irrlicht/examples/01.HelloWorld_Android/android_tools.cpp

// This file is part of the "Irrlicht Engine".
// For conditions of distribution and use, see copyright notice in irrlicht.h

#include "android_tools.h"
#include <android/log.h>	// for the occasional debugging, style: __android_log_print(ANDROID_LOG_VERBOSE, "Irrlicht", "%s\n", "We do log");

namespace irr 
{
namespace android
{

// Not all DisplayMetrics are available through the NDK. 
// So we access the Java classes with the JNI interface.
// You can access other Java classes available in Android in similar ways.
// Function based roughly on the code from here: http://stackoverflow.com/questions/13249164/android-using-jni-from-nativeactivity
bool getDisplayMetrics(android_app* app, SDisplayMetrics & metrics)
{
	if (!app || !app->activity || !app->activity->vm )
		return false;
	
	JNIEnv* jni = 0;
	app->activity->vm->AttachCurrentThread(&jni, NULL);
	if (!jni )
		return false;

	
	// get all the classes we want to access from the JVM
	jclass classNativeActivity = jni->FindClass("android/app/NativeActivity");
	jclass classWindowManager = jni->FindClass("android/view/WindowManager");
	jclass classDisplay = jni->FindClass("android/view/Display");
	jclass classDisplayMetrics = jni->FindClass("android/util/DisplayMetrics");
	
	if (!classNativeActivity || !classWindowManager || !classDisplay || !classDisplayMetrics)
	{
		app->activity->vm->DetachCurrentThread();
		return false;
	}
	
	
	// Get all the methods we want to access from the JVM classes
	// Note: You can get the signatures (third parameter of GetMethodID) for all 
	// functions of a class with the javap tool, like in the following example for class DisplayMetrics:
	// javap -s -classpath myandroidpath/adt-bundle-linux-x86_64-20131030/sdk/platforms/android-10/android.jar android/util/DisplayMetrics
	jmethodID idNativeActivity_getWindowManager = jni->GetMethodID( classNativeActivity
												, "getWindowManager"
												, "()Landroid/view/WindowManager;"); 
	jmethodID idWindowManager_getDefaultDisplay = jni->GetMethodID( classWindowManager
												, "getDefaultDisplay"
												, "()Landroid/view/Display;");
	jmethodID idDisplayMetrics_constructor = jni->GetMethodID( classDisplayMetrics
														, "<init>"
														, "()V");
	jmethodID idDisplay_getMetrics = jni->GetMethodID( classDisplay
										 , "getMetrics"
										 , "(Landroid/util/DisplayMetrics;)V");
	
	if (!idNativeActivity_getWindowManager || !idWindowManager_getDefaultDisplay || !idDisplayMetrics_constructor 
		|| !idDisplay_getMetrics)
	{
		app->activity->vm->DetachCurrentThread();
		return false;
	}
	

	// In Java the following code would be: getWindowManager().getDefaultDisplay().getMetrics(metrics);
	// Note: If you need to call java functions in time-critical places you can split getting the jmethodID's 
	// and calling the functions into separate functions as you only have to get the jmethodID's once.
	jobject windowManager = jni->CallObjectMethod(app->activity->clazz, idNativeActivity_getWindowManager);
	
	if (!windowManager)
	{
		app->activity->vm->DetachCurrentThread();
		return false;
	}
	jobject display = jni->CallObjectMethod(windowManager, idWindowManager_getDefaultDisplay);
	if (!display)
	{
		app->activity->vm->DetachCurrentThread();
		return false;
	}
	jobject displayMetrics = jni->NewObject( classDisplayMetrics, idDisplayMetrics_constructor);
	if (!displayMetrics)
	{
		app->activity->vm->DetachCurrentThread();
		return false;
	}
	jni->CallVoidMethod(display, idDisplay_getMetrics, displayMetrics);
	
	// access the fields of DisplayMetrics (we ignore the DENSITY constants)
	jfieldID idDisplayMetrics_widthPixels = jni->GetFieldID( classDisplayMetrics, "widthPixels", "I");
	jfieldID idDisplayMetrics_heightPixels = jni->GetFieldID( classDisplayMetrics, "heightPixels", "I");
	jfieldID idDisplayMetrics_density = jni->GetFieldID( classDisplayMetrics, "density", "F");
	jfieldID idDisplayMetrics_densityDpi = jni->GetFieldID( classDisplayMetrics, "densityDpi", "I");
	jfieldID idDisplayMetrics_scaledDensity = jni->GetFieldID( classDisplayMetrics, "scaledDensity", "F");
	jfieldID idDisplayMetrics_xdpi = jni->GetFieldID(classDisplayMetrics, "xdpi", "F");
	jfieldID idDisplayMetrics_ydpi = jni->GetFieldID(classDisplayMetrics, "ydpi", "F");
	
	if ( idDisplayMetrics_widthPixels )
		metrics.widthPixels = jni->GetIntField(displayMetrics, idDisplayMetrics_widthPixels);
	if ( idDisplayMetrics_heightPixels )
		metrics.heightPixels = jni->GetIntField(displayMetrics, idDisplayMetrics_heightPixels);
	if (idDisplayMetrics_density )
		metrics.density = jni->GetFloatField(displayMetrics, idDisplayMetrics_density);
	if (idDisplayMetrics_densityDpi)
		metrics.densityDpi = jni->GetIntField(displayMetrics, idDisplayMetrics_densityDpi);
	if (idDisplayMetrics_scaledDensity)
		metrics.scaledDensity = jni->GetFloatField(displayMetrics, idDisplayMetrics_scaledDensity);
	if ( idDisplayMetrics_xdpi )
		metrics.xdpi = jni->GetFloatField(displayMetrics, idDisplayMetrics_xdpi);
	if ( idDisplayMetrics_ydpi )
		metrics.ydpi = jni->GetFloatField(displayMetrics, idDisplayMetrics_ydpi);
	
	app->activity->vm->DetachCurrentThread();
	return true;
}

void setSoftInputVisibility(android_app* app, bool visible)
{
	// NOTE: Unfortunately ANativeActivity_showSoftInput from the NDK does not work and Google does not care.
	// This is based on the solution from @Ratamovic from here: http://stackoverflow.com/questions/5864790/how-to-show-the-soft-keyboard-on-native-activity
	
	if (!app || !app->activity || !app->activity->vm )
		return;
	
	JNIEnv* jni = 0;
	app->activity->vm->AttachCurrentThread(&jni, NULL);
	if (!jni )
		return;
	
	// get all the classes we want to access from the JVM (could be cached)
	jclass classNativeActivity = jni->FindClass("android/app/NativeActivity");
	jclass classInputMethodManager = jni->FindClass("android/view/inputmethod/InputMethodManager");
	jclass classWindow = jni->FindClass("android/view/Window");
	jclass classView = jni->FindClass("android/view/View");
	
	if (classNativeActivity && classInputMethodManager && classWindow)
	{
		// Get all the methods we want to access from the JVM classes (could be cached)
		jmethodID mid_getSystemService = jni->GetMethodID(classNativeActivity, "getSystemService","(Ljava/lang/String;)Ljava/lang/Object;");
		jmethodID mid_showSoftInput = jni->GetMethodID(classInputMethodManager, "showSoftInput", "(Landroid/view/View;I)Z");
		
		jmethodID mid_hideSoftInput = jni->GetMethodID(classInputMethodManager, "hideSoftInputFromWindow", "(Landroid/os/IBinder;I)Z");
		jmethodID mid_getWindow = jni->GetMethodID(classNativeActivity, "getWindow", "()Landroid/view/Window;");
		jmethodID mid_getWindowToken = jni->GetMethodID(classView, "getWindowToken", "()Landroid/os/IBinder;");
		jmethodID mid_getDecorView = jni->GetMethodID(classWindow, "getDecorView", "()Landroid/view/View;");

		if ( mid_getSystemService && mid_showSoftInput && mid_hideSoftInput && mid_getWindow && mid_getDecorView && mid_getWindowToken )
		{
			jstring paramInput = jni->NewStringUTF("input_method"); 
			jobject objInputMethodManager = jni->CallObjectMethod(app->activity->clazz, mid_getSystemService, paramInput); 
			jni->DeleteLocalRef(paramInput); 

			jobject objWindow = jni->CallObjectMethod(app->activity->clazz, mid_getWindow);
			
			if ( visible && objInputMethodManager && objWindow)
			{
				jobject objDecorView = jni->CallObjectMethod(objWindow, mid_getDecorView);				
				if ( objDecorView )
				{
					int showFlags = 0;
					jni->CallBooleanMethod(objInputMethodManager, mid_showSoftInput, objDecorView, showFlags);
				}
			}
			else if ( !visible && objInputMethodManager && objWindow )
			{
				jobject objDecorView = jni->CallObjectMethod(objWindow, mid_getDecorView);				
				if ( objDecorView )
				{
					jobject objBinder = jni->CallObjectMethod(objDecorView, mid_getWindowToken);							
					if ( objBinder )
					{
						int hideFlags = 0;
						jni->CallBooleanMethod(objInputMethodManager, mid_hideSoftInput, objBinder, hideFlags);
					}
				}
			}
		}
	}
	
	app->activity->vm->DetachCurrentThread();	
}

} // namespace android
} // namespace irr