Fill Sine Graph Android

问题

I have this code:

public class TestView extends View {

private Path mPath;
private Paint mPaint = new Paint();

public TestView(Context context) {
    this(context, null);
}

public TestView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
}

public TestView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    mPath = new Path();
    mPath.moveTo(0, 0);
    mPath.quadTo(50, -50, 100, 0);
    mPath.quadTo(150, 50, 200, 0);
    mPath.quadTo(250, -50, 300, 0);
    mPath.quadTo(350, 50, 400, 0);
    mPath.quadTo(450, -50, 500, 0);
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    canvas.save();
    canvas.translate(0, getMeasuredHeight() / 2F);
    // just making sure to clip starting and ending curve
    canvas.clipRect(50, -100, 450, 100, Region.Op.INTERSECT);
    canvas.drawPath(mPath, mPaint);
    canvas.restore();
}
}

That produces this:

But I want this (pardon my Paint skills):

Any help on filling area under this sine curve will be appreciated.

回答1:

change your values to

mPath.moveTo(0,100);
mPath.quadTo(50, -50, 100, 0);
mPath.quadTo(150, 50, 200, 0);
mPath.quadTo(250, -50, 300, 0);
mPath.quadTo(350, 50, 400, 0);
mPath.quadTo(450, -50, 500, 100);

回答2:

Never mind, this produced what I wanted:

    mPath = new Path();
    mPath.moveTo(0, 0);
    mPath.quadTo(50, -100, 100, -50);
    mPath.quadTo(150, -0, 200, -50);
    mPath.quadTo(250, -100, 300, -50);
    mPath.quadTo(350, -0, 400, -50);
    mPath.quadTo(450, -100, 500, -0);
    mPath.close();

来源：https://stackoverflow.com/questions/19519856/fill-sine-graph-android