Add support for stretch views. (#161)

For the case where:
- align items attribute is set to stretch
OR
- align self attribute for individual flex item is set to stretch

flexbox/src/androidTest/java/com/google/android/flexbox/FlexboxHelperTest.java

@@ -411,4 +411,25 @@ public class FlexboxHelperTest {
         assertThat(view3.getMeasuredWidth(), isEqualAllowingError(333));
         assertThat(view4.getMeasuredWidth(), isEqualAllowingError(333));
     }
+
+    @Test
+    public void testMakeCombinedLong() {
+        int higher = -1;
+        int lower = 10;
+        long combined = mFlexboxHelper.makeCombinedLong(lower, higher);
+        assertThat(mFlexboxHelper.extractHigherInt(combined), is(higher));
+        assertThat(mFlexboxHelper.extractLowerInt(combined), is(lower));
+
+        higher = Integer.MAX_VALUE;
+        lower = Integer.MIN_VALUE;
+        combined = mFlexboxHelper.makeCombinedLong(lower, higher);
+        assertThat(mFlexboxHelper.extractHigherInt(combined), is(higher));
+        assertThat(mFlexboxHelper.extractLowerInt(combined), is(lower));
+
+        higher = View.MeasureSpec.makeMeasureSpec(500, View.MeasureSpec.EXACTLY);
+        lower = View.MeasureSpec.makeMeasureSpec(300, View.MeasureSpec.UNSPECIFIED);
+        combined = mFlexboxHelper.makeCombinedLong(lower, higher);
+        assertThat(mFlexboxHelper.extractHigherInt(combined), is(higher));
+        assertThat(mFlexboxHelper.extractLowerInt(combined), is(lower));
+    }
 }

flexbox/src/androidTest/java/com/google/android/flexbox/test/FlexboxLayoutManagerTest.java

@@ -18,6 +18,7 @@ package com.google.android.flexbox.test;
 
 import com.google.android.flexbox.AlignContent;
 import com.google.android.flexbox.AlignItems;
+import com.google.android.flexbox.AlignSelf;
 import com.google.android.flexbox.FlexDirection;
 import com.google.android.flexbox.FlexWrap;
 import com.google.android.flexbox.FlexboxLayoutManager;
@@ -1421,6 +1422,164 @@ public class FlexboxLayoutManagerTest {
         assertThat(layoutManager.getChildCount(), is(not(200)));
     }
 
+    @Test
+    @FlakyTest
+    public void testAlignItems_stretch_direction_row() throws Throwable {
+        final FlexboxTestActivity activity = mActivityRule.getActivity();
+        final FlexboxLayoutManager layoutManager = new FlexboxLayoutManager();
+        final TestAdapter adapter = new TestAdapter();
+        mActivityRule.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                activity.setContentView(R.layout.recyclerview);
+                RecyclerView recyclerView = (RecyclerView) activity.findViewById(R.id.recyclerview);
+                layoutManager.setFlexDirection(FlexDirection.ROW);
+                layoutManager.setAlignItems(AlignItems.STRETCH);
+                recyclerView.setLayoutManager(layoutManager);
+                recyclerView.setAdapter(adapter);
+                FlexboxLayoutManager.LayoutParams lp1 = createLayoutParams(activity, 70, 80);
+                adapter.addItem(lp1);
+                FlexboxLayoutManager.LayoutParams lp2 = createLayoutParams(activity, 70, 50);
+                adapter.addItem(lp2);
+                FlexboxLayoutManager.LayoutParams lp3 = createLayoutParams(activity, 70, 30);
+                adapter.addItem(lp3);
+                // RecyclerView width: 320, height: 240.
+            }
+        });
+        InstrumentationRegistry.getInstrumentation().waitForIdleSync();
+
+        assertThat(layoutManager.getFlexDirection(), is(FlexDirection.ROW));
+        assertThat(layoutManager.getAlignItems(), is(AlignItems.STRETCH));
+        assertThat(layoutManager.getFlexItemCount(), is(3));
+        assertThat(layoutManager.getFlexLines().size(), is(1));
+        // Verify all items heights are stretched
+        assertThat(layoutManager.getChildAt(0).getHeight(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+        assertThat(layoutManager.getChildAt(1).getHeight(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+        assertThat(layoutManager.getChildAt(2).getHeight(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+    }
+
+    @Test
+    @FlakyTest
+    public void testAlignItems_stretch_direction_column() throws Throwable {
+        final FlexboxTestActivity activity = mActivityRule.getActivity();
+        final FlexboxLayoutManager layoutManager = new FlexboxLayoutManager();
+        final TestAdapter adapter = new TestAdapter();
+        mActivityRule.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                activity.setContentView(R.layout.recyclerview);
+                RecyclerView recyclerView = (RecyclerView) activity.findViewById(R.id.recyclerview);
+                layoutManager.setFlexDirection(FlexDirection.COLUMN);
+                layoutManager.setAlignItems(AlignItems.STRETCH);
+                recyclerView.setLayoutManager(layoutManager);
+                recyclerView.setAdapter(adapter);
+                FlexboxLayoutManager.LayoutParams lp1 = createLayoutParams(activity, 80, 70);
+                adapter.addItem(lp1);
+                FlexboxLayoutManager.LayoutParams lp2 = createLayoutParams(activity, 50, 70);
+                adapter.addItem(lp2);
+                FlexboxLayoutManager.LayoutParams lp3 = createLayoutParams(activity, 30, 70);
+                adapter.addItem(lp3);
+                // RecyclerView width: 320, height: 240.
+            }
+        });
+        InstrumentationRegistry.getInstrumentation().waitForIdleSync();
+
+        assertThat(layoutManager.getFlexDirection(), is(FlexDirection.COLUMN));
+        assertThat(layoutManager.getAlignItems(), is(AlignItems.STRETCH));
+        assertThat(layoutManager.getFlexItemCount(), is(3));
+        assertThat(layoutManager.getFlexLines().size(), is(1));
+        // Verify all items widths are stretched
+        assertThat(layoutManager.getChildAt(0).getWidth(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+        assertThat(layoutManager.getChildAt(1).getWidth(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+        assertThat(layoutManager.getChildAt(2).getWidth(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+    }
+
+    @Test
+    @FlakyTest
+    public void testAlignSelf_stretch_direction_row() throws Throwable {
+        final FlexboxTestActivity activity = mActivityRule.getActivity();
+        final FlexboxLayoutManager layoutManager = new FlexboxLayoutManager();
+        final TestAdapter adapter = new TestAdapter();
+        mActivityRule.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                activity.setContentView(R.layout.recyclerview);
+                RecyclerView recyclerView = (RecyclerView) activity.findViewById(R.id.recyclerview);
+                layoutManager.setFlexDirection(FlexDirection.ROW);
+                layoutManager.setAlignItems(AlignItems.FLEX_START);
+                recyclerView.setLayoutManager(layoutManager);
+                recyclerView.setAdapter(adapter);
+                FlexboxLayoutManager.LayoutParams lp1 = createLayoutParams(activity, 70, 80);
+                adapter.addItem(lp1);
+                FlexboxLayoutManager.LayoutParams lp2 = createLayoutParams(activity, 70, 50);
+                adapter.addItem(lp2);
+                FlexboxLayoutManager.LayoutParams lp3 = createLayoutParams(activity, 70, 30);
+                lp3.setAlignSelf(AlignSelf.STRETCH);
+                adapter.addItem(lp3);
+                // RecyclerView width: 320, height: 240.
+            }
+        });
+        InstrumentationRegistry.getInstrumentation().waitForIdleSync();
+
+        assertThat(layoutManager.getFlexDirection(), is(FlexDirection.ROW));
+        assertThat(layoutManager.getAlignItems(), is(AlignItems.FLEX_START));
+        assertThat(layoutManager.getFlexItemCount(), is(3));
+        assertThat(layoutManager.getFlexLines().size(), is(1));
+        // Verify the item whose align self is set to stretch is stretched
+        assertThat(layoutManager.getChildAt(0).getHeight(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+        assertThat(layoutManager.getChildAt(1).getHeight(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 50)));
+        assertThat(layoutManager.getChildAt(2).getHeight(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+    }
+
+    @Test
+    @FlakyTest
+    public void testAlignSelf_stretch_direction_column() throws Throwable {
+        final FlexboxTestActivity activity = mActivityRule.getActivity();
+        final FlexboxLayoutManager layoutManager = new FlexboxLayoutManager();
+        final TestAdapter adapter = new TestAdapter();
+        mActivityRule.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                activity.setContentView(R.layout.recyclerview);
+                RecyclerView recyclerView = (RecyclerView) activity.findViewById(R.id.recyclerview);
+                layoutManager.setFlexDirection(FlexDirection.COLUMN);
+                layoutManager.setAlignItems(AlignItems.FLEX_START);
+                recyclerView.setLayoutManager(layoutManager);
+                recyclerView.setAdapter(adapter);
+                FlexboxLayoutManager.LayoutParams lp1 = createLayoutParams(activity, 80, 70);
+                adapter.addItem(lp1);
+                FlexboxLayoutManager.LayoutParams lp2 = createLayoutParams(activity, 50, 70);
+                adapter.addItem(lp2);
+                FlexboxLayoutManager.LayoutParams lp3 = createLayoutParams(activity, 30, 70);
+                lp3.setAlignSelf(AlignSelf.STRETCH);
+                adapter.addItem(lp3);
+                // RecyclerView width: 320, height: 240.
+            }
+        });
+        InstrumentationRegistry.getInstrumentation().waitForIdleSync();
+
+        assertThat(layoutManager.getFlexDirection(), is(FlexDirection.COLUMN));
+        assertThat(layoutManager.getAlignItems(), is(AlignItems.FLEX_START));
+        assertThat(layoutManager.getFlexItemCount(), is(3));
+        assertThat(layoutManager.getFlexLines().size(), is(1));
+        // Verify the item whose align self is set to stretch is stretched
+        assertThat(layoutManager.getChildAt(0).getWidth(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+        assertThat(layoutManager.getChildAt(1).getWidth(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 50)));
+        assertThat(layoutManager.getChildAt(2).getWidth(),
+                isEqualAllowingError(TestUtil.dpToPixel(activity, 80)));
+    }
+
     /**
      * Creates a new flex item.
      *

flexbox/src/main/java/com/google/android/flexbox/AlignSelf.java

@@ -37,4 +37,19 @@ public @interface AlignSelf {
      * the {@link AlignItems} attribute from its parent.
      */
     int AUTO = -1;
+
+    /** This item's edge is placed on the cross start line. */
+    int FLEX_START = AlignItems.FLEX_START;
+
+    /** This item's edge is placed on the cross end line. */
+    int FLEX_END = AlignItems.FLEX_END;
+
+    /** This item's edge is centered along the cross axis. */
+    int CENTER = AlignItems.CENTER;
+
+    /** This items is aligned based on their text's baselines. */
+    int BASELINE = AlignItems.BASELINE;
+
+    /** This item is stretched to fill the flex line's cross size. */
+    int STRETCH = AlignItems.STRETCH;
 }

flexbox/src/main/java/com/google/android/flexbox/FlexboxLayoutManager.java

@@ -454,6 +454,7 @@ public class FlexboxLayoutManager extends RecyclerView.LayoutManager implements
         ensureOrientationHelper();
         ensureLayoutState();
         mFlexboxHelper.ensureMeasureSpecCache(childCount);
+        mFlexboxHelper.ensureMeasuredSizeCache(childCount);
         mFlexboxHelper.ensureIndexToFlexLine(childCount);
 
         mLayoutState.mShouldRecycle = false;
@@ -884,8 +885,8 @@ public class FlexboxLayoutManager extends RecyclerView.LayoutManager implements
             // retrieved from Recycler, in that case measured width/height are set to 0 even
             // each visible child should be measured at least once in the FlexboxHelper
             long measureSpec = mFlexboxHelper.mMeasureSpecCache[i];
-            int widthSpec = mFlexboxHelper.extractWidthMeasureSpec(measureSpec);
-            int heightSpec = mFlexboxHelper.extractHeightMeasureSpec(measureSpec);
+            int widthSpec = mFlexboxHelper.extractLowerInt(measureSpec);
+            int heightSpec = mFlexboxHelper.extractHigherInt(measureSpec);
             LayoutParams lp = (LayoutParams) view.getLayoutParams();
             if (shouldMeasureChild(view, widthSpec, heightSpec, lp)) {
                 // TODO: Need to consider decorator length
@@ -1007,8 +1008,8 @@ public class FlexboxLayoutManager extends RecyclerView.LayoutManager implements
             // retrieved from Recycler, in that case measured width/height are set to 0 even
             // each visible child should be measured at least once in the FlexboxHelper
             long measureSpec = mFlexboxHelper.mMeasureSpecCache[i];
-            int widthSpec = mFlexboxHelper.extractWidthMeasureSpec(measureSpec);
-            int heightSpec = mFlexboxHelper.extractHeightMeasureSpec(measureSpec);
+            int widthSpec = mFlexboxHelper.extractLowerInt(measureSpec);
+            int heightSpec = mFlexboxHelper.extractHigherInt(measureSpec);
             LayoutParams lp = (LayoutParams) view.getLayoutParams();
             if (shouldMeasureChild(view, widthSpec, heightSpec, lp)) {
                 // TODO: Need to consider decorator length