Question

When i went through couple of android examples, in that i find some values are hard coded,

For eg:

<ImageView
    android:id="@+id/icon"
    android:layout_width="22px"
    android:layout_height="22px"
    android:layout_marginLeft="4px"
    android:layout_marginRight="10px"
    android:layout_marginTop="4px"
    android:src="@drawable/ic_launcher" >
</ImageView>

In this image view values are hard coded, for my custom layout.. how to avoid these kinds of hard coding?
Is this the correct way in android?, does it have any impact on various screen size devices?

Answer 1

You need to read some developer docs:

http://developer.android.com/guide/practices/screens_support.html
http://developer.android.com/guide/practices/screens_support.html#screen-independence

NO:

<ImageView
    android:id="@+id/icon"
    android:layout_width="22px"
    android:layout_height="22px"
    android:layout_marginLeft="4px"
    android:layout_marginRight="10px"
    android:layout_marginTop="4px"
    android:src="@drawable/ic_launcher" >
</ImageView>

Above will not scale well across screens

Yes:

<ImageView
    android:id="@+id/icon"
    android:layout_width="22dip"
    android:layout_height="22dip"
    android:src="@drawable/ic_launcher" >
</ImageView>

Above will scale its pixels ‘independently’ per device

or

<ImageView
    android:id="@+id/icon"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:src="@drawable/ic_launcher" >
</ImageView>

Above will draw itself relative to the screen size

or

<ImageView
    android:id="@+id/icon"
    android:layout_width="0dip"
    android:layout_weight="1"
    android:layout_height="22dip"
    android:src="@drawable/ic_launcher" >
</ImageView>

Above will draw itself relative to the screen size and the other views on the screen

or

ImageView imageView = new ImageView(this);
        imageView.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
        imageView.setImageDrawable(R.drawable.background);

        layout.addView(imageView);

Above is created programmatically