UI之自定义View

UI 绘制及自定义view？

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2.1 绘制相关对象

1)Bitmap 对象

2)Canvas 画板

3)Paint 画笔

4).........

2.2 自定义view

1)自定义类的编写

a)直接或间接继承view

b)添加构造方法及重写相关方法(例如onDraw)

public class MyListView extends ListView {

public MyListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}

public MyListView(Context context, AttributeSet attrs) {
super(context, attrs);
}

public MyListView(Context context) {
super(context);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
heightMeasureSpec=MeasureSpec.makeMeasureSpec(
Integer.MAX_VALUE>>2,//此view高度的最大值
MeasureSpec.AT_MOST);//扩展模式
super.onMeasure(widthMeasureSpec,
heightMeasureSpec);
Log.i("TAG", "onMeasure");
}
}

public class MainActivity extends Activity {

private List<String> list=new ArrayList<String>();
public MainActivity() {
for(char i='A';i<='Z';i++){
list.add(String.valueOf(i));
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ScrollView sView=(ScrollView) findViewById(R.id.scrollId);
ListView lsv=(ListView) findViewById(R.id.lsvId);
lsv.setAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1,list));
//平滑滚动到顶点位置。
sView.smoothScrollTo(0, 0);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}

-<ScrollView tools:context=".MainActivity" android:layout_height="match_parent" android:layout_width="match_parent" android:id="@+id/scrollId" xmlns:tools="http://schemas.android.com/tools" xmlns:android="http://schemas.android.com/apk/res/android">

-<LinearLayout android:layout_height="wrap_content" android:layout_width="match_parent" android:orientation="vertical">

<ImageView android:layout_height="150dp" android:layout_width="match_parent" android:id="@+id/imgId" android:scaleType="fitXY" android:src="@drawable/a"/>

<包名.MyListView android:layout_height="match_parent" android:layout_width="match_parent" android:id="@+id/lsvId"/>

</LinearLayout>

</ScrollView>

2)属性（Attribute）的自定义(可选)

a)定义属性文件:res/values/attrs.xml

b)属性文件声明属性

<resources>

    <declare-styleable name="CircleView">

        <attr name="radius" format="integer" />

    </declare-styleable>

</resources>

c)在布局文件中给属性赋值(首先要定义命名空间)

d)在自定义View类的构造方法中获得布局文件中定义的属性值