I have read Android guidelines regarding different screen sizes, but still I have some considerations.
Client has given me an image from PSD file which has certain resolution that fits
1080 X 1920. I just use wrap_content, and it perfectly fits the part
of screen.
I am not using DP to define its width-height, If i was using DP it would have
adjusted image according to screen sizes.
My questions are,
Does wrap_content works the same way as Density Pixels?
Is it also responsive, and changes the image width-height according
to different screens?
If not, then Is it necessary to use DP to support different screen
sizes ?
Thanks
The setting wrap_content tells your view to size itself to the dimensions required by its content. In the case of your test, your image is 1080x1920 and your device's screen resolution is likely 1080x1920 as well, hence the perfect fit. Since you set the width and height to wrap_content, Android is simply trying to use as much screen space as it needs to correctly display the amount of content it was supplied. In this case, since the available screen space matches the size of the content, it just fits perfectly.
But what if the device screen isn't 1080x1920? In that case, Android will only use as much space as it can, but still attempt to fit the image inside the bounds of the available screen space. In other words, the system will appropriately scale the image down to get it in the container you have provided for it. But this can lead to awkward fits if the aspect ratio isn't the same as the image. For instance, see this screenshot below:
This image is 1920x1080, but notice that it doesn't quite fit. That's because this nexus 7 screen is 1824x1200 when viewed in landscape. Additionally, the toolbar at the top of the screen is eating up available screenspace, making my viewable area even smaller and more awkwardly shaped. So while the system would love this image to extend all the way to the left and right borders, it can't, because then that would mean the height would be bigger than the viewable space. Since I used wrap_content to display this image, the system is using as much vertical space as it can, and the result is that the image doesn't quite fit the horizontal space.
So to more directly address your questions, yes wrap_content is a relative size setting that will make it easier to get a consistent look across multiple screen sizes, similar to using dp. But realize that there are hundreds, if not thousands of available Android devices on the market, and they all have varying screen sizes and densities. So your drawables may not always appear the way you want them on every device.
The way to overcome this is to supply multiple versions of your assets and provide alternate layout files for different screen sizes and densities. Once you do that, all you can do is test, test, and test some more. Use emulators for weird screen densities or devices you don't own, just to make sure you're getting the look you want. In the case of your 1920x1080 image, it looks great on that one device, but how will it fit a large tablet or a tiny handset that is smaller than the resolution of the image? These are situations you must account for in your design.
I suggest you read these resources, as they are hugely helpful in learning how to deal with issues resulting from varying screen sizes and densities:
http://developer.android.com/guide/practices/screens_support.html
http://developer.android.com/training/multiscreen/screensizes.html
Related
In my activity, I use DisplayMetrics to dynamically get the pixel height and width of the screen, and then I assign each of the components in the Activity sizes based on those dimensions. I wanted to know how this could be affected by screens that have different densities? Is it a good idea to use pixels?
Edit:
The purpose of using pixels dynamically is so that my layout scales based on the given screen. I just want to know how density will play into this. For example, if I have two screens with a height of 1024px and width of 800px, but one is twice as dense as the other, and I want to use 40% of the height and 40% of the width (this is just hypothetical) for a button, why should the density matter? This will just mean that the size of the button will have more pixels in the higher density screen, but the physical size of the button will be the same as DisplayMetrics will always give me the absolute size in pixels. Or am I wrong about this?
See this question and its answers. You will get the answer to your question.
Edit:
From one of the answers on the mentioned question
If you are any serious about developing an Android app for more than one type of device, you should have read the screens support development document at least once. In addition to that it is always a good thing to know the actual number of active devices that have a particular screen configuration.
Screen Sizes and Densities
To help in your case it is proposed to use dp units instead of pixels, but still there will be differences from one device to another.
On a tablet screen with a high pixel density, the elements probably will occupy less relative space.
If you want to improve it more then you will have to do the dimensions calculation by your own.
Or use a layout that auto distributes the space, for example the LinearLayout
Also you have to take into account that it is the system that decides the size of some widgets, for example the standard buttons
I am developing an Android application where the server sends all the values corresponding to dimensions in pixels for 1920*1080 resolution device.I need the app to be supported on multiple screen resolutions.I went through Android documentation on supporting multiple screen resolutions.It suggests to convert pixels to dip and then render.I did that in my application but the views are not rendered as required.So I tried applying simple unitary method by dynamically getting the screen width and height and then scaling all dimensions based on current screen width and height.
Say my current screen width is X and height is Y.So what I did was
Scaling factor in horizontal direction = New Screen Width/1920.
Scaled dimension in horizontal direction = Scaling factor in horizontal direction * Dimension from server in horizontal direction.
Similarly for vertical direction.
The application is now looking fine on my device.But is it a reliable way of doing things ? Should I be dealing with density of display too ?
DP is probably the better approach, if you elaborate a bit on what you mean by 'not rendered as required' I can try to help.
I can think of two main issues with your current method:
Different aspect ratios of devices. Using your method you will end up with distorted imagery. For example a square in 'server dimensions' is 400x400. In a 800x480 phone, that square will be 162x177 - no longer a square. Depending on your visuals and purpose of your app, this may or may not be an issue. If it is an issue, you need to account for that.
Physical views' size. One of the purposes of the DP method is to ensure a view will have (almost ) the same size across different devices, mainly never too small to handle for the user. So using the DP approach, a 100dp button will be 200px on a high density device, and 100px on a medium density device. This way the button is physically the same size on both devices.
But your method ignores that. Take the square from the first example - it will always be a fifth (400/1920) of the width of the screen. This can be either huge or tiny, depending on the device dimensions. Again, depending on your needs this may or may not be a problem.
Your method can work, as long as you account for these (and maybe more) problems. But it does require special care and probably more coding and work to make it work perfectly compared to simply using DP.
My layout as shown below looks very different depending on what screen size it is projected on to. I'm aware I can improve this somewhat using different layouts for each screen size but considering I have followed the best practises described in the android multiple screen support documentation (using dps, no absolute layouts etc) I wasn't expecting the results to look this bad so I fear there is a further underlying problem.
Code:
http://pastebin.com/D96ue9sc
Your layout is fine and completely as I would expect it. You shouldn't mix up density independent pixels with fully dynamically layouts.
DP just means that the value is calculated according the density types. The density itself has nothing to do with screen resolutions. 60dp are 60px on a mdpi device, it doesn't matter if the screen is full HD or just 480x360. But the result is, of course, very different because the calculated 60px are nothing on a HD screen but a lot on a small one.
You have not other possibility but to provide different layouts according to the screen size/resolution.
I have a problem with supporting different screen sizes. My application has different drawables for mdpi (320x480), hdpi (480x800) or ldpi (240x432). I also have different layout for small, normal-notlong, normal-long. Every size scaling or placement features are done in dp. However my problem is that I need to precisely place an element on the screen so it will perfectly fit to the background. One example here is an image that I download and show inside a frame that is part of the background. Or I also draw a circle (using drawArc) on the top of an imageview object and need to place it precisely to fit a 'black hole' that is on that image. Because the position is dependent on the background I place the elements with parent margins. As I wrote I am using dp for that. However If I fit my setting for a 320x480 3" screen and then change to 3.1" the elements are slightly misplaced and don't fit the background. The same if I have 480x800 3.5" device but change to 3.6" - the elements are misplaced slightly but that is enaught to look poorly in the design. What can I do about it? I am sure there has to be a way to achieve this on any screen size - i.e. games must use some kind of that mechanism and they work on any screen size. Can any one help?
I'm creating a splash screen that will display while my Android application loads. I'd like to create it at the correct size so Android won't auto-scale it up or down to fit the screen. (It's a bitmap image, a photograph of an oil painting, so I can't just turn it into a nine-patch.)
But there are at least three important screen sizes I care about: 320x480, 480x854 (Droid), and 480x800 (Nexus One).
I've read the documentation on supporting multiple screen sizes, but I still don't see how I'm supposed to configure different splash screens for Droid/Nexus one (they're both "hdpi" resources as far as Android is concerned), and I don't know exactly how large my splash screen should be in any case. (How tall is the OS title bar/menu in Droid? N1?)
What size should I make these images, and how do I tell Android to use the correct size on a given screen?
You don't need to worry about the absolute screen size or status bars or anything — that's why we have nine-patch images.
What I did was have an image that looked good for each resolution — essentially a logo on a transparent background, with some text at the bottom.
Then I chopped off quite a lot of space at the top and side edges, made a nine-patch border round the image, with a single pixel near the left, right and top edges. This allows the image to expand evenly at the sides and top to fill the screen.
Edit, in response to Dan's comment below:
Yes, there is a way to determine which graphics should be used for which explicit screen sizes, but it's deprecated.
Just as there are drawable-hdpi and -ldpi resource qualifiers, it's also possible to use drawable-HHHxWWW — the larger pixel dimension coming first.
e.g. drawable-800x480 and drawable-854x480
Okay, firstly: you can find the device model via android.os.Build and use that to determine which image to show.
Secondly, I personally wouldn't bother. Layouts should be done in dip since every android screen is 320x480 dip I believe, and android maintains aspect ratio among devices very well through this in my experience. A 480x800 splash set to fill parent has been pretty reliable on both N1 and the droid as far as I have encountered.
Another solution that I implemented is to put an ImageView that fills the screen (width and height both "MATCH_PARENT") with scale type "centerCrop". This way, the image is not stretched but cropped along the edges. Try not to put important content (logos and stuff like that) close to the edges. If it is a photograph, I hope that the edges are "expendable" and can be cropped out.