Java tutorial
/* * Copyright 2015 Google Inc. * * 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.arbo.gaogao.view; import android.content.Context; import android.graphics.Canvas; import android.graphics.Paint; import android.support.annotation.ColorInt; import android.support.annotation.ColorRes; import android.support.annotation.DimenRes; import android.support.annotation.NonNull; import android.support.v4.content.ContextCompat; import android.support.v7.widget.RecyclerView; import android.view.View; /** * A {@link RecyclerView.ItemDecoration} which draws dividers (along the right & bottom) * for certain {@link RecyclerView.ViewHolder} types. */ public class GridItemDividerDecoration extends RecyclerView.ItemDecoration { private final float dividerSize; private final Paint paint; public GridItemDividerDecoration(float dividerSize, @ColorInt int dividerColor) { this.dividerSize = dividerSize; paint = new Paint(); paint.setColor(dividerColor); paint.setStyle(Paint.Style.FILL); } public GridItemDividerDecoration(@NonNull Context context, @DimenRes int dividerSizeResId, @ColorRes int dividerColorResId) { this(context.getResources().getDimensionPixelSize(dividerSizeResId), ContextCompat.getColor(context, dividerColorResId)); } @Override public void onDrawOver(Canvas canvas, RecyclerView parent, RecyclerView.State state) { if (parent.isAnimating()) return; final int childCount = parent.getChildCount(); final RecyclerView.LayoutManager lm = parent.getLayoutManager(); for (int i = 0; i < childCount; i++) { final View child = parent.getChildAt(i); RecyclerView.ViewHolder viewHolder = parent.getChildViewHolder(child); if (requiresDivider(viewHolder)) { final int right = lm.getDecoratedRight(child); final int bottom = lm.getDecoratedBottom(child); // draw the bottom divider canvas.drawRect(lm.getDecoratedLeft(child), bottom - dividerSize, right, bottom, paint); // draw the right edge divider canvas.drawRect(right - dividerSize, lm.getDecoratedTop(child), right, bottom - dividerSize, paint); } } } private boolean requiresDivider(RecyclerView.ViewHolder viewHolder) { return true; } }