Android 中View.onDraw(Canvas canvas)的使用方法
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：
如：
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<com.android.test.TestView
android:id="@+id/testview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
</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;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.View;
public class TestActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new TestView(this));
}
public class TestView extends View {
private Paint mPaint = new Paint();
public TestView(Context context) {
super(context);
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
String text = "Android - 机器人";
mPaint.setColor(Color.WHITE);
Paint paint = new Paint();
paint.setColor(Color.RED);
String familyName = "宋体";
Typeface font = Typeface.create(familyName,Typeface.BOLD);
paint.setTypeface(font);
paint.setTextSize(22);
canvas.drawRect(new Rect(0, 0, 320, 240), mPaint);
canvas.drawText(text, 0, 100, paint);
}
}
}
运行效果如下图：
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