如何在android中绘制像条形码系统一样的矩形

Question

我想做条形码系统，但我只是想绘制方形。我正确地写了Draw类，但我不能正确调用活动类吗？我们怎样才能以正确的方式调用Activtity？我只想给它一个方形的外观。

Draw.java

public class Draw extends LinearLayout {
private Bitmap bm;
private Canvas cv;
private Paint eraser;
private int holesBottomMargin = 70;
private int holeRadius = 40;

public Draw(Context context) {
    super(context);
    Init();
}

public Draw(Context context, AttributeSet attrs) {
    super(context, attrs);
    Init();
}

public Draw(Context context, AttributeSet attrs,
                  int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    Init();
}

private void Init() {
    eraser = new Paint();
    eraser.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
    eraser.setAntiAlias(true);
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    if (w != oldw || h != oldh) {
        bm = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        cv = new Canvas(bm);
    }
    super.onSizeChanged(w, h, oldw, oldh);
}

@Override
protected void onDraw(Canvas canvas) {
    int w = getWidth();
    int h = getHeight();

    bm.eraseColor(Color.TRANSPARENT);

    // set the view background color
    cv.drawColor(Color.BLACK);

    // drawing footer square contains the buy now button
    Paint paint = new Paint();
    paint.setARGB(255, 250, 250, 250);
    paint.setStrokeWidth(0);
    paint.setStyle(Paint.Style.FILL);
    cv.drawRect(0, h, w, h - pxFromDp(getContext(), holesBottomMargin), paint);

    // adding punching holes on the ticket by erasing them
    cv.drawCircle(0, 0, holeRadius, eraser); // top-left hole
    cv.drawCircle(w / 2, 0, holeRadius, eraser); // top-middle hole
    cv.drawCircle(w, 0, holeRadius, eraser); // top-right
    cv.drawCircle(0, h - pxFromDp(getContext(), holesBottomMargin), holeRadius, eraser); // bottom-left hole
    cv.drawCircle(w, h - pxFromDp(getContext(), holesBottomMargin), holeRadius, eraser); // bottom right hole

    // drawing the image
    canvas.drawBitmap(bm, 0, 0, null);


    // drawing dashed lines at the bottom
    Path mPath = new Path();
    mPath.moveTo(holeRadius, h - pxFromDp(getContext(), holesBottomMargin));
    mPath.quadTo(w - holeRadius, h - pxFromDp(getContext(), holesBottomMargin), w - holeRadius, h - pxFromDp(getContext(), holesBottomMargin));

    // dashed line
    Paint dashed = new Paint();
    dashed.setARGB(255, 200, 200, 200);
    dashed.setStyle(Paint.Style.STROKE);
    dashed.setStrokeWidth(2);
    dashed.setPathEffect(new DashPathEffect(new float[]{10, 5}, 0));
    canvas.drawPath(mPath, dashed);

    super.onDraw(canvas);
}

public static float pxFromDp(final Context context, final float dp) {
    return dp * context.getResources().getDisplayMetrics().density;
}
}

Activity.java

    Draw draw=new Draw(this);
    frameLayout=findViewById(R.id.frame);
    frameLayout.addView(draw);

您的建议对我很重要