measure()函数中又会调用以下的函数：
而对于ViewGroup则不须要实现该函数，由于作为容器是“没有内容“的。其包括了多个子view，而子View已经实现了自己的绘制方法，因此仅仅须要告诉子view绘制自己就能够了。也就是以下的dispatchDraw()方法;
|
View(Context context)
Simple constructor to use when creating a view from code.
|
|
|
View(Context context, AttributeSet attrs)
Constructor that is called when inflating a view from XML.
|
|
|
View(Context context, AttributeSet attrs, int defStyle) Perform inflation from XML and apply a class-specific base style.
|
public class MyView
extends View {
private String
mtext;
private
int msrc;
public MyView(Context context) {
super(context);
//
TODO Auto-generated constructor stub
}
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
//
TODO Auto-generated constructor stub
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) {
//
TODO Auto-generated method stub
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>
public class MyImageView
extends LinearLayout {
public MyImageView(Context context) {
super(context);
//
TODO Auto-generated constructor stub
}
public MyImageView(Context context, AttributeSet attrs) {
super(context, attrs);
//
TODO Auto-generated constructor stub
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();
}
}
<?
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>
<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>
六、自己定义View的方法