Fix flickering issues with low processor mode on Android

misc/scripts/clang_format.sh

@@ -19,6 +19,10 @@ while read -r f; do
         continue
     elif [[ "$f" == "platform/android/java/lib/src/org/godotengine/godot/input/InputManager"* ]]; then
         continue
+    elif [[ "$f" == "platform/android/java/lib/src/org/godotengine/godot/gl/GLSurfaceView"* ]]; then
+        continue
+    elif [[ "$f" == "platform/android/java/lib/src/org/godotengine/godot/gl/EGLLogWrapper"* ]]; then
+        continue
     fi
 
     python misc/scripts/copyright_headers.py "$f"

platform/android/java/lib/src/org/godotengine/godot/GodotGLRenderView.java

@@ -29,6 +29,8 @@
 /*************************************************************************/
 
 package org.godotengine.godot;
+import org.godotengine.godot.gl.GLSurfaceView;
+import org.godotengine.godot.gl.GodotRenderer;
 import org.godotengine.godot.input.GodotGestureHandler;
 import org.godotengine.godot.input.GodotInputHandler;
 import org.godotengine.godot.utils.GLUtils;
@@ -43,7 +45,6 @@ import org.godotengine.godot.xr.regular.RegularFallbackConfigChooser;
 import android.annotation.SuppressLint;
 import android.content.Context;
 import android.graphics.PixelFormat;
-import android.opengl.GLSurfaceView;
 import android.os.Build;
 import android.view.GestureDetector;
 import android.view.KeyEvent;

platform/android/java/lib/src/org/godotengine/godot/GodotLib.java

@@ -30,6 +30,8 @@
 
 package org.godotengine.godot;
 
+import org.godotengine.godot.gl.GodotRenderer;
+
 import android.app.Activity;
 import android.hardware.SensorEvent;
 import android.view.Surface;
@@ -68,7 +70,7 @@ public class GodotLib {
 	 * @param p_surface
 	 * @param p_width
 	 * @param p_height
-	 * @see android.opengl.GLSurfaceView.Renderer#onSurfaceChanged(GL10, int, int)
+	 * @see org.godotengine.godot.gl.GLSurfaceView.Renderer#onSurfaceChanged(GL10, int, int)
 	 */
 	public static native void resize(Surface p_surface, int p_width, int p_height);
 
@@ -85,9 +87,9 @@ public class GodotLib {
 
 	/**
 	 * Invoked on the GL thread to draw the current frame.
-	 * @see android.opengl.GLSurfaceView.Renderer#onDrawFrame(GL10)
+	 * @see org.godotengine.godot.gl.GLSurfaceView.Renderer#onDrawFrame(GL10)
 	 */
-	public static native void step();
+	public static native boolean step();
 
 	/**
 	 * Forward touch events from the main thread to the GL thread.

platform/android/java/lib/src/org/godotengine/godot/gl/EGLLogWrapper.java

@@ -0,0 +1,566 @@
+// clang-format off
+
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.godotengine.godot.gl;
+
+import android.opengl.GLDebugHelper;
+import android.opengl.GLException;
+
+import java.io.IOException;
+import java.io.Writer;
+
+import javax.microedition.khronos.egl.EGL;
+import javax.microedition.khronos.egl.EGL10;
+import javax.microedition.khronos.egl.EGL11;
+import javax.microedition.khronos.egl.EGLConfig;
+import javax.microedition.khronos.egl.EGLContext;
+import javax.microedition.khronos.egl.EGLDisplay;
+import javax.microedition.khronos.egl.EGLSurface;
+
+class EGLLogWrapper implements EGL11 {
+	private EGL10 mEgl10;
+	Writer mLog;
+	boolean mLogArgumentNames;
+	boolean mCheckError;
+	private int mArgCount;
+
+
+	public EGLLogWrapper(EGL egl, int configFlags, Writer log) {
+		mEgl10 = (EGL10) egl;
+		mLog = log;
+		mLogArgumentNames =
+				(GLDebugHelper.CONFIG_LOG_ARGUMENT_NAMES & configFlags) != 0;
+		mCheckError =
+				(GLDebugHelper.CONFIG_CHECK_GL_ERROR & configFlags) != 0;
+	}
+
+	public boolean eglChooseConfig(EGLDisplay display, int[] attrib_list,
+								   EGLConfig[] configs, int config_size, int[] num_config) {
+		begin("eglChooseConfig");
+		arg("display", display);
+		arg("attrib_list", attrib_list);
+		arg("config_size", config_size);
+		end();
+
+		boolean result = mEgl10.eglChooseConfig(display, attrib_list, configs,
+				config_size, num_config);
+		arg("configs", configs);
+		arg("num_config", num_config);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglCopyBuffers(EGLDisplay display, EGLSurface surface,
+								  Object native_pixmap) {
+		begin("eglCopyBuffers");
+		arg("display", display);
+		arg("surface", surface);
+		arg("native_pixmap", native_pixmap);
+		end();
+
+		boolean result = mEgl10.eglCopyBuffers(display, surface, native_pixmap);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public EGLContext eglCreateContext(EGLDisplay display, EGLConfig config,
+									   EGLContext share_context, int[] attrib_list) {
+		begin("eglCreateContext");
+		arg("display", display);
+		arg("config", config);
+		arg("share_context", share_context);
+		arg("attrib_list", attrib_list);
+		end();
+
+		EGLContext result = mEgl10.eglCreateContext(display, config,
+				share_context, attrib_list);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public EGLSurface eglCreatePbufferSurface(EGLDisplay display,
+											  EGLConfig config, int[] attrib_list) {
+		begin("eglCreatePbufferSurface");
+		arg("display", display);
+		arg("config", config);
+		arg("attrib_list", attrib_list);
+		end();
+
+		EGLSurface result = mEgl10.eglCreatePbufferSurface(display, config,
+				attrib_list);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public EGLSurface eglCreatePixmapSurface(EGLDisplay display,
+											 EGLConfig config, Object native_pixmap, int[] attrib_list) {
+		begin("eglCreatePixmapSurface");
+		arg("display", display);
+		arg("config", config);
+		arg("native_pixmap", native_pixmap);
+		arg("attrib_list", attrib_list);
+		end();
+
+		EGLSurface result = mEgl10.eglCreatePixmapSurface(display, config,
+				native_pixmap, attrib_list);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public EGLSurface eglCreateWindowSurface(EGLDisplay display,
+											 EGLConfig config, Object native_window, int[] attrib_list) {
+		begin("eglCreateWindowSurface");
+		arg("display", display);
+		arg("config", config);
+		arg("native_window", native_window);
+		arg("attrib_list", attrib_list);
+		end();
+
+		EGLSurface result = mEgl10.eglCreateWindowSurface(display, config,
+				native_window, attrib_list);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglDestroyContext(EGLDisplay display, EGLContext context) {
+		begin("eglDestroyContext");
+		arg("display", display);
+		arg("context", context);
+		end();
+
+		boolean result = mEgl10.eglDestroyContext(display, context);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglDestroySurface(EGLDisplay display, EGLSurface surface) {
+		begin("eglDestroySurface");
+		arg("display", display);
+		arg("surface", surface);
+		end();
+
+		boolean result = mEgl10.eglDestroySurface(display, surface);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglGetConfigAttrib(EGLDisplay display, EGLConfig config,
+									  int attribute, int[] value) {
+		begin("eglGetConfigAttrib");
+		arg("display", display);
+		arg("config", config);
+		arg("attribute", attribute);
+		end();
+		boolean result = mEgl10.eglGetConfigAttrib(display, config, attribute,
+				value);
+		arg("value", value);
+		returns(result);
+		checkError();
+		return false;
+	}
+
+	public boolean eglGetConfigs(EGLDisplay display, EGLConfig[] configs,
+								 int config_size, int[] num_config) {
+		begin("eglGetConfigs");
+		arg("display", display);
+		arg("config_size", config_size);
+		end();
+
+		boolean result = mEgl10.eglGetConfigs(display, configs, config_size,
+				num_config);
+		arg("configs", configs);
+		arg("num_config", num_config);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public EGLContext eglGetCurrentContext() {
+		begin("eglGetCurrentContext");
+		end();
+
+		EGLContext result = mEgl10.eglGetCurrentContext();
+		returns(result);
+
+		checkError();
+		return result;
+	}
+
+	public EGLDisplay eglGetCurrentDisplay() {
+		begin("eglGetCurrentDisplay");
+		end();
+
+		EGLDisplay result = mEgl10.eglGetCurrentDisplay();
+		returns(result);
+
+		checkError();
+		return result;
+	}
+
+	public EGLSurface eglGetCurrentSurface(int readdraw) {
+		begin("eglGetCurrentSurface");
+		arg("readdraw", readdraw);
+		end();
+
+		EGLSurface result = mEgl10.eglGetCurrentSurface(readdraw);
+		returns(result);
+
+		checkError();
+		return result;
+	}
+
+	public EGLDisplay eglGetDisplay(Object native_display) {
+		begin("eglGetDisplay");
+		arg("native_display", native_display);
+		end();
+
+		EGLDisplay result = mEgl10.eglGetDisplay(native_display);
+		returns(result);
+
+		checkError();
+		return result;
+	}
+
+	public int eglGetError() {
+		begin("eglGetError");
+		end();
+
+		int result = mEgl10.eglGetError();
+		returns(getErrorString(result));
+
+		return result;
+	}
+
+	public boolean eglInitialize(EGLDisplay display, int[] major_minor) {
+		begin("eglInitialize");
+		arg("display", display);
+		end();
+		boolean result = mEgl10.eglInitialize(display, major_minor);
+		returns(result);
+		arg("major_minor", major_minor);
+		checkError();
+		return result;
+	}
+
+	public boolean eglMakeCurrent(EGLDisplay display, EGLSurface draw,
+								  EGLSurface read, EGLContext context) {
+		begin("eglMakeCurrent");
+		arg("display", display);
+		arg("draw", draw);
+		arg("read", read);
+		arg("context", context);
+		end();
+		boolean result = mEgl10.eglMakeCurrent(display, draw, read, context);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglQueryContext(EGLDisplay display, EGLContext context,
+								   int attribute, int[] value) {
+		begin("eglQueryContext");
+		arg("display", display);
+		arg("context", context);
+		arg("attribute", attribute);
+		end();
+		boolean result = mEgl10.eglQueryContext(display, context, attribute,
+				value);
+		returns(value[0]);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public String eglQueryString(EGLDisplay display, int name) {
+		begin("eglQueryString");
+		arg("display", display);
+		arg("name", name);
+		end();
+		String result = mEgl10.eglQueryString(display, name);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglQuerySurface(EGLDisplay display, EGLSurface surface,
+								   int attribute, int[] value) {
+		begin("eglQuerySurface");
+		arg("display", display);
+		arg("surface", surface);
+		arg("attribute", attribute);
+		end();
+		boolean result = mEgl10.eglQuerySurface(display, surface, attribute,
+				value);
+		returns(value[0]);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglSwapBuffers(EGLDisplay display, EGLSurface surface) {
+		begin("eglSwapBuffers");
+		arg("display", display);
+		arg("surface", surface);
+		end();
+		boolean result = mEgl10.eglSwapBuffers(display, surface);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglTerminate(EGLDisplay display) {
+		begin("eglTerminate");
+		arg("display", display);
+		end();
+		boolean result = mEgl10.eglTerminate(display);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglWaitGL() {
+		begin("eglWaitGL");
+		end();
+		boolean result = mEgl10.eglWaitGL();
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	public boolean eglWaitNative(int engine, Object bindTarget) {
+		begin("eglWaitNative");
+		arg("engine", engine);
+		arg("bindTarget", bindTarget);
+		end();
+		boolean result = mEgl10.eglWaitNative(engine, bindTarget);
+		returns(result);
+		checkError();
+		return result;
+	}
+
+	private void checkError() {
+		int eglError;
+		if ((eglError = mEgl10.eglGetError()) != EGL_SUCCESS) {
+			String errorMessage = "eglError: " + getErrorString(eglError);
+			logLine(errorMessage);
+			if (mCheckError) {
+				throw new GLException(eglError, errorMessage);
+			}
+		}
+	}
+
+	private void logLine(String message) {
+		log(message + '\n');
+	}
+
+	private void log(String message) {
+		try {
+			mLog.write(message);
+		} catch (IOException e) {
+			// Ignore exception, keep on trying
+		}
+	}
+
+	private void begin(String name) {
+		log(name + '(');
+		mArgCount = 0;
+	}
+
+	private void arg(String name, String value) {
+		if (mArgCount++ > 0) {
+			log(", ");
+		}
+		if (mLogArgumentNames) {
+			log(name + "=");
+		}
+		log(value);
+	}
+
+	private void end() {
+		log(");\n");
+		flush();
+	}
+
+	private void flush() {
+		try {
+			mLog.flush();
+		} catch (IOException e) {
+			mLog = null;
+		}
+	}
+
+	private void arg(String name, int value) {
+		arg(name, Integer.toString(value));
+	}
+
+	private void arg(String name, Object object) {
+		arg(name, toString(object));
+	}
+
+	private void arg(String name, EGLDisplay object) {
+		if (object == EGL10.EGL_DEFAULT_DISPLAY) {
+			arg(name, "EGL10.EGL_DEFAULT_DISPLAY");
+		} else if (object == EGL_NO_DISPLAY) {
+			arg(name, "EGL10.EGL_NO_DISPLAY");
+		} else {
+			arg(name, toString(object));
+		}
+	}
+
+	private void arg(String name, EGLContext object) {
+		if (object == EGL10.EGL_NO_CONTEXT) {
+			arg(name, "EGL10.EGL_NO_CONTEXT");
+		} else {
+			arg(name, toString(object));
+		}
+	}
+
+	private void arg(String name, EGLSurface object) {
+		if (object == EGL10.EGL_NO_SURFACE) {
+			arg(name, "EGL10.EGL_NO_SURFACE");
+		} else {
+			arg(name, toString(object));
+		}
+	}
+
+	private void returns(String result) {
+		log(" returns " + result + ";\n");
+		flush();
+	}
+
+	private void returns(int result) {
+		returns(Integer.toString(result));
+	}
+
+	private void returns(boolean result) {
+		returns(Boolean.toString(result));
+	}
+
+	private void returns(Object result) {
+		returns(toString(result));
+	}
+
+	private String toString(Object obj) {
+		if (obj == null) {
+			return "null";
+		} else {
+			return obj.toString();
+		}
+	}
+
+	private void arg(String name, int[] arr) {
+		if (arr == null) {
+			arg(name, "null");
+		} else {
+			arg(name, toString(arr.length, arr, 0));
+		}
+	}
+
+	private void arg(String name, Object[] arr) {
+		if (arr == null) {
+			arg(name, "null");
+		} else {
+			arg(name, toString(arr.length, arr, 0));
+		}
+	}
+
+	private String toString(int n, int[] arr, int offset) {
+		StringBuilder buf = new StringBuilder();
+		buf.append("{\n");
+		int arrLen = arr.length;
+		for (int i = 0; i < n; i++) {
+			int index = offset + i;
+			buf.append(" [" + index + "] = ");
+			if (index < 0 || index >= arrLen) {
+				buf.append("out of bounds");
+			} else {
+				buf.append(arr[index]);
+			}
+			buf.append('\n');
+		}
+		buf.append("}");
+		return buf.toString();
+	}
+
+	private String toString(int n, Object[] arr, int offset) {
+		StringBuilder buf = new StringBuilder();
+		buf.append("{\n");
+		int arrLen = arr.length;
+		for (int i = 0; i < n; i++) {
+			int index = offset + i;
+			buf.append(" [" + index + "] = ");
+			if (index < 0 || index >= arrLen) {
+				buf.append("out of bounds");
+			} else {
+				buf.append(arr[index]);
+			}
+			buf.append('\n');
+		}
+		buf.append("}");
+		return buf.toString();
+	}
+
+	private static String getHex(int value) {
+		return "0x" + Integer.toHexString(value);
+	}
+
+	public static String getErrorString(int error) {
+		switch (error) {
+			case EGL_SUCCESS:
+				return "EGL_SUCCESS";
+			case EGL_NOT_INITIALIZED:
+				return "EGL_NOT_INITIALIZED";
+			case EGL_BAD_ACCESS:
+				return "EGL_BAD_ACCESS";
+			case EGL_BAD_ALLOC:
+				return "EGL_BAD_ALLOC";
+			case EGL_BAD_ATTRIBUTE:
+				return "EGL_BAD_ATTRIBUTE";
+			case EGL_BAD_CONFIG:
+				return "EGL_BAD_CONFIG";
+			case EGL_BAD_CONTEXT:
+				return "EGL_BAD_CONTEXT";
+			case EGL_BAD_CURRENT_SURFACE:
+				return "EGL_BAD_CURRENT_SURFACE";
+			case EGL_BAD_DISPLAY:
+				return "EGL_BAD_DISPLAY";
+			case EGL_BAD_MATCH:
+				return "EGL_BAD_MATCH";
+			case EGL_BAD_NATIVE_PIXMAP:
+				return "EGL_BAD_NATIVE_PIXMAP";
+			case EGL_BAD_NATIVE_WINDOW:
+				return "EGL_BAD_NATIVE_WINDOW";
+			case EGL_BAD_PARAMETER:
+				return "EGL_BAD_PARAMETER";
+			case EGL_BAD_SURFACE:
+				return "EGL_BAD_SURFACE";
+			case EGL11.EGL_CONTEXT_LOST:
+				return "EGL_CONTEXT_LOST";
+			default:
+				return getHex(error);
+		}
+	}
+}

platform/android/java/lib/src/org/godotengine/godot/gl/GodotRenderer.java

@@ -28,38 +28,38 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
 
-package org.godotengine.godot;
+package org.godotengine.godot.gl;
 
+import org.godotengine.godot.GodotLib;
 import org.godotengine.godot.plugin.GodotPlugin;
 import org.godotengine.godot.plugin.GodotPluginRegistry;
-import org.godotengine.godot.utils.GLUtils;
-
-import android.opengl.GLSurfaceView;
 
 import javax.microedition.khronos.egl.EGLConfig;
 import javax.microedition.khronos.opengles.GL10;
 
 /**
- * Godot's renderer implementation.
+ * Godot's GL renderer implementation.
  */
-class GodotRenderer implements GLSurfaceView.Renderer {
+public class GodotRenderer implements GLSurfaceView.Renderer {
 	private final GodotPluginRegistry pluginRegistry;
 	private boolean activityJustResumed = false;
 
-	GodotRenderer() {
+	public GodotRenderer() {
 		this.pluginRegistry = GodotPluginRegistry.getPluginRegistry();
 	}
 
-	public void onDrawFrame(GL10 gl) {
+	public boolean onDrawFrame(GL10 gl) {
 		if (activityJustResumed) {
 			GodotLib.onRendererResumed();
 			activityJustResumed = false;
 		}
 
-		GodotLib.step();
+		boolean swapBuffers = GodotLib.step();
 		for (GodotPlugin plugin : pluginRegistry.getAllPlugins()) {
 			plugin.onGLDrawFrame(gl);
 		}
+
+		return swapBuffers;
 	}
 
 	public void onSurfaceChanged(GL10 gl, int width, int height) {
@@ -76,13 +76,13 @@ class GodotRenderer implements GLSurfaceView.Renderer {
 		}
 	}
 
-	void onActivityResumed() {
+	public void onActivityResumed() {
 		// We defer invoking GodotLib.onRendererResumed() until the first draw frame call.
 		// This ensures we have a valid GL context and surface when we do so.
 		activityJustResumed = true;
 	}
 
-	void onActivityPaused() {
+	public void onActivityPaused() {
 		GodotLib.onRendererPaused();
 	}
 }

platform/android/java/lib/src/org/godotengine/godot/xr/ovr/OvrConfigChooser.java

@@ -30,8 +30,9 @@
 
 package org.godotengine.godot.xr.ovr;
 
+import org.godotengine.godot.gl.GLSurfaceView;
+
 import android.opengl.EGLExt;
-import android.opengl.GLSurfaceView;
 
 import javax.microedition.khronos.egl.EGL10;
 import javax.microedition.khronos.egl.EGLConfig;

platform/android/java/lib/src/org/godotengine/godot/xr/ovr/OvrContextFactory.java

@@ -30,8 +30,9 @@
 
 package org.godotengine.godot.xr.ovr;
 
+import org.godotengine.godot.gl.GLSurfaceView;
+
 import android.opengl.EGL14;
-import android.opengl.GLSurfaceView;
 
 import javax.microedition.khronos.egl.EGL10;
 import javax.microedition.khronos.egl.EGLConfig;

platform/android/java/lib/src/org/godotengine/godot/xr/ovr/OvrWindowSurfaceFactory.java

@@ -30,7 +30,7 @@
 
 package org.godotengine.godot.xr.ovr;
 
-import android.opengl.GLSurfaceView;
+import org.godotengine.godot.gl.GLSurfaceView;
 
 import javax.microedition.khronos.egl.EGL10;
 import javax.microedition.khronos.egl.EGLConfig;

platform/android/java/lib/src/org/godotengine/godot/xr/regular/RegularConfigChooser.java

@@ -30,10 +30,9 @@
 
 package org.godotengine.godot.xr.regular;
 
+import org.godotengine.godot.gl.GLSurfaceView;
 import org.godotengine.godot.utils.GLUtils;
 
-import android.opengl.GLSurfaceView;
-
 import javax.microedition.khronos.egl.EGL10;
 import javax.microedition.khronos.egl.EGLConfig;
 import javax.microedition.khronos.egl.EGLDisplay;

platform/android/java/lib/src/org/godotengine/godot/xr/regular/RegularContextFactory.java

@@ -30,9 +30,9 @@
 
 package org.godotengine.godot.xr.regular;
 
+import org.godotengine.godot.gl.GLSurfaceView;
 import org.godotengine.godot.utils.GLUtils;
 
-import android.opengl.GLSurfaceView;
 import android.util.Log;
 
 import javax.microedition.khronos.egl.EGL10;

platform/android/java/lib/src/org/godotengine/godot/xr/regular/RegularFallbackConfigChooser.java

@@ -30,8 +30,6 @@
 
 package org.godotengine.godot.xr.regular;
 
-import org.godotengine.godot.utils.GLUtils;
-
 import android.util.Log;
 
 import javax.microedition.khronos.egl.EGL10;

platform/android/java/nativeSrcsConfigs/CMakeLists.txt

@@ -17,4 +17,4 @@ target_include_directories(${PROJECT_NAME}
         SYSTEM PUBLIC
         ${GODOT_ROOT_DIR})
 
-add_definitions(-DUNIX_ENABLED -DVULKAN_ENABLED -DTOOLS_ENABLED)
+add_definitions(-DUNIX_ENABLED -DVULKAN_ENABLED -DANDROID_ENABLED)

platform/android/java_godot_lib_jni.cpp

@@ -213,9 +213,9 @@ JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_back(JNIEnv *env, jcl
 	}
 }
 
-JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_step(JNIEnv *env, jclass clazz) {
+JNIEXPORT jboolean JNICALL Java_org_godotengine_godot_GodotLib_step(JNIEnv *env, jclass clazz) {
 	if (step.get() == -1) {
-		return;
+		return true;
 	}
 
 	if (step.get() == 0) {
@@ -224,12 +224,12 @@ JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_step(JNIEnv *env, jcl
 		Main::setup2(Thread::get_caller_id());
 		input_handler = new AndroidInputHandler();
 		step.increment();
-		return;
+		return true;
 	}
 
 	if (step.get() == 1) {
 		if (!Main::start()) {
-			return; // should exit instead and print the error
+			return true; // should exit instead and print the error
 		}
 
 		godot_java->on_godot_setup_completed(env);
@@ -243,9 +243,12 @@ JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_step(JNIEnv *env, jcl
 	DisplayServerAndroid::get_singleton()->process_magnetometer(magnetometer);
 	DisplayServerAndroid::get_singleton()->process_gyroscope(gyroscope);
 
-	if (os_android->main_loop_iterate()) {
+	bool should_swap_buffers = false;
+	if (os_android->main_loop_iterate(&should_swap_buffers)) {
 		godot_java->force_quit(env);
 	}
+
+	return should_swap_buffers;
 }
 
 void touch_preprocessing(JNIEnv *env, jclass clazz, jint input_device, jint ev, jint pointer, jint pointer_count, jfloatArray positions, jint buttons_mask, jfloat vertical_factor, jfloat horizontal_factor) {

platform/android/java_godot_lib_jni.h

@@ -42,7 +42,7 @@ JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_ondestroy(JNIEnv *env
 JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_setup(JNIEnv *env, jclass clazz, jobjectArray p_cmdline);
 JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_resize(JNIEnv *env, jclass clazz, jobject p_surface, jint p_width, jint p_height);
 JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_newcontext(JNIEnv *env, jclass clazz, jobject p_surface);
-JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_step(JNIEnv *env, jclass clazz);
+JNIEXPORT jboolean JNICALL Java_org_godotengine_godot_GodotLib_step(JNIEnv *env, jclass clazz);
 JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_back(JNIEnv *env, jclass clazz);
 void touch_preprocessing(JNIEnv *env, jclass clazz, jint input_device, jint ev, jint pointer, jint pointer_count, jfloatArray positions, jint buttons_mask = 0, jfloat vertical_factor = 0, jfloat horizontal_factor = 0);
 JNIEXPORT void JNICALL Java_org_godotengine_godot_GodotLib_touch__IIII_3F(JNIEnv *env, jclass clazz, jint input_device, jint ev, jint pointer, jint pointer_count, jfloatArray positions);

platform/android/os_android.cpp

@@ -36,6 +36,7 @@
 #include "main/main.h"
 #include "platform/android/display_server_android.h"
 #include "scene/main/scene_tree.h"
+#include "servers/rendering_server.h"
 
 #include "dir_access_jandroid.h"
 #include "file_access_android.h"
@@ -181,12 +182,18 @@ void OS_Android::main_loop_begin() {
 	}
 }
 
-bool OS_Android::main_loop_iterate() {
+bool OS_Android::main_loop_iterate(bool *r_should_swap_buffers) {
 	if (!main_loop) {
 		return false;
 	}
 	DisplayServerAndroid::get_singleton()->process_events();
-	return Main::iteration();
+	bool exit = Main::iteration();
+
+	if (r_should_swap_buffers) {
+		*r_should_swap_buffers = !is_in_low_processor_usage_mode() || RenderingServer::get_singleton()->has_changed();
+	}
+
+	return exit;
 }
 
 void OS_Android::main_loop_end() {

platform/android/os_android.h

@@ -96,7 +96,7 @@ public:
 	virtual MainLoop *get_main_loop() const override;
 
 	void main_loop_begin();
-	bool main_loop_iterate();
+	bool main_loop_iterate(bool *r_should_swap_buffers = nullptr);
 	void main_loop_end();
 	void main_loop_focusout();
 	void main_loop_focusin();