Recyclerview 的万能分割线
package com.example.administrator.haocai.widget;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.util.Log;
import android.view.View;
/**
* Date: 2016/10/26. 10:32
* Creator: henry
* Email: [email protected]
* Description: 万能分割线
*/
public class DividerItemDecoration extends RecyclerView.ItemDecoration {
private Paint mPaint;
//取名mDivider似乎更恰当
private Drawable mDrawable;
//分割线高度，默认为1px
private int mDividerHeight = 2;
//列表的方向
private int mOrientation;
//系统自带的参数
private static final int[] ATTRS = new int[]{android.R.attr.listDivider};
//水平
public static final int HORIZONTAL_LIST = RecyclerView.HORIZONTAL;
//垂直
public static final int VERTICAL_LIST = RecyclerView.VERTICAL;
//水平+垂直
public static final int BOTH_SET = 2;
/**
* 默认分割线：高度为2px，颜色为灰色
*
* @param context 上下文
* @param orientation 列表方向
*/
public DividerItemDecoration(Context context, int orientation) {
this.setOrientation(orientation);
//获取xml配置的参数
final TypedArray a = context.obtainStyledAttributes(ATTRS);
//typedArray.getDrawable(attr)这句是说我们可以通过我们的资源获得资源，使用我们的资源名attr去获得资源id
//看不懂就用自己写一个分割线的图片吧，方法：ContextCompat.getDrawable(context, drawableId);
mDrawable = a.getDrawable(0);
//官方的解释是：回收TypedArray，以便后面重用。在调用这个函数后，你就不能再使用这个TypedArray。
//在TypedArray后调用recycle主要是为了缓存。
a.recycle();
}
/**
* 自定义分割线
*
* @param context 上下文
* @param orientation 列表方向
* @param drawableId 分割线图片
*/
public DividerItemDecoration(Context context, int orientation, int drawableId) {
this.setOrientation(orientation);
//旧的getDrawable方法弃用了，这个是新的
mDrawable = ContextCompat.getDrawable(context, drawableId);
mDividerHeight = mDrawable.getIntrinsicHeight();
}
/**
* 自定义分割线
*
* @param context 上下文
* @param orientation 列表方向
* @param dividerHeight 分割线高度
* @param dividerColor 分割线颜色
*/
public DividerItemDecoration(Context context, int orientation,
int dividerHeight, int dividerColor) {
this.setOrientation(orientation);
mDividerHeight = dividerHeight;
Log.e("mDividerHeight", mDividerHeight + "===================");
//抗锯齿画笔
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(dividerColor);
//填满颜色
mPaint.setStyle(Paint.Style.FILL);
}
/**
* 设置方向
*
* @param orientation
*/
public void setOrientation(int orientation) {
if (orientation < 0 || orientation > 2)
throw new IllegalArgumentException("invalid orientation");
mOrientation = orientation;
}
/**
* 绘制分割线之后,需要留出一个外边框,就是说item之间的间距要换一下
*
* @param outRect outRect.set(0, 0, 0, 0);的四个参数理解成margin就好了
* @param view 视图
* @param parent 父级view
* @param state
*/
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
//下面super...代码其实调用的就是那个过时的getItemOffsets,也就是说这个方法体内容也可以通通移到那个过时的getItemOffsets中
super.getItemOffsets(outRect, view, parent, state);
//获取layoutParams参数
RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) view.getLayoutParams();
//当前位置
int itemPosition = layoutParams.getViewLayoutPosition();
//ItemView数量
int childCount = parent.getAdapter().getItemCount();
switch (mOrientation) {
case BOTH_SET:
//获取Layout的相关参数
int spanCount = this.getSpanCount(parent);
if (isLastRaw(parent, itemPosition, spanCount, childCount)) {
// 如果是最后一行，则不需要绘制底部
outRect.set(0, 0, mDividerHeight, 0);
} else if (isLastColum(parent, itemPosition, spanCount, childCount)) {
// 如果是最后一列，则不需要绘制右边
outRect.set(0, 0, 0, mDividerHeight);
} else {
outRect.set(0, 0, mDividerHeight, mDividerHeight);
}
break;
case VERTICAL_LIST:
childCount -= 1;
//水平布局右侧留Margin,如果是最后一列,就不要留Margin了
outRect.set(0, 0, (itemPosition != childCount) ? mDividerHeight : 0, 0);
break;
case HORIZONTAL_LIST:
childCount -= 1;
//垂直布局底部留边，最后一行不留
outRect.set(0, 0, 0, (itemPosition != childCount) ? mDividerHeight : 0);
break;
}
}
/**
* 绘制分割线
*
* @param c
* @param parent
* @param state
*/
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
super.onDraw(c, parent, state);
if (mOrientation == VERTICAL_LIST) {
drawVertical(c, parent);
} else if (mOrientation == HORIZONTAL_LIST) {
drawHorizontal(c, parent);
} else {
drawHorizontal(c, parent);
drawVertical(c, parent);
}
}
/**
* 绘制横向 item 分割线
*
* @param canvas 画布
* @param parent 父容器
*/
private void drawHorizontal(Canvas canvas, RecyclerView parent) {
final int x = parent.getPaddingLeft();
final int width = parent.getMeasuredWidth() - parent.getPaddingRight();
//getChildCount()(ViewGroup.getChildCount) 返回的是显示层面上的“所包含的子 View 个数”。
final int childSize = parent.getChildCount();
for (int i = 0; i < childSize; i++) {
final View child = parent.getChildAt(i);
RecyclerView.LayoutParams layoutParams =
(RecyclerView.LayoutParams) child.getLayoutParams();
//item底部的Y轴坐标+margin值
final int y = child.getBottom() + layoutParams.bottomMargin;
final int height = y + mDividerHeight;
Log.e("height", height + "===================");
if (mDrawable != null) {
//setBounds(x,y,width,height); x:组件在容器X轴上的起点 y:组件在容器Y轴上的起点
// width:组件的长度 height:组件的高度
mDrawable.setBounds(x, y, width, height);
mDrawable.draw(canvas);
}
if (mPaint != null) {
canvas.drawRect(x, y, width, height, mPaint);
}
}
}
/**
* 绘制纵向 item 分割线
*
* @param canvas
* @param parent
*/
private void drawVertical(Canvas canvas, RecyclerView parent) {
final int top = parent.getPaddingTop();
final int bottom = parent.getMeasuredHeight() - parent.getPaddingBottom();
final int childSize = parent.getChildCount();
for (int i = 0; i < childSize; i++) {
final View child = parent.getChildAt(i);
RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();
final int left = child.getRight() + layoutParams.rightMargin;
final int right = left + mDividerHeight;
if (mDrawable != null) {
mDrawable.setBounds(left, top, right, bottom);
mDrawable.draw(canvas);
}
if (mPaint != null) {
canvas.drawRect(left, top, right, bottom, mPaint);
}
}
}
/**
* 获取列数
*
* @param parent
* @return
*/
private int getSpanCount(RecyclerView parent) {
int spanCount = -1;
RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
spanCount = ((StaggeredGridLayoutManager) layoutManager)
.getSpanCount();
}
return spanCount;
}
private boolean isLastColum(RecyclerView parent, int pos, int spanCount,
int childCount) {
RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
int orientation = ((GridLayoutManager) layoutManager)
.getOrientation();
if (orientation == StaggeredGridLayoutManager.VERTICAL) {
// 如果是最后一列，则不需要绘制右边
if ((pos + 1) % spanCount == 0)
return true;
} else {
childCount = childCount - childCount % spanCount;
// 如果是最后一列，则不需要绘制右边
if (pos >= childCount)
return true;
}
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
int orientation = ((StaggeredGridLayoutManager) layoutManager)
.getOrientation();
if (orientation == StaggeredGridLayoutManager.VERTICAL) {
// 如果是最后一列，则不需要绘制右边
if ((pos + 1) % spanCount == 0)
return true;
} else {
childCount = childCount - childCount % spanCount;
// 如果是最后一列，则不需要绘制右边
if (pos >= childCount)
return true;
}
}
return false;
}
private boolean isLastRaw(RecyclerView parent, int pos, int spanCount,
int childCount) {
int orientation;
RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
childCount = childCount - childCount % spanCount;
orientation = ((GridLayoutManager) layoutManager)
.getOrientation();
if (orientation == StaggeredGridLayoutManager.VERTICAL) {
// 如果是最后一行，则不需要绘制底部
childCount = childCount - childCount % spanCount;
if (pos >= childCount)
return true;
} else {// StaggeredGridLayoutManager 横向滚动
// 如果是最后一行，则不需要绘制底部
if ((pos + 1) % spanCount == 0)
return true;
}
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
orientation = ((StaggeredGridLayoutManager) layoutManager)
.getOrientation();
if (orientation == StaggeredGridLayoutManager.VERTICAL) {
// 如果是最后一行，则不需要绘制底部
childCount = childCount - childCount % spanCount;
if (pos >= childCount)
return true;
} else {// StaggeredGridLayoutManager 横向滚动
// 如果是最后一行，则不需要绘制底部
if ((pos + 1) % spanCount == 0)
return true;
}
}
return false;
}
}