Implement stretching the views by taking ALIGN_ITEMS_STRETCH and

ALIGN_SELF_STRETCH into account.

Change-Id: I4915c77407decdd218db1117a7697ea8f9ddd7cf

library/src/androidTest/java/com/google/android/libraries/flexbox/test/FlexboxAndroidTest.java

@@ -28,6 +28,7 @@ import static android.support.test.espresso.assertion.PositionAssertions.isRight
 import static android.support.test.espresso.assertion.PositionAssertions.isTopAlignedWith;
 import static android.support.test.espresso.matcher.ViewMatchers.withId;
 import static org.hamcrest.core.Is.is;
+import static org.hamcrest.core.IsNot.not;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThat;
 
@@ -611,6 +612,66 @@ public class FlexboxAndroidTest {
         assertThat(textView3.getTop(), is(textView1.getHeight()));
     }
 
+    @Test
+    public void testAlignItems_stretch() throws Throwable {
+        final FlexboxTestActivity activity = mActivityRule.getActivity();
+        mActivityRule.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                activity.setContentView(R.layout.activity_stretch_test);
+            }
+        });
+        FlexboxLayout flexboxLayout = (FlexboxLayout) activity.findViewById(R.id.flexbox_layout);
+
+        assertThat(flexboxLayout.getAlignItems(), is(FlexboxLayout.ALIGN_ITEMS_STRETCH));
+        onView(withId(R.id.text1)).check(isTopAlignedWith(withId(R.id.flexbox_layout)));
+        onView(withId(R.id.text1)).check(isLeftAlignedWith(withId(R.id.flexbox_layout)));
+        onView(withId(R.id.text2)).check(isTopAlignedWith(withId(R.id.flexbox_layout)));
+        onView(withId(R.id.text2)).check(isRightOf(withId(R.id.text1)));
+        onView(withId(R.id.text3)).check(isLeftAlignedWith(withId(R.id.flexbox_layout)));
+        onView(withId(R.id.text3)).check(isBelow(withId(R.id.text1)));
+        onView(withId(R.id.text3)).check(isBelow(withId(R.id.text2)));
+
+        // There should be 2 flex lines in the layout with the given layout.
+        int flexLineSize = flexboxLayout.getHeight() / 2;
+        TextView textView1 = (TextView) activity.findViewById(R.id.text1);
+        TextView textView2 = (TextView) activity.findViewById(R.id.text2);
+        TextView textView3 = (TextView) activity.findViewById(R.id.text3);
+        assertThat(textView1.getHeight(), is(flexLineSize));
+        assertThat(textView2.getHeight(), is(flexLineSize));
+        assertThat(textView3.getHeight(), is(flexLineSize));
+    }
+
+    @Test
+    public void testAlignSelf_stretch() throws Throwable {
+        final FlexboxTestActivity activity = mActivityRule.getActivity();
+        mActivityRule.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                activity.setContentView(R.layout.activity_align_self_stretch_test);
+            }
+        });
+        FlexboxLayout flexboxLayout = (FlexboxLayout) activity.findViewById(R.id.flexbox_layout);
+
+        onView(withId(R.id.text1)).check(isTopAlignedWith(withId(R.id.flexbox_layout)));
+        onView(withId(R.id.text1)).check(isLeftAlignedWith(withId(R.id.flexbox_layout)));
+        onView(withId(R.id.text2)).check(isTopAlignedWith(withId(R.id.flexbox_layout)));
+        onView(withId(R.id.text2)).check(isRightOf(withId(R.id.text1)));
+        onView(withId(R.id.text3)).check(isLeftAlignedWith(withId(R.id.flexbox_layout)));
+        onView(withId(R.id.text3)).check(isBelow(withId(R.id.text1)));
+        onView(withId(R.id.text3)).check(isBelow(withId(R.id.text2)));
+
+        // There should be 2 flex lines in the layout with the given layout.
+        // Only the first TextView's alignSelf is set to ALIGN_SELF_STRETCH
+        int flexLineSize = flexboxLayout.getHeight() / 2;
+        TextView textView1 = (TextView) activity.findViewById(R.id.text1);
+        TextView textView2 = (TextView) activity.findViewById(R.id.text2);
+        TextView textView3 = (TextView) activity.findViewById(R.id.text3);
+        assertThat(textView1.getHeight(), is(flexLineSize));
+        assertThat(textView2.getHeight(), not(flexLineSize));
+        assertThat(textView3.getHeight(), not(flexLineSize));
+    }
+
     private TextView createTextView(Context context, String text, int order) {
         TextView textView = new TextView(context);
         textView.setText(text);

library/src/androidTest/res/layout/activity_align_self_stretch_test.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Copyright 2016 Google Inc. All rights reserved.
+
+  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.
+  -->
+<com.google.android.libraries.flexbox.FlexboxLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:id="@+id/flexbox_layout"
+    android:layout_width="360dp"
+    android:layout_height="360dp"
+    app:flexDirection="row"
+    app:flexWrap="wrap"
+    app:alignItems="flex_start"
+    app:alignContent="stretch"
+    >
+
+    <TextView
+        android:id="@+id/text1"
+        android:layout_width="140dp"
+        android:layout_height="80dp"
+        android:text="1"
+        app:layout_alignSelf="stretch"
+        />
+
+    <TextView
+        android:id="@+id/text2"
+        android:layout_width="140dp"
+        android:layout_height="80dp"
+        android:text="2"
+        />
+
+    <TextView
+        android:id="@+id/text3"
+        android:layout_width="140dp"
+        android:layout_height="80dp"
+        android:text="3"
+        />
+</com.google.android.libraries.flexbox.FlexboxLayout>
\ No newline at end of file

library/src/androidTest/res/layout/activity_stretch_test.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Copyright 2016 Google Inc. All rights reserved.
+
+  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.
+  -->
+<com.google.android.libraries.flexbox.FlexboxLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:id="@+id/flexbox_layout"
+    android:layout_width="360dp"
+    android:layout_height="360dp"
+    app:flexDirection="row"
+    app:flexWrap="wrap"
+    app:alignItems="stretch"
+    >
+
+    <TextView
+        android:id="@+id/text1"
+        android:layout_width="140dp"
+        android:layout_height="80dp"
+        android:text="1"
+        />
+
+    <TextView
+        android:id="@+id/text2"
+        android:layout_width="140dp"
+        android:layout_height="80dp"
+        android:text="2"
+        />
+
+    <TextView
+        android:id="@+id/text3"
+        android:layout_width="140dp"
+        android:layout_height="80dp"
+        android:text="3"
+        />
+</com.google.android.libraries.flexbox.FlexboxLayout>
\ No newline at end of file

library/src/main/java/com/google/android/libraries/flexbox/FlexboxLayout.java

@@ -347,7 +347,22 @@ public class FlexboxLayout extends ViewGroup {
             }
         }
 
-        // TODO: handle stretch attributes
+        // Now cross size for each flex line is determined.
+        // Expand the views if alignItems (or alignSelf in each child view) is stretch
+        if (mAlignItems == ALIGN_ITEMS_STRETCH) {
+            int viewIndex = 0;
+            for (FlexLine flexLine : mFlexLines) {
+                for (int i = 0; i < flexLine.itemCount; i++, viewIndex++) {
+                    stretchViewVerticallyAt(viewIndex, flexLine.crossSize);
+                }
+            }
+        } else {
+            for (FlexLine flexLine : mFlexLines) {
+                for (Integer index : flexLine.indicesAlignSelfStretch) {
+                    stretchViewVerticallyAt(index, flexLine.crossSize);
+                }
+            }
+        }
 
         // Set this FlexboxLayout's width and height depending on the calculated length of main axis
         // and cross axis.
@@ -415,6 +430,21 @@ public class FlexboxLayout extends ViewGroup {
         }
     }
 
+    /**
+     * Expand the view vertically to the size of the crossSize (considering the view margins)
+     * @param index the absolute index of the view to be expanded
+     * @param crossSize the cross size
+     */
+    private void stretchViewVerticallyAt(int index, int crossSize) {
+        View child = getReorderedChildAt(index);
+        LayoutParams lp = (LayoutParams) child.getLayoutParams();
+        int newHeight = crossSize - lp.topMargin - lp.bottomMargin;
+        newHeight = Math.max(newHeight, 0);
+        child.measure(MeasureSpec
+                        .makeMeasureSpec(child.getMeasuredWidth(), MeasureSpec.EXACTLY),
+                MeasureSpec.makeMeasureSpec(newHeight, MeasureSpec.EXACTLY));
+    }
+
     /**
      * Determine if a wrap is required (add a new flex line).
      *