How to hack any Whatsapp account

 

When you’re designing your application, you might have com-

plex views that will show up in different activities. Imagine that 

you’re creating a card game and you want to show the user’s 

hand in a layout similar to figure 3.1. How would you create a 

layout like that? 

 You might say that playing with margins will be enough for 

that type of layout. That’s true. You can do something similar 

to the previous figure with a RelativeLayout and add margins 

to its children. The XML looks like the following: 

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

<RelativeLayout

xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent" >

<View

android:layout_width="100dp"

android:layout_height="150dp"

android:background="#FF0000" />

<View

android:layout_width="100dp"

android:layout_height="150dp"

android:layout_marginLeft="30dp"

android:layout_marginTop="20dp"

android:background="#00FF00" />

<View

android:layout_width="100dp"

android:layout_height="150dp"

android:layout_marginLeft="60dp"

android:layout_marginTop="40dp"

android:background="#0000FF" />

</RelativeLayout>

</FrameLayout>

The result of the previous XML can be seen in 

figure 3.2.

 In this hack, we’ll look at another way of creating 

the same type of layout—we’ll create a custom View-

Group. The benefits of using a custom ViewGroup

instead of adding margins by hand in an XML file are 

these:

 It’s easier to maintain if you’re using it in differ-

ent activities.

Figure 3.1 User’s 

hand in a card game

Figure 3.2 Card layout created 
using the default Android widgets

 You can use custom attributes to customize the position of the ViewGroup chil-

dren.

 The XML will be easier to understand because it’ll be more concise.

 If you need to change the margins, you won’t need to recalculate by hand every

child’s margin.

Let’s take a look at how Android draws views.

Understanding how Android draws views

To create a custom ViewGroup, you’ll need to understand how Android draws views. I

won’t go into the details, but you’ll need to understand the following paragraph from

the documentation (see section 3.5), because it explains how you can draw a layout:

Drawing the layout is a two-pass process: a measure pass and a layout pass. The

measuring pass is implemented in measure(int, int) and is a top-down

traversal of the View tree. Each View pushes dimension specifications down

the tree during the recursion. At the end of the measure pass, every View has

stored its measurements. The second pass happens in layout(int, int, int,

int) and is also top-down. During this pass each parent is responsible for

positioning all of its children using the sizes computed in the measure pass.

To understand the concept, let’s analyze the way to draw a ViewGroup. The first step is

to measure its width and height, and we do this in the onMeasure() method. Inside

that method, the ViewGroup will calculate its size by going through its children. We’ll

make the final pass in the onLayout() method. Inside this second method, the View-

Group will lay out its children using the information gathered in the onMeasure()

pass.