关于缩放，使用了view.setScaleX/Y 方法，api11以上即可。

重写dispatchDraw()，绘制选中项的焦点效果。(注意带阴影的焦点图需要微调偏移量)

要将选中项绘制显示在顶层，所以要改变GridView的子View绘制顺序；

所以要重写bringChildToFront、getChildDrawingOrder，同时要打开setChildrenDrawingOrderEnabled(true)。

在缩放代码中添加了监听器，用于调用端，设置回调。

注意： 如果GridView的最后一行的个数少于列数，在较少的列上向下，会报异常。 还有就是当快速切换时，可能会看到默认的listSelector，可以将其设置为透明的。

package com.stone.tvapplication.widget;

import android.content.Context;

import android.content.res.TypedArray;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Rect;

import android.graphics.drawable.Drawable;

import android.util.AttributeSet;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AbsListView;

import android.widget.GridView;

import android.widget.ImageView;

import android.widget.RelativeLayout;

import android.widget.TextView;

import com.stone.tvapplication.R;

import com.stone.tvapplication.util.AdaptionAlgo;

/**

* 重写dispatchDraw，在选中项上绘制一个focus-drawable

*

* author : stone

* email : aa86799@163.com

* time : 16/5/11 10 20

*/

public class TvFocusGridView extends GridView {

private Drawable mFocusBackDrawable;

private Rect mFocusBackRect;

private int mSelectedPosition;

private View mSelectedView;

private float mScaleX;

private float mScaleY;

private onItemFocusSelectedListener mOnItemFocusSelectedListener;

public TvFocusGridView(Context context) {

this(context, null);

}

public TvFocusGridView(Context context, AttributeSet attrs) {

this(context, attrs, 0);

}

public TvFocusGridView(Context context, AttributeSet attrs, int defStyleAttr) {

super(context, attrs, defStyleAttr);

setClipChildren(false);

setClipToPadding(false);

setChildrenDrawingOrderEnabled(true);//设置绘制顺序可重定义，需要重写getChildDrawingOrder来变化绘制顺序

TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.TvFocusGridView);

mFocusBackDrawable = array.getDrawable(R.styleable.TvFocusGridView_focus_background);

array.recycle();

mFocusBackRect = new Rect();

mFocusBackDrawable.getPadding(mFocusBackRect); //Drawable中实际填充图像的Rect

// System.out.println("mFocusBackRect-->" + mFocusBackRect);

}

public interface onItemFocusSelectedListener {

void onFocused(View child, int position);

void unfocused(View child, int position);

}

public void setOnItemFocusSelectedListener(onItemFocusSelectedListener onItemFocusSelectedListener) {

this.mOnItemFocusSelectedListener = onItemFocusSelectedListener;

}

@Override

protected void dispatchDraw(Canvas canvas) {

super.dispatchDraw(canvas);

if (mFocusBackDrawable == null) {

return;

}

drawSelector(canvas);

}

private void drawSelector(Canvas canvas) {

View view = getSelectedView();

if (view == null) return;

bringChildToFront(view);

if (isFocused()) {

scaleSelectedView(view);

Rect gvVisibleRect = new Rect();

this.getGlobalVisibleRect(gvVisibleRect); //GridView可见区 在屏幕中的绝对坐标 rect

Rect selectedViewRect = new Rect();

if (mSelectedView instanceof ViewGroup) {

mSelectedView.getGlobalVisibleRect(selectedViewRect); //选中View可见区 在屏幕中的绝对坐标 rect

selectedViewRect.offset(-gvVisibleRect.left, - gvVisibleRect.top); //偏移

selectedViewRect.left -= mFocusBackRect.left + 40;//+阴影偏移

selectedViewRect.top -= mFocusBackRect.top + 20;

selectedViewRect.right += mFocusBackRect.right + 40;

selectedViewRect.bottom += mFocusBackRect.bottom + 20;

mFocusBackDrawable.setBounds(selectedViewRect);

mFocusBackDrawable.draw(canvas);

}

}

}

/**

* 使子view位置在上层

* @param child

*/

@Override

public void bringChildToFront(View child) { //重写，不调用父类方法；获取child的实际position

// super.bringChildToFront(child);

mSelectedPosition = indexOfChild(child);

invalidate();

}

@Override

protected int getChildDrawingOrder(int childCount, int i) {//交换 选中项与最后一项 绘制的顺序

if (mSelectedPosition != AbsListView.INVALID_POSITION) {

if (i == mSelectedPosition) {

return childCount - 1;

}

if (i == childCount - 1) {

return mSelectedPosition;

}

}

return super.getChildDrawingOrder(childCount, i);

}

private void scaleSelectedView(View view) {//缩放

unScalePreView();

mSelectedView = view;

mSelectedView.setScaleX(mScaleX); //api11

mSelectedView.setScaleY(mScaleY);

if (mOnItemFocusSelectedListener != null) {

mOnItemFocusSelectedListener.onFocused(mSelectedView, indexOfChild(mSelectedView));

}

}

private void unScalePreView() {//还原

if (mSelectedView != null) {

mSelectedView.setScaleX(1);

mSelectedView.setScaleY(1);

if (mOnItemFocusSelectedListener != null) {

mOnItemFocusSelectedListener.unfocused(mSelectedView, indexOfChild(mSelectedView));

}

mSelectedView = null;

}

}

@Override

protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) {//整个GridView焦点状态

if (!gainFocus) {

unScalePreView();

requestLayout();

}

super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);

}

public void setScale(float scaleX, float scaleY) {

this.mScaleX = scaleX;

this.mScaleY = scaleY;

}

}

调用端设置与监听：

mGridView.setAdapter(mAdapter);

mGridView.setScale(1.2f, 1.2f);

mGridView.setHorizontalSpacing(AdaptionAlgo.scaleX(30));

mGridView.setVerticalSpacing(AdaptionAlgo.scaleY(30));

mGridView.setPadding(60, 40, 60, 40);

mGridView.setOnItemFocusSelectedListener(new TvFocusGridView.onItemFocusSelectedListener() {

@Override

public void onFocused(View child, int position) {

TextView tv = getViewById(child, R.id.tv_text);

tv.setTextColor(Color.RED);

}

@Override

public void unfocused(View child, int position) {

TextView tv = getViewById(child, R.id.tv_text);

tv.setTextColor(Color.MAGENTA);

}

});