Question

除了使用触摸，我想画任何东西。我按照this教程。但是我的绘图并不是从我触摸屏幕的那一刻开始的。

我也试过包括状态栏和标题栏的高度，但它没有用。

我的活动代码：

public class MainActivity extends Activity implements OnTouchListener {

ImageView imageView;
Bitmap bitmap;
Canvas canvas;
Paint paint;
float downx = 0, downy = 0, upx = 0, upy = 0;

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

    imageView = (ImageView) this.findViewById(R.id.imageView1);

    DisplayMetrics metrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(metrics);

    bitmap = Bitmap.createBitmap(metrics.widthPixels, metrics.heightPixels,
            Bitmap.Config.ARGB_8888);
    canvas = new Canvas(bitmap);
    paint = new Paint();
    paint.setColor(Color.GREEN);
    imageView.setImageBitmap(bitmap);

    imageView.setOnTouchListener(this);
}

public int getStatusBarHeight() {
    Rect r = new Rect();
    Window w = getWindow();
    w.getDecorView().getWindowVisibleDisplayFrame(r);
    return r.top;
}

public int getTitleBarHeight() {
    int viewTop = getWindow().findViewById(Window.ID_ANDROID_CONTENT)
            .getTop();
    return (viewTop - getStatusBarHeight());
}

public boolean onTouch(View v, MotionEvent event) {
    int action = event.getAction();
    switch (action) {
    case MotionEvent.ACTION_DOWN:
        downx = event.getX();
        downy = event.getY() - getStatusBarHeight() - getTitleBarHeight();
        break;
    case MotionEvent.ACTION_MOVE:
        upx = event.getX();
        upy = event.getY()+ getStatusBarHeight() + getTitleBarHeight();
        canvas.drawLine(downx, downy, upx, upy, paint);
        imageView.invalidate();
        downx = upx;
        downy = upy;
        break;
    case MotionEvent.ACTION_UP:
        break;
    case MotionEvent.ACTION_CANCEL:
        break;
    default:
        break;
    }
    return true;
}

@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;
}

@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();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}
}

Answer 1

yourcode

DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
bitmap = Bitmap.createBitmap(metrics.widthPixels, metrics.heightPixels,Bitmap.Config.ARGB_8888);

按照link所示进行更改并检查

Display currentDisplay = getWindowManager().getDefaultDisplay();
float dw = currentDisplay.getWidth();
float dh = currentDisplay.getHeight();

bitmap = Bitmap.createBitmap((int) dw, (int) dh,Bitmap.Config.ARGB_8888);

Android：触摸绘制无法正常工作

1 个答案: