昨天写的自定义View,所有的属性都是写死的,拓展性基本为零。今天讲解自定义View属性的设置,首先在res的values文件夹下创建一个attrs.xml文件。代码如下:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="ScrollTextView">
<attr name="textSize" format="dimension"></attr>
<attr name="textColor" format="color"></attr>
<attr name="textString" format="string"></attr>
<attr name="scrollVelocity" format="enum">
<enum name="slow" value="1"></enum>
<enum name="midd" value="2"></enum>
<enum name="fast" value="3"></enum>
</attr>
</declare-styleable>
</resources>
这里添加了四个属性,其中scrollVelocity设置为枚举类型,有三个属性值。在自定义控件里要获取这些属性值,自定义View代码如下:
public class ScrollTextView extends View {
private Paint paint;
private int x = 0;
private MyThread myThread;
private int textSize;
private int color;
private int value;
private int speed;
private String text;
public ScrollTextView(Context context) {
this(context, null);
init();
}
public ScrollTextView(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray ta = context.obtainStyledAttributes(attrs,
R.styleable.ScrollTextView);
textSize = (int) ta.
getDimension(R.styleable.ScrollTextView_textSize, 45);
color = ta.
getColor(R.styleable.ScrollTextView_textColor, Color.RED);
value = ta.
getInt(R.styleable.ScrollTextView_scrollVelocity, 0);
text = ta.
getString(R.styleable.ScrollTextView_textString);
if (value == 1) {
speed = 1;
} else if (value == 2) {
speed = 2;
} else {
speed = 3;
}
init();
ta.recycle();
}
private void init() {
paint = new Paint();
paint.setTextSize(textSize);
paint.setColor(color);
if (myThread == null) {
myThread = new MyThread();
myThread.start();
}
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawText(text, x, 70, paint);
}
class MyThread extends Thread {
@Override
public void run() {
while (true) {
x += speed;
if (x > getWidth()) {
x = (int) -paint.measureText(text);
}
postInvalidate();
try {
Thread.sleep(5);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
在构造方法里调用obtainStyledAttributes方法得到TypeArray对象,就可以以此获得各个属性值了。
在activity_main.xml里调用这个控件和添加自定义的属性,如下:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:yayun="http://schemas.android.com/apk/res-auto"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ad.scrolltextview.ScrollTextView
android:layout_width="match_parent"
android:layout_height="60dp"
yayun:scrollVelocity="slow"
yayun:textColor="@color/colorPrimaryDark"
yayun:textSize="80px"
yayun:textString="TANGTANGTANG" />
</RelativeLayout>
MainActivity.java代码如下:
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
运行实例如下:
可以在布局文件中修改属性如下:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:yayun="http://schemas.android.com/apk/res-auto"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ad.scrolltextview.ScrollTextView
android:layout_width="match_parent"
android:layout_height="60dp"
yayun:scrollVelocity="fast"
yayun:textColor="@color/colorAccent"
yayun:textSize="40px"
yayun:textString="TANGBAOBAO" />
</RelativeLayout>
再次运行实例如下:
如果您喜欢,请转发至朋友圈,在此感谢。