Develop Reference

why in Android 1024x600 is considered as mdpi?

I'm new with Android, and i don't know why android consider 1024x600 as mdpi,
in my application i'm using some images, and there is no drawable folder for the 1024x600

Display resolution (e.g. 1024x600) and screen density (e.g. mdpi) are related but independent concepts.
Screen size:
Actual physical size, measured as the screen's diagonal.
For simplicity, Android groups all actual screen sizes into four generalized sizes: small, normal, large, and extra large.
Screen density:
The quantity of pixels within a physical area of the screen; usually referred to as dpi (dots per inch). For example, a "low" density screen has fewer pixels within a given physical area, compared to a "normal" or "high" density screen.
Resolution:
The total number of physical pixels on a screen. When adding support for multiple screens, applications do not work directly with resolution; applications should be concerned only with screen size and density, as specified by the generalized size and density groups.
Grossly oversimplifying, you generally provide different resources for different screen sizes when you want them to be different in phones and tablets (e.g. for layouts), and different resources for different densities so that the system doesn't need to scale them, which could cause artifacts (e.g. for images).

What resolution of Drawables i should use for this display metrics?

I want to make my application to multiple screen support. so to achieve this i read the Android developers guildeline https://developer.android.com/guide/practices/screens_support.html and i have created the different drawable and layout folders to put different size of images.
I tested the application in different devices and it looks fine in those devices, while i found that in one of 7" tablet the images are too small. to confirm this i created simple project and put same name of images in different folder and found that this device uses ldpi drawables and in generally the size of ldpi drawable used to be 36x36 and that causes the issue, if i increase this drawable size then it will not compatible with other low-density devices.
Here is the Dispaly Metrics of the device in which i am having a problem.
{density=0.75, width=800, height=444, scaledDensity=0.75, xdpi=160.0, ydpi=160.42105}
How to deal with this problem ? if anyone have this issue before then please give me some advice. any idea and help will be appreciated.
Thanks & Regards

You can get more control over this:
Specify multiple different images for different screen resolutions and densities. To do so read supporting multiple screens. If you need even more precision in image scaling and quality you can use the fundamental size of screen attribute which is sw<N>dp - you can specify the smallest width of the screen where your image should be used. This is a qualifier name for a resource folder.
Some values you might use here for common screen sizes:
320, for devices with screen configurations such as:
240x320 ldpi (QVGA handset)
320x480 mdpi (handset)
480x800 hdpi (high density handset)
480, for screens such as 480x800 mdpi (tablet/handset).
600, for screens such as 600x1024 mdpi (7" tablet).
720, for screens such as 720x1280 mdpi (10" tablet).
Just specify your device width and put your edited image that fits the best in corresponding sw<N>dp folder in your case sw<444>dp.
You should also have a look at other qualifiers that make Android choosing image at runtime (screen density, Available width, Available height, Screen size or Screen aspect). By combining these qualifiers and testing carefully you will be sure that the user has the best experience on each device.
Shortly, put your image under drawable-sw<444>dp folder. (444-smaller screen metric)

Application Skeleton to support multiple screens

As we know Android coming with various device which having different
Features, Resolution, and Screen-size so while developing an Application which support
multiple (small and big) screen there is an obstacle of size and layout.
This leads to different combinations of screen sizes, resolutions, and DPIs and creates quite a challenge when designing and developing for Android devices. While some other Manufacturer (non Android) have different resolutions and DPI, they share the same screen size and the resolutions follow the same aspect ratio. Therefore, an image can be created to fit the non Android devices.
My question is that is there a proper flow or architecture that one should follow to meet the requirement?
Remember we do have Tablets of different Size and Resolution.
I'm aware that Android Developer contains this information but my view is from implementation.
From my knowledge what I understood is that for designing Android graphics even Programmer must know the designing concept.

Finally created a structure which handle layouts and icon for multiple screen.
Android generalises device displays into categories based on two parameters:
Screen size, the physical size of the display (measured diagonally)
Screen density, the physical pixel density of the display (in pixels-per-inch, or ppi)`
To determine screen size & density quickly, please install "What's my Size" app for Android.
Screen size
Android defines four generalised screen sizes:
Qualifier Size
small ~3 inches (approx)
normal ~4 inches (approx)
large Exceeds 4 inches
xlarge Exceeds 7 inches
Most phones are classified as small or normal (roughly 3 to 4 inches diagonally). But now, there are many phones with large screen such as Galaxy S4, HTC One, Xperia Z
A small tablet like the Samsung Galaxy Tab is classified as large (larger than 4 inches)
Extra-large applies to large devices, for example large tablets
Android defines four generalised screen densities:
Qualifier Description Nominal value
ldpi low density 120 ppi
mdpi medium density 160 ppi
hdpi high density 240 ppi
xhdpi extra high density 320 ppi
Typically:
screen size has most impact on your app layouts
screen density has most impact on your image and graphic resources
It is listed here the percentage difference of device screen
Ldpi- 75%
Mdpi- 100% (base according to Android developer site)
Hdpi- 150%
XHdpi- 200%
But as we know now most of device coming with 480X800 so I'm consider this as based device, so our new calculation will like this
Ldpi- 50%
Mdpi- 66.67%
Hdpi- 100%
XHdpi- 133.33%
which means that first icon and design will be created for 480X800 only and then for rest ones(i.e. Ldpi, Mdpi, Xhdpi).
There are images which are common for all layout and must uniform in color and shape(no complex shape, no curve) so for this kind of image we are creating 9patch which to be put in “drawable(no-suffix)” folder. To create 9Patch image you can either use DrawNinePatch or BetterNinePatch
Now just rename your images based on Android's standards and complete your application with hdpi and then just take drawable-hdpi folder and Open Adode Photoshop(recommended)
create Action of multiple size(just change the size according to percentage ratio) once Action created for all size then just do Batch Automate and give source(drawable-hdpi) and destination(drawable-ldpi, drawable-mdpi, drawable-xdpi).
The reason I insist you to use Photoshop because it will resize automatically your image with Actions and one more plus point is that you need not to rename the file(it will assign same name as original one).
once you completed with creation of all images, refresh your project and test it.
Sometimes there may be possibility that the layout which support screen(xhdpi, hdpi, mdpi) may be get cut in small screen(ldpi) so for handling this just create separate Layout folder(layout-small) for it and add ScrollView(mostly). Thats it.
Tablet
Tablets are categorized into two size.
7"(1024X(600-48(navigation bar))) = 1024X552 (drawable-large)
10"(1280X(800-48(navigation bar))) = 1280X752 (drawable-xlarge)
In this we need to create image for both the screen and just put them accordingly
So all in all we will have this folder in our application to support multiple screen.
drawable
drawable-ldpi
drawable-mdpi
drawable-hdpi
drawable-xhdpi
drawable-large
drawable-xlarge
will be more qualifier combination with Screen size and Screen density
drawable-large-ldpi
drawable-large-mdpi
drawable-large-hdpi
drawable-large-xhdpi
more qualifier with Screen density and Version
drawable-ldpi-v11
drawable-mdpi-v11
drawable-hdpi-v11
drawable-xhdpi-v11
and more qualifier with Screen size and Version
drawable-large-v11
drawable-xlarge-v11
and more qualifier with Smallest width concept(SW)
drawable-sw???dp
Further more in Android V3.0 Honeycomb they introduced new concept of SW(smallest width) in which device are categorized into screen width, so if we are creating a folder named drawable-sw360dp then the device with 720dp(either width or height) will use resource from the this folder.
for example to find the Samsung Galaxy S3 dp to suffix to drawable-sw?dp
With reference of DP Calculation, If you want to support your layout or drawable to S3 then the calculation says
px= Device's width = 720
dpi= Device's density= 320
formula given
px = dp * (dpi / 160)
interchanging formula because we have px's value
dp = px / (dpi / 160)
now putting value,
dp= 720 / (320/160);
dp=360.
so drawable-sw360dp will do the job
Get you Device configuaration from GsmArena
Sameway you can also create folder according to Device's Android API version i.e. drawable-hdpi-v11` so the device which is having API11 and it is Hdpi then it will use this resources.
Additional Tips:
Use relative layouts, dp, sp, and mm
dp units - device independent pixels normalised to 1 physical pixel on a 160 ppi screen i.e. medium density. Scaled at runtime. Use for screen element dimensions
sp units - scaled pixels, specified as floating point values, based on dp units but additionally scaled for the user's font-size preference setting. Scaled at runtime. Use for font sizes
you should always use RelativeLayout for layouts; AbsoluteLayout is deprecated and should not be used.
Use appropriate image formats - PNG versus JPEG
Android "prefers" PNG for bitmap image files, "accepts" JPEG, and "discourages" GIF.
However, PNG and JPEG are not equivalents. They have different quality trade offs, and PNG is not always best:
JPEG can offer up to 50% file-size reductions over PNG, which is significant if your app is image-intensive
A higher quality "lossy" JPEG may look better than a highly compressed "lossless" PNG, for the same file size
Add labels to your images and graphics for debugging
Use the supports-screens element
Configure your emulators with real device values
Conventionally, desktop systems display at 72ppi (Mac), or 96ppi (Windows, Linux). Compared with mobile, desktop displays are always low density.
Always configure your Android emulators to mimic real device values, and always set them to scale to emulate device density.
In Eclipse, it's easy to create multiple emulators (from the Eclipse menu bar, select Window > AVD Manager > New) configured with values for real devices:
Name the emulator for the real device it's emulating
Specify Resolution, don't use Built-in generic sizes
Set the device density to match the real device (in the Hardware pane set Abstracted LCD Property to the real density, always an integer value)
When you launch the device, always select Scale display to real size, and type in the real screen dimension in inches.
If you don't set the device density, the emulator defaults to low density, and always loads ldpi-specific resources. Resolution (pixel dimensions) will be correct, but your density-dependent image resources will not display as intended.
Of course, nothing you do will reproduce higher density image quality on a lower density desktop display.
Here is the Data collected during a 7-day period ending on October 1, 2012. To see the latest statistic about Android platform version, go to here
Based on Screen Size
Based on Screen Density

Designers should create base designs of
base size of mdpi devices * density conversion factor of highest supported density bucket
size.Base screen size is 320 X 480 px and density buckets are as follows:
ldpi: 0.75
mdpi: 1.0 (base density)
hdpi: 1.5
xhdpi: 2.0
xxhdpi: 3.0
xxxhdpi: 4.0
And to tackle extra available space on Android devices should use stretchable components in both the directions (horizontally and vertically). Detailed info is available here:
http://vinsol.com/blog/2014/11/20/tips-for-designers-from-a-developer/

Android screen sizes in Pixels for ldpi, mdpi, hpdi?

I've read 10 articles yet still cant find any relation between ldpi, mdpi, hdpi and the actual dimensions in pixels!? Can anybody give a straightforward answer please(if there is one!)
I'm basically trying to put together a splash screen that needs to work on multiple devices without stretching - but i'm struggling as everything I try is either squashed or stretched!?
Cheers
Paul

The ldpi, mdpi and hdpi refer to screen density, which means how much pixels can fit into a single inch.
the ratio in pixels between them is:
ldpi = 1:0.75
mdpi = 1:1
hdpi = 1:1.5
xhdpi = 1:2
xxhdpi = 1:3
xxxhdpi = 1:4
so lets take an image with about the size of 100X100:
for mdpi it should be 100X100
for ldpi it should be 75X75
for hdpi it should be 150X150
for xhdpi it should be 200X200
for xxhdpi it should be 300X300
for xxxhdpi it should be 400X400
this way, for screens with the same size but different DPI, all the images seem the same size on screen.
Also you have multiple screen size types small, normal, large, xlarge and each one of them can be ldpi, mdpi, hdpi, xhdpi, xxhdpi (Nexus 10) or xxxhdpi.
You can try to create a splash screen image that fit to each and every screen type
which gives you 4*5 = 20 different images (it seems to much for me).
For now only the Nexus 10 is at the xxhdpi category.

Install ImageMagick and use this shell script to generate your splash and icon files for multiple devices - iOS, Android, Bada and Windows Phone. You can use cygwin/gitbash if you are on Windows
I just did and I'm pretty happy with it :-)
The screen sizes are inside the script and are -
480x800 - screen-hdpi-portrait.png
320x200 - screen-ldpi-landscape.png
720x1280 - screen-xhdpi-portrait.png
320x480 - screen-mdpi-portrait.png
480x320 - screen-mdpi-landscape.png
200x320 - screen-ldpi-portrait.png
800x480 - screen-hdpi-landscape.png

The definitions are:
xlarge screens are at least 960dp x 720dp. large screens are at
least 640dp x 480dp. normal screens are at least 470dp x 320dp.
small screens are at least 426dp x 320dp. (Android does not currently
support screens smaller than this.)
Also, check out this blogpost from Dianne Hackborne:
http://android-developers.blogspot.com/2011/07/new-tools-for-managing-screen-sizes.html
Probably the easiest thing is to use an image view and set the scaletype to CENTER_CROP.
(Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or larger than the corresponding dimension of the view).
Make sure that you use the src tag rather than setting the background.
<ImageView
android:id="#+id/home_video_layout"
android:src="#drawable/splash_image"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:scaleType="centerCrop"
/>
Updated:
Understanding Screen Densities and the “dp”
Resolution is the actual number of pixels available in the display, density is how many pixels appear within a constant area of the display, and size is the amount of physical space available for displaying your interface. These are interrelated: increase the resolution and density together, and size stays about the same. This is why the 320x480 screen on a G1 and 480x800 screen on a Droid are both the same screen size: the 480x800 screen has more pixels, but it is also higher density.
To remove the size/density calculations from the picture, the Android framework works wherever possible in terms of "dp" units, which are corrected for density. In medium-density ("mdpi") screens, which correspond to the original Android phones, physical pixels are identical to dp's; the devices’ dimensions are 320x480 in either scale. A more recent phone might have physical-pixel dimensions of 480x800 but be a high-density device. The conversion factor from hdpi to mdpi in this case is 1.5, so for a developer's purposes, the device is 320x533 in dp's.

I have found this online dip <--> pixels calculator very useful.
https://pixplicity.com/dp-px-converter/

I support previous answers but don't forget the power of Draw9Patch or using NinePatchDrawables

These refer to screen pixel density, not screen dimension. You need to look into screen size specifiers like small, medium, large, and xlarge instead if you really need to change behavior based on screen size in pixels.
The Android docs explain what densities and sizes match these identifiers.

Android devices can have different width-to-height ratios, while your image has a fixed one. If you do not want your image stretched, you will have to fill the blank spaces above and below or left and right.

How does Android decide which layout folder to use?

In my application I have 3 different layout folders:
layout
layout-large
layout-xlarge
I did this according to the available Android device screens, described here. So I thought that the screen size in inches is the only thing that is used to decide which layout folder to use. But recent tests with various 7 inch emulator showed that sometimes the layout and sometimes the layout-large folder is used. So can anybody tell me which other factors are used?

7 inch Android tablets are HDPI and large.
xlarge didn't exist at the time they were made, and although most of them have pixel densities around 160 (MDPI) they present themselves as HDPI devices because it looks better.
So the 7inch tablets don't quite fit into the resources system properly, because there wasn't really a way to fit them in prior to 3.0 which introduced new screen-size qualifiers.

I think size in inches is the only thing that matters. There was a question on here a while back where someone has having some odd results with trying to make emulators pick from the correct layout folders for 7 inch devices. I have a Galaxy tab though and it will always take from layout-large, or layout-hdpi.
Edit: perhaps I was incorrect it seems that type of screen and pixel count may matter too -
* small: Screens based on the space available on a low-density QVGA screen. Considering a portrait HVGA display, this has the same available width but less height—it is 3:4 vs. HVGA's 2:3 aspect ratio. The minimum layout size for this screen configuration is approximately 320x426 dp units. Examples are QVGA low density and VGA high density.
* normal: Screens based on the traditional medium-density HVGA screen. A screen is considered to be normal if it is at least this size (independent of density) and not larger. The minimum layout size for this screen configuration is approximately 320x470 dp units. Examples of such screens a WQVGA low density, HVGA medium density, WVGA high density.
* large: Screens based on the space available on a medium-density VGA screen. Such a screen has significantly more available space in both width and height than an HVGA display. The minimum layout size for this screen configuration is approximately 480x640 dp units. Examples are VGA and WVGA medium density screens.
* xlarge: Screens that are considerably larger than the traditional medium-density HVGA screen. The minimum layout size for this screen configuration is approximately 720x960 dp units. In most cases, devices with extra large screens would be too large to carry in a pocket and would most likely be tablet-style devices. Added in API Level 9.
If you happen to have folders with more than one qualifier like layout-large-mdpi etc you have to pay attention to the precedence order also. this page should help out.

According to Google's android screen support guide res/layout is used for normal screens and is the default folder in which the OS looks.