Added RTL support for StepperLayout's inner ViewPager

Piotr Zawadzki · zawadz88 · commit e3be95de9817 · 2017-05-16T19:21:53.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -32,7 +32,7 @@ before_script:
   - printf 'bintray.user=dummy_user\nbintray.apikey=dummy_api_key' > local.properties
 
 script:
-  - ./gradlew check
+  - ./gradlew check install
 
 after_success:
   - bash <(curl -s https://codecov.io/bash)
diff --git a/material-stepper/build.gradle b/material-stepper/build.gradle
@@ -84,4 +84,6 @@ tasks.matching {it instanceof Test}.all {
 check.dependsOn 'checkstyle', 'findbugs', 'pmd', 'jacocoTestReport'
 
 apply from: '../installv1.gradle'
-apply from: '../bintrayv1.gradle'
+apply from: '../bintrayv1.gradle'
+
+install.mustRunAfter check
diff --git a/material-stepper/src/main/java/com/stepstone/stepper/StepperLayout.java b/material-stepper/src/main/java/com/stepstone/stepper/StepperLayout.java
@@ -331,9 +331,13 @@ public void setAdapter(@NonNull StepAdapter stepAdapter, @IntRange(from = 0) int
     }
 
     /**
-     * Overrides the default page transformer used in the underlying {@link ViewPager}
+     * Overrides the default page transformer used in the underlying {@link com.stepstone.stepper.internal.widget.StepViewPager}.
+     * If you're supporting RTL make sure your {@link android.support.v4.view.ViewPager.PageTransformer} accounts for it.
      *
      * @param pageTransformer new page transformer
+     *
+     * @see com.stepstone.stepper.internal.widget.StepViewPager
+     * @see com.stepstone.stepper.internal.widget.pagetransformer.StepPageTransformerFactory
      */
     public void setPageTransformer(@Nullable ViewPager.PageTransformer pageTransformer) {
         mPager.setPageTransformer(false, pageTransformer);
diff --git a/material-stepper/src/main/java/com/stepstone/stepper/internal/widget/StepViewPager.java b/material-stepper/src/main/java/com/stepstone/stepper/internal/widget/StepViewPager.java
@@ -22,21 +22,24 @@
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 
+import com.stepstone.stepper.internal.widget.pagetransformer.StepPageTransformerFactory;
+
 import static android.support.annotation.RestrictTo.Scope.LIBRARY;
 
 /**
- * A non-swipeable viewpager.<br>
+ * A non-swipeable viewpager with RTL support.<br>
  * <a href="http://stackoverflow.com/questions/9650265/how-do-disable-paging-by-swiping-with-finger-in-viewpager-but-still-be-able-to-s">Source</a>
  */
 @RestrictTo(LIBRARY)
-public class NonSwipeableViewPager extends ViewPager {
+public class StepViewPager extends ViewPager {
 
-    public NonSwipeableViewPager(Context context) {
-        super(context);
+    public StepViewPager(Context context) {
+        this(context, null);
     }
 
-    public NonSwipeableViewPager(Context context, AttributeSet attrs) {
+    public StepViewPager(Context context, AttributeSet attrs) {
         super(context, attrs);
+        setPageTransformer(false, StepPageTransformerFactory.createPageTransformer(context));
     }
 
     @Override
@@ -50,4 +53,5 @@ public boolean onTouchEvent(MotionEvent event) {
         // Never allow swiping to switch between pages
         return false;
     }
+
 }
diff --git a/material-stepper/src/main/java/com/stepstone/stepper/internal/widget/pagetransformer/StepPageTransformerFactory.java b/material-stepper/src/main/java/com/stepstone/stepper/internal/widget/pagetransformer/StepPageTransformerFactory.java
@@ -0,0 +1,36 @@
+package com.stepstone.stepper.internal.widget.pagetransformer;
+
+import android.content.Context;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.annotation.RestrictTo;
+import android.support.v4.view.ViewPager;
+
+import com.stepstone.stepper.R;
+
+import static android.support.annotation.RestrictTo.Scope.LIBRARY;
+
+/**
+ * Creates a page transformer to be used by {@link com.stepstone.stepper.internal.widget.StepViewPager}.
+ *
+ * @author Piotr Zawadzki
+ */
+@RestrictTo(LIBRARY)
+public final class StepPageTransformerFactory {
+
+    private StepPageTransformerFactory() {
+    }
+
+    /**
+     * Creates a {@link android.support.v4.view.ViewPager.PageTransformer}.
+     * If layout direction is in RTL it returns {@link StepperRtlPageTransformer}, <i>null</i> otherwise.
+     * @param context context
+     * @return page transformer
+     */
+    @Nullable
+    public static ViewPager.PageTransformer createPageTransformer(@NonNull Context context) {
+        boolean rtlEnabled = context.getResources().getBoolean(R.bool.ms_rtlEnabled);
+        return rtlEnabled ? new StepperRtlPageTransformer() : null;
+    }
+
+}
diff --git a/material-stepper/src/main/java/com/stepstone/stepper/internal/widget/pagetransformer/StepperRtlPageTransformer.java b/material-stepper/src/main/java/com/stepstone/stepper/internal/widget/pagetransformer/StepperRtlPageTransformer.java
@@ -0,0 +1,40 @@
+package com.stepstone.stepper.internal.widget.pagetransformer;
+
+import android.support.annotation.RestrictTo;
+import android.support.v4.view.ViewPager;
+import android.view.View;
+
+import static android.support.annotation.RestrictTo.Scope.LIBRARY;
+
+/**
+ * A {@link android.support.v4.view.ViewPager.PageTransformer} which reverses
+ * the direction in which the pages slide in.
+ *
+ * @author Piotr Zawadzki
+ */
+@RestrictTo(LIBRARY)
+public class StepperRtlPageTransformer implements ViewPager.PageTransformer {
+
+    @Override
+    public void transformPage(View view, float position) {
+        /* This moves the View to the other side.
+        *
+        * Lets assume that ViewPager has a width of 300dp.
+        * This means that Views also have a width of 300dp.
+        * The view that's in front and center has a position on screen equal to 0dp.
+        * By view position we mean the position of view's left edge.
+        *
+        * Now, assuming we have a View on the right which is visible in 33% (its left 33% are visible)
+        * we know that its actual position on the screen would be 200dp = 300dp * (100% - 33%).
+        *
+        * In this state from transformPage(..) method would be called with position = 0.67
+        *
+        * The line below would move the view by 400dp = -2 * 0.67 * 300dp to the left.
+        * So effectively the view would be at -200dp and it's right 100dp would be visible.
+        *
+        * Thus, the view would be actually sliding to the other side which we expect when in RTL layout direction.
+        */
+        view.setTranslationX(-2 * position * view.getWidth());
+
+    }
+}
diff --git a/material-stepper/src/main/res/layout/ms_stepper_layout.xml b/material-stepper/src/main/res/layout/ms_stepper_layout.xml
@@ -18,7 +18,7 @@
         android:layout_height="0dp"
         android:layout_weight="1">
 
-        <com.stepstone.stepper.internal.widget.NonSwipeableViewPager
+        <com.stepstone.stepper.internal.widget.StepViewPager
             android:id="@+id/ms_stepPager"
             android:layout_width="match_parent"
             android:layout_height="match_parent" />
diff --git a/material-stepper/src/main/res/values-ldrtl/booleans.xml b/material-stepper/src/main/res/values-ldrtl/booleans.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <bool name="ms_rtlEnabled">true</bool>
+
+</resources>
diff --git a/material-stepper/src/main/res/values/booleans.xml b/material-stepper/src/main/res/values/booleans.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <bool name="ms_rtlEnabled">false</bool>
+
+</resources>
diff --git a/material-stepper/src/test/java/com/stepstone/stepper/StepperLayoutSanityTest.java b/material-stepper/src/test/java/com/stepstone/stepper/StepperLayoutSanityTest.java
@@ -1,7 +1,6 @@
 package com.stepstone.stepper;
 
 import android.content.Context;
-import android.os.Build;
 import android.support.annotation.IntRange;
 import android.support.annotation.NonNull;
 import android.support.v4.app.Fragment;
@@ -10,14 +9,13 @@
 import android.util.AttributeSet;
 
 import com.stepstone.stepper.adapter.AbstractFragmentStepAdapter;
+import com.stepstone.stepper.test.runner.StepperRobolectricTestRunner;
 import com.stepstone.stepper.viewmodel.StepViewModel;
 
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.robolectric.Robolectric;
-import org.robolectric.RobolectricTestRunner;
-import org.robolectric.annotation.Config;
 
 import static com.stepstone.stepper.test.assertion.StepperLayoutAssert.assertThat;
 import static org.mockito.Mockito.mock;
@@ -26,15 +24,14 @@
 /**
  * @author Piotr Zawadzki
  */
-@RunWith(RobolectricTestRunner.class)
-@Config(sdk = Build.VERSION_CODES.LOLLIPOP, constants = BuildConfig.class)
+@RunWith(StepperRobolectricTestRunner.class)
 public class StepperLayoutSanityTest {
 
     private static final String TYPE_PROGRESS_BAR = "progress_bar";
     private static final String TYPE_DOTS = "dots";
     private static final String TYPE_TABS = "tabs";
 
-    private FragmentActivity activity;
+    FragmentActivity activity;
 
     @Before
     public void setUp() throws Exception {
diff --git a/material-stepper/src/test/java/com/stepstone/stepper/internal/widget/pagetransformer/StepPageTransformerFactoryTest.java b/material-stepper/src/test/java/com/stepstone/stepper/internal/widget/pagetransformer/StepPageTransformerFactoryTest.java
@@ -0,0 +1,69 @@
+package com.stepstone.stepper.internal.widget.pagetransformer;
+
+import android.os.Build;
+import android.support.v4.view.ViewPager;
+
+import com.stepstone.stepper.test.runner.StepperRobolectricTestRunner;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.instanceOf;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+/**
+ * @author Piotr Zawadzki
+ */
+@RunWith(StepperRobolectricTestRunner.class)
+public class StepPageTransformerFactoryTest {
+
+    @Test
+    @Config(sdk = Build.VERSION_CODES.JELLY_BEAN_MR1, qualifiers = StepperRobolectricTestRunner.QUALIFIER_LDRTL)
+    public void should_create_rtl_page_transformer_on_JB_MR1_when_RTL_locale_selected() {
+        //when
+        ViewPager.PageTransformer pageTransformer = StepPageTransformerFactory.createPageTransformer(RuntimeEnvironment.application);
+
+        //then
+        assertNotNull("PageTransformer cannot be null", pageTransformer);
+        assertThat(pageTransformer, is(instanceOf(StepperRtlPageTransformer.class)));
+    }
+
+    @Test
+    @Config(sdk = Build.VERSION_CODES.JELLY_BEAN_MR1)
+    public void should_return_null_by_default_on_JB_MR1() {
+        //when
+        ViewPager.PageTransformer pageTransformer = StepPageTransformerFactory.createPageTransformer(RuntimeEnvironment.application);
+
+        //then
+        assertNull("PageTransformer must be null", pageTransformer);
+    }
+
+    @Test
+    @Config(sdk = Build.VERSION_CODES.JELLY_BEAN)
+    public void should_return_null_by_default_on_JB() {
+        //when
+        ViewPager.PageTransformer pageTransformer = StepPageTransformerFactory.createPageTransformer(RuntimeEnvironment.application);
+
+        //then
+        assertNull("PageTransformer must be null", pageTransformer);
+    }
+
+    /**
+     * Layout direction qualifiers were added in JB MR1 so below this OS version RTL should be ignored.
+     */
+    @Test
+    @Config(sdk = Build.VERSION_CODES.JELLY_BEAN, qualifiers = StepperRobolectricTestRunner.QUALIFIER_LDRTL)
+    public void should_return_null_on_JB_when_RTL_locale_selected() {
+        //when
+        ViewPager.PageTransformer pageTransformer = StepPageTransformerFactory.createPageTransformer(RuntimeEnvironment.application);
+
+        //then
+        assertNull("PageTransformer must be null", pageTransformer);
+    }
+
+}
diff --git a/material-stepper/src/test/java/com/stepstone/stepper/internal/widget/pagetransformer/StepperRtlPageTransformerTest.java b/material-stepper/src/test/java/com/stepstone/stepper/internal/widget/pagetransformer/StepperRtlPageTransformerTest.java
@@ -0,0 +1,75 @@
+package com.stepstone.stepper.internal.widget.pagetransformer;
+
+import android.view.View;
+
+import com.stepstone.stepper.test.runner.StepperRobolectricTestRunner;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+
+import static org.mockito.AdditionalMatchers.or;
+import static org.mockito.Matchers.eq;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/**
+ * @author Piotr Zawadzki
+ */
+@RunWith(StepperRobolectricTestRunner.class)
+public class StepperRtlPageTransformerTest {
+
+    private static final int VIEW_WIDTH = 320;
+
+    @Mock
+    View mockView;
+
+    StepperRtlPageTransformer pageTransformer = new StepperRtlPageTransformer();
+
+    @Before
+    public void setUp() {
+        when(mockView.getWidth()).thenReturn(VIEW_WIDTH);
+    }
+
+    @Test
+    public void should_reset_translationX_when_at_front_center() {
+        //when
+        pageTransformer.transformPage(mockView, 0.0f);
+
+        //then
+        verify(mockView).setTranslationX(isZero());
+    }
+
+    @Test
+    public void should_reverse_view_when_at_one_full_position_to_the_right() {
+        //when
+        pageTransformer.transformPage(mockView, 1.0f);
+
+        //then
+        verify(mockView).setTranslationX(-2 * VIEW_WIDTH);
+    }
+
+    @Test
+    public void should_reverse_view_when_at_one_full_position_to_the_left() {
+        //when
+        pageTransformer.transformPage(mockView, -1.0f);
+
+        //then
+        verify(mockView).setTranslationX(2 * VIEW_WIDTH);
+    }
+
+    @Test
+    public void should_reverse_view_when_in_the_middle() {
+        //when
+        pageTransformer.transformPage(mockView, 0.5f);
+
+        //then
+        verify(mockView).setTranslationX(-VIEW_WIDTH);
+    }
+
+    private float isZero() {
+        return or(eq(0.0f), eq(-0.0f));
+    }
+
+}
diff --git a/material-stepper/src/test/java/com/stepstone/stepper/test/TestApplication.java b/material-stepper/src/test/java/com/stepstone/stepper/test/TestApplication.java
@@ -0,0 +1,28 @@
+package com.stepstone.stepper.test;
+
+import android.app.Application;
+
+import org.mockito.MockitoAnnotations;
+import org.robolectric.TestLifecycleApplication;
+
+import java.lang.reflect.Method;
+
+/**
+ * @author Piotr Zawadzki
+ */
+public class TestApplication extends Application implements TestLifecycleApplication {
+
+        @Override
+        public void beforeTest(Method method) {
+        }
+
+        @Override
+        public void prepareTest(Object test) {
+            MockitoAnnotations.initMocks(test);//initialize all the mocks that were specified using annotations
+        }
+
+        @Override
+        public void afterTest(Method method) {
+        }
+
+}
diff --git a/material-stepper/src/test/java/com/stepstone/stepper/test/runner/StepperRobolectricTestRunner.java b/material-stepper/src/test/java/com/stepstone/stepper/test/runner/StepperRobolectricTestRunner.java

Original file line number	Diff line number	Diff line change
`@@ -331,9 +331,13 @@ public void setAdapter(@NonNull StepAdapter stepAdapter, @IntRange(from = 0) int`
`331`	`331`	`}`
`332`	`332`
`333`	`333`	`/**`
`334`		`- * Overrides the default page transformer used in the underlying {@link ViewPager}`
	`334`	`+ * Overrides the default page transformer used in the underlying {@link com.stepstone.stepper.internal.widget.StepViewPager}.`
	`335`	`+ * If you're supporting RTL make sure your {@link android.support.v4.view.ViewPager.PageTransformer} accounts for it.`
`335`	`336`	`*`
`336`	`337`	`* @param pageTransformer new page transformer`
	`338`	`+ *`
	`339`	`+ * @see com.stepstone.stepper.internal.widget.StepViewPager`
	`340`	`+ * @see com.stepstone.stepper.internal.widget.pagetransformer.StepPageTransformerFactory`
`337`	`341`	`*/`
`338`	`342`	`public void setPageTransformer(@Nullable ViewPager.PageTransformer pageTransformer) {`
`339`	`343`	`mPager.setPageTransformer(false, pageTransformer);`