自定义View的学习（一） 自绘制控件

一、自绘控件

就是自己绘制的控件，通过onDraw（）方法将控件绘制出来  自定义一个可点击的View  这个View可以记住用户点击的次数

public class CounterView extends View implements OnClickListener {
 
    private Paint mPaint;
 
    private Rect mBounds;
 
    private int mCount;
 
    public CounterView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mBounds = new Rect();
        setOnClickListener(this);
    }
 
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        mPaint.setColor(Color.BLUE);
        canvas.drawRect(0, 0, getWidth(), getHeight(), mPaint);
        mPaint.setColor(Color.YELLOW);
        mPaint.setTextSize(30);
        String text = String.valueOf(mCount);
        mPaint.getTextBounds(text, 0, text.length(), mBounds);
        float textWidth = mBounds.width();
        float textHeight = mBounds.height();
        canvas.drawText(text, getWidth() / 2 - textWidth / 2, getHeight() / 2
                + textHeight / 2, mPaint);
    }
 
    @Override
    public void onClick(View v) {
        mCount++;
        invalidate();
    }
 
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
 
    <com.example.customview.CounterView
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_centerInParent="true" />
 
</RelativeLayout>