Android: OnDraw and associate the class with the ImageView in the xml

I'm trying to override the default drawing for a particular ImageView in my XML layout file.

All the examples, I've seen do this using setContentView in the activity. I want to leave the main content view alone, and just handle the drawing for the one image control. I'm at a loss on how to associate the id of the imageview with the new instantiated class to handle the OnDraw.

I may very well be going about this backwards, so any help is appreciated.

as in below:

littleImage = (ImageView) findViewById(R.id.myImageView);

Vi开发者_Go百科ew myView = new MyCustomView(littleImage.getContext());

// NO! NO! I want to leave the 'main' view alone
//setContentView(myView);

public void test()
{
    littleImage.invalidate();
}

the layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:layout_width="wrap_content"
   android:layout_height="fill_parent"
    >
    <TextView android:id="@+id/label_title"
        android:layout_width="320dip"
        android:layout_height="wrap_content"
        android:text="@string/app_name"
        android:textSize="20sp"
        android:gravity="center_horizontal"
        android:background="#6B8AAD"
    />
    <ImageView
        android:id="@+id/image"
        android:clickable="false"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scaleType="fitCenter"
    />
    <ImageView
        android:id="@+id/myImageView"
        android:clickable="false"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scaleType="fitCenter"
        android:visibility="invisible"
    />
</LinearLayout>

As you see, I've tried the imageViews getContext, but that didn't help. How can I get this to trigger OnDraw?

The best way to achieve this is by creating a class LittleImage that Extends ImageView

public class LittleImage extends ImageView
{
    public LittleImage(Context context, AttributeSet attrs)
    {
        super(context, attrs);
    }
    @Override
    public void onDraw(Canvas canvas)
    {
        // Do you custom drawing here...
    }
}

Than, in your xml layout you can use:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="wrap_content"
    android:layout_height="fill_parent">
    <TextView android:id="@+id/label_title"
        android:layout_width="320dip"
        android:layout_height="wrap_content"
        android:text="@string/app_name"
        android:textSize="20sp"
        android:gravity="center_horizontal"
        android:background="#6B8AAD"/>
    <ImageView
        android:id="@+id/image"
        android:clickable="false"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scaleType="fitCenter"
    />
    <com.yourpackage.LittleImage
        android:id="@+id/myImageView"
        android:clickable="false"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scaleType="fitCenter"
        android:visibility="invisible"
    />
</LinearLayout>