自定义View（二）增加View的属性

     增加View的属性有两种方法    1、在View类中添加    2、在xml资源文件中添加

一、在View类中添加    例：实现一个带文字的图片

  

public class MyView extends View {
    
    private String mtext;
    private int msrc;

    public MyView(Context context) {
        super(context);
    }

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
        int resourceId = 0;
        int textId = attrs.getAttributeResourceValue(null, "Text",0);
        int srcId = attrs.getAttributeResourceValue(null, "Src", 0);
        mtext = context.getResources().getText(textId).toString();
        msrc = srcId;
    }
    
    @Override
    protected void onDraw(Canvas canvas) {
        Paint paint = new Paint();
        paint.setColor(Color.RED);
        InputStream is = getResources().openRawResource(msrc); 
                Bitmap mBitmap = BitmapFactory.decodeStream(is);
                int bh = mBitmap.getHeight();
                int bw = mBitmap.getWidth();
            canvas.drawBitmap(mBitmap, 0,0, paint);
        //canvas.drawCircle(40, 90, 15, paint);
        canvas.drawText(mtext, bw/2, 30, paint);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <com.example.myimageview2.MyView
        android:id="@+id/myView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        Text="@string/hello_world"
        Src="@drawable/xh"/>

</LinearLayout>

二、 在xml资源文件中添加

public class MyImageView extends LinearLayout {

    public MyImageView(Context context) {
        super(context);
    }

    public MyImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        int resourceId = -1;
        TypedArray typedArray = context.obtainStyledAttributes(attrs,
                R.styleable.MyImageView);
        ImageView iv = new ImageView(context);
        TextView tv = new TextView(context);
        int N = typedArray.getIndexCount();
        for (int i = 0; i < N; i++) {
            int attr = typedArray.getIndex(i);
            switch (attr) {
            case R.styleable.MyImageView_Oriental:
                resourceId = typedArray.getInt(
                        R.styleable.MyImageView_Oriental, 0);
                this.setOrientation(resourceId == 1 ? LinearLayout.HORIZONTAL
                        : LinearLayout.VERTICAL);
                break;
            case R.styleable.MyImageView_Text:
                resourceId = typedArray.getResourceId(
                        R.styleable.MyImageView_Text, 0);
                tv.setText(resourceId > 0 ? typedArray.getResources().getText(
                        resourceId) : typedArray
                        .getString(R.styleable.MyImageView_Text));
                break;
            case R.styleable.MyImageView_Src:
                resourceId = typedArray.getResourceId(
                        R.styleable.MyImageView_Src, 0);
                iv.setImageResource(resourceId > 0 ?resourceId:R.drawable.ic_launcher);
                break;   
            }
        }
        addView(iv);
        addView(tv);
        typedArray.recycle();
    }
}

在values文件夹下的  attrs.xml中声明属性

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <declare-styleable name="MyImageView">
        <attr name="Text" format="reference|string"></attr>
        <attr name="Oriental" >
            <enum name="Horizontal" value="1"></enum>
            <enum name="Vertical" value="0"></enum>
        </attr>
        <attr name="Src" format="reference|integer"></attr>
    </declare-styleable>

</resources>

 

在MainActivity中布局文件的使用   必须声明红色部分 才能在自定义的View中使用绿色部分的属性

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:uview="http://schemas.android.com/apk/res/com.example.myimageview2"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

    <com.example.myimageview2.MyImageView
        android:id="@+id/myImageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        uview:Text="这是一个图片说明" 
        uview:Src="@drawable/tw"
        uview:Oriental="Vertical">
    </com.example.myimageview2.MyImageView>

</LinearLayout>