com.mark.app.widget.recycler_view.LLMDivider.java Source code

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Here is the source code for com.mark.app.widget.recycler_view.LLMDivider.java

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/*
 * Copyright (C) 2014 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.mark.app.widget.recycler_view;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.LinearLayout;

/**
 * RecyclerViewLinearLayoutManager
 * ???{@link android.support.v7.widget.DividerItemDecoration}
 */
public class LLMDivider extends RecyclerView.ItemDecoration {

    public static final int HORIZONTAL_LIST = LinearLayout.HORIZONTAL;
    public static final int VERTICAL_LIST = LinearLayout.VERTICAL;

    private static final int[] ATTRS = new int[] { android.R.attr.listDivider };

    private Drawable mDivider;

    /**
     * Current orientation. Either {@link #HORIZONTAL_LIST} or {@link #VERTICAL_LIST}.
     */
    private int mOrientation;

    private final Rect mBounds = new Rect();

    /**
     * ????
     */
    private boolean mEnableLastItemDivider;

    /**
     * Creates a divider {@link RecyclerView.ItemDecoration} that can be used with a
     * {@link LinearLayoutManager}.
     *
     * @param context     Current context, it will be used to access resources.
     * @param orientation Divider orientation. Should be {@link #HORIZONTAL_LIST} or {@link #VERTICAL_LIST}.
     */
    public LLMDivider(Context context, int orientation) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();
        setOrientation(orientation);
    }

    /**
     * Sets the orientation for this divider. This should be called if
     * {@link RecyclerView.LayoutManager} changes orientation.
     *
     * @param orientation {@link #HORIZONTAL_LIST} or {@link #VERTICAL_LIST}
     */
    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
            throw new IllegalArgumentException("Invalid orientation. It should be either HORIZONTAL or VERTICAL");
        }
        mOrientation = orientation;
    }

    /**
     * ????
     *
     * @param enableLastItemDivider boolean
     */
    public void setEnableLastItemDivider(boolean enableLastItemDivider) {
        mEnableLastItemDivider = enableLastItemDivider;
    }

    /**
     * Sets the {@link Drawable} for this divider.
     *
     * @param drawable Drawable that should be used as a divider.
     */
    public void setDivider(@NonNull Drawable drawable) {
        mDivider = drawable;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (parent.getLayoutManager() == null) {
            return;
        }
        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }
    }

    private void drawVertical(Canvas canvas, RecyclerView parent) {
        canvas.save();
        final int left;
        final int right;
        if (getParentClipToPadding(parent)) {
            left = parent.getPaddingLeft();
            right = parent.getWidth() - parent.getPaddingRight();
            canvas.clipRect(left, parent.getPaddingTop(), right, parent.getHeight() - parent.getPaddingBottom());
        } else {
            left = 0;
            right = parent.getWidth();
        }

        // ???
        final int childCount = mEnableLastItemDivider ? parent.getChildCount() : parent.getChildCount() - 1;
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            parent.getLayoutManager().getDecoratedBoundsWithMargins(child, mBounds);
            final int bottom = mBounds.bottom + Math.round(ViewCompat.getTranslationY(child));
            final int top = bottom - mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(canvas);
        }
        canvas.restore();
    }

    private void drawHorizontal(Canvas canvas, RecyclerView parent) {
        canvas.save();
        final int top;
        final int bottom;
        if (getParentClipToPadding(parent)) {
            top = parent.getPaddingTop();
            bottom = parent.getHeight() - parent.getPaddingBottom();
            canvas.clipRect(parent.getPaddingLeft(), top, parent.getWidth() - parent.getPaddingRight(), bottom);
        } else {
            top = 0;
            bottom = parent.getHeight();
        }

        // ???
        final int childCount = mEnableLastItemDivider ? parent.getChildCount() : parent.getChildCount() - 1;
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            parent.getLayoutManager().getDecoratedBoundsWithMargins(child, mBounds);
            final int right = mBounds.right + Math.round(ViewCompat.getTranslationX(child));
            final int left = right - mDivider.getIntrinsicWidth();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(canvas);
        }
        canvas.restore();
    }

    /**
     * 21RecyclerView??clipToPadding
     *
     * @param parent RecyclerView
     * @return boolean
     */
    private boolean getParentClipToPadding(RecyclerView parent) {
        return Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP || parent.getClipToPadding();
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int childLayoutPosition = parent.getChildAdapterPosition(view);
        if (!mEnableLastItemDivider && childLayoutPosition == parent.getAdapter().getItemCount() - 1) {
            outRect.set(0, 0, 0, 0);
            return;
        }
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }
}