学步园

View通过View.onDraw(Canvas canvas)来Draw.

我们可以定义自己的继承于View的TestView,然后重载View.onDraw(Canvas canvas).

对于自定义的TestView如何与Activity关联？有以下两种方式：

1. 直接在setContentView(View view)里面加进去自定义的View：setContentView(new TestView(this)).
2. 另外，可以在layout文件里面可以使用自定义的View(如何自定义的View为内部类，就会失效)，如：

<?xml version="1.0" encoding="utf-8"?><br /> <FrameLayout<br /> android:layout_width="fill_parent"<br /> android:layout_height="fill_parent"<br /> xmlns:android="http://schemas.android.com/apk/res/android"><br /> <com.android.test.TestView<br /> android:id="@+id/testview"<br /> android:layout_width="fill_parent"<br /> android:layout_height="fill_parent"/><br /> </FrameLayout>

以下为使用onDraw(Canvas canvas)画矩形区域，及在其上画文本的实例（通过使用内部类使程序显得更加简洁，紧凑）：

package com.android.test;<br /> import android.app.Activity;<br /> import android.content.Context;<br /> import android.graphics.Canvas;<br /> import android.graphics.Color;<br /> import android.graphics.Paint;<br /> import android.graphics.Rect;<br /> import android.graphics.Typeface;<br /> import android.os.Bundle;<br /> import android.view.View;<br /> public class TestActivity extends Activity {<br /> /** Called when the activity is first created. */<br /> @Override<br /> public void onCreate(Bundle savedInstanceState) {<br /> super.onCreate(savedInstanceState);<br /> setContentView(new TestView(this));<br /> }<br /> public class TestView extends View {<br /> private Paint mPaint = new Paint();<br /> public TestView(Context context) {<br /> super(context);<br /> }</p> <p> @Override<br /> protected void onDraw(Canvas canvas) {<br /> // TODO Auto-generated method stub<br /> super.onDraw(canvas);</p> <p> String text = "Android - 机器人";<br /> mPaint.setColor(Color.WHITE);</p> <p> Paint paint = new Paint();<br /> paint.setColor(Color.RED);</p> <p> String familyName = "宋体";<br /> Typeface font = Typeface.create(familyName,Typeface.BOLD);<br /> paint.setTypeface(font);</p> <p> paint.setTextSize(22);</p> <p> canvas.drawRect(new Rect(0, 0, 320, 240), mPaint);<br /> canvas.drawText(text, 0, 100, paint);<br /> }<br /> }<br /> }

运行效果如下图：