hku.fyp14017.blencode.ui.fragment.FormulaEditorFragment.java Source code

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Here is the source code for hku.fyp14017.blencode.ui.fragment.FormulaEditorFragment.java

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/*
 * Catroid: An on-device visual programming system for Android devices
 * Copyright (C) 2010-2014 The Catrobat Team
 * (<http://developer.fyp14017.hku/credits>)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * An additional term exception under section 7 of the GNU Affero
 * General Public License, version 3, is available at
 * http://developer.fyp14017.hku/license_additional_term
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.hku/licenses/>.
 */
package hku.fyp14017.blencode.ui.fragment;

import android.app.AlertDialog;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.Intent;
import android.content.IntentFilter;
import android.graphics.Rect;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnKeyListener;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.Toast;

import com.actionbarsherlock.app.ActionBar;
import com.actionbarsherlock.app.SherlockFragment;
import com.actionbarsherlock.app.SherlockFragmentActivity;
import com.actionbarsherlock.view.Menu;

import hku.fyp14017.blencode.ProjectManager;
import hku.fyp14017.blencode.R;
import hku.fyp14017.blencode.content.bricks.Brick;
import hku.fyp14017.blencode.formulaeditor.Formula;
import hku.fyp14017.blencode.formulaeditor.FormulaEditorEditText;
import hku.fyp14017.blencode.formulaeditor.FormulaElement;
import hku.fyp14017.blencode.formulaeditor.InternFormulaParser;
import hku.fyp14017.blencode.ui.BottomBar;
import hku.fyp14017.blencode.ui.ScriptActivity;
import hku.fyp14017.blencode.ui.dialogs.CustomAlertDialogBuilder;
import hku.fyp14017.blencode.ui.dialogs.FormulaEditorComputeDialog;
import hku.fyp14017.blencode.ui.dialogs.NewStringDialog;
import hku.fyp14017.blencode.ProjectManager;
import hku.fyp14017.blencode.content.bricks.Brick;
import hku.fyp14017.blencode.formulaeditor.Formula;
import hku.fyp14017.blencode.formulaeditor.FormulaEditorEditText;
import hku.fyp14017.blencode.ui.BottomBar;
import hku.fyp14017.blencode.ui.ScriptActivity;
import hku.fyp14017.blencode.ui.dialogs.CustomAlertDialogBuilder;
import hku.fyp14017.blencode.ui.dialogs.FormulaEditorComputeDialog;
import hku.fyp14017.blencode.ui.dialogs.NewStringDialog;

public class FormulaEditorFragment extends SherlockFragment
        implements OnKeyListener, ViewTreeObserver.OnGlobalLayoutListener {

    private static final int PARSER_OK = -1;
    private static final int PARSER_STACK_OVERFLOW = -2;
    private static final int PARSER_INPUT_SYNTAX_ERROR = -3;

    private static final int SET_FORMULA_ON_CREATE_VIEW = 0;
    private static final int SET_FORMULA_ON_SWITCH_EDIT_TEXT = 1;
    private static final int TIME_WINDOW = 2000;

    public static final String FORMULA_EDITOR_FRAGMENT_TAG = "formula_editor_fragment";
    public static final String BRICK_BUNDLE_ARGUMENT = "brick";
    public static final String FORMULA_BUNDLE_ARGUMENT = "formula";

    private Context context;
    private Brick currentBrick;
    private Formula currentFormula;
    private FormulaEditorEditText formulaEditorEditText;
    private LinearLayout formulaEditorKeyboard;
    private ImageButton formularEditorFieldDeleteButton;
    private LinearLayout formulaEditorBrick;
    private Toast toast;
    private View brickView;
    private long[] confirmSwitchEditTextTimeStamp = { 0, 0 };
    private int confirmSwitchEditTextCounter = 0;
    private CharSequence previousActionBarTitle;
    private View fragmentView;
    private VariableDeletedReceiver variableDeletedReceiver;

    public FormulaEditorFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setHasOptionsMenu(true);
        setUpActionBar();
        currentBrick = (Brick) getArguments().getSerializable(BRICK_BUNDLE_ARGUMENT);
        currentFormula = (Formula) getArguments().getSerializable(FORMULA_BUNDLE_ARGUMENT);
    }

    private void setUpActionBar() {
        ActionBar actionBar = getSherlockActivity().getSupportActionBar();
        previousActionBarTitle = ProjectManager.getInstance().getCurrentSprite().getName();
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setTitle(hku.fyp14017.blencode.R.string.formula_editor_title);
    }

    private void resetActionBar() {
        ActionBar actionBar = getSherlockActivity().getSupportActionBar();
        actionBar.setTitle(previousActionBarTitle);
    }

    public static void showFragment(View view, Brick brick, Formula formula) {

        SherlockFragmentActivity activity = null;
        activity = (SherlockFragmentActivity) view.getContext();

        FormulaEditorFragment formulaEditorFragment = (FormulaEditorFragment) activity.getSupportFragmentManager()
                .findFragmentByTag(FORMULA_EDITOR_FRAGMENT_TAG);

        FragmentManager fragmentManager = activity.getSupportFragmentManager();
        FragmentTransaction fragTransaction = fragmentManager.beginTransaction();

        if (formulaEditorFragment == null) {
            formulaEditorFragment = new FormulaEditorFragment();
            Bundle bundle = new Bundle();
            bundle.putSerializable(BRICK_BUNDLE_ARGUMENT, brick);
            bundle.putSerializable(FORMULA_BUNDLE_ARGUMENT, formula);
            formulaEditorFragment.setArguments(bundle);

            fragTransaction.add(hku.fyp14017.blencode.R.id.script_fragment_container, formulaEditorFragment,
                    FORMULA_EDITOR_FRAGMENT_TAG);
            fragTransaction.hide(fragmentManager.findFragmentByTag(ScriptFragment.TAG));
            fragTransaction.show(formulaEditorFragment);
            BottomBar.hideBottomBar(activity);
        } else if (formulaEditorFragment.isHidden()) {
            formulaEditorFragment.updateBrickViewAndFormula(brick, formula);
            fragTransaction.hide(fragmentManager.findFragmentByTag(ScriptFragment.TAG));
            fragTransaction.show(formulaEditorFragment);
            BottomBar.hideBottomBar(activity);
        } else {
            formulaEditorFragment.setInputFormula(formula, SET_FORMULA_ON_SWITCH_EDIT_TEXT);
        }
        fragTransaction.commit();
    }

    public void updateBrickView() {
        updateBrickView(currentBrick);
    }

    private void updateBrickView(Brick newBrick) {
        currentBrick = newBrick;
        formulaEditorBrick.removeAllViews();
        View newBrickView = newBrick.getView(context, 0, null);
        formulaEditorBrick.addView(newBrickView, new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT));
        brickView = newBrickView;
        fragmentView.getViewTreeObserver().addOnGlobalLayoutListener(this);

    }

    private void updateBrickViewAndFormula(Brick newBrick, Formula newFormula) {
        updateBrickView(newBrick);
        currentFormula = newFormula;
        setInputFormula(newFormula, SET_FORMULA_ON_CREATE_VIEW);
        fragmentView.getViewTreeObserver().addOnGlobalLayoutListener(this);
        updateButtonViewOnKeyboard();
    }

    private void onUserDismiss() {
        formulaEditorEditText.endEdit();
        currentFormula.prepareToRemove();

        SherlockFragmentActivity activity = getSherlockActivity();
        FragmentManager fragmentManager = activity.getSupportFragmentManager();
        FragmentTransaction fragTransaction = fragmentManager.beginTransaction();
        fragTransaction.hide(this);
        fragTransaction.show(fragmentManager.findFragmentByTag(ScriptFragment.TAG));
        fragTransaction.commit();

        resetActionBar();

        BottomBar.showBottomBar(activity);
        BottomBar.showPlayButton(activity);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        fragmentView = inflater.inflate(hku.fyp14017.blencode.R.layout.fragment_formula_editor, container, false);
        fragmentView.setFocusableInTouchMode(true);
        fragmentView.requestFocus();

        formularEditorFieldDeleteButton = (ImageButton) fragmentView
                .findViewById(hku.fyp14017.blencode.R.id.formula_editor_edit_field_clear);

        context = getActivity();
        brickView = currentBrick.getView(context, 0, null);

        formulaEditorBrick = (LinearLayout) fragmentView
                .findViewById(hku.fyp14017.blencode.R.id.formula_editor_brick_space);

        formulaEditorBrick.addView(brickView, new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,
                LinearLayout.LayoutParams.MATCH_PARENT));

        formulaEditorEditText = (FormulaEditorEditText) fragmentView
                .findViewById(hku.fyp14017.blencode.R.id.formula_editor_edit_field);

        formulaEditorKeyboard = (LinearLayout) fragmentView
                .findViewById(hku.fyp14017.blencode.R.id.formula_editor_keyboardview);
        formulaEditorEditText.init(this);

        fragmentView.getViewTreeObserver().addOnGlobalLayoutListener(this);

        setInputFormula(currentFormula, SET_FORMULA_ON_CREATE_VIEW);

        return fragmentView;
    }

    @Override
    public void onStart() {
        formulaEditorKeyboard.setClickable(true);
        formularEditorFieldDeleteButton.setClickable(true);

        getView().requestFocus();
        View.OnTouchListener touchListener = new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent event) {
                Log.i("info", "viewId: " + view.getId());
                if (event.getAction() == MotionEvent.ACTION_UP) {
                    updateButtonViewOnKeyboard();
                    view.setPressed(false);
                    return true;
                }

                if (event.getAction() == MotionEvent.ACTION_DOWN) {

                    view.setPressed(true);

                    switch (view.getId()) {
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_compute:
                        InternFormulaParser internFormulaParser = formulaEditorEditText.getFormulaParser();
                        FormulaElement formulaElement = internFormulaParser.parseFormula();
                        if (formulaElement == null) {
                            if (internFormulaParser.getErrorTokenIndex() >= 0) {
                                formulaEditorEditText.setParseErrorCursorAndSelection();
                            }
                            return false;
                        }
                        Formula formulaToCompute = new Formula(formulaElement);
                        FormulaEditorComputeDialog computeDialog = new FormulaEditorComputeDialog(context);
                        computeDialog.setFormula(formulaToCompute);
                        computeDialog.show();
                        return true;
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_undo:
                        formulaEditorEditText.undo();
                        return true;
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_redo:
                        formulaEditorEditText.redo();
                        return true;
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_function:
                        showFormulaEditorListFragment(FormulaEditorListFragment.FUNCTION_TAG,
                                hku.fyp14017.blencode.R.string.formula_editor_function);
                        return true;
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_logic:
                        showFormulaEditorListFragment(FormulaEditorListFragment.LOGIC_TAG,
                                hku.fyp14017.blencode.R.string.formula_editor_logic);
                        return true;
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_object:
                        showFormulaEditorListFragment(FormulaEditorListFragment.OBJECT_TAG,
                                hku.fyp14017.blencode.R.string.formula_editor_choose_object_variable);
                        return true;
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_sensors:
                        showFormulaEditorListFragment(FormulaEditorListFragment.SENSOR_TAG,
                                hku.fyp14017.blencode.R.string.formula_editor_sensors);
                        return true;
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_variables:
                        showFormulaEditorVariableListFragment(FormulaEditorVariableListFragment.VARIABLE_TAG,
                                hku.fyp14017.blencode.R.string.formula_editor_variables);
                        return true;
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_ok:
                        endFormulaEditor();
                        return true;
                    case hku.fyp14017.blencode.R.id.formula_editor_keyboard_string:
                        FragmentManager fragmentManager = ((SherlockFragmentActivity) context)
                                .getSupportFragmentManager();
                        Fragment dialogFragment = fragmentManager
                                .findFragmentByTag(NewStringDialog.DIALOG_FRAGMENT_TAG);

                        if (dialogFragment == null) {
                            dialogFragment = NewStringDialog.newInstance();
                        }

                        ((NewStringDialog) dialogFragment).show(fragmentManager,
                                NewStringDialog.DIALOG_FRAGMENT_TAG);
                        return true;
                    default:
                        formulaEditorEditText.handleKeyEvent(view.getId(), "");
                        return true;
                    }

                }
                return false;
            }
        };

        for (int index = 0; index < formulaEditorKeyboard.getChildCount(); index++) {
            LinearLayout child = (LinearLayout) formulaEditorKeyboard.getChildAt(index);
            for (int nestedIndex = 0; nestedIndex < child.getChildCount(); nestedIndex++) {
                View view = child.getChildAt(nestedIndex);
                view.setOnTouchListener(touchListener);
            }
        }
        formularEditorFieldDeleteButton.setOnTouchListener(touchListener);

        updateButtonViewOnKeyboard();

        super.onStart();
    }

    @Override
    public void onPrepareOptionsMenu(Menu menu) {
        for (int index = 0; index < menu.size(); index++) {
            menu.getItem(index).setVisible(false);
        }

        getSherlockActivity().getSupportActionBar().setDisplayShowTitleEnabled(true);
        getSherlockActivity().getSupportActionBar()
                .setTitle(getString(hku.fyp14017.blencode.R.string.formula_editor_title));

        super.onPrepareOptionsMenu(menu);
    }

    private void setInputFormula(Formula newFormula, int mode) {

        int orientation = getResources().getConfiguration().orientation;

        switch (mode) {
        case SET_FORMULA_ON_CREATE_VIEW:
            formulaEditorEditText.enterNewFormula(currentFormula.getInternFormulaState());
            currentFormula.highlightTextField(brickView, orientation);
            refreshFormulaPreviewString();
            break;
        case SET_FORMULA_ON_SWITCH_EDIT_TEXT:

            if (currentFormula == newFormula && formulaEditorEditText.hasChanges()) {
                formulaEditorEditText.quickSelect();
                break;
            }
            if (formulaEditorEditText.hasChanges()) {
                confirmSwitchEditTextTimeStamp[0] = confirmSwitchEditTextTimeStamp[1];
                confirmSwitchEditTextTimeStamp[1] = System.currentTimeMillis();
                confirmSwitchEditTextCounter++;
                if (!saveFormulaIfPossible()) {
                    return;
                }
            }

            formulaEditorEditText.endEdit();

            currentFormula = newFormula;
            formulaEditorEditText.enterNewFormula(newFormula.getInternFormulaState());

            refreshFormulaPreviewString();

            break;
        default:
            break;
        }
    }

    public boolean saveFormulaIfPossible() {
        InternFormulaParser formulaToParse = formulaEditorEditText.getFormulaParser();
        FormulaElement formulaParseTree = formulaToParse.parseFormula();
        int err = formulaToParse.getErrorTokenIndex();
        switch (err) {
        case PARSER_OK:
            currentFormula.setRoot(formulaParseTree);
            if (formulaEditorBrick != null) {
                currentFormula.refreshTextField(brickView);
            }
            formulaEditorEditText.formulaSaved();
            showToast(hku.fyp14017.blencode.R.string.formula_editor_changes_saved);
            return true;
        case PARSER_STACK_OVERFLOW:
            return checkReturnWithoutSaving(PARSER_STACK_OVERFLOW);
        default:
            formulaEditorEditText.setParseErrorCursorAndSelection();
            return checkReturnWithoutSaving(PARSER_INPUT_SYNTAX_ERROR);
        }
    }

    private boolean checkReturnWithoutSaving(int errorType) {
        Log.i("info", "confirmSwitchEditTextCounter=" + confirmSwitchEditTextCounter + " "
                + (System.currentTimeMillis() <= confirmSwitchEditTextTimeStamp[0] + TIME_WINDOW));

        if ((System.currentTimeMillis() <= confirmSwitchEditTextTimeStamp[0] + TIME_WINDOW)
                && (confirmSwitchEditTextCounter > 1)) {
            confirmSwitchEditTextTimeStamp[0] = 0;
            confirmSwitchEditTextTimeStamp[1] = 0;
            confirmSwitchEditTextCounter = 0;
            currentFormula.setDisplayText(null);
            showToast(hku.fyp14017.blencode.R.string.formula_editor_changes_discarded);
            return true;
        } else {
            switch (errorType) {
            case PARSER_INPUT_SYNTAX_ERROR:
                showToast(hku.fyp14017.blencode.R.string.formula_editor_parse_fail);
                break;
            case PARSER_STACK_OVERFLOW:
                showToast(hku.fyp14017.blencode.R.string.formula_editor_parse_fail_formula_too_long);
                break;
            }
            return false;
        }

    }

    /*
     * TODO Remove Toasts from this class and replace them with something useful
     * This is a hack more than anything else. We shouldn't use Toasts if we're going to change the message all the time
     */
    private void showToast(int resourceId) {
        if (toast == null || toast.getView().getWindowVisibility() != View.VISIBLE) {
            toast = Toast.makeText(getActivity().getApplicationContext(), resourceId, Toast.LENGTH_SHORT);
        } else {
            toast.setText(resourceId);
        }
        toast.show();
    }

    @Override
    public boolean onKey(View view, int keyCode, KeyEvent event) {
        Log.i("info", "onKey() in FE-Fragment! keyCode: " + keyCode);
        switch (keyCode) {
        case KeyEvent.KEYCODE_BACK:
            if (formulaEditorEditText.hasChanges()) {
                AlertDialog.Builder builder = new CustomAlertDialogBuilder(getActivity());
                builder.setTitle(hku.fyp14017.blencode.R.string.formula_editor_discard_changes_dialog_title)
                        .setMessage(hku.fyp14017.blencode.R.string.formula_editor_discard_changes_dialog_message)
                        .setNegativeButton(hku.fyp14017.blencode.R.string.no, new OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog, int which) {

                                showToast(hku.fyp14017.blencode.R.string.formula_editor_changes_discarded);
                                currentFormula.setDisplayText(null);
                                onUserDismiss();
                            }
                        }).setPositiveButton(hku.fyp14017.blencode.R.string.yes, new OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                if (saveFormulaIfPossible()) {
                                    onUserDismiss();
                                }
                            }
                        }).create().show();

            } else {
                onUserDismiss();
            }

            return true;
        }
        return false;
    }

    private void endFormulaEditor() {
        if (formulaEditorEditText.hasChanges()) {
            if (saveFormulaIfPossible()) {
                onUserDismiss();
            }
        } else {
            onUserDismiss();
        }
    }

    public void refreshFormulaPreviewString() {
        refreshFormulaPreviewString(formulaEditorEditText.getStringFromInternFormula());
    }

    public void refreshFormulaPreviewString(String newString) {
        currentFormula.setDisplayText(newString);

        updateBrickView();

        currentFormula.refreshTextField(brickView, newString);

        int orientation = getResources().getConfiguration().orientation;
        currentFormula.highlightTextField(brickView, orientation);
    }

    private void showFormulaEditorListFragment(String tag, int actionbarResId) {
        FragmentManager fragmentManager = ((SherlockFragmentActivity) context).getSupportFragmentManager();
        Fragment fragment = fragmentManager.findFragmentByTag(tag);

        if (fragment == null) {
            fragment = new FormulaEditorListFragment();
            Bundle bundle = new Bundle();
            bundle.putString(FormulaEditorListFragment.ACTION_BAR_TITLE_BUNDLE_ARGUMENT,
                    context.getString(actionbarResId));
            bundle.putString(FormulaEditorListFragment.FRAGMENT_TAG_BUNDLE_ARGUMENT, tag);
            fragment.setArguments(bundle);
            fragmentManager.beginTransaction()
                    .add(hku.fyp14017.blencode.R.id.script_fragment_container, fragment, tag).commit();
        }
        ((FormulaEditorListFragment) fragment).showFragment(context);
    }

    private void showFormulaEditorVariableListFragment(String tag, int actionbarResId) {
        FragmentManager fragmentManager = ((SherlockFragmentActivity) context).getSupportFragmentManager();
        Fragment fragment = fragmentManager.findFragmentByTag(tag);

        if (fragment == null) {
            if (getActivity().getClass().equals(ScriptActivity.class)) {
                fragment = new FormulaEditorVariableListFragment(false);
            } else {
                fragment = new FormulaEditorVariableListFragment(true);
            }
            Bundle bundle = new Bundle();
            bundle.putString(FormulaEditorVariableListFragment.ACTION_BAR_TITLE_BUNDLE_ARGUMENT,
                    context.getString(actionbarResId));
            bundle.putString(FormulaEditorVariableListFragment.FRAGMENT_TAG_BUNDLE_ARGUMENT, tag);
            fragment.setArguments(bundle);
            fragmentManager.beginTransaction()
                    .add(hku.fyp14017.blencode.R.id.script_fragment_container, fragment, tag).commit();
        }
        ((FormulaEditorVariableListFragment) fragment).setAddButtonListener(getSherlockActivity());
        ((FormulaEditorVariableListFragment) fragment).showFragment(context);
    }

    @SuppressWarnings("deprecation")
    @Override
    public void onGlobalLayout() {
        fragmentView.getViewTreeObserver().removeGlobalOnLayoutListener(this);

        Rect brickRect = new Rect();
        Rect keyboardRec = new Rect();
        formulaEditorBrick.getGlobalVisibleRect(brickRect);
        formulaEditorKeyboard.getGlobalVisibleRect(keyboardRec);

        formulaEditorEditText.setMaxHeight(keyboardRec.top - brickRect.bottom);

    }

    public void addResourceToActiveFormula(int resource, String name) {
        formulaEditorEditText.handleKeyEvent(resource, name);
    }

    public void addResourceToActiveFormula(int resource) {
        formulaEditorEditText.handleKeyEvent(resource, "");
    }

    public void addUserVariableToActiveFormula(String userVariableName) {
        formulaEditorEditText.handleKeyEvent(0, userVariableName);
    }

    public void addStringToActiveFormula(String string) {
        formulaEditorEditText.handleKeyEvent(hku.fyp14017.blencode.R.id.formula_editor_keyboard_string, string);
    }

    private class VariableDeletedReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent.getAction().equals(ScriptActivity.ACTION_VARIABLE_DELETED)) {
                updateBrickView(currentBrick);
            }
        }
    }

    @Override
    public void onPause() {
        super.onPause();

        if (variableDeletedReceiver != null) {
            getActivity().unregisterReceiver(variableDeletedReceiver);
        }
    }

    @Override
    public void onResume() {
        super.onResume();

        if (variableDeletedReceiver == null) {
            variableDeletedReceiver = new VariableDeletedReceiver();
        }

        IntentFilter filterVariableDeleted = new IntentFilter(ScriptActivity.ACTION_VARIABLE_DELETED);
        getActivity().registerReceiver(variableDeletedReceiver, filterVariableDeleted);
        BottomBar.hideBottomBar(getSherlockActivity());
    }

    public void updateButtonViewOnKeyboard() {

        ImageButton undo = (ImageButton) getSherlockActivity()
                .findViewById(hku.fyp14017.blencode.R.id.formula_editor_keyboard_undo);
        if (!formulaEditorEditText.getHistory().undoIsPossible()) {
            undo.setImageResource(hku.fyp14017.blencode.R.drawable.icon_undo_disabled);
            undo.setEnabled(false);
        } else {
            undo.setImageResource(hku.fyp14017.blencode.R.drawable.icon_undo);
            undo.setEnabled(true);
        }

        ImageButton redo = (ImageButton) getSherlockActivity()
                .findViewById(hku.fyp14017.blencode.R.id.formula_editor_keyboard_redo);
        if (!formulaEditorEditText.getHistory().redoIsPossible()) {
            redo.setImageResource(hku.fyp14017.blencode.R.drawable.icon_redo_disabled);
            redo.setEnabled(false);
        } else {
            redo.setImageResource(hku.fyp14017.blencode.R.drawable.icon_redo);
            redo.setEnabled(true);
        }

        ImageButton backspace = (ImageButton) getSherlockActivity()
                .findViewById(hku.fyp14017.blencode.R.id.formula_editor_edit_field_clear);
        if (!formulaEditorEditText.isThereSomethingToDelete()) {
            backspace.setImageResource(hku.fyp14017.blencode.R.drawable.icon_backspace_disabled);
            backspace.setEnabled(false);
        } else {
            backspace.setImageResource(hku.fyp14017.blencode.R.drawable.icon_backspace);
            backspace.setEnabled(true);
        }

    }
}