java - 保存画布只保存背景不保存绘图

Question

我有一个画布，我正在显示来自媒体商店的图片作为它的背景，然后我在上面画画。我想保存背景+在它上面绘制的内容，但我只能保存背景，这对我来说没用。我试图了解我做错了什么。我基本上按照人们在这里的建议做了，但没有帮助。

这是我拥有的代码：编辑：这次我在这里上传了所有代码

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.util.ArrayList;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Path;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.provider.MediaStore;
import android.view.Display;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Toast;

public class CanvasDrawingActivity extends  Activity   {
private ArrayList<Path> _graphics = new ArrayList<Path>();
private Paint mPaint;
public static final int GET_FROM_GALLERY = 1;
public static final int IMAGE_CAPTURE = 0;
public static final int SELECT_IMAGE_FROM_DEVICE = 1;
public Bitmap myBitmap;
public int isFirstTime = 0;
public DrawingPanel mPanel;
static int id = 1;
public Uri fileUri ;

@Override
public void onCreate(Bundle savedInstanceState) {
    mPanel = new DrawingPanel(this);
    mPanel.setId(findId());
    super.onCreate(savedInstanceState);
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    //https://stackoverflow.com/questions/10937659/android-image-doesnt-save-using-native-camera-app-on-nexus-s
    File f = new File(Environment.getExternalStorageDirectory().getPath(), String.format("%d.jpg", System.currentTimeMillis()));
    fileUri= Uri.fromFile(f);
    intent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri);

    startActivityForResult(intent, IMAGE_CAPTURE);
    setContentView(R.layout.main);
}


public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    return true;
}

public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case R.id.save:
        savePicture();
        return true;
    case R.id.clear:
        // startActivity(new Intent(this, Clear.class));
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

public void savePicture(){
    long now = System.currentTimeMillis();
    OutputStream fos;
    try {
        fos = new FileOutputStream(String.format(Environment.getExternalStorageDirectory().getAbsolutePath()+"/edited_%d.jpg",now));
        myBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos); 
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    finish();  //close the activity. 
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    //Detects request codes
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == IMAGE_CAPTURE && resultCode == RESULT_OK) {
        Uri result; 
        result = fileUri;
        //refresh storage
        sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));
        try {
            myBitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), result);
            startDrawing();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    else if (resultCode == Activity.RESULT_CANCELED){

    }
}

public void startDrawing(){
    setContentView(mPanel);
    mPaint = new Paint();
    mPaint.setDither(true);
    mPaint.setColor(0xFFFFFF00);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(3);
}

public int findId(){  
    View v = findViewById(id);  
    while (v != null){  
        v = findViewById(++id);  
    }  
    return id++;  
}


class DrawingPanel extends SurfaceView implements SurfaceHolder.Callback {
    private DrawingThread _thread;
    private Path path;

    public DrawingPanel(Context context) {
        super(context);
        setDrawingCacheEnabled(true);
        getHolder().addCallback(this);
        _thread = new DrawingThread(getHolder(), this);
    }


    @Override
    public boolean onTouchEvent(MotionEvent event) {
        synchronized (_thread.getSurfaceHolder()) {
            if(event.getAction() == MotionEvent.ACTION_DOWN){
                path = new Path();
                path.moveTo(event.getX(), event.getY());
                path.lineTo(event.getX(), event.getY());
            }else if(event.getAction() == MotionEvent.ACTION_MOVE){
                path.lineTo(event.getX(), event.getY());
                if(_graphics.size() > 0) {
                    _graphics.remove(_graphics.size() - 1);
                }
                _graphics.add(path);
            }else if(event.getAction() == MotionEvent.ACTION_UP){
                path.lineTo(event.getX(), event.getY());
                _graphics.remove(_graphics.size() - 1);
                _graphics.add(path);
            }
            return true;
        }
    }

    //Source: http://thinkandroid.wordpress.com/2009/12/25/resizing-a-bitmap/
    public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) {
        int width = bm.getWidth();
        int height = bm.getHeight();
        float scaleWidth = ((float) newWidth) / width;
        float scaleHeight = ((float) newHeight) / height;
        // create a matrix for the manipulation
        Matrix matrix = new Matrix();
        // resize the bit map
        matrix.postScale(scaleWidth, scaleHeight);
        // recreate the new Bitmap
        Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false);
        return resizedBitmap;
    }

    /**
     * Converts a immutable bitmap to a mutable bitmap. This operation doesn't allocates
     * more memory that there is already allocated.
     * 
     * @param imgIn - Source image. It will be released, and should not be used more
     * @return a copy of imgIn, but muttable.
     */
    public Bitmap convertToMutable(Bitmap imgIn) {
        try {
            //this is the file going to use temporally to save the bytes. 
            // This file will not be a image, it will store the raw image data.
            File file = new File(Environment.getExternalStorageDirectory() + File.separator + "temp.tmp");

            //Open an RandomAccessFile
            //Make sure you have added uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
            //into AndroidManifest.xml file
            RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");

            // get the width and height of the source bitmap.
            int width = imgIn.getWidth();
            int height = imgIn.getHeight();
            Config type = imgIn.getConfig();

            //Copy the byte to the file
            //Assume source bitmap loaded using options.inPreferredConfig = Config.ARGB_8888;
            FileChannel channel = randomAccessFile.getChannel();
            MappedByteBuffer map = channel.map(MapMode.READ_WRITE, 0, imgIn.getRowBytes()*height);
            imgIn.copyPixelsToBuffer(map);
            //recycle the source bitmap, this will be no longer used.
            imgIn.recycle();
            System.gc();// try to force the bytes from the imgIn to be released

            //Create a new bitmap to load the bitmap again. Probably the memory will be available. 
            imgIn = Bitmap.createBitmap(width, height, type);
            map.position(0);
            //load it back from temporary 
            imgIn.copyPixelsFromBuffer(map);
            //close the temporary file and channel , then delete that also
            channel.close();
            randomAccessFile.close();

            // delete the temp file
            file.delete();

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } 

        return imgIn;
    }


    @Override
    public void onDraw(Canvas canvas) {
        Display display = getWindowManager().getDefaultDisplay();
        int width = display.getWidth();
        int height = display.getHeight();
        myBitmap = getResizedBitmap(myBitmap, height, width);

        if (isFirstTime<3){
            myBitmap = convertToMutable(myBitmap);
            canvas.drawBitmap(myBitmap, 0, 0, null);
            isFirstTime++;
        }

        for (Path path : _graphics) {
            //canvas.drawPoint(graphic.x, graphic.y, mPaint);
            canvas.drawPath(path, mPaint);
        }
    }

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

    }

    public void surfaceCreated(SurfaceHolder holder) {          
        // TODO Auto-generated method stub
        _thread.setRunning(true);
        _thread.start();
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // TODO Auto-generated method stub
        boolean retry = true;
        _thread.setRunning(false);
        while (retry) {
            try {
                _thread.join();
                retry = false;
            } catch (InterruptedException e) {
                // we will try it again and again...
            }
        }
    }
}

class DrawingThread extends Thread {
    private SurfaceHolder _surfaceHolder;
    private DrawingPanel _panel;
    private boolean _run = false;

    public DrawingThread(SurfaceHolder surfaceHolder, DrawingPanel panel) {
        _surfaceHolder = surfaceHolder;
        _panel = panel;
    }

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

    public SurfaceHolder getSurfaceHolder() {
        return _surfaceHolder;
    }

    @Override
    public void run() {
        Canvas c;
        while (_run) {
            c = null;
            try {
                c = _surfaceHolder.lockCanvas(null);
                synchronized (_surfaceHolder) {
                    if (c!=null)
                        _panel.onDraw(c);
                }
            } finally {
                // do this in a finally so that if an exception is thrown
                // during the above, we don't leave the Surface in an
                // inconsistent state
                if (c != null) {
                    _surfaceHolder.unlockCanvasAndPost(c);
                }
            }
        }
    }
}

}

这是 main.xml

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

和 menu.xml：

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
<item
    android:id="@+id/save"
    android:title="Save"/>
<item
    android:id="@+id/clear"
    android:title="Clear"/>
</menu>

任何帮助，将不胜感激。谢谢！！

编辑：我让它工作！这里是！

@Override
public void onCreate(Bundle savedInstanceState) {
    mPanel = new DrawingPanel(this);
    mPanel.setId(findId());
    super.onCreate(savedInstanceState);
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    //https://stackoverflow.com/questions/10937659/android-image-doesnt-save-using-native-camera-app-on-nexus-s
    File f = new File(Environment.getExternalStorageDirectory().getPath(), String.format("%d.jpg", System.currentTimeMillis()));
    fileUri= Uri.fromFile(f);
    intent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri);

    startActivityForResult(intent, IMAGE_CAPTURE);
    setContentView(R.layout.main);
}


public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    return true;
}

public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case R.id.save:
        savePicture();
        return true;
    case R.id.clear:
        // startActivity(new Intent(this, Clear.class));
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

public void savePicture(){
    long now = System.currentTimeMillis();
    OutputStream fos;
    try {
        //SAVE THIS ONE- replicate all paths
        Canvas canvas = new Canvas(myBitmap);
        for (Path path : _graphicsToSave)
        {
            canvas.drawPath(path, mPaint);
        }

        fos = new FileOutputStream(String.format(Environment.getExternalStorageDirectory().getAbsolutePath()+"/edited_%d.jpg",now));
        myBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos); 
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    finish();  //close the activity. 
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    //Detects request codes
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == IMAGE_CAPTURE && resultCode == RESULT_OK) {
        Uri result; 
        result = fileUri;
        //refresh storage
        sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));
        try {
            myBitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), result);

            //resize the picture to match the screen size
            Display display = getWindowManager().getDefaultDisplay();
            int width = display.getWidth();
            int height = display.getHeight();
            myBitmap = getResizedBitmap(myBitmap, height, width);
            startDrawing();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    else if (resultCode == Activity.RESULT_CANCELED){

    }
}

//Source: http://thinkandroid.wordpress.com/2009/12/25/resizing-a-bitmap/
public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) {
    int width = bm.getWidth();
    int height = bm.getHeight();
    float scaleWidth = ((float) newWidth) / width;
    float scaleHeight = ((float) newHeight) / height;
    // create a matrix for the manipulation
    Matrix matrix = new Matrix();
    // resize the bit map
    matrix.postScale(scaleWidth, scaleHeight);
    // recreate the new Bitmap
    Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false);
    return resizedBitmap;
}


public void startDrawing(){
    setContentView(mPanel);
    mPaint = new Paint();
    mPaint.setDither(true);
    mPaint.setColor(0xFFFFFF00);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(3);
}

public int findId(){  
    View v = findViewById(id);  
    while (v != null){  
        v = findViewById(++id);  
    }  
    return id++;  
}


class DrawingPanel extends SurfaceView implements SurfaceHolder.Callback {
    private DrawingThread _thread;
    private Path path;

    public DrawingPanel(Context context) {
        super(context);
        setDrawingCacheEnabled(true);
        getHolder().addCallback(this);
        _thread = new DrawingThread(getHolder(), this);
    }


    @Override
    public boolean onTouchEvent(MotionEvent event) {
        synchronized (_thread.getSurfaceHolder()) {
            if(event.getAction() == MotionEvent.ACTION_DOWN){
                path = new Path();
                path.moveTo(event.getX(), event.getY());
                path.lineTo(event.getX(), event.getY());
            }else if(event.getAction() == MotionEvent.ACTION_MOVE){
                path.lineTo(event.getX(), event.getY());
                if(_graphics.size() > 0) {
                    _graphics.remove(_graphics.size() - 1);
                }
                _graphics.add(path);
            }else if(event.getAction() == MotionEvent.ACTION_UP){
                path.lineTo(event.getX(), event.getY());
                _graphics.remove(_graphics.size() - 1);
                _graphics.add(path);
                _graphicsToSave.add(path);
            }
            return true;
        }
    }




    @Override
    public void onDraw(Canvas canvas) {


        if (isFirstTime<3){
            canvas.drawBitmap(myBitmap, 0, 0, null);
            isFirstTime++;
        }

        for (Path path : _graphics) {
            canvas.drawPath(path, mPaint);
        }
    }

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

    }

    public void surfaceCreated(SurfaceHolder holder) {            
        // TODO Auto-generated method stub
        _thread.setRunning(true);
        _thread.start();
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // TODO Auto-generated method stub
        boolean retry = true;
        _thread.setRunning(false);
        while (retry) {
            try {
                _thread.join();
                retry = false;
            } catch (InterruptedException e) {
                // we will try it again and again...
            }
        }
    }
}

class DrawingThread extends Thread {
    private SurfaceHolder _surfaceHolder;
    private DrawingPanel _panel;
    private boolean _run = false;

    public DrawingThread(SurfaceHolder surfaceHolder, DrawingPanel panel) {
        _surfaceHolder = surfaceHolder;
        _panel = panel;
    }

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

    public SurfaceHolder getSurfaceHolder() {
        return _surfaceHolder;
    }

    @Override
    public void run() {
        Canvas c;
        while (_run) {
            c = null;
            try {
                c = _surfaceHolder.lockCanvas(null);
                synchronized (_surfaceHolder) {
                    if (c!=null)
                        _panel.onDraw(c);
                }
            } finally {
                // do this in a finally so that if an exception is thrown
                // during the above, we don't leave the Surface in an
                // inconsistent state
                if (c != null) {
                    _surfaceHolder.unlockCanvasAndPost(c);
                }
            }
        }
    }
}

}

Answer 1

View mView;
mView.setDrawingCacheEnabled(true);

Bitmap newimg = mView.getDrawingCache();

请获取位图并尝试保存该位图。让我知道您需要更多帮助

Answer 2

要绘制一些东西，您需要 4 个基本组件：一个用于保存像素的位图、一个用于承载绘制调用（写入位图）的画布、一个绘图图元（例如 Rect、Path、文本、位图）和一个绘图（用于描述绘图的颜色和样式）。

您当前粘贴的代码代码显示您正在保存 myBitmap，但它没有显示您是否将 myBitmap 设置为用于绘图的位图。可能不是完整的代码。
我能想到这个问题的唯一原因是你没有在你保存的位图上绘图。这是我为手指画创建的代码的链接。你可以参考这段代码来了解位图是如何提供给画布的，以及路径是如何在位图上绘制的。