-paste loops between the computer and the device,
the device clipboard is not set if it already contains the expected
content.

But the condition was wrong: it was not set also if it was empty.

Refs 1223a72eb8
Fixes #1658 <https://github.com/Genymobile/scrcpy/issues/1658>

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

@@ -55,10 +55,10 @@ public class Controller {
     public void control() throws IOException {
         // on start, power on the device
         if (!device.isScreenOn()) {
-            device.injectKeycode(KeyEvent.KEYCODE_WAKEUP);
+            device.injectKeycode(KeyEvent.KEYCODE_POWER);
 
             // dirty hack
-            // After the keycode is injected, the device is powered on asynchronously.
+            // After POWER is injected, the device is powered on asynchronously.
             // To turn the device screen off while mirroring, the client will send a message that
             // would be handled before the device is actually powered on, so its effect would
             // be "canceled" once the device is turned back on.
@@ -248,8 +248,8 @@ public class Controller {
     }
 
     private boolean pressBackOrTurnScreenOn() {
-        int keycode = device.isScreenOn() ? KeyEvent.KEYCODE_BACK : KeyEvent.KEYCODE_WAKEUP;
+        int keycode = device.isScreenOn() ? KeyEvent.KEYCODE_BACK : KeyEvent.KEYCODE_POWER;
-        if (keepPowerModeOff && keycode == KeyEvent.KEYCODE_WAKEUP) {
+        if (keepPowerModeOff && keycode == KeyEvent.KEYCODE_POWER) {
             schedulePowerModeOff();
         }
         return device.injectKeycode(keycode);

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

@@ -223,7 +223,7 @@ public final class Device {
         }
 
         String currentClipboard = getClipboardText();
-        if (currentClipboard == null || currentClipboard.equals(text)) {
+        if (currentClipboard != null && currentClipboard.equals(text)) {
             // The clipboard already contains the requested text.
             // Since pasting text from the computer involves setting the device clipboard, it could be set twice on a copy-paste. This would cause
             // the clipboard listeners to be notified twice, and that would flood the Android keyboard clipboard history. To workaround this