2011.09.26（3）——— android sample之Notepad(带下划线的TestView)

2011.09.26（3）——— android sample之Notepad(带下划线的TestView)
参考：http://www.cnblogs.com/phinecos/archive/2009/08/27/1555221.html

notepad里面用于记事的TextView

public static class LinedEditText extends EditText {        private Rect mRect;        private Paint mPaint;        // we need this constructor for LayoutInflater        public LinedEditText(Context context, AttributeSet attrs) {            super(context, attrs);                        mRect = new Rect();            mPaint = new Paint();            mPaint.setStyle(Paint.Style.STROKE);            mPaint.setColor(0x800000FF);        }                @Override        protected void onDraw(Canvas canvas) {            int count = getLineCount();            Rect r = mRect;            Paint paint = mPaint;            for (int i = 0; i < count; i++) {                int baseline = getLineBounds(i, r);                canvas.drawLine(r.left, baseline + 1, r.right, baseline + 1, paint);            }            super.onDraw(canvas);        }    }

主要工作就是重载onDraw方法，利用从TextView继承下来的getLineCount函数获取文本所占的行数，以及getLineBounds来获取特定行的基准高度值，而且这个函数第二个参数会返回此行的“外包装”值。再利用这些值绘制这一行的线条。

xml

<view xmlns:android="http://schemas.android.com/apk/res/android"    class="com.example.android.notepad.NoteEditor$LinedEditText"    android:id="@+id/note"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:background="@android:color/transparent"    android:padding="5dip"    android:scrollbars="vertical"    android:fadingEdge="vertical"    android:gravity="top"    android:textSize="22sp"    android:capitalize="sentences"/>

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