Android 过度绘制性能优化<6>
过度绘制:专家的理解如下:
Overdraw(过度绘制)描述的是屏幕上的某个像素在同一帧的时间内被绘制了多次。在多层次重叠的UI结构里面，如果不可见的UI也在做绘制的操作，会导致某些像素区域被绘制了多次。这样就会浪费大量的CPU以及GPU资源
过度绘制在以前做项目中优化性能的时候就涉及到了,检查过度绘制倒是挺简单的,进入手机设置APP页面,开发者选项->Debug GPU overdraw选项,选择Show overdraw areas即可,所以的APP布局页面都会显示特别的背景颜色.
判断是否过度绘制就是根据上面显示出来的背景颜色来确定,是否存在过度绘制:
1X Overdraw : 代表同一个像素点上面只绘制了一次(比如仅仅设置了背景),
2X Overdraw : 代表绘制了两次.
其他的一次类推.
下面做一个APP验证一下:
<1> : 新建Android 工程,工程树如下:
<2> : 所有程序代码如下:
DurianMainActivity.java:
package org.durian.durianoverdraw; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.support.v7.app.ActionBarActivity; import android.util.Log; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.ImageView; import android.widget.ListView; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; public class DurianMainActivity extends ActionBarActivity implements View.OnClickListener { private final static String TAG = "DurianMainActivity"; private ListView mList; private DurianBaseAdapter mDurianBaseAdapter; private ImageView image; private Bitmap bitmap; private Button mButton; private Button mTranButton; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.durian_main); mList = (ListView) findViewById(R.id.list); image = (ImageView) findViewById(R.id.loadimage); mDurianBaseAdapter = new DurianBaseAdapter(this); mList.setAdapter(mDurianBaseAdapter); mButton = (Button) findViewById(R.id.button); mButton.setOnClickListener(this); mTranButton=(Button)findViewById(R.id.trans); mTranButton.setOnClickListener(this); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.menu_durian_main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); //noinspection SimplifiableIfStatement if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } private Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { super.handleMessage(msg); bitmap = BitmapFactory.decodeByteArray(buffer, 0, buffer.length); image.setImageBitmap(bitmap); } }; private byte buffer[]; private Bitmap imageLoadFromNet(String link) { URL url = null; try { url = new URL(link); } catch (MalformedURLException e) { e.printStackTrace(); } HttpURLConnection conn; try { conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET"); conn.setConnectTimeout(5000); InputStream in = conn.getInputStream(); int len = 0; byte buf[] = new byte[1024]; ByteArrayOutputStream out = new ByteArrayOutputStream(); while ((len = in.read(buf)) != -1) { out.write(buf, 0, len); } out.close(); buffer = out.toByteArray(); } catch (IOException e) { e.printStackTrace(); } return null; } @Override public void onClick(View v) { int id = v.getId(); switch (id) { case R.id.button: new Thread(new Runnable() { @Override public void run() { bitmap = imageLoadFromNet("http://pic.qiantucdn.com/58pic/16/06/95/58PIC4n58PICQTX_1024.jpg"); mHandler.sendEmptyMessage(0); } }).start(); break; case R.id.trans: image.setBackgroundColor(0x00ffffff); break; } } }
DurianBaseAdapter.java
package org.durian.durianoverdraw; import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.Window; import android.widget.BaseAdapter; import android.widget.ImageView; import android.widget.TextView; /** * Project name : DurianOverDraw * Created by zhibao.liu on 2016/1/11. * Time : 10:00 * Email [email protected] * Action : durian */ public class DurianBaseAdapter extends BaseAdapter { private Context mContext; private LayoutInflater mInflater; private ViewHolder holder; public DurianBaseAdapter(Context context){ mContext=context; mInflater= LayoutInflater.from(mContext); holder=new ViewHolder(); } @Override public int getCount() { return 3; } @Override public Object getItem(int position) { return null; } @Override public long getItemId(int position) { return 0; } @Override public View getView(int position, View convertView, ViewGroup parent) { if(convertView==null) { convertView=mInflater.inflate(R.layout.list_item,null); holder.imageView=(ImageView) convertView.findViewById(R.id.image); holder.titleText=(TextView)convertView.findViewById(R.id.title); holder.summaryText=(TextView)convertView.findViewById(R.id.summary); holder.imageView.setBackgroundColor(0xffffffff); } return convertView; } private class ViewHolder{ ImageView imageView; TextView titleText; TextView summaryText; } }
durian_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ListView
android:id="@+id/list"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="load image" />
<Button
android:id="@+id/trans"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Transparent" />
</LinearLayout>
<LinearLayout
android:id="@+id/image_trans"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<ImageView
android:id="@+id/loadimage"
android:background="#54625D"
android:layout_width="450dp"
android:layout_height="240dp"
/>
</LinearLayout>
</LinearLayout>
list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="96dp"
android:orientation="horizontal">
<ImageView
android:id="@+id/image"
android:layout_width="48dp"
android:layout_height="48dp"
android:layout_marginStart="16dp"
android:layout_marginTop="8dp"
android:background="#ffff0f"
android:src="@mipmap/ic_launcher"
/>
<LinearLayout
android:background="#fffffe"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="12dp"
android:orientation="vertical">
<LinearLayout
android:background="#fffffe"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#EEEEEF"
android:text="title" />
</LinearLayout>
<TextView
android:id="@+id/summary"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#EEEEEF"
android:text="summary" />
</LinearLayout>
</LinearLayout>
<3> : 运行结果:
根据上面的list_item布局,
title 颜色是深红色,即4X,summary是浅红色,即3X,title的背景是1X,summary背景2X
<4> : 下面看一个重点对象,我预先设置了一个ImageView,并且事先设置了它的背景:
点击"LOAD IMAGE"按钮:
注意图片和背景重叠的区域是浅绿色,浅绿色即2X,包含了两次渲染,即有两个"背景"
再点击"Transparent" 按钮:
发现了吧,颜色变了,变成1X了.也就是降低了图片的渲染工作.提供了性能.
上面主程序最好还调整一下:
package org.durian.durianoverdraw;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class DurianMainActivity extends ActionBarActivity implements View.OnClickListener {
private final static String TAG = "DurianMainActivity";
private ListView mList;
private DurianBaseAdapter mDurianBaseAdapter;
private ImageView image;
private Bitmap bitmap;
private Button mButton;
private Button mTranButton;
private LinearLayout mlinear;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.durian_main);
mList = (ListView) findViewById(R.id.list);
image = (ImageView) findViewById(R.id.loadimage);
mDurianBaseAdapter = new DurianBaseAdapter(this);
mList.setAdapter(mDurianBaseAdapter);
mButton = (Button) findViewById(R.id.button);
mButton.setOnClickListener(this);
mTranButton=(Button)findViewById(R.id.trans);
mTranButton.setOnClickListener(this);
mlinear=(LinearLayout)findViewById(R.id.image_trans);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_durian_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
bitmap = BitmapFactory.decodeByteArray(buffer, 0, buffer.length);
image.setImageBitmap(bitmap);
}
};
private byte buffer[];
private Bitmap imageLoadFromNet(String link) {
URL url = null;
try {
url = new URL(link);
} catch (MalformedURLException e) {
e.printStackTrace();
}
HttpURLConnection conn;
try {
conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
InputStream in = conn.getInputStream();
int len = 0;
byte buf[] = new byte[1024];
ByteArrayOutputStream out = new ByteArrayOutputStream();
while ((len = in.read(buf)) != -1) {
out.write(buf, 0, len);
}
out.close();
buffer = out.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
public void onClick(View v) {
int id = v.getId();
switch (id) {
case R.id.button:
new Thread(new Runnable() {
@Override
public void run() {
bitmap = imageLoadFromNet("http://pic.qiantucdn.com/58pic/16/06/95/58PIC4n58PICQTX_1024.jpg");
mHandler.sendEmptyMessage(0);
}
}).start();
break;
case R.id.trans:
image.setBackgroundColor(0x00ffffff);
mlinear.setBackgroundColor(0x00ffffff);
break;
}
}
}
后面这个图片下载并且显示,然后做过度绘制优化,可以看出,当图片下载以后,因为最上层是图片显示的,所以背景可以通过程序设置成完全透明的(因为背景user看不到,不需要显示),从而可以防止过度绘制.