Setting Drawable Folder to Use for Different Resolutions

Setting drawable folder to use for different resolutions

How do I force the Nexus to use resources in drawable-xhdpi and then
the 10 inch tab to use drawable-xxhdpi?

You can't.

The qualifiers hdpi,xhdpi,xxhdpi describes the screen density of the device, not the size of screen.
From the official doc

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. For simplicity, Android groups all
actual screen densities into four generalized densities: low, medium,
high, and extra high.

If you want to support tablets also, use large, xlarge qualifiers. Nexus 7 is a large-hdpi tablet(technically it's tvdpi, but takes images from hdpi). So if you want to put images for Nexus 7, make a folder named drawable-large-hdpi and put the images there.

Note: This is the special case for Nexus 7. Because even though Nexus 7 is a 7 inch tablet, it has resolution of 1280 * 800. So it's an hdpi device. But normal 7 inch devices have lower resolutions of 1024 * 600. So they are mdpi devices. So the drawable qualifier can change. (From my own experience, first put a folder drawable-large-mdpi for 7 inch devices and check it on Nexus 7. If there is no problem with images, you dont have to put another folder. Because if a particular folder is not present, Android will check for the nearest possible folder and optimize it for the device screen)

Now regarding the 10 inch tablets case, they are xlarge devices and their densities can change from mdpi to xhdpi(Nexus 10). But many have resolution of 1280 * 800 and they are mdpi devices.

The better practice is to put the following drawables

// for Phones
drawable-ldpi
drawable-mdpi
drawable-hdpi

//for 7 inch tablets
drawable-large-mdpi
drawable-large-hdpi(for Nexus 7)

// for 10 inch tablets
drawable-xlarge-mdpi

Android Studio: Drawable Folder: How to put Images for Multiple dpi?

The standard procedures are:

1. Choose Project > app > scr > main
2. Right click "res", choose "New" and choose "Android resource directory"
   
3. In the opened dialog, at Resource Type choose "drawable"
   
4. In the list Available qualifier choose Density, then click the right arrow at the middle.
   
5. Choose the Density that you like then press OK
   

drawable folders - What resolutions do I need

These are the resolutions in dpi:

ldpi:    120 dpi  
mdpi:    160 dpi  
hdpi:    240 dpi  
xhdpi:   320 dpi  
xxhdpi:  480 dpi  
xxxhdpi: 640 dpi  

You have to calculate the dimensions in pixels basing on the resulution:

Scale factor:

ldpi:    0.75  
mdpi:    1.0  
hdpi:    1.5  
xhdpi:   2.0  
xxhdpi:  3.0  
xxxhdpi: 4.0

You COULD have all the images in the xxxhdpi folder and let Android scale them down... but not always you'd get nice results (Android scaling DOWN is good, but not as good as pre-sized images).

Nowadays I guess that an xxhdpi resolution is enough, but tomorrow...

It would be scaled UP on an xxxhdpi screen, with not-so-good results (visible pixellation).

A solution would be using svg graphics (which is a vectorial standard based on xml), but you'd need an external library (there are several open source / free - you choose the one which fits best) to render them in a standard control.

Drawable folder different screen resolution issues

you can use drawable-large for tab

Different image sizes for resolution-specific Drawable folders

What you're looking for is the scale-factor for each folder. This works by taking the mdpi folder as the "base" scale of 1.0.

Scale-factors for each folder are as follows:

• ldpi > 0.75
• mdpi > 1.0
• hdpi > 1.5
• xhdpi > 2.0
• xxhdpi > 3.0
• xxxhdpi > 4.0

So, for example, taking a 48*48px image as your base mdpi image, you'd end up with 32, 48, 72, 96, 144 and 192px images.

Fore more detail, including the source for each of these values, check out shoe-rat's excellent answer from which I sourced much of this one.

Drawable folders for high resolution handhelds

Well, as I said above I can't find any handhelds with Android on it that's got a resolution of 640x960. So I based all my images on 720x1280 instead and put the 640x960 resolution stuff in a large-hdpi folder.

Now my app looks great on the latest Nexus, the Galaxy S3, HTC One-X and all of the other newer hires models. I think the tablets when looking for resources will go for large first, then hdpi where they will find the 2x scaled images.

This is what I ended up with:

xhdpi: 720x1280

large-hdpi: 640x960

hdpi: 480x640

mdpi: 320x480

ldpi: 240x320

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