[Galaxy S III Mini Original Android Development] mandayugana:
I just played with apktool to fix the circle on pattern lock scren. It seems Android resizes the circle png image, but not perfect. As a result, the circle is not perfectly rounded. Sometimes it's annoying to see that. :p

I don't know much about Android development, since I am a web developer. I edited the keyguard_pattern_view.xml in Keyguard.apk and changing some element's margin values. After applying it, The circle is now perfectly rounded.

In case anyone wants to try this, I attach the patched Keyguard.apk from 20151129, signed with ZipSigner using platform key.

Before:

<?xml version="1.0" encoding="utf-8"?>
<com.android.keyguard.KeyguardPatternView android:gravity="center_horizontal" android:orientation="vertical" android:id="@id/keyguard_pattern_view" android:layout_width="fill_parent" android:layout_height="fill_parent" android:contentDescription="@string/keyguard_accessibility_pattern_unlock" androidprv:layout_maxHeight="@dimen/keyguard_security_height" androidprv:layout_maxWidth="@dimen/keyguard_security_width"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:androidprv="http://schemas.android.com/apk/res/com.android.keyguard">
<FrameLayout android:layout_width="fill_parent" android:layout_height="fill_parent">
<LinearLayout android:layout_gravity="center" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content">
<include android:layout_width="fill_parent" android:layout_height="wrap_content" layout="@layout/keyguard_message_area" />
<FrameLayout android:id="@id/keyguard_bouncer_frame" android:background="@drawable/kg_bouncer_bg_white" android:layout_width="fill_parent" android:layout_height="0.0dip" android:layout_weight="1.0">
<com.android.internal.widget.LockPatternView android:gravity="center" android:layout_gravity="center_horizontal" android:id="@id/lockPatternView" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_marginBottom="4.0dip" android:layout_weight="1.0" android:contentDescription="@string/keyguard_accessibility_pattern_area" android:layout_marginStart="8.0dip" android:layout_marginEnd="8.0dip" />
</FrameLayout>
<include android:gravity="center_horizontal" android:layout_gravity="bottom|center" android:orientation="vertical" android:id="@id/keyguard_selector_fade_container" android:layout_width="fill_parent" android:layout_height="wrap_content" layout="@layout/keyguard_eca" />
</LinearLayout>
</FrameLayout>
</com.android.keyguard.KeyguardPatternView>

After:

<?xml version="1.0" encoding="utf-8"?>
<com.android.keyguard.KeyguardPatternView android:gravity="center_horizontal" android:orientation="vertical" android:id="@id/keyguard_pattern_view" android:layout_width="fill_parent" android:layout_height="fill_parent" android:contentDescription="@string/keyguard_accessibility_pattern_unlock" androidprv:layout_maxHeight="@dimen/keyguard_security_height" androidprv:layout_maxWidth="@dimen/keyguard_security_width"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:androidprv="http://schemas.android.com/apk/res/com.android.keyguard">
<FrameLayout android:layout_width="fill_parent" android:layout_height="fill_parent">
<LinearLayout android:layout_gravity="center" android:orientation="vertical" android:layout_width="wrap_content" android:layout_height="wrap_content">
<include android:layout_width="fill_parent" android:layout_height="wrap_content" layout="@layout/keyguard_message_area" />
<FrameLayout android:id="@id/keyguard_bouncer_frame" android:background="@drawable/kg_bouncer_bg_white" android:layout_width="fill_parent" android:layout_height="0.0dip" android:layout_weight="1.0" android:layout_marginBottom="4.0dip">
<com.android.internal.widget.LockPatternView android:gravity="center" android:layout_gravity="center_horizontal" android:id="@id/lockPatternView" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_marginBottom="0.0dip" android:layout_weight="1.0" android:contentDescription="@string/keyguard_accessibility_pattern_area" android:layout_marginStart="0.0dip" android:layout_marginEnd="0.0dip" />
</FrameLayout>
<include android:gravity="center_horizontal" android:layout_gravity="bottom|center" android:orientation="vertical" android:id="@id/keyguard_selector_fade_container" android:layout_width="fill_parent" android:layout_height="wrap_content" layout="@layout/keyguard_eca" />
</LinearLayout>
</FrameLayout>
</com.android.keyguard.KeyguardPatternView>