如何制作具有透明背景的SurfaceView？

Question

我有一个简单的布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/RelativeLayout1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/backgroundtimer"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/TextView1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="@string/hello" />

    <com.fmech.zenclock.surface.ZenClockSurface
        android:id="@+id/zenClockSurface1"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"/>

</RelativeLayout>

我有一个ZenClockSurface类

package com.fmech.zenclock.surface;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.PixelFormat;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class ZenClockSurface extends SurfaceView implements SurfaceHolder.Callback{

    private DrawClock drawClock;

    public ZenClockSurface(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        this.getHolder().setFormat(PixelFormat.TRANSLUCENT);
        getHolder().addCallback(this);
    }

    public ZenClockSurface(Context context) {
        super(context);
        this.getHolder().setFormat(PixelFormat.TRANSLUCENT);
        getHolder().addCallback(this);
    }

    public ZenClockSurface(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.getHolder().setFormat(PixelFormat.TRANSLUCENT);
        getHolder().addCallback(this);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {
        // TODO Auto-generated method stub

    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        //this.getHolder().setFormat(PixelFormat.TRANSPARENT);
        drawClock = new DrawClock(getHolder(), getResources());
        drawClock.setRunning(true);
        drawClock.start();

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        boolean retry = true;
        // завершаем работу потока
        drawClock.setRunning(false);
        while (retry) {
            try {
                drawClock.join();
                retry = false;
            } catch (InterruptedException e) {
            }
        }

    }

    class DrawClock extends Thread{
        private boolean runFlag = false;
        private SurfaceHolder surfaceHolder;
        private Bitmap picture;
        private Matrix matrix;
        private long prevTime;
        private Paint painter;

        public DrawClock(SurfaceHolder surfaceHolder, Resources resources){
            this.surfaceHolder = surfaceHolder;

            this.surfaceHolder.setFormat(PixelFormat.TRANSLUCENT);
            picture = BitmapFactory.decodeResource(resources, R.drawable.ic_launcher);

            matrix = new Matrix();
            this.painter=new Paint();
            this.painter.setStyle(Paint.Style.FILL);

        }

        public void setRunning(boolean run) {
            runFlag = run;
        }

        @Override
        public void run() {
            Canvas canvas;
            while (runFlag) {

                    matrix.preRotate(1.0f, picture.getWidth() / 2, picture.getHeight() / 2);
                canvas = null;
                try {
                    //surfaceHolder.getSurface().setAlpha(0.5f);
                    canvas = surfaceHolder.lockCanvas(null);
                    synchronized (surfaceHolder) {

                        canvas.drawColor(Color.TRANSPARENT);

                        canvas.drawBitmap(picture, matrix, this.painter);
                    }
                } 
                finally {
                    if (canvas != null) {
                        surfaceHolder.unlockCanvasAndPost(canvas);
                    }
                }
            }
        }
    }
}

活动的代码

package com.fmech.zenclock.surface;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;

public class ZenClockSurfaceActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().setFormat(PixelFormat.TRANSLUCENT);
        setContentView(R.layout.main);


    }
}

我想让Android图片的背景颜色变为透明，但是我现在得到的是黑色背景。

我在RelativeLayout上放了一张图片，但SurfaceView旋转时Android图标没有透明度。

我该如何使其透明？

- Dmitry Nelepov

---

我忘记在两个构造函数中添加this.getHolder().setFormat(PixelFormat.TRANSLUCENT);。 - Rasel

Answer 1

是的，我做到了，我解决了这个问题。

活动代码

package com.fmech.zenclock.surface;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class ZenClockSurfaceActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ZenClockSurface sfvTrack = (ZenClockSurface)findViewById(R.id.zenClockSurface1);
        sfvTrack.setZOrderOnTop(true);    // necessary
        SurfaceHolder sfhTrack = sfvTrack.getHolder();
        sfhTrack.setFormat(PixelFormat.TRANSLUCENT);

    }
}

表面码

package com.fmech.zenclock.surface;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.PixelFormat;
import android.graphics.Region;
import android.util.AttributeSet;
import android.view.Surface.OutOfResourcesException;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class ZenClockSurface extends SurfaceView implements
        SurfaceHolder.Callback {

    private DrawClock drawClock;

    public ZenClockSurface(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        getHolder().addCallback(this);
    }

    public ZenClockSurface(Context context) {
        super(context);
        getHolder().addCallback(this);
    }

    public ZenClockSurface(Context context, AttributeSet attrs) {
        super(context, attrs);
        getHolder().addCallback(this);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {

    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        drawClock = new DrawClock(getHolder(), getResources());
        drawClock.setRunning(true);
        drawClock.start();

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        boolean retry = true;
        drawClock.setRunning(false);
        while (retry) {
            try {
                drawClock.join();
                retry = false;
            } catch (InterruptedException e) {
            }
        }

    }

    class DrawClock extends Thread {
        private boolean runFlag = false;
        private SurfaceHolder surfaceHolder;
        private Bitmap picture;
        private Matrix matrix;
        private Paint painter;

        public DrawClock(SurfaceHolder surfaceHolder, Resources resources) {
            this.surfaceHolder = surfaceHolder;

            picture = BitmapFactory.decodeResource(resources,
                    R.drawable.ic_launcher);
            matrix = new Matrix();
            this.painter = new Paint();
            this.painter.setStyle(Paint.Style.FILL);
            this.painter.setAntiAlias(true);
            this.painter.setFilterBitmap(true);
        }

        public void setRunning(boolean run) {
            runFlag = run;
        }

        @Override
        public void run() {
            Canvas canvas;
            while (runFlag) {


                matrix.preRotate(1.0f, picture.getWidth() / 2,
                        picture.getHeight() / 2);
                canvas = null;
                try {
                    canvas = surfaceHolder.lockCanvas(null);
                    synchronized (surfaceHolder) {
                        canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);
                        canvas.drawBitmap(picture, matrix, this.painter);
                    }
                } catch (IllegalArgumentException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }  finally {
                    if (canvas != null) {
                        surfaceHolder.unlockCanvasAndPost(canvas);
                    }
                }
            }
        }
    }
}

它能正常工作。

- Dmitry Nelepov

---

drawColor(0, android.graphics.PorterDuff.Mode.CLEAR); 非常感谢，我已经找了好几个小时了！我以为 drawColor(Color.TRANSPARENT); 会起作用...但它没有，你的解决方案救了我一命..！ - tom91136

它对我没用。 我已将布局的背景设置为颜色＃f0f0f0，但SurfaceView的背景仍然保持黑色。 - Genry

@Dmitry Nelepov：我尝试了相同的代码，但对我没有起作用。SurfaceView 的颜色仍然是黑色的。 - user2085965

我只看到一个黑色的表面，什么都没有显示出来，有什么帮助吗？ - Amit Hooda

Answer 2

在API 3和4中，您不能将任何东西放在SurfaceView后面。引用Dianne Hackborn的话说：

SurfaceView实际上在您的窗口后面，并且是为您打了一个洞以便您看到它。因此，您可以在窗口顶部放置东西，但是窗口中的任何内容都无法出现在其后面。

http://groups.google.com/group/android-developers/browse_thread/thread/8d88ef9bb22da574

---

从API 5开始，您可以使用setZOrderOnTop。诀窍是您必须在构造函数中执行此操作，以便在视图附加到窗口之前调用它：

public ZenClockSurface(Context context, AttributeSet attrs) {
  super(context, attrs);

  setZOrderOnTop(true);

  SurfaceHolder holder = getHolder();
  holder.setFormat(PixelFormat.TRANSLUCENT);
}

- chiuki

---

这不正确。下一个活动中的更改会使SorfaceView透明。public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ZenClockSurface sfvTrack = (ZenClockSurface)findViewById(R.id.zenClockSurface1); sfvTrack.setZOrderOnTop(true); // 必要 SurfaceHolder sfhTrack = sfvTrack.getHolder(); sfhTrack.setFormat(PixelFormat.TRANSLUCENT); } - Dmitry Nelepov

但我仍然有困难，现在图片所在的网站是黑色的。 - Dmitry Nelepov

感谢Rainwork指出setZOrderOnTop！我已经编辑了我的答案。如果可以的话，请告诉我它是否有效。 - chiuki

setZOrderOnTop - 它解决了问题，但并不完全。然后图像会出现黑色的“幽灵”背景。我回答了我的问题，并提供了完整的代码，对我来说运行良好。 - Dmitry Nelepov

我建议使用 setZOrderMediaOverlay(true) 而不是 setZOrderOnTop(true)，因为 setZOrderMediaOverlay 使其像普通视图一样工作，可以在任何视图的后面和前面。 - Diljeet