The document discusses ConstraintLayout, a layout for Android that allows building complex interfaces with a flat view hierarchy. It provides more flexibility than RelativeLayout. Key points covered include: - ConstraintLayout uses relationships between views to position them rather than nested view groups, improving performance. - Basic usage involves specifying at least one horizontal and vertical constraint per view to define its position. Additional tools like guidelines, barriers, chains and aspect ratios expand its capabilities. - The layout can be created and modified visually using Android Studio's layout editor or by editing the XML code. This makes the layout easier to work with compared to other options.

1. ConstraintLayout:
Why and how to use
Farhan Rahman Arnob • 21.01.2018

2. Overview
● ConstraintLayout allows you to create
large and complex layouts with a flat
view hierarchy (no nested view
groups).
● It's similar to RelativeLayout in that all
views are laid out according to
relationships between sibling views
and the parent layout, but it's more
flexible than RelativeLayout and
easier to use with Android Studio’s
Layout Editor.

3. WHY CONSTRAINT LAYOUT?
Reason
● A flat view hierarchy. Shallow
layout load fast!
● Easy modification.
● Time efficient update.
● Drag-and-dropping instead of
editing the XML.

4. HOW TO CREATE BASIC CONSTRAINT LAYOUT
View’s height/width mode:
1. Wrap Content: The view
expands only as much as
needed to fit its contents.
2. Fixed: You specify a specific
dimension
3. The view expands as much as
possible to meet the
constraints on each side

5. HOW TO CREATE BASIC CONSTRAINT LAYOUT
Basic Criteria:
● To define a view's position,
must add at least one
horizontal and one vertical
constraint for the view.

6. HOW TO CREATE BASIC CONSTRAINT LAYOUT
Guideline:
● want to allocate resource
space based on percentage
or split screen into a
dimension .
● If you click on red you get
different mode like
percentage, left fixed, right
fixed.
● Two types: vertical &
Horizontal

7. HOW TO CREATE BASIC CONSTRAINT LAYOUT
Barrier:
● want to create a barrier
based on multiple view’s
position range, use this.
● Here, View C got reposition
due to max length from A &
B.

8. HOW TO CREATE BASIC CONSTRAINT LAYOUT
Align:
● If you want to align based on
view do like like this.
● To create left align connect
child’s left point with parent’s
left point. & for right align
connect right points.
● For center align, connect left
and right both.

9. HOW TO CREATE BASIC CONSTRAINT LAYOUT
Baseline alignment(Text
align):
● If you want to align text use
text use this.
● One click on selected view
and you will get “ab” option.
Click “ab” and you will get
baseline bar. By drag and
drop you can connect to base
lines.

10. HOW TO CREATE BASIC CONSTRAINT LAYOUT
Constraint bias:
● When you add a constraint to
both sides of a view , the view
becomes centered between
the two constraints with a
bias(5) of 50% by default.

11. HOW TO CREATE BASIC CONSTRAINT LAYOUT
Chain layout:
● A chain is a group of views
that are linked to each other
with bi-directional position
constraints.
● Select both views (shift +
click) and then click right
button. Chin option will
appear.
● Can chain two to more.

12. HOW TO CREATE BASIC CONSTRAINT LAYOUT
Aspect Ratio:
● Useful for image view.
● Click on ratio enable bar (1).
Ratio box (4) will open.
● Need at least one match
parent(2) in vertically or
horizontally.

13. For more information
Visit: https://codelabs.developers.google.com/codelabs/constraint-layout/
Any Question?
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14. Thank you