// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package org.chromium.chrome.browser.feed;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.view.View;
import androidx.recyclerview.widget.RecyclerView;
// Used to draw the background for the feed containment.
public class FeedItemDecoration extends RecyclerView.ItemDecoration {
/** Allows to mock for testing purpose. */
public interface DrawableProvider {
Drawable getDrawable(int resId);
}
private final FeedSurfaceCoordinator mCoordinator;
private final Drawable mTopRoundedBackground;
private final Drawable mBottomRoundedBackground;
private final Drawable mBottomLeftRoundedBackground;
private final Drawable mBottomRightRoundedBackground;
private final Drawable mNotRoundedBackground;
private final int mGutterPadding;
private final int mAdditionalBottomCardPadding;
public FeedItemDecoration(
Context context,
FeedSurfaceCoordinator coordinator,
DrawableProvider drawableProvider,
int gutterPadding) {
mCoordinator = coordinator;
mTopRoundedBackground =
drawableProvider.getDrawable(R.drawable.home_surface_ui_background_top_rounded);
mNotRoundedBackground =
drawableProvider.getDrawable(R.drawable.home_surface_ui_background_not_rounded);
mBottomRoundedBackground =
drawableProvider.getDrawable(R.drawable.home_surface_ui_background_bottom_rounded);
if (mCoordinator.useStaggeredLayout()) {
mBottomLeftRoundedBackground =
drawableProvider.getDrawable(
R.drawable.home_surface_ui_background_bottomleft_rounded);
mBottomRightRoundedBackground =
drawableProvider.getDrawable(
R.drawable.home_surface_ui_background_bottomright_rounded);
} else {
mBottomLeftRoundedBackground = null;
mBottomRightRoundedBackground = null;
}
mGutterPadding = gutterPadding;
mAdditionalBottomCardPadding =
context.getResources()
.getDimensionPixelSize(R.dimen.feed_containment_bottom_card_padding);
}
@Override
public void onDraw(Canvas canvas, RecyclerView parent, RecyclerView.State state) {
super.onDraw(canvas, parent, state);
if (mCoordinator.useStaggeredLayout()) {
drawBackgroundForStaggeredLayout(canvas, parent);
} else {
drawBackgroundForStandardLayout(canvas, parent);
}
}
private void drawBackgroundForStandardLayout(Canvas canvas, RecyclerView parent) {
for (int i = 0; i < parent.getChildCount(); ++i) {
View child = parent.getChildAt(i);
int position = parent.getChildAdapterPosition(child);
// Skip the non-feed elements.
if (!belongsToFeedContainment(position)) {
continue;
}
Rect bounds = new Rect();
parent.getDecoratedBoundsWithMargins(child, bounds);
// The last card comes with the divider which may overlap the bottom edge of
// the feed containment. To work around this, we add an additional bottom padding to
// the card.
if (isLastViewInFeedContainment(position)) {
bounds.bottom += mAdditionalBottomCardPadding;
}
// Draw the background for the view.
Drawable background = getBackgroundDrawable(position);
background.setBounds(bounds);
background.draw(canvas);
}
}
private void drawBackgroundForStaggeredLayout(Canvas canvas, RecyclerView parent) {
// When the feed is rendered in 2-column staggered layout, the total height of each
// column may not be equal due to the unfilled empty space at the end of one column.
// We need to find the bottom position of last card in each column so that we can
// "expand" the last card of the shorter column to be on par with the other column.
int leftColumnBottom = 0;
int rightColumnBottom = 0;
boolean reachLastViewInFeedContainment = false;
boolean reachFullSpanBottomViewInFeedContainment = false;
// Scan the child views until finding the one that is laid in multi-column. `i` is the index
// that points to such view after the for loop.
int indexOfFirstViewInMultiColumn = 0;
for (;
indexOfFirstViewInMultiColumn < parent.getChildCount();
++indexOfFirstViewInMultiColumn) {
View child = parent.getChildAt(indexOfFirstViewInMultiColumn);
int position = parent.getChildAdapterPosition(child);
// Skip the non-feed elements.
if (!belongsToFeedContainment(position)) {
continue;
}
// Skip the views which take the full span, like section header and sign-in promo.
int columnIndex = getColumnIndex(child);
if (columnIndex != -1) {
break;
}
}
// Continue checking the child views that are laid in multi-column in order to find the
// bottom position of each column.
for (int i = indexOfFirstViewInMultiColumn; i < parent.getChildCount(); ++i) {
View child = parent.getChildAt(i);
int position = parent.getChildAdapterPosition(child);
int columnIndex = getColumnIndex(child);
// There may be full-span view, like loading more indicator, beyond the card views
// laid in multi-column. If so, don't need to go further.
if (columnIndex == -1) {
reachFullSpanBottomViewInFeedContainment = true;
break;
}
Rect bounds = new Rect();
parent.getDecoratedBoundsWithMargins(child, bounds);
if (columnIndex == 0) {
if (bounds.bottom > leftColumnBottom) {
leftColumnBottom = bounds.bottom;
}
} else {
if (bounds.bottom > rightColumnBottom) {
rightColumnBottom = bounds.bottom;
}
}
// Don't need to go further if reaching the last view in feed containment.
if (isLastViewInFeedContainment(position)) {
reachLastViewInFeedContainment = true;
break;
}
}
int minBottom = Math.min(leftColumnBottom, rightColumnBottom);
int maxBottom = Math.max(leftColumnBottom, rightColumnBottom);
// We may just show the feed in single column even staggered layout is used, like the
// following feed. When this occurs, minBottom is 0.
boolean multiColumn = minBottom > 0;
// Now update the bounds and draw the background.
for (int i = 0; i < parent.getChildCount(); ++i) {
View child = parent.getChildAt(i);
int position = parent.getChildAdapterPosition(child);
// Skip the non-feed elements.
if (!belongsToFeedContainment(position)) {
continue;
}
Rect bounds = new Rect();
parent.getDecoratedBoundsWithMargins(child, bounds);
// Extend the bounds to compensate the gutter between columns and the unfilled empty
// space.
int columnIndex = getColumnIndex(child);
if (multiColumn) {
if (columnIndex != -1) {
if (columnIndex == 0) {
// For the card in the left column, include the gutter space.
bounds.right += 2 * mGutterPadding;
}
// For the bottom card in the shorter column, expand it to match the bottom card
// in the other column.
if ((reachLastViewInFeedContainment || reachFullSpanBottomViewInFeedContainment)
&& minBottom != maxBottom
&& bounds.bottom == minBottom) {
bounds.bottom += maxBottom - minBottom;
}
// The last card comes with the divider which may overlap the bottom edge of
// the feed containment if the last card is in the longer column. To work around
// this, we add an additional bottom padding to both bottom cards.
if (reachLastViewInFeedContainment && bounds.bottom == maxBottom) {
bounds.bottom += mAdditionalBottomCardPadding;
}
}
}
// Add an additional bottom padding for the last card that takes the full span.
if ((columnIndex == -1 || !multiColumn) && isLastViewInFeedContainment(position)) {
bounds.bottom += mAdditionalBottomCardPadding;
}
// Draw the background for the extended bounds.
Drawable background;
if (multiColumn
&& reachLastViewInFeedContainment
&& bounds.bottom == maxBottom + mAdditionalBottomCardPadding) {
background =
(columnIndex == 0)
? mBottomLeftRoundedBackground
: mBottomRightRoundedBackground;
} else {
background = getBackgroundDrawable(position);
}
background.setBounds(bounds);
background.draw(canvas);
}
}
// Returns the column index of the view in the staggered layout. Returns -1 if the view
// takes the full span.
private int getColumnIndex(View view) {
return mCoordinator.getHybridListRenderer().getListLayoutHelper().getColumnIndex(view);
}
private boolean belongsToFeedContainment(int position) {
// Exclude the NTP header views that appear above the feed header and the last view
// which is used to provide the bottom margin for the feed containment.
return position >= mCoordinator.getSectionHeaderPosition()
&& position < mCoordinator.getContentManager().getItemCount() - 1;
}
private boolean isLastViewInFeedContainment(int position) {
return position == mCoordinator.getContentManager().getItemCount() - 2;
}
private Drawable getBackgroundDrawable(int position) {
if (position == mCoordinator.getSectionHeaderPosition()) {
return mTopRoundedBackground;
} else if (isLastViewInFeedContainment(position)) {
return mBottomRoundedBackground;
} else {
return mNotRoundedBackground;
}
}
int getAdditionalBottomCardPaddingForTesting() {
return mAdditionalBottomCardPadding;
}
}
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