src/com/android/calculator2/Calculator.java - platform/packages/apps/Calculator.git - Git at Google

 /*
  * Copyright (C) 2014 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 com.android.calculator2;

 import android.animation.Animator;
 import android.animation.Animator.AnimatorListener;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.AnimatorSet;
 import android.animation.ArgbEvaluator;
 import android.animation.ObjectAnimator;
 import android.animation.ValueAnimator;
 import android.animation.ValueAnimator.AnimatorUpdateListener;
 import android.app.Activity;
 import android.graphics.Rect;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.v4.view.ViewPager;
 import android.text.Editable;
 import android.text.TextUtils;
 import android.text.TextWatcher;
 import android.view.KeyEvent;
 import android.view.View;
 import android.view.View.OnKeyListener;
 import android.view.View.OnLongClickListener;
 import android.view.ViewAnimationUtils;
 import android.view.ViewGroupOverlay;
 import android.view.animation.AccelerateDecelerateInterpolator;
 import android.widget.Button;
 import android.widget.TextView;

 import com.android.calculator2.CalculatorEditText.OnTextSizeChangeListener;
 import com.android.calculator2.CalculatorExpressionEvaluator.EvaluateCallback;

 public class Calculator extends Activity
         implements OnTextSizeChangeListener, EvaluateCallback, OnLongClickListener {

     private static final String NAME = Calculator.class.getName();

     // instance state keys
     private static final String KEY_CURRENT_STATE = NAME + "_currentState";
     private static final String KEY_CURRENT_EXPRESSION = NAME + "_currentExpression";

     /**
      * Constant for an invalid resource id.
      */
     public static final int INVALID_RES_ID = -1;

     private enum CalculatorState {
         INPUT, EVALUATE, RESULT, ERROR
     }

     private final TextWatcher mFormulaTextWatcher = new TextWatcher() {
         @Override
         public void beforeTextChanged(CharSequence charSequence, int start, int count, int after) {
         }

         @Override
         public void onTextChanged(CharSequence charSequence, int start, int count, int after) {
         }

         @Override
         public void afterTextChanged(Editable editable) {
             setState(CalculatorState.INPUT);
             mEvaluator.evaluate(editable, Calculator.this);
         }
     };

     private final OnKeyListener mFormulaOnKeyListener = new OnKeyListener() {
         @Override
         public boolean onKey(View view, int keyCode, KeyEvent keyEvent) {
             switch (keyCode) {
                 case KeyEvent.KEYCODE_NUMPAD_ENTER:
                 case KeyEvent.KEYCODE_ENTER:
                     if (keyEvent.getAction() == KeyEvent.ACTION_UP) {
                         onEquals();
                     }
                     // ignore all other actions
                     return true;
             }
             return false;
         }
     };

     private final Editable.Factory mFormulaEditableFactory = new Editable.Factory() {
         @Override
         public Editable newEditable(CharSequence source) {
             final boolean isEdited = mCurrentState == CalculatorState.INPUT
                     || mCurrentState == CalculatorState.ERROR;
             return new CalculatorExpressionBuilder(source, mTokenizer, isEdited);
         }
     };

     private CalculatorState mCurrentState;
     private CalculatorExpressionTokenizer mTokenizer;
     private CalculatorExpressionEvaluator mEvaluator;

     private View mDisplayView;
     private CalculatorEditText mFormulaEditText;
     private CalculatorEditText mResultEditText;
     private ViewPager mPadViewPager;
     private View mDeleteButton;
     private View mClearButton;
     private View mEqualButton;

     private Animator mCurrentAnimator;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_calculator);

         mDisplayView = findViewById(R.id.display);
         mFormulaEditText = (CalculatorEditText) findViewById(R.id.formula);
         mResultEditText = (CalculatorEditText) findViewById(R.id.result);
         mPadViewPager = (ViewPager) findViewById(R.id.pad_pager);
         mDeleteButton = findViewById(R.id.del);
         mClearButton = findViewById(R.id.clr);

         mEqualButton = findViewById(R.id.pad_numeric).findViewById(R.id.eq);
         if (mEqualButton == null || mEqualButton.getVisibility() != View.VISIBLE) {
             mEqualButton = findViewById(R.id.pad_operator).findViewById(R.id.eq);
         }

         mTokenizer = new CalculatorExpressionTokenizer(this);
         mEvaluator = new CalculatorExpressionEvaluator(mTokenizer);

         savedInstanceState = savedInstanceState == null ? Bundle.EMPTY : savedInstanceState;
         setState(CalculatorState.values()[
                 savedInstanceState.getInt(KEY_CURRENT_STATE, CalculatorState.INPUT.ordinal())]);
         mFormulaEditText.setText(mTokenizer.getLocalizedExpression(
                 savedInstanceState.getString(KEY_CURRENT_EXPRESSION, "")));
         mEvaluator.evaluate(mFormulaEditText.getText(), this);

         mFormulaEditText.setEditableFactory(mFormulaEditableFactory);
         mFormulaEditText.addTextChangedListener(mFormulaTextWatcher);
         mFormulaEditText.setOnKeyListener(mFormulaOnKeyListener);
         mFormulaEditText.setOnTextSizeChangeListener(this);
         mDeleteButton.setOnLongClickListener(this);
     }

     @Override
     protected void onSaveInstanceState(@NonNull Bundle outState) {
         // If there's an animation in progress, end it immediately to ensure the state is
         // up-to-date before it is serialized.
         if (mCurrentAnimator != null) {
             mCurrentAnimator.end();
         }

         super.onSaveInstanceState(outState);

         outState.putInt(KEY_CURRENT_STATE, mCurrentState.ordinal());
         outState.putString(KEY_CURRENT_EXPRESSION,
                 mTokenizer.getNormalizedExpression(mFormulaEditText.getText().toString()));
     }

     private void setState(CalculatorState state) {
         if (mCurrentState != state) {
             mCurrentState = state;

             if (state == CalculatorState.RESULT || state == CalculatorState.ERROR) {
                 mDeleteButton.setVisibility(View.GONE);
                 mClearButton.setVisibility(View.VISIBLE);
             } else {
                 mDeleteButton.setVisibility(View.VISIBLE);
                 mClearButton.setVisibility(View.GONE);
             }

             if (state == CalculatorState.ERROR) {
                 final int errorColor = getResources().getColor(R.color.calculator_error_color);
                 mFormulaEditText.setTextColor(errorColor);
                 mResultEditText.setTextColor(errorColor);
                 getWindow().setStatusBarColor(errorColor);
             } else {
                 mFormulaEditText.setTextColor(
                         getResources().getColor(R.color.display_formula_text_color));
                 mResultEditText.setTextColor(
                         getResources().getColor(R.color.display_result_text_color));
                 getWindow().setStatusBarColor(
                         getResources().getColor(R.color.calculator_accent_color));
             }
         }
     }

     @Override
     public void onBackPressed() {
         if (mPadViewPager == null || mPadViewPager.getCurrentItem() == 0) {
             // If the user is currently looking at the first pad (or the pad is not paged),
             // allow the system to handle the Back button.
             super.onBackPressed();
         } else {
             // Otherwise, select the previous pad.
             mPadViewPager.setCurrentItem(mPadViewPager.getCurrentItem() - 1);
         }
     }

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

         // If there's an animation in progress, end it immediately to ensure the state is
         // up-to-date before the pending user interaction is handled.
         if (mCurrentAnimator != null) {
             mCurrentAnimator.end();
         }
     }

     public void onButtonClick(View view) {
         switch (view.getId()) {
             case R.id.eq:
                 onEquals();
                 break;
             case R.id.del:
                 onDelete();
                 break;
             case R.id.clr:
                 onClear();
                 break;
             case R.id.fun_cos:
             case R.id.fun_ln:
             case R.id.fun_log:
             case R.id.fun_sin:
             case R.id.fun_tan:
                 // Add left parenthesis after functions.
                 mFormulaEditText.append(((Button) view).getText() + "(");
                 break;
             default:
                 mFormulaEditText.append(((Button) view).getText());
                 break;
         }
     }

     @Override
     public boolean onLongClick(View view) {
         if (view.getId() == R.id.del) {
             onClear();
             return true;
         }
         return false;
     }

     @Override
     public void onEvaluate(String expr, String result, int errorResourceId) {
         if (mCurrentState == CalculatorState.INPUT) {
             mResultEditText.setText(result);
         } else if (errorResourceId != INVALID_RES_ID) {
             onError(errorResourceId);
         } else if (!TextUtils.isEmpty(result)) {
             onResult(result);
         } else if (mCurrentState == CalculatorState.EVALUATE) {
             // The current expression cannot be evaluated -> return to the input state.
             setState(CalculatorState.INPUT);
         }

         mFormulaEditText.requestFocus();
     }

     @Override
     public void onTextSizeChanged(final TextView textView, float oldSize) {
         if (mCurrentState != CalculatorState.INPUT) {
             // Only animate text changes that occur from user input.
             return;
         }

         // Calculate the values needed to perform the scale and translation animations,
         // maintaining the same apparent baseline for the displayed text.
         final float textScale = oldSize / textView.getTextSize();
         final float translationX = (1.0f - textScale) *
                 (textView.getWidth() / 2.0f - textView.getPaddingEnd());
         final float translationY = (1.0f - textScale) *
                 (textView.getHeight() / 2.0f - textView.getPaddingBottom());

         final AnimatorSet animatorSet = new AnimatorSet();
         animatorSet.playTogether(
                 ObjectAnimator.ofFloat(textView, View.SCALE_X, textScale, 1.0f),
                 ObjectAnimator.ofFloat(textView, View.SCALE_Y, textScale, 1.0f),
                 ObjectAnimator.ofFloat(textView, View.TRANSLATION_X, translationX, 0.0f),
                 ObjectAnimator.ofFloat(textView, View.TRANSLATION_Y, translationY, 0.0f));
         animatorSet.setDuration(getResources().getInteger(android.R.integer.config_mediumAnimTime));
         animatorSet.setInterpolator(new AccelerateDecelerateInterpolator());
         animatorSet.start();
     }

     private void onEquals() {
         if (mCurrentState == CalculatorState.INPUT) {
             setState(CalculatorState.EVALUATE);
             mEvaluator.evaluate(mFormulaEditText.getText(), this);
         }
     }

     private void onDelete() {
         // Delete works like backspace; remove the last character from the expression.
         final Editable formulaText = mFormulaEditText.getEditableText();
         final int formulaLength = formulaText.length();
         if (formulaLength > 0) {
             formulaText.delete(formulaLength - 1, formulaLength);
         }
     }

     private void reveal(View sourceView, int colorRes, AnimatorListener listener) {
         final ViewGroupOverlay groupOverlay =
                 (ViewGroupOverlay) getWindow().getDecorView().getOverlay();

         final Rect displayRect = new Rect();
         mDisplayView.getGlobalVisibleRect(displayRect);

         // Make reveal cover the display and status bar.
         final View revealView = new View(this);
         revealView.setBottom(displayRect.bottom);
         revealView.setLeft(displayRect.left);
         revealView.setRight(displayRect.right);
         revealView.setBackgroundColor(getResources().getColor(colorRes));
         groupOverlay.add(revealView);

         final int[] clearLocation = new int[2];
         sourceView.getLocationInWindow(clearLocation);
         clearLocation[0] += sourceView.getWidth() / 2;
         clearLocation[1] += sourceView.getHeight() / 2;

         final int revealCenterX = clearLocation[0] - revealView.getLeft();
         final int revealCenterY = clearLocation[1] - revealView.getTop();

         final double x1_2 = Math.pow(revealView.getLeft() - revealCenterX, 2);
         final double x2_2 = Math.pow(revealView.getRight() - revealCenterX, 2);
         final double y_2 = Math.pow(revealView.getTop() - revealCenterY, 2);
         final float revealRadius = (float) Math.max(Math.sqrt(x1_2 + y_2), Math.sqrt(x2_2 + y_2));

         final Animator revealAnimator =
                 ViewAnimationUtils.createCircularReveal(revealView,
                         revealCenterX, revealCenterY, 0.0f, revealRadius);
         revealAnimator.setDuration(
                 getResources().getInteger(android.R.integer.config_longAnimTime));

         final Animator alphaAnimator = ObjectAnimator.ofFloat(revealView, View.ALPHA, 0.0f);
         alphaAnimator.setDuration(
                 getResources().getInteger(android.R.integer.config_mediumAnimTime));
         alphaAnimator.addListener(listener);

         final AnimatorSet animatorSet = new AnimatorSet();
         animatorSet.play(revealAnimator).before(alphaAnimator);
         animatorSet.setInterpolator(new AccelerateDecelerateInterpolator());
         animatorSet.addListener(new AnimatorListenerAdapter() {
             @Override
             public void onAnimationEnd(Animator animator) {
                 groupOverlay.remove(revealView);
                 mCurrentAnimator = null;
             }
         });

         mCurrentAnimator = animatorSet;
         animatorSet.start();
     }

     private void onClear() {
         if (TextUtils.isEmpty(mFormulaEditText.getText())) {
             return;
         }

         final View sourceView = mClearButton.getVisibility() == View.VISIBLE
                 ? mClearButton : mDeleteButton;
         reveal(sourceView, R.color.calculator_accent_color, new AnimatorListenerAdapter() {
             @Override
             public void onAnimationStart(Animator animation) {
                 mFormulaEditText.getEditableText().clear();
             }
         });
     }

     private void onError(final int errorResourceId) {
         if (mCurrentState != CalculatorState.EVALUATE) {
             // Only animate error on evaluate.
             mResultEditText.setText(errorResourceId);
             return;
         }

         reveal(mEqualButton, R.color.calculator_error_color, new AnimatorListenerAdapter() {
             @Override
             public void onAnimationStart(Animator animation) {
                 setState(CalculatorState.ERROR);
                 mResultEditText.setText(errorResourceId);
             }
         });
     }

     private void onResult(final String result) {
         // Calculate the values needed to perform the scale and translation animations,
         // accounting for how the scale will affect the final position of the text.
         final float resultScale =
                 mFormulaEditText.getVariableTextSize(result) / mResultEditText.getTextSize();
         final float resultTranslationX = (1.0f - resultScale) *
                 (mResultEditText.getWidth() / 2.0f - mResultEditText.getPaddingEnd());
         final float resultTranslationY = (1.0f - resultScale) *
                 (mResultEditText.getHeight() / 2.0f - mResultEditText.getPaddingBottom()) +
                 (mFormulaEditText.getBottom() - mResultEditText.getBottom()) +
                 (mResultEditText.getPaddingBottom() - mFormulaEditText.getPaddingBottom());
         final float formulaTranslationY = -mFormulaEditText.getBottom();

         // Use a value animator to fade to the final text color over the course of the animation.
         final int resultTextColor = mResultEditText.getCurrentTextColor();
         final int formulaTextColor = mFormulaEditText.getCurrentTextColor();
         final ValueAnimator textColorAnimator =
                 ValueAnimator.ofObject(new ArgbEvaluator(), resultTextColor, formulaTextColor);
         textColorAnimator.addUpdateListener(new AnimatorUpdateListener() {
             @Override
             public void onAnimationUpdate(ValueAnimator valueAnimator) {
                 mResultEditText.setTextColor((int) valueAnimator.getAnimatedValue());
             }
         });

         final AnimatorSet animatorSet = new AnimatorSet();
         animatorSet.playTogether(
                 textColorAnimator,
                 ObjectAnimator.ofFloat(mResultEditText, View.SCALE_X, resultScale),
                 ObjectAnimator.ofFloat(mResultEditText, View.SCALE_Y, resultScale),
                 ObjectAnimator.ofFloat(mResultEditText, View.TRANSLATION_X, resultTranslationX),
                 ObjectAnimator.ofFloat(mResultEditText, View.TRANSLATION_Y, resultTranslationY),
                 ObjectAnimator.ofFloat(mFormulaEditText, View.TRANSLATION_Y, formulaTranslationY));
         animatorSet.setDuration(getResources().getInteger(android.R.integer.config_longAnimTime));
         animatorSet.setInterpolator(new AccelerateDecelerateInterpolator());
         animatorSet.addListener(new AnimatorListenerAdapter() {
             @Override
             public void onAnimationStart(Animator animation) {
                 mResultEditText.setText(result);
             }

             @Override
             public void onAnimationEnd(Animator animation) {
                 // Reset all of the values modified during the animation.
                 mResultEditText.setTextColor(resultTextColor);
                 mResultEditText.setScaleX(1.0f);
                 mResultEditText.setScaleY(1.0f);
                 mResultEditText.setTranslationX(0.0f);
                 mResultEditText.setTranslationY(0.0f);
                 mFormulaEditText.setTranslationY(0.0f);

                 // Finally update the formula to use the current result.
                 mFormulaEditText.setText(result);
                 setState(CalculatorState.RESULT);

                 mCurrentAnimator = null;
             }
         });

         mCurrentAnimator = animatorSet;
         animatorSet.start();
     }
 }
	/*
	* Copyright (C) 2014 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 com.android.calculator2;

	import android.animation.Animator;
	import android.animation.Animator.AnimatorListener;
	import android.animation.AnimatorListenerAdapter;
	import android.animation.AnimatorSet;
	import android.animation.ArgbEvaluator;
	import android.animation.ObjectAnimator;
	import android.animation.ValueAnimator;
	import android.animation.ValueAnimator.AnimatorUpdateListener;
	import android.app.Activity;
	import android.graphics.Rect;
	import android.os.Bundle;
	import android.support.annotation.NonNull;
	import android.support.v4.view.ViewPager;
	import android.text.Editable;
	import android.text.TextUtils;
	import android.text.TextWatcher;
	import android.view.KeyEvent;
	import android.view.View;
	import android.view.View.OnKeyListener;
	import android.view.View.OnLongClickListener;
	import android.view.ViewAnimationUtils;
	import android.view.ViewGroupOverlay;
	import android.view.animation.AccelerateDecelerateInterpolator;
	import android.widget.Button;
	import android.widget.TextView;

	import com.android.calculator2.CalculatorEditText.OnTextSizeChangeListener;
	import com.android.calculator2.CalculatorExpressionEvaluator.EvaluateCallback;

	public class Calculator extends Activity
	implements OnTextSizeChangeListener, EvaluateCallback, OnLongClickListener {

	private static final String NAME = Calculator.class.getName();

	// instance state keys
	private static final String KEY_CURRENT_STATE = NAME + "_currentState";
	private static final String KEY_CURRENT_EXPRESSION = NAME + "_currentExpression";

	/**
	* Constant for an invalid resource id.
	*/
	public static final int INVALID_RES_ID = -1;

	private enum CalculatorState {
	INPUT, EVALUATE, RESULT, ERROR
	}

	private final TextWatcher mFormulaTextWatcher = new TextWatcher() {
	@Override
	public void beforeTextChanged(CharSequence charSequence, int start, int count, int after) {
	}

	@Override
	public void onTextChanged(CharSequence charSequence, int start, int count, int after) {
	}

	@Override
	public void afterTextChanged(Editable editable) {
	setState(CalculatorState.INPUT);
	mEvaluator.evaluate(editable, Calculator.this);
	}
	};

	private final OnKeyListener mFormulaOnKeyListener = new OnKeyListener() {
	@Override
	public boolean onKey(View view, int keyCode, KeyEvent keyEvent) {
	switch (keyCode) {
	case KeyEvent.KEYCODE_NUMPAD_ENTER:
	case KeyEvent.KEYCODE_ENTER:
	if (keyEvent.getAction() == KeyEvent.ACTION_UP) {
	onEquals();
	}
	// ignore all other actions
	return true;
	}
	return false;
	}
	};

	private final Editable.Factory mFormulaEditableFactory = new Editable.Factory() {
	@Override
	public Editable newEditable(CharSequence source) {
	final boolean isEdited = mCurrentState == CalculatorState.INPUT
	\|\| mCurrentState == CalculatorState.ERROR;
	return new CalculatorExpressionBuilder(source, mTokenizer, isEdited);
	}
	};

	private CalculatorState mCurrentState;
	private CalculatorExpressionTokenizer mTokenizer;
	private CalculatorExpressionEvaluator mEvaluator;

	private View mDisplayView;
	private CalculatorEditText mFormulaEditText;
	private CalculatorEditText mResultEditText;
	private ViewPager mPadViewPager;
	private View mDeleteButton;
	private View mClearButton;
	private View mEqualButton;

	private Animator mCurrentAnimator;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_calculator);

	mDisplayView = findViewById(R.id.display);
	mFormulaEditText = (CalculatorEditText) findViewById(R.id.formula);
	mResultEditText = (CalculatorEditText) findViewById(R.id.result);
	mPadViewPager = (ViewPager) findViewById(R.id.pad_pager);
	mDeleteButton = findViewById(R.id.del);
	mClearButton = findViewById(R.id.clr);

	mEqualButton = findViewById(R.id.pad_numeric).findViewById(R.id.eq);
	if (mEqualButton == null \|\| mEqualButton.getVisibility() != View.VISIBLE) {
	mEqualButton = findViewById(R.id.pad_operator).findViewById(R.id.eq);
	}

	mTokenizer = new CalculatorExpressionTokenizer(this);
	mEvaluator = new CalculatorExpressionEvaluator(mTokenizer);

	savedInstanceState = savedInstanceState == null ? Bundle.EMPTY : savedInstanceState;
	setState(CalculatorState.values()[
	savedInstanceState.getInt(KEY_CURRENT_STATE, CalculatorState.INPUT.ordinal())]);
	mFormulaEditText.setText(mTokenizer.getLocalizedExpression(
	savedInstanceState.getString(KEY_CURRENT_EXPRESSION, "")));
	mEvaluator.evaluate(mFormulaEditText.getText(), this);

	mFormulaEditText.setEditableFactory(mFormulaEditableFactory);
	mFormulaEditText.addTextChangedListener(mFormulaTextWatcher);
	mFormulaEditText.setOnKeyListener(mFormulaOnKeyListener);
	mFormulaEditText.setOnTextSizeChangeListener(this);
	mDeleteButton.setOnLongClickListener(this);
	}

	@Override
	protected void onSaveInstanceState(@NonNull Bundle outState) {
	// If there's an animation in progress, end it immediately to ensure the state is
	// up-to-date before it is serialized.
	if (mCurrentAnimator != null) {
	mCurrentAnimator.end();
	}

	super.onSaveInstanceState(outState);

	outState.putInt(KEY_CURRENT_STATE, mCurrentState.ordinal());
	outState.putString(KEY_CURRENT_EXPRESSION,
	mTokenizer.getNormalizedExpression(mFormulaEditText.getText().toString()));
	}

	private void setState(CalculatorState state) {
	if (mCurrentState != state) {
	mCurrentState = state;

	if (state == CalculatorState.RESULT \|\| state == CalculatorState.ERROR) {
	mDeleteButton.setVisibility(View.GONE);
	mClearButton.setVisibility(View.VISIBLE);
	} else {
	mDeleteButton.setVisibility(View.VISIBLE);
	mClearButton.setVisibility(View.GONE);
	}

	if (state == CalculatorState.ERROR) {
	final int errorColor = getResources().getColor(R.color.calculator_error_color);
	mFormulaEditText.setTextColor(errorColor);
	mResultEditText.setTextColor(errorColor);
	getWindow().setStatusBarColor(errorColor);
	} else {
	mFormulaEditText.setTextColor(
	getResources().getColor(R.color.display_formula_text_color));
	mResultEditText.setTextColor(
	getResources().getColor(R.color.display_result_text_color));
	getWindow().setStatusBarColor(
	getResources().getColor(R.color.calculator_accent_color));
	}
	}
	}

	@Override
	public void onBackPressed() {
	if (mPadViewPager == null \|\| mPadViewPager.getCurrentItem() == 0) {
	// If the user is currently looking at the first pad (or the pad is not paged),
	// allow the system to handle the Back button.
	super.onBackPressed();
	} else {
	// Otherwise, select the previous pad.
	mPadViewPager.setCurrentItem(mPadViewPager.getCurrentItem() - 1);
	}
	}

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

	// If there's an animation in progress, end it immediately to ensure the state is
	// up-to-date before the pending user interaction is handled.
	if (mCurrentAnimator != null) {
	mCurrentAnimator.end();
	}
	}

	public void onButtonClick(View view) {
	switch (view.getId()) {
	case R.id.eq:
	onEquals();
	break;
	case R.id.del:
	onDelete();
	break;
	case R.id.clr:
	onClear();
	break;
	case R.id.fun_cos:
	case R.id.fun_ln:
	case R.id.fun_log:
	case R.id.fun_sin:
	case R.id.fun_tan:
	// Add left parenthesis after functions.
	mFormulaEditText.append(((Button) view).getText() + "(");
	break;
	default:
	mFormulaEditText.append(((Button) view).getText());
	break;
	}
	}

	@Override
	public boolean onLongClick(View view) {
	if (view.getId() == R.id.del) {
	onClear();
	return true;
	}
	return false;
	}

	@Override
	public void onEvaluate(String expr, String result, int errorResourceId) {
	if (mCurrentState == CalculatorState.INPUT) {
	mResultEditText.setText(result);
	} else if (errorResourceId != INVALID_RES_ID) {
	onError(errorResourceId);
	} else if (!TextUtils.isEmpty(result)) {
	onResult(result);
	} else if (mCurrentState == CalculatorState.EVALUATE) {
	// The current expression cannot be evaluated -> return to the input state.
	setState(CalculatorState.INPUT);
	}

	mFormulaEditText.requestFocus();
	}

	@Override
	public void onTextSizeChanged(final TextView textView, float oldSize) {
	if (mCurrentState != CalculatorState.INPUT) {
	// Only animate text changes that occur from user input.
	return;
	}

	// Calculate the values needed to perform the scale and translation animations,
	// maintaining the same apparent baseline for the displayed text.
	final float textScale = oldSize / textView.getTextSize();
	final float translationX = (1.0f - textScale) *
	(textView.getWidth() / 2.0f - textView.getPaddingEnd());
	final float translationY = (1.0f - textScale) *
	(textView.getHeight() / 2.0f - textView.getPaddingBottom());

	final AnimatorSet animatorSet = new AnimatorSet();
	animatorSet.playTogether(
	ObjectAnimator.ofFloat(textView, View.SCALE_X, textScale, 1.0f),
	ObjectAnimator.ofFloat(textView, View.SCALE_Y, textScale, 1.0f),
	ObjectAnimator.ofFloat(textView, View.TRANSLATION_X, translationX, 0.0f),
	ObjectAnimator.ofFloat(textView, View.TRANSLATION_Y, translationY, 0.0f));
	animatorSet.setDuration(getResources().getInteger(android.R.integer.config_mediumAnimTime));
	animatorSet.setInterpolator(new AccelerateDecelerateInterpolator());
	animatorSet.start();
	}

	private void onEquals() {
	if (mCurrentState == CalculatorState.INPUT) {
	setState(CalculatorState.EVALUATE);
	mEvaluator.evaluate(mFormulaEditText.getText(), this);
	}
	}

	private void onDelete() {
	// Delete works like backspace; remove the last character from the expression.
	final Editable formulaText = mFormulaEditText.getEditableText();
	final int formulaLength = formulaText.length();
	if (formulaLength > 0) {
	formulaText.delete(formulaLength - 1, formulaLength);
	}
	}

	private void reveal(View sourceView, int colorRes, AnimatorListener listener) {
	final ViewGroupOverlay groupOverlay =
	(ViewGroupOverlay) getWindow().getDecorView().getOverlay();

	final Rect displayRect = new Rect();
	mDisplayView.getGlobalVisibleRect(displayRect);

	// Make reveal cover the display and status bar.
	final View revealView = new View(this);
	revealView.setBottom(displayRect.bottom);
	revealView.setLeft(displayRect.left);
	revealView.setRight(displayRect.right);
	revealView.setBackgroundColor(getResources().getColor(colorRes));
	groupOverlay.add(revealView);

	final int[] clearLocation = new int[2];
	sourceView.getLocationInWindow(clearLocation);
	clearLocation[0] += sourceView.getWidth() / 2;
	clearLocation[1] += sourceView.getHeight() / 2;

	final int revealCenterX = clearLocation[0] - revealView.getLeft();
	final int revealCenterY = clearLocation[1] - revealView.getTop();

	final double x1_2 = Math.pow(revealView.getLeft() - revealCenterX, 2);
	final double x2_2 = Math.pow(revealView.getRight() - revealCenterX, 2);
	final double y_2 = Math.pow(revealView.getTop() - revealCenterY, 2);
	final float revealRadius = (float) Math.max(Math.sqrt(x1_2 + y_2), Math.sqrt(x2_2 + y_2));

	final Animator revealAnimator =
	ViewAnimationUtils.createCircularReveal(revealView,
	revealCenterX, revealCenterY, 0.0f, revealRadius);
	revealAnimator.setDuration(
	getResources().getInteger(android.R.integer.config_longAnimTime));

	final Animator alphaAnimator = ObjectAnimator.ofFloat(revealView, View.ALPHA, 0.0f);
	alphaAnimator.setDuration(
	getResources().getInteger(android.R.integer.config_mediumAnimTime));
	alphaAnimator.addListener(listener);

	final AnimatorSet animatorSet = new AnimatorSet();
	animatorSet.play(revealAnimator).before(alphaAnimator);
	animatorSet.setInterpolator(new AccelerateDecelerateInterpolator());
	animatorSet.addListener(new AnimatorListenerAdapter() {
	@Override
	public void onAnimationEnd(Animator animator) {
	groupOverlay.remove(revealView);
	mCurrentAnimator = null;
	}
	});

	mCurrentAnimator = animatorSet;
	animatorSet.start();
	}

	private void onClear() {
	if (TextUtils.isEmpty(mFormulaEditText.getText())) {
	return;
	}

	final View sourceView = mClearButton.getVisibility() == View.VISIBLE
	? mClearButton : mDeleteButton;
	reveal(sourceView, R.color.calculator_accent_color, new AnimatorListenerAdapter() {
	@Override
	public void onAnimationStart(Animator animation) {
	mFormulaEditText.getEditableText().clear();
	}
	});
	}

	private void onError(final int errorResourceId) {
	if (mCurrentState != CalculatorState.EVALUATE) {
	// Only animate error on evaluate.
	mResultEditText.setText(errorResourceId);
	return;
	}

	reveal(mEqualButton, R.color.calculator_error_color, new AnimatorListenerAdapter() {
	@Override
	public void onAnimationStart(Animator animation) {
	setState(CalculatorState.ERROR);
	mResultEditText.setText(errorResourceId);
	}
	});
	}

	private void onResult(final String result) {
	// Calculate the values needed to perform the scale and translation animations,
	// accounting for how the scale will affect the final position of the text.
	final float resultScale =
	mFormulaEditText.getVariableTextSize(result) / mResultEditText.getTextSize();
	final float resultTranslationX = (1.0f - resultScale) *
	(mResultEditText.getWidth() / 2.0f - mResultEditText.getPaddingEnd());
	final float resultTranslationY = (1.0f - resultScale) *
	(mResultEditText.getHeight() / 2.0f - mResultEditText.getPaddingBottom()) +
	(mFormulaEditText.getBottom() - mResultEditText.getBottom()) +
	(mResultEditText.getPaddingBottom() - mFormulaEditText.getPaddingBottom());
	final float formulaTranslationY = -mFormulaEditText.getBottom();

	// Use a value animator to fade to the final text color over the course of the animation.
	final int resultTextColor = mResultEditText.getCurrentTextColor();
	final int formulaTextColor = mFormulaEditText.getCurrentTextColor();
	final ValueAnimator textColorAnimator =
	ValueAnimator.ofObject(new ArgbEvaluator(), resultTextColor, formulaTextColor);
	textColorAnimator.addUpdateListener(new AnimatorUpdateListener() {
	@Override
	public void onAnimationUpdate(ValueAnimator valueAnimator) {
	mResultEditText.setTextColor((int) valueAnimator.getAnimatedValue());
	}
	});

	final AnimatorSet animatorSet = new AnimatorSet();
	animatorSet.playTogether(
	textColorAnimator,
	ObjectAnimator.ofFloat(mResultEditText, View.SCALE_X, resultScale),
	ObjectAnimator.ofFloat(mResultEditText, View.SCALE_Y, resultScale),
	ObjectAnimator.ofFloat(mResultEditText, View.TRANSLATION_X, resultTranslationX),
	ObjectAnimator.ofFloat(mResultEditText, View.TRANSLATION_Y, resultTranslationY),
	ObjectAnimator.ofFloat(mFormulaEditText, View.TRANSLATION_Y, formulaTranslationY));
	animatorSet.setDuration(getResources().getInteger(android.R.integer.config_longAnimTime));
	animatorSet.setInterpolator(new AccelerateDecelerateInterpolator());
	animatorSet.addListener(new AnimatorListenerAdapter() {
	@Override
	public void onAnimationStart(Animator animation) {
	mResultEditText.setText(result);
	}

	@Override
	public void onAnimationEnd(Animator animation) {
	// Reset all of the values modified during the animation.
	mResultEditText.setTextColor(resultTextColor);
	mResultEditText.setScaleX(1.0f);
	mResultEditText.setScaleY(1.0f);
	mResultEditText.setTranslationX(0.0f);
	mResultEditText.setTranslationY(0.0f);
	mFormulaEditText.setTranslationY(0.0f);

	// Finally update the formula to use the current result.
	mFormulaEditText.setText(result);
	setState(CalculatorState.RESULT);

	mCurrentAnimator = null;
	}
	});

	mCurrentAnimator = animatorSet;
	animatorSet.start();
	}
	}