Convert server to an Android project

To simplify the device server-side build, use gradle to create an APK,
even if we use it as a simple jar, by running its main() method.

server/src/main/AndroidManifest.xml

@@ -0,0 +1,2 @@
+<!-- not a real Android application, it is run by app_process manually -->
+<manifest package="com.genymobile.scrcpy"/>

server/src/main/aidl/android/view/IRotationWatcher.aidl

@@ -20,6 +20,6 @@ package android.view;
 /**
  * {@hide}
  */
-oneway interface IRotationWatcher {
-    void onRotationChanged(int rotation);
+interface IRotationWatcher {
+    oneway void onRotationChanged(int rotation);
 }

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

@@ -40,6 +40,12 @@ public final class Device {
     }
 
     private ScreenInfo computeScreenInfo(int maximumSize) {
+        // Compute the video size and the padding of the content inside this video.
+        // Principle:
+        // - scale down the great side of the screen to maximumSize (if necessary);
+        // - scale down the other side so that the aspect ratio is preserved;
+        // - ceil this value to the next multiple of 8 (H.264 only accepts multiples of 8)
+        // - this may introduce black bands, so store the padding (typically a few pixels)
         DisplayInfo displayInfo = serviceManager.getDisplayManager().getDisplayInfo();
         boolean rotated = (displayInfo.getRotation() & 1) != 0;
         Size deviceSize = displayInfo.getSize();

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

@@ -53,9 +53,7 @@ public class ScreenStreamerSession {
         List<String> command = new ArrayList<>();
         command.add("screenrecord");
         command.add("--output-format=h264");
-        if (videoSize != null) {
-            command.add("--size=" + videoSize.getWidth() + "x" + videoSize.getHeight());
-        }
+        command.add("--size=" + videoSize.getWidth() + "x" + videoSize.getHeight());
         command.add("-");
         Process process = new ProcessBuilder(command).start();
         process.getOutputStream().close();

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

@@ -0,0 +1,151 @@
+package com.genymobile.scrcpy;
+
+import android.view.KeyEvent;
+import android.view.MotionEvent;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+
+public class ControlEventReaderTest {
+
+    @Test
+    public void testParseKeycodeEvent() throws IOException {
+        ControlEventReader reader = new ControlEventReader();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+        dos.writeByte(ControlEvent.TYPE_KEYCODE);
+        dos.writeByte(KeyEvent.ACTION_UP);
+        dos.writeInt(KeyEvent.KEYCODE_ENTER);
+        dos.writeInt(KeyEvent.META_CTRL_ON);
+        byte[] packet = bos.toByteArray();
+
+        reader.readFrom(new ByteArrayInputStream(packet));
+        ControlEvent event = reader.next();
+
+        Assert.assertEquals(ControlEvent.TYPE_KEYCODE, event.getType());
+        Assert.assertEquals(KeyEvent.ACTION_UP, event.getAction());
+        Assert.assertEquals(KeyEvent.KEYCODE_ENTER, event.getKeycode());
+        Assert.assertEquals(KeyEvent.META_CTRL_ON, event.getMetaState());
+    }
+
+    @Test
+    public void testParseTextEvent() throws IOException {
+        ControlEventReader reader = new ControlEventReader();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+        dos.writeByte(ControlEvent.TYPE_TEXT);
+        byte[] text = "testé".getBytes(StandardCharsets.UTF_8);
+        dos.writeByte(text.length);
+        dos.write("testé".getBytes(StandardCharsets.UTF_8));
+        byte[] packet = bos.toByteArray();
+
+        reader.readFrom(new ByteArrayInputStream(packet));
+        ControlEvent event = reader.next();
+
+        Assert.assertEquals(ControlEvent.TYPE_TEXT, event.getType());
+        Assert.assertEquals("testé", event.getText());
+    }
+
+    @Test
+    public void testParseMouseEvent() throws IOException {
+        ControlEventReader reader = new ControlEventReader();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+        dos.writeByte(ControlEvent.TYPE_KEYCODE);
+        dos.writeByte(MotionEvent.ACTION_DOWN);
+        dos.writeInt(MotionEvent.BUTTON_PRIMARY);
+        dos.writeInt(KeyEvent.META_CTRL_ON);
+        byte[] packet = bos.toByteArray();
+
+        reader.readFrom(new ByteArrayInputStream(packet));
+        ControlEvent event = reader.next();
+
+        Assert.assertEquals(ControlEvent.TYPE_KEYCODE, event.getType());
+        Assert.assertEquals(MotionEvent.ACTION_DOWN, event.getAction());
+        Assert.assertEquals(MotionEvent.BUTTON_PRIMARY, event.getKeycode());
+        Assert.assertEquals(KeyEvent.META_CTRL_ON, event.getMetaState());
+    }
+
+    @Test
+    public void testMultiEvents() throws IOException {
+        ControlEventReader reader = new ControlEventReader();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+
+        dos.writeByte(ControlEvent.TYPE_KEYCODE);
+        dos.writeByte(KeyEvent.ACTION_UP);
+        dos.writeInt(KeyEvent.KEYCODE_ENTER);
+        dos.writeInt(KeyEvent.META_CTRL_ON);
+
+        dos.writeByte(ControlEvent.TYPE_KEYCODE);
+        dos.writeByte(MotionEvent.ACTION_DOWN);
+        dos.writeInt(MotionEvent.BUTTON_PRIMARY);
+        dos.writeInt(KeyEvent.META_CTRL_ON);
+
+        byte[] packet = bos.toByteArray();
+        reader.readFrom(new ByteArrayInputStream(packet));
+
+        ControlEvent event = reader.next();
+        Assert.assertEquals(ControlEvent.TYPE_KEYCODE, event.getType());
+        Assert.assertEquals(KeyEvent.ACTION_UP, event.getAction());
+        Assert.assertEquals(KeyEvent.KEYCODE_ENTER, event.getKeycode());
+        Assert.assertEquals(KeyEvent.META_CTRL_ON, event.getMetaState());
+
+        event = reader.next();
+        Assert.assertEquals(ControlEvent.TYPE_KEYCODE, event.getType());
+        Assert.assertEquals(MotionEvent.ACTION_DOWN, event.getAction());
+        Assert.assertEquals(MotionEvent.BUTTON_PRIMARY, event.getKeycode());
+        Assert.assertEquals(KeyEvent.META_CTRL_ON, event.getMetaState());
+    }
+
+    @Test
+    public void testPartialEvents() throws IOException {
+        ControlEventReader reader = new ControlEventReader();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+
+        dos.writeByte(ControlEvent.TYPE_KEYCODE);
+        dos.writeByte(KeyEvent.ACTION_UP);
+        dos.writeInt(KeyEvent.KEYCODE_ENTER);
+        dos.writeInt(KeyEvent.META_CTRL_ON);
+
+        dos.writeByte(ControlEvent.TYPE_KEYCODE);
+        dos.writeByte(MotionEvent.ACTION_DOWN);
+
+        byte[] packet = bos.toByteArray();
+        reader.readFrom(new ByteArrayInputStream(packet));
+
+        ControlEvent event = reader.next();
+        Assert.assertEquals(ControlEvent.TYPE_KEYCODE, event.getType());
+        Assert.assertEquals(KeyEvent.ACTION_UP, event.getAction());
+        Assert.assertEquals(KeyEvent.KEYCODE_ENTER, event.getKeycode());
+        Assert.assertEquals(KeyEvent.META_CTRL_ON, event.getMetaState());
+
+        event = reader.next();
+        Assert.assertNull(event); // the event is not complete
+
+        bos.reset();
+        dos.writeInt(MotionEvent.BUTTON_PRIMARY);
+        dos.writeInt(KeyEvent.META_CTRL_ON);
+        packet = bos.toByteArray();
+        reader.readFrom(new ByteArrayInputStream(packet));
+
+        // the event is now complete
+        event = reader.next();
+        Assert.assertEquals(ControlEvent.TYPE_KEYCODE, event.getType());
+        Assert.assertEquals(MotionEvent.ACTION_DOWN, event.getAction());
+        Assert.assertEquals(MotionEvent.BUTTON_PRIMARY, event.getKeycode());
+        Assert.assertEquals(KeyEvent.META_CTRL_ON, event.getMetaState());
+    }
+}