Android：如何使用onDraw（）和drawPath？

Question

我是java和android的新手（一般来说是面向对象代码的新手）。 我正在开发我的第一个项目，它将是android锁定模式屏幕的一个克隆，它会为标记的每个点喷出一个数值。

我已设法处理触摸事件以将我的点更改为标记并在TextView中设置数值，但我无法弄清楚如何实现onDraw（）以在每个标记点之间绘制线条。说实话，我真的不明白该方法的构建方式或传递方式。我正在寻找一个简洁的解释，甚至是一个我可以使用的dummie-proof教程。任何帮助表示赞赏。

我确定我的代码很丑陋而且远没有效率，这是我最终会清理的东西。这是我到目前为止所拥有的。

public class MainActivity extends Activity implements View.OnTouchListener {

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

    //set an onTouchListener to the RelativeLayout layoutLockWrapper
    ViewGroup lockwrapper = (RelativeLayout) findViewById(R.id.layoutLockWrapper);
    lockwrapper.setOnTouchListener(this);

}

public boolean onTouch(View v, MotionEvent event) {


    //declaring the ImageViews
    ImageView topleft = (ImageView) findViewById(R.id.ivTopLeft);
    ImageView topmid = (ImageView) findViewById(R.id.ivTopMid);
    ImageView topright = (ImageView) findViewById(R.id.ivTopRight);
    ImageView midleft = (ImageView) findViewById(R.id.ivMidLeft);
    ImageView midmid = (ImageView) findViewById(R.id.ivMidMid);
    ImageView midright = (ImageView) findViewById(R.id.ivMidRight);
    ImageView botleft = (ImageView) findViewById(R.id.ivBotLeft);
    ImageView botmid = (ImageView) findViewById(R.id.ivBotMid);
    ImageView botright = (ImageView) findViewById(R.id.ivBotRight);


    // I have a ton of integers here to declare the coordinates of each imageview
    // there's 48 of them so I will leave them out for readability 

    EditText etLockCode = (EditText) findViewById(R.id.etLockcode);

    //strings to get the last value of etLockCode and update with an additional character
    String s = etLockCode.getText().toString();
    String s1 = s+"1";
    String s2 = s+"2";
    String s3 = s+"3";
    String s4 = s+"4";
    String s5 = s+"5";
    String s6 = s+"6";
    String s7 = s+"7";
    String s8 = s+"8";
    String s9 = s+"9";

//case switch for handling touch events on layoutLockWrapper
    switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
            break;
        case MotionEvent.ACTION_UP:
            break;
        case MotionEvent.ACTION_POINTER_UP:
            break;
        case MotionEvent.ACTION_MOVE:

      //logic for switching the buttons source when inside the move path
        float tx = event.getX();
        float ty = event.getY();


        if (tx <= r1 & tx >= l1 & ty >= t1 & ty <= b1 & etLockCode.getTag() != 1) {
            topleft.setImageResource(R.mipmap.checked);

            etLockCode.setText(s1);
            etLockCode.setTag(1);
        } else if (tx <= r2 & tx >= l2 & ty >= t2 & ty <= b2 & etLockCode.getTag() != 2) {
            topmid.setImageResource(R.mipmap.checked);

            etLockCode.setText(s2);
            etLockCode.setTag(2);
        } else if (tx <= r3 & tx >= l3 & ty >= t3 & ty <= b3 & etLockCode.getTag() != 3) {
            topright.setImageResource(R.mipmap.checked);

            etLockCode.setText(s3);
            etLockCode.setTag(3);
        } else if (tx <= r4 & tx >= l4 & ty >= t4 & ty <= b4 & etLockCode.getTag() != 4) {
            midleft.setImageResource(R.mipmap.checked);

            etLockCode.setText(s4);
            etLockCode.setTag(4);
        } else if (tx <= r5 & tx >= l5 & ty >= t5 & ty <= b5 & etLockCode.getTag() != 5) {
            midmid.setImageResource(R.mipmap.checked);

            etLockCode.setText(s5);
            etLockCode.setTag(5);
        } else if (tx <= r6 & tx >= l6 & ty >= t6 & ty <= b6 & etLockCode.getTag() != 6) {
            midright.setImageResource(R.mipmap.checked);

            etLockCode.setText(s6);
            etLockCode.setTag(6);
        } else if (tx <= r7 & tx >= l7 & ty >= t7 & ty <= b7 & etLockCode.getTag() != 7) {
            botleft.setImageResource(R.mipmap.checked);

            etLockCode.setText(s7);
            etLockCode.setTag(7);
        } else if (tx <= r8 & tx >= l8 & ty >= t8 & ty <= b8 & etLockCode.getTag() != 8) {
            botmid.setImageResource(R.mipmap.checked);

            etLockCode.setText(s8);
            etLockCode.setTag(8);
        } else if (tx <= r9 & tx >= l9 & ty >= t9 & ty <= b9 & etLockCode.getTag() != 9) {
            botright.setImageResource(R.mipmap.checked);

            etLockCode.setText(s9);
            etLockCode.setTag(9);
        }
    }

    return true;
    }
}