手指画在屏幕的一半

Question

我正在测试来自 sdk 示例的 Fingerpaint 演示。当然它工作得很好，但我猜，有没有办法让它只在屏幕的一半上工作，所以我可以把按钮或图像放在另一半上？如果不可能，我会将图像作为该画布的背景，但我正在寻找其他解决方案。

public class MainActivity extends Activity {

DrawingView dv ;
private Paint mPaint;    

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    dv = new DrawingView(this);
    setContentView(dv);
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(Color.GREEN);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(12);
}

public class DrawingView extends View {

    public int width;
    public  int height;
    private Bitmap  mBitmap;
    private Canvas  mCanvas;
    private Path    mPath;
    private Paint   mBitmapPaint;
    Context context;
    private Paint circlePaint;
    private Path circlePath;

    public DrawingView(Context c) {
        super(c);
        context=c;
        mPath = new Path();
        mBitmapPaint = new Paint(Paint.DITHER_FLAG);
        circlePaint = new Paint();
        circlePath = new Path();
        circlePaint.setAntiAlias(true);
        circlePaint.setColor(Color.BLUE);
        circlePaint.setStyle(Paint.Style.STROKE);
        circlePaint.setStrokeJoin(Paint.Join.MITER);
        circlePaint.setStrokeWidth(4f);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);

        mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        mCanvas = new Canvas(mBitmap);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        canvas.drawBitmap( mBitmap, 0, 0, mBitmapPaint);
        canvas.drawPath( mPath,  mPaint);
        canvas.drawPath( circlePath,  circlePaint);
    }

    private float mX, mY;
    private static final float TOUCH_TOLERANCE = 4;

    private void touch_start(float x, float y) {
        mPath.reset();
        mPath.moveTo(x, y);
        mX = x;
        mY = y;
    }

    private void touch_move(float x, float y) {
        float dx = Math.abs(x - mX);
        float dy = Math.abs(y - mY);
        if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
            mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
            mX = x;
            mY = y;

            circlePath.reset();
            circlePath.addCircle(mX, mY, 30, Path.Direction.CW);
        }
    }

    private void touch_up() {
        mPath.lineTo(mX, mY);
        circlePath.reset();
        // commit the path to our offscreen
        mCanvas.drawPath(mPath,  mPaint);
        // kill this so we don't double draw
        mPath.reset();
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                touch_start(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_MOVE:
                touch_move(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                touch_up();
                invalidate();
                break;
        }
        return true;
    }
}
} 

我知道可以通过将它设置为位图来在 imageview 上绘图，这样我就可以控制画布的大小，但我不知道如何在指纹情况下使用它

ImageView img;
Button top;
Paint paint = new Paint();
Bitmap bmp = Bitmap.createBitmap(600, 600, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bmp);


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

img = (ImageView) findViewById(R.id.img);
top = (Button) findViewById(R.id.top);


top.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {

        paint.setAntiAlias(true);

        paint.setColor(Color.BLACK);
        paint.setStrokeWidth(25);
        canvas.drawLine(100,100,200,100,paint);
        img.setImageBitmap(bmp);
    }
});

Answer 1

我对这个库一无所知，但我会尝试创建一个类似这样的 XML 布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="match_parent"
    android:orientation="vertical" android:gravity="center_horizontal">

    <LinearLayout
        android:layout_width="match_parent" android:layout_height="wrap_content"

    <!-- Whatever layout you want with buttons and such -->

    </LinearLayout>

    <LinearLayout id="@+id/container
        android:layout_width="match_parent" 
        android:layout_height="0dp"
        android:layout_weight="1" />
</LinearLayout>

然后在你的代码中：

@Override
protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.layout_file_name);

dv = new DrawingView(this);
mPaint = new Paint();
// Set up DrawingView

ViewGroup container = (ViewGroup) findViewById(R.id.container);
container.addView(dv);