Develop Reference

How to calculate image size for different devices dpi

I have a listview layout with images
It looks like this
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="match_parent"
android:layout_height="240dp"
android:adjustViewBounds="true"
android:id="#+id/listview_item_imageView"
android:layout_gravity="center_horizontal|top" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#FAC308"
android:id="#+id/listview_item_title"
android:text="TITLE"
android:textSize="20sp"
android:paddingBottom="40dp"
android:layout_centerInParent="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#ffffff"
android:id="#+id/listview_item_subtitle"
android:paddingTop="40dp"
android:text="SUBTITLE"
android:textSize="20sp"
android:layout_centerInParent="true" />
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/orangeSeparator"
android:src="#drawable/orangeseparator"
android:layout_centerInParent="true" />
If I run it on device with 720x1280 240dpi it looks like this
If I run it on device with 720x1280 320dpi it looks like this
I get images from the internet, so I cant prepare different versions.
How to make it look similar across all the devices ?

You can use fitXY Android Developer,
android:scaleType="fitXY"
or you can also create different drawable resources from the original one, with Photoshop or any similar program

in your container you have
android:layout_height="match_parent"
and in the image:
android:layout_height="240dp"
you have to have the same height or 'wrap_content' for your container not to have those gaps.
you can also add to the imageview:
android:scaleType="centerCrop"
another thing is that you can use specific library to handle loading of network images.

You can look this article . Make your app supporting different dpi variations and different screen types: Supporting Different Screens

Android Single Layout to FIt All Screen Sizes

I am updating my Android app and realized that I have created a layout for every possible screen size (layout-small, layout-large, etc...) It would be a huge pain to go through every XML file and manually make a small change. I am attempting to create a single XML file to support all screen sizes. After reviewing the Android documentation and other questions on stackoverflow, it seems LinearLayout is the best choice as you can provide a weightSum and layout_weight for each item in the layout. This is not working as expected (see below code and images). I am doing this correctly? Do I have to go back to creating a RelativeLayout for every possible screen size?
My images are an a single drawable folder and my layouts are in a single layout folder.
XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/bg"
android:gravity="center"
android:orientation="vertical"
android:weightSum="100" >
<ImageButton
android:id="#+id/btn1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:src="#drawable/image0"
android:background="#null"
android:layout_weight="30" />
<ImageButton
android:id="#+id/btn2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:src="#drawable/image1"
android:background="#null"
android:layout_weight="30" />
<ImageButton
android:id="#+id/key"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="30"
android:background="#null"
android:src="#drawable/image0_key" />
<TextView
android:id="#+id/tvScore"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="Score: 0"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_weight="10"
android:layout_gravity="left" />
</LinearLayout>
Resulting View (overflow of items and layout not consistent for screen sizes)
Nexus One:
Tablet:
EDIT:
I have added the following drawable-____ folders. It produces the same result.

You might want to consider creating compatibility layout folders. :)

Yes we have a solution for the same by using android's percent layout we can now use app:layout_heightPercent and app:layout_widthPercent to fit all the screens using single layout.
compile 'com.android.support:percent:23.0.0'
Why use LinearLayout weight property now we have simpler solution.
Demo HERE !
GitHub project HERE !
Consider a simple sample
<android.support.percent.PercentRelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/fifty_huntv"
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#ff7acfff"
android:text="20% - 50%"
android:textColor="#android:color/white"
app:layout_heightPercent="20%"
app:layout_widthPercent="50%" />
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_toRightOf="#id/fifty_huntv"
android:background="#ffff5566"
android:text="80%-50%"
app:layout_heightPercent="80%"
app:layout_widthPercent="50%"
/>
</android.support.percent.PercentRelativeLayout>
Hope it's useful for someone :-)

Use Below layout for arranging your ImageButton and TextView. It works for all screen size Layouts.
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/mLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:weightSum="3" />
<ImageButton
android:id="#+id/imageBtn1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="#drawable/ic_launcher" />
<ImageButton
android:id="#+id/imageBtn2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="#drawable/ic_launcher" />
<TextView
android:id="#+id/tv1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Score: 0" />
</LinearLayout>

Never put an weight sum like hundred ,just try using single digits

DisplayMetric dm =new DisplayMetric();
getWindowManager().getDefaultDisplay().getMetrics(dm);
int h= dm.heightPixels;
int w= dm.widthPixels;
h=h/10; // 10 is for example for 10% of display height
w=((w*20)/100); // 20%of display width
LinearLayout.LayoutParams params= new LinearLayout.LayoutParams(w,h);
YourObject.setLayoutParams(params);
//(YourObject) can be everything such as button , image button, textview,...

There are two issues here, one is to fill the size of the screen and the other is supporting the various resolution sizes of mobiles. Even within xxxhdpi, there are variations as new flagship Samsung Mobiles are drifting to 19.5 x 16.
Linear layout along with weight attributes does give a good coverage but beware of the nested tags and performance. It worked out well for most of the scenarios I have handled.
In addition, as pointed out in other answers, different drawables/resources for the standard sizes helps maintaining similar view in all devices.

How to make layouts grow and shrink?

I'm playing around with making a random recipe collection app.
Now I came across a problem: at the moment I have designed it with my mobile's resolution in mind. But what if the app is used on a device with larger resolution eg. a tablet.
What I want to achieve is that I want the buttons to grow shrink depending on the resolution. For example: when holding my phone vertically, there are 2 columns of buttons. When holding it horizontally, there still are 2 columns, but the view gets wider. Then there should be 4 columns to fill as much of the white space as possible.
Two pictures to illustrate my thoughts:
vertical
horizontal with 2 more columns
My code:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffcc33"
android:orientation="vertical"
android:paddingTop="10dp"
android:paddingLeft="10dp"
android:paddingRight="10dp" >
<LinearLayout android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:weightSum="1000" >
<EditText
android:id="#+id/search_box"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="left"
android:layout_weight="1000"
android:ems="5"
android:hint="#string/search_hint" />
<Button
android:id="#+id/search_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right"
android:text="#string/search_button" />
</LinearLayout>
<ScrollView android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center" >
<RelativeLayout
android:layout_width="225dp"
android:layout_height="wrap_content"
android:layout_below="#+id/search_box"
android:layout_gravity="center"
android:layout_marginTop="15dp" >
<Button
android:id="#+id/btn_lihatoidud"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#android:color/transparent"
android:drawableTop="#drawable/lihatoidud"
android:layout_alignParentTop="true"
android:text="Lihatoidud"
android:textSize="18sp" />
<Button
android:id="#+id/btn_kypsetised"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/btn_lihatoidud"
android:layout_marginTop="15dp"
android:background="#android:color/transparent"
android:drawableTop="#drawable/kypsetised"
android:text="Küpsetised"
android:textSize="18sp" />
<Button
android:id="#+id/btn_seenetoidud"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/btn_kypsetised"
android:layout_marginTop="15dp"
android:background="#android:color/transparent"
android:drawableTop="#drawable/seenetoidud"
android:text="Seenetoidud"
android:textSize="18sp" />
<Button
android:id="#+id/btn_juustutoidud"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/btn_seenetoidud"
android:layout_marginTop="15dp"
android:background="#android:color/transparent"
android:drawableTop="#drawable/juustutoidud"
android:text="Juustutoidud"
android:textSize="18sp" />
<Button
android:id="#+id/btn_lisandid"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/btn_juustutoidud"
android:layout_marginTop="15dp"
android:background="#android:color/transparent"
android:drawableTop="#drawable/lisandid"
android:text="Lisandid"
android:textSize="18sp" />
<Button
android:id="#+id/btn_supid"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:background="#android:color/transparent"
android:drawableTop="#drawable/supid"
android:text="Supid"
android:textSize="18sp" />
<Button
android:id="#+id/btn_voileivad"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="#+id/btn_supid"
android:layout_marginTop="15dp"
android:background="#android:color/transparent"
android:drawableTop="#drawable/voileivad"
android:text="Võileivad"
android:textSize="18sp" />
<Button
android:id="#+id/btn_pudrud"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="#+id/btn_voileivad"
android:layout_marginTop="15dp"
android:background="#android:color/transparent"
android:drawableTop="#drawable/pudrud"
android:text="Pudrud"
android:textSize="18sp" />
<Button
android:id="#+id/btn_joogid"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="#+id/btn_pudrud"
android:layout_marginTop="15dp"
android:background="#android:color/transparent"
android:drawableTop="#drawable/joogid"
android:text="Joogid"
android:textSize="18sp" />
</RelativeLayout>
</LinearLayout>
</ScrollView>
</LinearLayout>

Android has a few mechanisms for dealing with this kind of thing. For most people simply having a different layout for different classes of device will be sufficient. i.e:
res/
layout/
my_layout.xml
layout-land/ # landscape
my_layout.xml
layout-sw600dp # bigger devices
my_layout.xml
layout-sw600dp-land # Big and landscape
Android will automatically pick the right layout on the device your app gets loaded on. See the Developer Guide for details there. Alternatively, you might need to define your own custom view that resizes your grid based on the available size. An example of this is a CellLayout, a class written for the grid of apps in Launcher

I would actually reccomend you use the GridView pattern.
https://developer.android.com/guide/topics/ui/layout/gridview.html
Benfits include
Easily customize able if you need multiple rows/columns
Faster performance because you re-use a lot the same views. Scales much better than scrollview approach
Here example with two column for Phones
Here example with four column for tablets
All changing only the number of columns the grid should show. The best way to do this by what "JRaymond" recommended, by having multiple values resposnes depending on if its a tablet/phone. Example
->values ->attrs_arin_view.xml
->values-land->attrs_arin_view.xml
->values-sw600dp -> attrs_arin_view.xml
inside values ->attrs_arin_view.xml
<resources>
<integer name="number_of_column">2</integer>
</resources>
and then change in the values-land to have number_of_column to 4.
Then in your in your xml you mention the integer once
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
>
<GridView
android:id="#+id/gridView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:horizontalSpacing="8dp"
android:numColumns="#integer/number_of_column"
android:padding="8dp"
tools:listitem="#layout/grid_cell_note"
>
</GridView>
</LinearLayout>

You need to create xml files for different screen sizes
http://developer.android.com/guide/practices/screens_support.html
design your XML files to use references instead of hardcoded strings. You can then assign a reference to layouts, buttons and so on which has a different value depending on screen sizes.
(use android:padding="#dimen/pagepadding" instead of android:padding="16dp" and define the dp in values/dimens.xml like this: <dimen name="pagepadding">16dp</dimen>)
To do that you have to create new folders in your Project like values-sw600dp for devices with 600dp smallest width (like Nexus 7 I believe) or values-sw720dp-land for devices with the smallest width of 720dp (10 inch tablets I believe) in landscape.
Do some reading on the developer page and on the internet for that. It's not too difficult

automatically resize ImageButtons in LinearLayout

Summary: I want a horizontal row of ImageButtons to scale down evenly to fit in the screen size.
I have a row of ImageButtons at the top of the screen. A left-aligned logo ImageButton and then right-aligned ImageButtons for various actions.
Yes, that does sound a lot like a Honeycomb/ICS Action Bar, but the code is targeted for Froyo, so I need to implement the design in 2.2-compatible layouts.
I programmatically detect when I'm on a 7" screen or larger and switch to larger images for the ImageButtons (as the drawable-xlarge directory only works for 10" and up, and drawable-large works for 4" and up).
This works great on a phone or on a 10" tablet. However, on a 7" tablet, the images are too large for the space in portrait mode (the app is locked to portrait mode).
I have tried many different approaches to making the images scale down, as I'd rather not use yet another set of images just for 7" tablets. But the images are not spaced properly, or scale at different levels, or only some of the images appear on the screen. I've used RelativeLayout, LinearLayout, android:weightSum, setting the images as background images, as src images, etc.
EDIT: Another quirk I noticed in my experimentation was that if I set the same layout_weight, the layout worked, forcing each item to have the same width. If I want some items to have different widths--which is necessary in this case, as the first button needs to be substantially wider--then the layout breaks when I set a layout_weight that doesn't match the others. Only one or two of the items appear on screen, the rest presumable being pushed off.
Here's the layout I'm using. This is my best so far--it works great on 10" tablets and phones, and is almost tolerable on 7" tablets. But the logo--which should be the same height as the buttons and about 2.5 times wider--is noticeably taller than the other buttons. Any suggestions on improving the layout?
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/actionBarLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0"
android:padding="5dip"
android:gravity="center_vertical"
android:orientation="horizontal"
android:background="#drawable/action_bar_bg"
>
<ImageButton
android:id="#+id/logoButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="#null"
android:src="#drawable/save_logo_03"
android:padding="2dip"
android:adjustViewBounds="true"
android:scaleType="centerInside"
/>
<View
android:id="#+id/spacer"
android:layout_width="50dip"
android:layout_height="1dip"
android:layout_weight="1"
android:visibility="invisible"
/>
<ImageButton
android:id="#+id/listButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:src="#drawable/list_button"
android:background="#null"
android:adjustViewBounds="true"
android:padding="2dip"
android:scaleType="centerInside"
/>
<ImageButton
android:id="#+id/mapButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="#null"
android:src="#drawable/map_button2"
android:adjustViewBounds="true"
android:padding="2dip"
android:scaleType="centerInside"
/>
<ImageButton
android:id="#+id/ltoButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="#null"
android:src="#drawable/lto_button"
android:adjustViewBounds="true"
android:padding="2dip"
android:scaleType="centerInside"
/>
<ImageButton
android:id="#+id/searchButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="#null"
android:src="#drawable/search_button"
android:adjustViewBounds="true"
android:padding="2dip"
android:scaleType="centerInside"
/>
</LinearLayout>

Unfortunately, in the end I did have to programmatically change the button sizes depending on the size of the screen.
My final layout looked like this (sanitized):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0"
android:padding="5dip"
android:gravity="center_vertical"
android:orientation="horizontal"
android:background="#drawable/action_bar_bg"
>
<ImageButton
android:id="#+id/logoButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="0"
android:background="#null"
android:padding="2dip"
android:adjustViewBounds="true"
android:src="#drawable/logo"
android:scaleType="centerInside"
/>
<View
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="1"/>
<ImageButton
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="0"
android:background="#null"
android:padding="2dip"
android:src="#drawable/button1"
android:scaleType="centerInside"
android:adjustViewBounds="true"
/>
<ImageButton
android:id="#+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="0"
android:background="#null"
android:padding="2dip"
android:src="#drawable/button2"
android:scaleType="centerInside"
android:adjustViewBounds="true"
/>
<ImageButton
android:id="#+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="0"
android:background="#null"
android:padding="2dip"
android:src="#drawable/button3"
android:scaleType="centerInside"
android:adjustViewBounds="true"
/>
<ImageButton
android:id="#+id/button4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="0"
android:background="#null"
android:padding="2dip"
android:src="#drawable/button4"
android:adjustViewBounds="true"
android:scaleType="centerInside"
/>
</LinearLayout>
Notice the empty View that fills up available space, pushing the other buttons over to the right side of the screen.
In the code, I check the screen size. If it seems to be >= 7", then I switch to larger images.
If it seems to be >=7" but < 9", then I programmatically change the size of the images--and that I had to experiment with to come up with just the right number for it to work. If I had more images or they changed, I would have to repeat it. I'm not proud of such an inflexible solution, but I couldn't find anything else that worked.

This is what I've got:
In your specific case, we can say that your app layout and buttons size are under dependecy of:
The mobile device screensize/resolution;
The number of buttons in the
row;
I recommend 2 approaches to you:
Implementing your layout with RelativeLayout and weight tags. Flexible layouts can be made very easy with these ones;
Programatically define your button sizes using DisplayMetrics class, something like the snippet in the end of this post, and use an extra .xml file (say integer.xml) where you can define a constant value for your number of buttons;
In this snippet, dm is a structure that holds your device resolutions.
DisplayMetrics dm = new DisplayMetrics();
context.getWindowManager().getDefaultDisplay().getMetrics(dm);
Hope it helped you! :)

Android 4x2 widget

Looking at the Facebook widget I realized its a 4x2 cell and this isn't one of the standard sizes. I have tried to re-create a widget of this size (either as 320x200 or 294x146 px) however the widget doesn't look good on all devices. The widget layout is :
<?xml version="1.0" encoding="utf-8"?>
<!-- Portrait -->
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="#+id/widget"
android:background="#drawable/widget_bg"
>
<TextView android:id="#+id/widget_title"
android:layout_width="fill_parent"
android:layout_height="60dip"
android:layout_marginTop="1dip"
android:textSize="20.0sp"
android:maxLines="3"
android:textColor="#000"
android:textStyle="bold"
android:gravity="center"
android:layout_marginLeft="10dip"
android:layout_marginRight="10dip"
android:layout_centerHorizontal="true"
android:layout_alignParentTop="true"
android:ellipsize="end"
/>
<ImageView android:id="#+id/widget_thumb"
android:layout_width="304dip"
android:layout_height="90dip"
android:layout_alignParentLeft="true"
android:layout_marginLeft="7dip"
android:src="#drawable/thumb_placeholder_large"
android:adjustViewBounds="true"
android:layout_below="#+id/widget_title"
android:background="#000"
/>
<!-- previous button -->
<Button
android:id="#+id/widget_previous"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_alignParentLeft="true"
android:layout_marginLeft="5dp"
android:layout_marginBottom="35dp"
android:layout_alignParentBottom="true"
android:background="#drawable/left_button"/>
<!-- Next Button -->
<Button
android:id="#+id/widget_next"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_marginRight="5dp"
android:layout_marginBottom="35dp"
android:layout_alignParentBottom="true"
android:background="#drawable/right_button" />
<!-- Indicator -->
<LinearLayout
android:id="#+id/widget_progressbar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_marginBottom="33dp"
android:layout_marginRight="50dp"
android:layout_alignParentBottom="true">
<!-- ProgressBar throws exception when it's set invisible from RemoteViews use a layout wrapper instead -->
<ProgressBar
android:layout_width="15dp"
android:layout_height="15dp">
</ProgressBar>
</LinearLayout>
</RelativeLayout>
On the Motorola Droid this layout fits properly, however on other devices the ImageView sits way below. Any help/suggestions are appreciated.
The drawable_bg.png is 294x146px.
Sandeep

The actual size of the widget depends on
the display resolution (pixels) of the device
the used home application (they have different notification bars and bottom bars)
the Android OS version (different versions also have different home apps)
So better make your layout "fill_parent" and your background image a "ninepatch" image.
Also use different background images for different display resolution (dpi) to make the background image look perfect.

i think you should consider creating more layouts for different screen sizes , and test them so you could make sure your widget looks good on all screen sizes .