RecycleView学习3 ItemDecoration 自定义

本文主要是介绍RecycleView学习3 ItemDecoration 自定义，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

RecycleView ItemDecoration设置RecycleView 间隔，设置方式RecycleView.addItemDecoration();

public class DividedLinerDecorator extends RecyclerView.ItemDecoration {private Paint mPaint;private Drawable mDivider;private int mDividerHeight = 1;private int mOrientation;private static final int[] ATTRS = new int[]{android.R.attr.listDivider};public DividedLinerDecorator(Context context, int orientation) {if (orientation != LinearLayoutManager.VERTICAL && orientation != LinearLayoutManager.HORIZONTAL) {throw new IllegalArgumentException("");}mOrientation = orientation;final TypedArray a = context.obtainStyledAttributes(ATTRS);mDivider = a.getDrawable(0);a.recycle();}public DividedLinerDecorator(Context context, int orientation, int drawableId) {this(context, orientation);mDivider = ContextCompat.getDrawable(context, drawableId);mDividerHeight = mDivider.getIntrinsicHeight();}public DividedLinerDecorator(Context context, int orientation, int dividerHeight, int dividerColor) {this(context, orientation);mDividerHeight = dividerHeight;mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);mPaint.setColor(dividerColor);mPaint.setStyle(Paint.Style.FILL);}//设置上下左右间距@Overridepublic void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {super.getItemOffsets(outRect, view, parent, state);if (mOrientation == LinearLayoutManager.HORIZONTAL){outRect.set(0, 0, 0, mDividerHeight);}else{outRect.set(0, 0, mDividerHeight, 0);}}//绘制间隔@Overridepublic void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {super.onDraw(c, parent, state);if (mOrientation == LinearLayoutManager.VERTICAL) {drawVertical(c, parent);} else {drawHorizontal(c, parent);}}private void drawHorizontal(Canvas canvas, RecyclerView parent) {final int left = parent.getPaddingLeft();final int right = parent.getMeasuredWidth() - parent.getPaddingRight();final int childSize = parent.getChildCount();for (int i = 0; i < childSize - 1; i++) {final View child = parent.getChildAt(i);RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();final int top = child.getBottom() + layoutParams.bottomMargin;final int bottom = top + mDividerHeight;if (mDivider != null) {mDivider.setBounds(left, top, right, bottom);mDivider.draw(canvas);}if (mPaint != null) {canvas.drawRect(left, top, right, bottom, mPaint);}}}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 - 1; 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 (mDivider != null) {mDivider.setBounds(left, top, right, bottom);mDivider.draw(canvas);}if (mPaint != null) {canvas.drawRect(left, top, right, bottom, mPaint);}}}
}

getItemOffsets 中设置上下左右的边界：

@Overridepublic void getItemOffsets( Rect outRect, View view,RecyclerView parent, RecyclerView.State state ) {if ( portrait ) {if ( parent.getChildPosition( view ) == 0 )outRect.top = space;outRect.bottom = space;} else {if ( parent.getChildPosition( view ) == 0 )outRect.left = space;outRect.right = space;}}

onDraw 可以不重写，按照默认绘制方式，重写之后可以绘制成任意样式。

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