Android 欢迎界面设计之图片渐隐效果
设计一款Android手机应用软件，欢迎界面必不可少，今天我将设计一个欢迎界面图片渐隐效果
第一步：在主界面实现消息处理器
MainView.java
public class MainView extends Activity{
//屏幕宽度
public static int screenWidth;
//屏幕高度
public static int screenHeight;
//欢迎界面对象
Welcome_View welcome;
Handler hd = new Handler(){
//重写handleMessage方法
public void handleMessage(Message msg){
switch(msg.what){
case 0:
//跳转到welcome_view
goToWelcomeView();
break;
case 1:
//跳转到main_view
goToMainView();
break;
}
}
};
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
//去除标题栏
requestWindowFeature(Window.FEATURE_NO_TITLE);
//去除状态栏
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
//创建DisplayMetrics对象，用于获取屏幕宽度和高度
DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
//屏幕宽度
screenWidth = dm.widthPixels;
//屏幕高度
screenHeight = dm.heightPixels;
//发送消息，交由handler处理
this.hd.sendEmptyMessage(0);
}
//跳转到欢迎界面函数
private void goToWelcomeView(){
if(welcome == null){
//welcome为空，新建一个
welcome = new Welcome_View(this);
}
//加载welcome，其实欢迎界面并不需要配置文件，直接加载类
setContentView(welcome);
}
//跳转到MainView
private void goToMainView(){
//创建Intent对象
Intent intent = new Intent();
//Main_view自己创建，就是一个新的activity，此处不坠余
intent.setClass(InitActivity.this, Main_View.class);
//开始activity跳转
startActivity(intent);
//关闭当前Activity
this.finish();
}
}
第二步：实现Welcome_View.java
Welcome_View.java
public class Welcome_View extends SurfaceView
implements SurfaceHolder.Callback{
//activity引用
MainView activity;
//画笔
Paint paint;
//屏幕宽度
int screenWidth = MainView.screenWidth;
//屏幕高度
int screenHeight =MainView.screenHeight;
//当前不透明度
int currentAlpha = 0;
//休眠时间
int sleepTime = 50;
//图片数组
Bitmap[] logos = new Bitmap[2];
//当前logo
Bitmap currentLogo;
//X坐标
int currentX;
//Y坐标
int currentY;
public Welcome_View(MainView activity) {
super(activity);
this.activity = activity;
//设置生命周期回调接口实现者
this.getHolder().addCallback(this);
paint = new Paint();
//打开抗锯齿
paint.setAntiAlias(true);
//加载图片
logos[0] = BitmapFactory.decodeResource(activity.getResources(), R.drawable.surface1);
logos[1] = BitmapFactory.decodeResource(activity.getResources(), R.drawable.surface2);
}
public void onDraw(Canvas canvas){
paint.setColor(Color.BLACK);
paint.setAlpha(255);
//绘制填充矩形清晰界面
canvas.drawRect(0, 0,screenWidth,screenHeight,paint);
if(currentLogo == null) return;
paint.setAlpha(currentAlpha);
//平面贴图
canvas.drawBitmap(currentLogo, currentX,currentY, paint);
}
//界面创建时调用
@Override
public void surfaceCreated(SurfaceHolder arg0) {
new Thread(){
@SuppressLint("WrongCall")
public void run(){
for(Bitmap bm : logos){//对数组进行循环
//初始化当前图片
currentLogo = bm;
//图片位置
currentX = (screenWidth - bm.getWidth())/2;
currentY = (screenHeight - bm.getHeight())/2;
for(int i = 255;i > -10;i = i-10){
//设置当前不透明度
currentAlpha = i;
if(currentAlpha < 0){
currentAlpha = 0;
}
//获取回调接口
SurfaceHolder myholder = Welcome_View.this.getHolder();
//获取画布
Canvas canvas = myholder.lockCanvas();
try{
synchronized(myholder){
onDraw(canvas);
}
}catch(Exception e){
e.printStackTrace();
}finally{
if(canvas != null){
myholder.unlockCanvasAndPost(canvas);
}
}
try{
if(i == 255){
Thread.sleep(1000);
}
Thread.sleep(sleepTime);
}catch(Exception e){
e.printStackTrace();
}
}
}
//发送消息，交由Handler处理，跳转到主界面
activity.hd.sendEmptyMessage(1);
}
}.start();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
}
}