Mobile App development - Orientation , Resolution and Width/Height

Question

Apple site says iPhone 5 Display is 1136-by-640-pixel resolution at 326 ppi. Generally resolution is practically spelled (Width x Height). In the iPhone 5, case we know 1136 is height and 640 is width when we hold the phone in portrait mode.

I am working on one Android project now I got confused with these mobile device resolutions. My app is targeted only for portrait: 1280x720, 960x540, 960x540, 800x480, 1920x1080, 1280x720, 1280x720, 1280x720, 960x540, 960x540

My questions are:

1. When we say 1136 x 640 which mean width x height of the device in landscape mode - correct?

2. Is it good idea to design the mobile App targeting just one resolution 320x480 (portrait only) and force the device to run in that 320x480 resolution? The library that I am using has the support for fixed resolution mode, and it's called as "Design Resolution" which accept (wxh).

Answer 1

To answer the first question: Yes, when Apple says 1136-by-640 pixel resolution they mean width-by-height in landscape mode.

To answer the second question: While it is not recommended that you design an app to only work in one orientation (portrait mode, for example), it is acceptable if that is what you need for your app. See the Apple Human Interface Guidelines. They say that if you do choose to support only one orientation, make sure that you also support that orientation when the device is turned 180 degrees. That is, make sure it flips when the user turns the device upside-down.

As for forcing a smaller resolution than the device is capable of displaying, that is never a good idea. See the Android Core App Guidelines which say that you should use the whole screen, and also suggest you support both orientations if possible.

Answer 2

I would say it's acceptable practice to develop an app for only one orientation, but force the orientation in the layout or code so when the user rotates the device it doesn't break the layout. When considering different screen resolutions you'll want to take into account possibilities of all your potential users. If you know the device resolution is going to be the same across all devices, by all means only code for that. If it will change you'll want to account for all. Since you're using portrait the resolution would be noted as 640x1136. It looks like your minimum target is 480x800 and max is 1080x1920, so I would suggest setting up emulators on all 3 sizes, and testing accordingly.