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[Carousel] Add full screen strategy
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PiperOrigin-RevId: 544471620
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imhappi authored and raajkumars committed Jul 5, 2023
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/*
* Copyright 2023 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
*
* https://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.google.android.material.carousel;

import static com.google.android.material.carousel.CarouselStrategyHelper.createLeftAlignedKeylineState;
import static java.lang.Math.min;

import androidx.recyclerview.widget.RecyclerView.LayoutParams;
import android.view.View;
import androidx.annotation.NonNull;

/**
* A {@link CarouselStrategy} that fits one full-width or full-height item into a container to
* create a layout to browse one item at a time.
*
* <p>Note that the item masks will be based on the items encompassing the full width or full height
* of the carousel. The carousel item dimensions should reflect this with `match_parent` dimensions.
*
* <p>This class will automatically be reversed by {@link CarouselLayoutManager} if being laid out
* right-to-left and does not need to make any account for layout direction itself.
*/
public class FullScreenCarouselStrategy extends CarouselStrategy {

@Override
@NonNull
KeylineState onFirstChildMeasuredWithMargins(@NonNull Carousel carousel, @NonNull View child) {
float availableSpace;
LayoutParams childLayoutParams = (LayoutParams) child.getLayoutParams();
float childMargins;
if (carousel.isHorizontal()) {
availableSpace = carousel.getContainerWidth();
childMargins = childLayoutParams.leftMargin + childLayoutParams.rightMargin;
} else {
availableSpace = carousel.getContainerHeight();
childMargins = childLayoutParams.topMargin + childLayoutParams.bottomMargin;
}
float targetChildSize = min(availableSpace + childMargins, availableSpace);
Arrangement arrangement = new Arrangement(
/* priority= */ 0,
/* targetSmallSize= */ 0,
/* minSmallSize= */ 0,
/* maxSmallSize= */ 0,
/* smallCount= */ 0,
/* targetMediumSize= */ 0,
/* mediumCount= */ 0,
targetChildSize,
/* largeCount= */ 1,
availableSpace);
return createLeftAlignedKeylineState(
child.getContext(), childMargins, availableSpace, arrangement);
}
}
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/*
* Copyright 2023 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.google.android.material.carousel;

import com.google.android.material.test.R;

import static com.google.android.material.carousel.CarouselHelper.createCarouselWithWidth;
import static com.google.android.material.carousel.CarouselHelper.createViewWithSize;
import static com.google.common.truth.Truth.assertThat;

import androidx.recyclerview.widget.RecyclerView.LayoutParams;
import android.view.View;
import androidx.test.core.app.ApplicationProvider;
import com.google.android.material.carousel.KeylineState.Keyline;
import java.util.List;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.robolectric.RobolectricTestRunner;

/** Tests for {@link FullScreenCarouselStrategy}. */
@RunWith(RobolectricTestRunner.class)
public class FullScreenCarouselStrategyTest {

@Test
public void testItemSmallerThanContainer_showsOneLarge() {
Carousel carousel = createCarouselWithWidth(400);
FullScreenCarouselStrategy config = new FullScreenCarouselStrategy();
View view = createViewWithSize(ApplicationProvider.getApplicationContext(), 100, 400);

KeylineState keylineState = config.onFirstChildMeasuredWithMargins(carousel, view);

// A fullscreen layout should be [xSmall-large-xSmall] where the xSmall items are
// outside the bounds of the carousel container and the large center item takes up the
// container's full width.
assertThat(keylineState.getKeylines()).hasSize(3);
assertThat(keylineState.getKeylines().get(0).locOffset).isLessThan(0F);
assertThat(keylineState.getKeylines().get(1).mask).isEqualTo(0F);
assertThat(keylineState.getKeylines().get(2).locOffset)
.isGreaterThan((float) carousel.getContainerHeight());
}

@Test
public void testKnownArrangement_correctlyCalculatesKeylineLocations() {
View view = createViewWithSize(ApplicationProvider.getApplicationContext(), 400, 200);

FullScreenCarouselStrategy config = new FullScreenCarouselStrategy();
float extraSmallSize =
view.getResources().getDimension(R.dimen.m3_carousel_gone_size);
// Keyline sizes for the fullscreen variant carousel are:
// {extraSmallSize, largeSize, extraSmallSize}
// The keyline loc offsets are placed so that an item centered on a keyline has the
// keyline size described above.
float[] locOffsets = new float[] {-extraSmallSize / 2f, 200, 400 + extraSmallSize / 2f};

List<Keyline> keylines =
config.onFirstChildMeasuredWithMargins(createCarouselWithWidth(400), view).getKeylines();
for (int i = 0; i < keylines.size(); i++) {
assertThat(keylines.get(i).locOffset).isEqualTo(locOffsets[i]);
}
}

@Test
public void testKnownArrangementWithMargins_correctlyCalculatesKeylineLocations() {
View view = createViewWithSize(ApplicationProvider.getApplicationContext(), 400, 200);
LayoutParams layoutParams = (LayoutParams) view.getLayoutParams();
layoutParams.leftMargin += 50;
layoutParams.rightMargin += 30;

FullScreenCarouselStrategy config = new FullScreenCarouselStrategy();
float extraSmallSize = view.getResources().getDimension(R.dimen.m3_carousel_gone_size);
// Keyline sizes for the fullscreen variant carousel are:
// {extraSmallSize, largeSize, extraSmallSize}
// The keyline loc offsets are placed so that an item centered on a keyline has the
// keyline size described above.
// The large size is based on whatever width is left over from the minimum small size.
float[] locOffsets =
new float[] {-(extraSmallSize + 80) / 2f, 200, 400 + (extraSmallSize + 80) / 2f};

List<Keyline> keylines =
config.onFirstChildMeasuredWithMargins(createCarouselWithWidth(400), view).getKeylines();
for (int i = 0; i < keylines.size(); i++) {
assertThat(keylines.get(i).locOffset).isEqualTo(locOffsets[i]);
}
}
}

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