Add initial commit.

.gitignore

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+*.iml
+.gradle
+/local.properties
+/.idea/workspace.xml
+/.idea/libraries
+.DS_Store
+/build
+/captures
+.externalNativeBuild

app/.gitignore

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+/build

app/build.gradle

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+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 24
+    buildToolsVersion "24.0.2"
+    defaultConfig {
+        applicationId "net.liutikas.stepperwidget"
+        minSdkVersion 9
+        targetSdkVersion 24
+        versionCode 1
+        versionName "1.0"
+        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+}
+
+dependencies {
+    compile fileTree(dir: 'libs', include: ['*.jar'])
+    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
+        exclude group: 'com.android.support', module: 'support-annotations'
+    })
+    compile 'com.android.support:appcompat-v7:24.2.1'
+    testCompile 'junit:junit:4.12'
+}

app/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# By default, the flags in this file are appended to flags specified
+# in /Users/aurimas/Library/Android/sdk/tools/proguard/proguard-android.txt
+# You can edit the include path and order by changing the proguardFiles
+# directive in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# Add any project specific keep options here:
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}

app/src/androidTest/java/net/liutikas/stepperwidget/ExampleInstrumentedTest.java

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+package net.liutikas.stepperwidget;
+
+import android.content.Context;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.*;
+
+/**
+ * Instrumentation test, which will execute on an Android device.
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+@RunWith(AndroidJUnit4.class)
+public class ExampleInstrumentedTest {
+    @Test
+    public void useAppContext() throws Exception {
+        // Context of the app under test.
+        Context appContext = InstrumentationRegistry.getTargetContext();
+
+        assertEquals("net.liutikas.stepperwidget", appContext.getPackageName());
+    }
+}

app/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="net.liutikas.stepperwidget">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

app/src/main/java/net/liutikas/stepperwidget/MainActivity.java

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+package net.liutikas.stepperwidget;
+
+import android.support.v7.app.AppCompatActivity;
+import android.os.Bundle;
+
+public class MainActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+    }
+}

app/src/main/java/net/liutikas/stepperwidget/StepperWidget.java

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+package net.liutikas.stepperwidget;
+
+import android.animation.Animator;
+import android.animation.ValueAnimator;
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.os.Build;
+import android.support.v4.view.animation.FastOutSlowInInterpolator;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.ImageButton;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+
+public class StepperWidget extends LinearLayout {
+    private final ImageButton mPlusButton;
+    private final ImageButton mMinusButton;
+    private final TextView mLabelOne;
+    private final TextView mLabelTwo;
+    private boolean mLabelOneVisible = false;
+    private int mCounter = 0;
+    private int mChange = 0;
+
+    private ValueAnimator mAnimator;
+
+    public StepperWidget(Context context) {
+        this(context, null);
+    }
+
+    public StepperWidget(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public StepperWidget(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs);
+        setOrientation(VERTICAL);
+        inflate(context, R.layout.stepper, this);
+        mPlusButton = (ImageButton) findViewById(R.id.plus);
+        mMinusButton = (ImageButton) findViewById(R.id.minus);
+        mLabelOne = (TextView) findViewById(R.id.label1);
+        mLabelTwo = (TextView) findViewById(R.id.label2);
+        mPlusButton.setOnClickListener(new OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                updateLabel(1);
+            }
+        });
+        mMinusButton.setOnClickListener(new OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                updateLabel(-1);
+            }
+        });
+        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.HONEYCOMB) {
+            initalizeAnimator();
+        }
+        updateLabel(0);
+    }
+
+    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
+    private void initalizeAnimator() {
+        mAnimator = ValueAnimator.ofInt(100);
+        mAnimator.setDuration(300);
+        mAnimator.setInterpolator(new FastOutSlowInInterpolator());
+        mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
+            @Override
+            public void onAnimationUpdate(ValueAnimator valueAnimator) {
+                Integer value = (Integer) valueAnimator.getAnimatedValue();
+                if (value < 100 && mChange == 0) {
+                    mAnimator.end();
+                } else if (mChange < 0) {
+                    getEnteringLabel().setTranslationY(100 - value);
+                    getLeavingLabel().setTranslationY(-value);
+                } else {
+                    getEnteringLabel().setTranslationY(-100 + value);
+                    getLeavingLabel().setTranslationY(value);
+                }
+            }
+        });
+        mAnimator.addListener(new Animator.AnimatorListener() {
+            @Override
+            public void onAnimationStart(Animator animator) {}
+
+            @Override
+            public void onAnimationEnd(Animator animator) {
+                getLeavingLabel().setVisibility(INVISIBLE);
+                mLabelOneVisible = !mLabelOneVisible;
+            }
+
+            @Override
+            public void onAnimationCancel(Animator animator) {}
+
+            @Override
+            public void onAnimationRepeat(Animator animator) {}
+        });
+    }
+
+    private TextView getEnteringLabel() {
+        return mLabelOneVisible ? mLabelTwo : mLabelOne;
+    }
+
+    private TextView getLeavingLabel() {
+        return mLabelOneVisible ? mLabelOne : mLabelTwo;
+    }
+
+    private void updateLabel(int change) {
+        mCounter += change;
+        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.HONEYCOMB) {
+            updateLabelAnimated(change);
+            return;
+        }
+        if (mLabelOneVisible) {
+            mLabelTwo.setText(Integer.toString(mCounter));
+            mLabelOne.setVisibility(INVISIBLE);
+            mLabelTwo.setVisibility(VISIBLE);
+        } else {
+            mLabelOne.setText(Integer.toString(mCounter));
+            mLabelOne.setVisibility(VISIBLE);
+            mLabelTwo.setVisibility(INVISIBLE);
+        }
+        mLabelOneVisible = !mLabelOneVisible;
+    }
+
+    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
+    private void updateLabelAnimated(final int change) {
+        if (mAnimator.isRunning()) {
+            mAnimator.end();
+        }
+        mChange = change;
+        final TextView enteringLabel = getEnteringLabel();
+        enteringLabel.setText(Integer.toString(mCounter));
+        enteringLabel.setVisibility(VISIBLE);
+
+        mAnimator.start();
+    }
+}