androidx.recyclerview.widget.RecyclerView#setPadding ( )源码实例Demo

private RecyclerView createRecyclerView(boolean listTypeGrid) {
  Context context = requireContext();
  RecyclerView recyclerView = new RecyclerView(context);
  recyclerView.setLayoutParams(
      new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
  int verticalPadding =
      context.getResources().getDimensionPixelSize(R.dimen.album_list_padding_vertical);
  recyclerView.setPadding(0, verticalPadding, 0, verticalPadding);
  recyclerView.setClipToPadding(false);
  if (listTypeGrid) {
    recyclerView.setLayoutManager(new GridLayoutManager(context, GRID_SPAN_COUNT));
  } else {
    recyclerView.setLayoutManager(new LinearLayoutManager(context));
    recyclerView.addItemDecoration(
        new DividerItemDecoration(context, DividerItemDecoration.VERTICAL));
  }
  return recyclerView;
}
 

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    mRecyclerView = (RecyclerView) view;
    mRecyclerView.setBackgroundColor(0xFF323232);
    mAdapter = new AdvancedListAdapter();
    mRecyclerView.setAdapter(mAdapter);
    int divider = getResources().getDimensionPixelSize(R.dimen.divider);
    mRecyclerView.setPadding(divider/2,divider/2,divider/2,divider/2);
    RecyclerView.LayoutManager layoutManager = new GridLayoutManager(getActivity(),2);

    mRecyclerView.setLayoutManager(layoutManager);
    mRecyclerView.addItemDecoration(new SpaceItemDecoration(divider));
    initCells();
}
 

protected void applyRecyclerViewPaddingForLayoutRes(@NonNull RecyclerView recyclerView, @LayoutRes int res) {
    int padding;
    if (res == R.layout.item_grid) {
        padding = (int) (getResources().getDisplayMetrics().density * 2);
    } else {
        padding = 0;
    }
    recyclerView.setPadding(padding, padding, padding, padding);
}
 

private void prepareListView(Context context) {
	mListView = new RecyclerView(context);
	mAdapter = new ItemAdapter();

	mListView.setClipToPadding(false);
	mListView.setPadding(0, getResources().getDimensionPixelSize(R.dimen.stepper_margin_top), 0, 0);

	mListView.addItemDecoration(new VerticalSpaceItemDecoration(
			getResources().getDimensionPixelSize(R.dimen.vertical_stepper_item_space_height)));
	mListView.setLayoutManager(new LinearLayoutManager(context));
	mListView.setAdapter(mAdapter);

	addView(mListView, new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
}
 

public MenuBottomSheetDialog(@NonNull Context context) {
    super(context);

    RecyclerView content = new RecyclerView(context);
    content.setLayoutManager(new LinearLayoutManager(context));
    content.setAdapter(new ItemAdapter());
    int verticalPadding = content.getResources().getDimensionPixelSize(R.dimen.bottom_sheet_menu_vertical_margin);
    content.setPadding(0, verticalPadding, 0, verticalPadding);
    setContentView(content);

    content.setBackgroundColor(StyledAttributesHelper.getColor(context, R.attr.colorBackgroundFloating, 0));
}
 

protected void applyRecyclerViewPaddingForLayoutRes(@NonNull RecyclerView recyclerView, @LayoutRes int res) {
    int padding;
    if (res == R.layout.item_grid) {
        padding = (int) (getResources().getDisplayMetrics().density * 2);
    } else {
        padding = 0;
    }
    recyclerView.setPadding(padding, padding, padding, padding);
}
 

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {

    if (parent.getPaddingLeft() != halfSpace) {
        parent.setPadding(halfSpace, halfSpace, halfSpace, halfSpace);
        parent.setClipToPadding(false);
    }

    outRect.top = halfSpace;
    outRect.bottom = halfSpace;
    outRect.left = halfSpace;
    outRect.right = halfSpace;
}
 

public GridMarginsDecoration(@Px float marginsVertical, @Px float marginsHorizontal, RecyclerView recyclerView) {
    this.marginsVertical = marginsVertical;
    this.marginsHorizontal = marginsHorizontal;
    recyclerView.setClipToPadding(false);
    recyclerView.setPadding(
            (int) marginsHorizontal / 2,
            (int) marginsVertical / 2,
            (int) marginsHorizontal / 2,
            (int) marginsVertical / 2
    );
}
 

private void setParentPadding(RecyclerView parent, @Px int padding, Rect insets) {
    parent.setPadding(
            padding + insets.left,
            padding,
            padding + insets.right,
            padding + insets.bottom
    );
    parent.setClipToPadding(false);
}
 

@NonNull
@Override
public final RecyclerView onCreateRecyclerView(final LayoutInflater inflater,
                                               final ViewGroup parent,
                                               final Bundle savedInstanceState) {
    RecyclerView recyclerView =
            super.onCreateRecyclerView(inflater, parent, savedInstanceState);
    recyclerView.setClipToPadding(false);
    int paddingTop =
            getActivity().getResources().getDimensionPixelSize(R.dimen.list_view_padding_top);
    recyclerView.setPadding(recyclerView.getPaddingLeft(), paddingTop,
            recyclerView.getPaddingRight(), recyclerView.getPaddingBottom());
    return recyclerView;
}
 

protected void applyRecyclerViewPaddingForLayoutRes(@NonNull RecyclerView recyclerView, @LayoutRes int res) {
    int padding;
    if (res == R.layout.item_grid) {
        padding = (int) (getResources().getDisplayMetrics().density * 2);
    } else {
        padding = 0;
    }
    recyclerView.setPadding(padding, padding, padding, padding);
}
 

/**
 * Removes the padding previously added to the <code>recyclerView</code>
 * for the edge spacing.  If no padding was previously added, then this
 * has no affect
 *
 * @param recyclerView The RecyclerView to remove the padding from
 */
protected void resetRecyclerPadding(@NonNull RecyclerView recyclerView) {
    recyclerView.setPadding(
            recyclerView.getPaddingLeft() - edgeSpacing,
            recyclerView.getPaddingTop(),
            recyclerView.getPaddingRight() - edgeSpacing,
            recyclerView.getPaddingBottom()
    );
}
 

@Override
public RecyclerView onCreateRecyclerView(LayoutInflater inflater, ViewGroup parent,
                                         Bundle savedInstanceState) {
    RecyclerView view = super.onCreateRecyclerView(inflater, parent, savedInstanceState);
    view.setBackgroundColor(ContextCompat.getColor(getContext(), R.color.background));

    int padding = (int) getResources().getDimension(R.dimen.global_padding);
    view.setPadding(padding, 0, padding, 0);

    view.addItemDecoration(new BackgroundDecoration(android.R.id.title));
    view.addItemDecoration(new DividerDecoration(getContext(), android.R.id.title));

    return view;
}
 

protected void initViews() {
    inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View view = inflater.inflate(R.layout.ultimate_recycler_view_layout, this);
    mRecyclerView = (RecyclerView) view.findViewById(R.id.ultimate_list);
    mSwipeRefreshLayout = (VerticalSwipeRefreshLayout) view.findViewById(R.id.swipe_refresh_layout);
    setScrollbars();
    mSwipeRefreshLayout.setEnabled(false);

    if (mRecyclerView != null) {
        mRecyclerView.setClipToPadding(mClipToPadding);
        if (mPadding != -1.1f) {
            mRecyclerView.setPadding(mPadding, mPadding, mPadding, mPadding);
        } else {
            mRecyclerView.setPadding(mPaddingLeft, mPaddingTop, mPaddingRight, mPaddingBottom);
        }
    }

    defaultFloatingActionButton = (FloatingActionButton) view.findViewById(R.id.defaultFloatingActionButton);
    setDefaultScrollListener();

    /**
     * empty view setup
     */
    mEmpty = (ViewStub) view.findViewById(R.id.emptyview);
    if (mEmptyId != 0) {
        mEmpty.setLayoutResource(mEmptyId);
        mEmptyView = mEmpty.inflate();
        mEmpty.setVisibility(View.GONE);
    }

    /**
     * floating button setup
     */
    mFloatingButtonViewStub = (ViewStub) view.findViewById(R.id.floatingActionViewStub);
    mFloatingButtonViewStub.setLayoutResource(mFloatingButtonId);
}
 

@Override
protected void initViews() {
    //super.initViews();
    LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View view = inflater.inflate(R.layout.custom_recycler_view_layout, this);
    mRecyclerView = (RecyclerView) view.findViewById(R.id.ultimate_list);
    mSwipeRefreshLayout = null;

    if (mRecyclerView != null) {

        mRecyclerView.setClipToPadding(mClipToPadding);
        if (mPadding != -1.1f) {
            mRecyclerView.setPadding(mPadding, mPadding, mPadding, mPadding);
        } else {
            mRecyclerView.setPadding(mPaddingLeft, mPaddingTop, mPaddingRight, mPaddingBottom);
        }
    }

    defaultFloatingActionButton = (FloatingActionButton) view.findViewById(R.id.defaultFloatingActionButton);
    setDefaultScrollListener();

    mEmpty = (ViewStub) view.findViewById(R.id.emptyview);
    mFloatingButtonViewStub = (ViewStub) view.findViewById(R.id.floatingActionViewStub);

    mEmpty.setLayoutResource(mEmptyId);

    mFloatingButtonViewStub.setLayoutResource(mFloatingButtonId);

    if (mEmptyId != 0)
        mEmptyView = mEmpty.inflate();
    mEmpty.setVisibility(View.GONE);

    if (mFloatingButtonId != 0) {
        mFloatingButtonView = mFloatingButtonViewStub.inflate();
        mFloatingButtonView.setVisibility(View.VISIBLE);
    }

}
 

private void adjustPaddings() {
    RecyclerView recyclerView = mRecyclerView;
    recyclerView.setPadding(recyclerView.getPaddingLeft(), recyclerView.getPaddingTop() + mPaddingTopSB,
            recyclerView.getPaddingRight(), recyclerView.getPaddingBottom());
}
 

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    int screenWidth = getScreenWidth();

    // Setup ViewPager with indicator
    ViewPager pager = findViewById(R.id.pager);
    DemoPagerAdapter pagerAdapter = new DemoPagerAdapter(8);
    pager.setAdapter(pagerAdapter);

    ScrollingPagerIndicator pagerIndicator = findViewById(R.id.pager_indicator);
    pagerIndicator.attachToPager(pager);

    // Setup ViewPager2 with indicator
    ViewPager2 pager2 = findViewById(R.id.pager2);
    DemoRecyclerViewAdapter pagerAdapter2 = new DemoRecyclerViewAdapter(8, ViewGroup.LayoutParams.MATCH_PARENT);
    pager2.setAdapter(pagerAdapter2);

    ScrollingPagerIndicator pagerIndicator2 = findViewById(R.id.pager_indicator2);
    pagerIndicator2.attachToPager(pager2);

    // Setup RecyclerView with indicator
    // One page will occupy 1/3 of screen width
    RecyclerView recyclerView = findViewById(R.id.recycler);
    recyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
    DemoRecyclerViewAdapter recyclerAdapter = new DemoRecyclerViewAdapter(8, screenWidth / 3);
    recyclerView.setAdapter(recyclerAdapter);

    recyclerView.setPadding(screenWidth / 3, 0, screenWidth / 3, 0);

    ScrollingPagerIndicator recyclerIndicator = findViewById(R.id.recycler_indicator);
    // Consider page in the middle current
    recyclerIndicator.attachToRecyclerView(recyclerView);

    SnapHelper snapHelper = new PagerSnapHelper();
    snapHelper.attachToRecyclerView(recyclerView);

    // Some controls
    NumberPicker pageCountPicker = findViewById(R.id.page_number_picker);
    pageCountPicker.setMaxValue(99);
    pageCountPicker.setMinValue(0);
    pageCountPicker.setValue(pagerAdapter.getCount());

    NumberPicker visibleDotCountPicker = findViewById(R.id.visible_dot_number_picker);
    visibleDotCountPicker.setMinValue(3);
    visibleDotCountPicker.setMaxValue(11);
    visibleDotCountPicker.setValue(pagerIndicator.getVisibleDotCount());

    visibleDotCountPicker.setOnValueChangedListener((picker, oldVal, newVal) -> {
        if (newVal % 2 == 0) {
            Toast.makeText(this, "Visible dot count must be odd number", Toast.LENGTH_SHORT).show();
            return;
        }
        pagerIndicator.setVisibleDotCount(newVal);
        recyclerIndicator.setVisibleDotCount(newVal);
    });

    pageCountPicker.setOnValueChangedListener((picker, oldVal, newVal) -> {
        if (pager.getCurrentItem() >= newVal - 1) {
            pager.setCurrentItem(newVal - 1, false);
        }
        pagerAdapter.setCount(newVal);
        recyclerAdapter.setCount(newVal);
    });
}
 

private void adjustPaddings() {
    RecyclerView recyclerView = mRecyclerView;
    recyclerView.setPadding(recyclerView.getPaddingLeft(), recyclerView.getPaddingTop() + mPaddingTopSB,
            recyclerView.getPaddingRight(), recyclerView.getPaddingBottom());
}
 

private void setParentPadding(RecyclerView parent, Rect insets) {
    parent.setPadding(insets.left, 0, insets.right, insets.bottom);
    parent.setClipToPadding(false);
}
 

/**
 * Calculates and adds the amount of spacing that needs to be between each
 * column, row, and the edges of the RecyclerView.  This pays attention to
 * the value from {@link #setSpacingMethod(SpacingMethod)}
 *
 * @param recyclerView The RecyclerView to use for determining the amount of space that needs to be added
 * @param gridItemWidth The requested width for the items
 * @param columnCount The number of columns to display
 */
protected void updateSpacing(@NonNull RecyclerView recyclerView, int gridItemWidth, int columnCount) {
    //Sets the decoration for the calculated spacing
    if (spacerDecoration == null) {
        spacerDecoration = new SpacerDecoration();
        spacerDecoration.setAllowedEdgeSpacing(SpacerDecoration.EDGE_SPACING_LEFT | SpacerDecoration.EDGE_SPACING_RIGHT);
        recyclerView.addItemDecoration(spacerDecoration);
    }

    edgeSpacing = minColumnSpacingEdge;
    int separatorSpacing = minColumnSpacingSeparator / 2;


    //Calculates the edge spacing requirements
    int padding = recyclerView.getPaddingLeft() + recyclerView.getPaddingRight();
    int usableWidth = recyclerView.getWidth() - padding;

    int separatorCount = columnCount -1;
    int spacerCount = 2 * columnCount;

    int freeSpace = usableWidth - (gridItemWidth * columnCount);
    int extraSpace = freeSpace - (2 * minColumnSpacingEdge) - (separatorCount * minColumnSpacingSeparator);

    //If we can add spacing, then we need to calculate how much and where to add it
    if (extraSpace >= spacerCount) {
        if (spacingMethod == SpacingMethod.ALL) {
            int totalMinEdges = minColumnSpacingEdge * 2;
            int totalMinSeparators = separatorCount * minColumnSpacingSeparator;

            //If the totalMinSpace is 0, then the percentage is edge count / separators + edges
            int totalMinSpace = totalMinEdges + totalMinSeparators;
            double edgeSpacePercentage = totalMinSpace == 0 ? (2 / (2 + separatorCount)) : (double)totalMinEdges / (double)totalMinSpace;
            int totalSeparatorSpace = (int)((1d - edgeSpacePercentage) * freeSpace);

            separatorSpacing = spacerCount == 0 ? 0 : totalSeparatorSpace / spacerCount;
            edgeSpacing = ((freeSpace - totalSeparatorSpace) / 2) + separatorSpacing;
        } else if (spacingMethod == SpacingMethod.EDGES) {
            edgeSpacing = (freeSpace - (separatorSpacing * spacerCount)) / 2;
        } else { //SEPARATOR
            separatorSpacing = spacerCount == 0 ? 0 : freeSpace / spacerCount;
        }

        edgeSpacing -= separatorSpacing;
    }

    //Updates the spacing using the decoration and padding
    recyclerView.setPadding(
            recyclerView.getPaddingLeft() + edgeSpacing,
            recyclerView.getPaddingTop(),
            recyclerView.getPaddingRight() + edgeSpacing,
            recyclerView.getPaddingBottom()
    );

    spacerDecoration.update(separatorSpacing, matchSpacing ? separatorSpacing : rowSpacing / 2);
}