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现在，我正在使用 CustomView 在画布上绘图，我需要将画布（可能作为位图）保存到 FileOutputStream 中，然后移动到具有相同功能的另一个 CustomView。

我不确定我是否应该使用不同的方法来实现这一点，但无论我在做什么，只要我调用 startActivity(i) 就会崩溃。

我的理解是，我的 CustomView 使用 onTouch() 绘制，它绘制到 Path 对象上，然后调用 onDraw(canvas)，它在 Canvas 上绘制 Path。（如果我错了，请纠正我）。

此画布是否包含位图对象？还是每次调用 onDraw 都需要写入在 onCreate() 期间创建的单独位图？或者我是否需要为每次调用 onDraw() 创建一个新的临时位图？我已经看到了很多不同的问答，但还没有找到理解。

这是我的主要活动：

公共类 MainActivity 扩展 Activity {

Bitmap pic;
CustomView mCustomView;
OnTouchListener touchListener;
Button eraseButton;
String [] files = { "File1.png", "File2.png", "File3.png" };

int color = Color.BLACK;

RelativeLayout layout;

private Paint paint = new Paint();
private Path path = new Path();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    layout = (RelativeLayout) findViewById(R.id.layout);
    mCustomView = new CustomView(this);
    //layout.buildDrawingCache(); should I use this?

    layout.addView(mCustomView);

    touchListener = new OnTouchListener() {
        public boolean onTouch(View v, MotionEvent event){
            float eventX = event.getX();
            float eventY = event.getY();

            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                path.moveTo(eventX, eventY);
                break;
            case MotionEvent.ACTION_MOVE:
            case MotionEvent.ACTION_UP:
                path.lineTo(eventX, eventY);
                break;
            }
            mCustomView.invalidate();
            return true;    
        }
    };
    mCustomView.setOnTouchListener(touchListener);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

public boolean onOptionsItemSelected(MenuItem item){
    switch (item.getItemId()) {
      case R.id.black:
          Toast.makeText(this, "You have chosen " + getResources().getString(R.string.black) + ".",
                        Toast.LENGTH_SHORT).show();
          paint.setColor(Color.BLACK);
          color = Color.BLACK;         
          break;
      case R.id.red:
          Toast.makeText(this, "You have chosen " + getResources().getString(R.string.red) + ".",
                        Toast.LENGTH_SHORT).show();
          paint.setColor(Color.RED); 
          color = Color.RED;
          break;
      case R.id.blue:
          Toast.makeText(this, "You have chosen " + getResources().getString(R.string.blue) + ".",
                        Toast.LENGTH_SHORT).show();
          paint.setColor(Color.BLUE); 
          color = Color.BLUE;
          break;
      case R.id.yellow:
          Toast.makeText(this, "You have chosen " + getResources().getString(R.string.yellow) + ".",
                        Toast.LENGTH_SHORT).show();
          paint.setColor(Color.YELLOW); 
          color = Color.YELLOW;
          break;
      case R.id.erase:
          Toast.makeText(this, "You have chosen to clear the screen. The current pen is now Black.", Toast.LENGTH_SHORT).show();
          paint.setColor(Color.BLACK);
          color = Color.BLACK;
          path.reset();
          mCustomView.invalidate();
          item.setChecked(false);
          break;
      case R.id.next:
          nextScreen(); //saves the bitmap, and call startActivity(), crashing now
          return true;
      default:
          return super.onOptionsItemSelected(item);
      }
      item.setChecked(true);
      return true;
}

public void nextScreen(){
    try {
        FileOutputStream out = openFileOutput(files[0], Context.MODE_PRIVATE);
        pic.compress(Bitmap.CompressFormat.PNG, 100, out);
        out.close();
    } catch (Exception e){
        Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show();
        return;
    }
    Intent i = new Intent(this.getApplicationContext(), SecondActivity.class);
    i.putExtra("filename.png", files);
    startActivity(i);
}

public class CustomView extends View {

    public CustomView(Context context) {
        super(context);
        paint.setAntiAlias(true);
        paint.setColor(color);
        paint.setStyle(Paint.Style.STROKE);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (pic == null){
            pic = Bitmap.createBitmap(getMeasuredWidth(), getMeasuredHeight(), Bitmap.Config.ARGB_8888); //is this correct?
        }
        canvas.drawPath(path, paint);
        canvas.drawBitmap(pic, 0, 0, paint); //is this correct?
    }
}

}

4

1 回答 1

0

如果你想保存视图，你应该使用public Bitmap getDrawingCache ()，见参考。尝试修改您的代码：

@Override
    protected void onDraw(Canvas canvas) {
        if (pic == null){
            pic = Bitmap.createBitmap(getMeasuredWidth(), getMeasuredHeight(), Bitmap.Config.ARGB_8888); //is this correct?
        }
        canvas.drawPath(path, paint);
        //canvas.drawBitmap(pic, 0, 0, paint); //is this correct?
    }

public void nextScreen(){
    try {
        Bitmap bitmap = mCustomView.getDrawingCache ();
        FileOutputStream out = openFileOutput(files[0], Context.MODE_PRIVATE);
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
        out.close();
    } catch (Exception e){
        Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show();
        return;
    }
    Intent i = new Intent(this.getApplicationContext(), SecondActivity.class);
    i.putExtra("filename.png", files);
    startActivity(i);
}
于 2013-09-29T02:28:10.543 回答