Big cleanup of Android-specific code:

- moved all logging and debugging functions to android_utils
- splitted a large function in user_callback_android.cpp into three
  functions (that handle fingers, stylus and mouse respectively)

src/lib/geogram/basic/android_utils.cpp

@@ -41,6 +41,7 @@
 
 #include <geogram/basic/android_utils.h>
 #include <geogram/basic/argused.h>
+#include <geogram/basic/string.h>
 #include <android_native_app_glue.h>
 
 namespace {
@@ -411,7 +412,80 @@ namespace GEO {
 	    leave_JNI_function(app, env, thread_attached);
 	    return result;
 	}
-
+    }
+}
+
+/*******************************************************************/
+
+namespace {
+    using namespace GEO;
+
+    static const char* event_type_to_str(int32_t event_type) {
+        switch(event_type) {
+        case AINPUT_EVENT_TYPE_KEY:
+            return "key";
+        case AINPUT_EVENT_TYPE_MOTION:
+            return "motion";
+        default:
+            return "unknown";
+        }
+    }
+
+    static const char* event_action_to_str(int32_t event_action) {
+        switch(event_action) {
+        case AKEY_EVENT_ACTION_DOWN:
+            return "key/motion_down";
+        case AKEY_EVENT_ACTION_UP:
+            return "key/motion_up";
+        case AMOTION_EVENT_ACTION_BUTTON_PRESS:
+            return "motion_button_press";
+        case AMOTION_EVENT_ACTION_BUTTON_RELEASE:
+            return "motion_button_release";
+        case AMOTION_EVENT_ACTION_HOVER_MOVE:
+            return "motion_hover_move";
+        case AMOTION_EVENT_ACTION_MOVE:
+            return "motion_move";
+        case AMOTION_EVENT_ACTION_SCROLL:
+            return "motion_scroll";
+        default:
+            return "unknown";
+        }
+    }
+
+    static const char* event_tool_type_to_str(int32_t event_tool_type) {
+        switch(event_tool_type) {
+        case AMOTION_EVENT_TOOL_TYPE_MOUSE:
+            return "mouse";
+        case AMOTION_EVENT_TOOL_TYPE_STYLUS:
+            return "stylus";
+        case AMOTION_EVENT_TOOL_TYPE_ERASER:
+            return "eraser";
+        case AMOTION_EVENT_TOOL_TYPE_FINGER:
+            return "finger";
+        default:
+            return "unknown";
+        }
+    }
+}
+
+namespace GEO {
+    namespace AndroidUtils {
+
+        void debug_show_event(AInputEvent* event) {
+            std::string msg = std::string("Event=") + " type:"   +
+                std::string(event_type_to_str(AInputEvent_getType(event)));
+
+            if(AInputEvent_getType(event) == AINPUT_EVENT_TYPE_MOTION) {
+                msg += " action:" + std::string(
+                        event_action_to_str(AMotionEvent_getAction(event))
+                    ) + " tool:" + std::string(
+                       event_tool_type_to_str(AMotionEvent_getToolType(event,0))
+                    ) + " nb_pointers:" + ::GEO::String::to_string(
+                        int(AMotionEvent_getPointerCount(event))
+                    ) ;
+            }
+            ::GEO::AndroidUtils::debug_log(msg);
+        }
     }
 }
 

src/lib/geogram/basic/android_utils.h

@@ -42,6 +42,8 @@
 
 #include <geogram/basic/common.h>
 #include <geogram/basic/numeric.h>
+#include <geogram/basic/argused.h>
+#include <android/log.h>
 #include <string>
 
 /**
@@ -50,6 +52,7 @@
  */
 
 struct android_app;
+struct AInputEvent;
 
 namespace GEO {
     namespace AndroidUtils {
@@ -111,9 +114,43 @@ namespace GEO {
 	 *  temporary files.
 	 */
 	std::string GEOGRAM_API temp_folder(android_app* app);
-    }
-}
 
+        /**
+         * \brief Displays a message in the android log in
+         *  Debug mode, ignored in Release mode.
+         * \details The message can be displayed using 
+         *   'adb logcat | grep GEOGRAM'
+         * \param[in] str the message to be displayed
+         */
+        inline void debug_log(const char* str) {
+            geo_argused(str);
+#ifdef GEO_DEBUG
+            __android_log_print(
+                ANDROID_LOG_VERBOSE, "GEOGRAM", "DBG: %s", str
+            );
+#endif
+        }
 
+        /**
+         * \brief Displays a message in the android log in
+         *  Debug mode, ignored in Release mode.
+         * \details The message can be displayed using 
+         *   'adb logcat | grep GEOGRAM'
+         * \param[in] str the message to be displayed
+         */
+        inline void debug_log(const std::string& str) {
+            debug_log(str.c_str());
+        }
 
+        /**
+         * \brief Displays an android event in the android log in
+         *  Debug mode, ignored in release mode.
+         * \details The message can be displayed using 
+         *   'adb logcat | grep GEOGRAM'
+         * \param[in] event the event to be displayed
+         */
+        void GEOGRAM_API debug_show_event(AInputEvent* event);
+
+    }
+}
 #endif

src/lib/geogram_gfx/gui/application.cpp

@@ -85,7 +85,6 @@
 #  include <EGL/eglext.h>
 #  include <GLES/gl.h>
 #  include <android_native_app_glue.h>
-#  include <android/log.h>
 
 #endif
 
@@ -1453,7 +1452,9 @@ namespace GEO {
 
 		// Check if we are exiting.
 		if (data_->app->destroyRequested != 0) {
-                    android_debug_log("Destroy requested, freeing resources");
+                    ::GEO::AndroidUtils::debug_log(
+                        "Destroy requested, freeing resources"
+                    );
 		    ImGui_terminate();
 		    GL_terminate();
 		    return;
@@ -1464,7 +1465,7 @@ namespace GEO {
 		one_frame();
 	    }
 	}
-        android_debug_log("End of main loop");
+        ::GEO::AndroidUtils::debug_log("End of main loop");
     }
 
     namespace {
@@ -1576,7 +1577,7 @@ namespace GEO {
                 "keyboard", "mouse", "finger", "stylus", "unknown"
             };
 
-            android_debug_log(
+            ::GEO::AndroidUtils::debug_log(
                 std::string("mouse CB  ") +
                 " (" + String::to_string(x) + "," + String::to_string(y) + ")" +
                 " btn=" + String::to_string(button) +