自定义View画板

PointView
public class PaintView extends View {

private Paint mPaint;//画笔工具
private Path mPath;//路径

public PaintView(Context context) {
    super(context);
    init();
}

public PaintView(Context context,  AttributeSet attrs) {
    super(context, attrs);
    init();
}

public PaintView(Context context,  AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
}

private void init(){
    mPaint = new Paint();
    mPaint.setStyle(Paint.Style.STROKE);//设置画笔为边线样式，另外还有FILL全填充
    mPaint.setColor(Color.BLACK);//设置画笔颜色
    mPaint.setStrokeWidth(5);//设置边线宽度

    mPath = new Path();//新建路径
}

/**
 * @author dingtao
 * @date 2018/11/29 4:44 PM
 *
 * 触摸方法
 */
@Override
public boolean onTouchEvent(MotionEvent event) {

    switch (event.getAction()){
        case MotionEvent.ACTION_UP://手指抬起
            break;
        case MotionEvent.ACTION_DOWN://手指按下，路径移动到触摸点
            mPath.moveTo(event.getX(),event.getY());//路径移动到触摸点
            break;
        case MotionEvent.ACTION_MOVE://手指移动
            mPath.lineTo(event.getX(),event.getY());//路径连线到移动的点
            break;
    }
    invalidate();//刷新控件，回调onDraw方法
    return true;
}

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

    canvas.drawPath(mPath,mPaint);//画路径
}

}
布局

<?xml version="1.0" encoding="utf-8"?>

<com.dingtao.shopcar.PaintView
    android:id="@+id/fan_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

PaintActivity public class PaintActivity extends AppCompatActivity {

FanView mFanView;

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

}

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