I'm creating an app for Android and I should load images from a CDN and I want to support all the possible screen sizes. How should be done?
Should be many different versions of the same image stored in the CDN in different folders? Or one only resolution can cover all the screen sizes if it has high resolution?
Also How I know the exact numberXnumber? how I can know that? I should try manually or there are guidelines?
For example if that helps I have an ImageView 100dpX100dp how I know how much should be the pixels?
Thanks
You should probably set up essentially the basic ranges that android uses, mdpi, hdpi, hdpi-x, hdpi-xx. So you would have low and medium resolution screens request cdn.com/mdpi/image.png, high resolution request cdn.com/hdpi/image.png and so on... You define the resolutions within each grouping, for example on hdpi-xx Your images may be 1920x1080, but on hdpi it is only 1280x720. Those are just examples pulled out of the air, but you can adjust to suit your needs.
You can even use the base android resource system to pull the correct url for each screensize.
i.e.
In the folder values-mdpi you put a string resource that will have the url with mdpi, and hdpi with the base url for hdpi, you get the idea.
For further information you the documentation here provides very clear examples and more detail.
Related
How to support multiple screen resolutions with Vue? I couldn't find anything about multiple resolutions supporting on nativescript-vue.org.
The default measurement is DIP (Density Independent Pixels) that makes your app mostly look good on different resolution.
But if you still prefer to write CSS specific to a platform / device / screen resolution / orientation, try nativescript-platform-css.
If you want to completely change the layout of your page then you might have to write different components and load them based on your screen resolution.
When I make a new Universal App in Visual Studio 2013 I get a number of graphics files for the logos, splash screens, etc. in the Assets folder, for example Square71x71Logo.scale-240.png. The Package.appxmanifest then maps these files to the various required things. For example Square71x71Logo.scale-240.png is mapped in Package.appxmanifest to Square 71x71 Logo.
The actual file is 170 pixels wide, 170 pixels high, Photoshop reads it as having 72 pixels per inch, and it has an 8 bit colour depth.
What does the .scale-240 part of the file name signify?
I'm replacing the file and I am not sure how to scale-240-ify the new image.
The scale-240 part of the file name is a resource qualifier that indicates that the file is used for 240% DPI systems.
Resource qualifiers allow the app to provide different versions of the same resource for different scenarios and refer them all internally by the base name:
Scaling for different DPI systems: .scale-100, .scale-140, .scale-180, .scale-240
Language (if the image has text in it): .lang-de-DE, .lang-en-us
Contrast (to simplify for high contrast modes): .contrast-high, .contrast-standard
Layout direction (if the image should be different in LTR vs RTL language settings): .layoutdir-RTL, .layoutdir-LTR
DirectX feature level: .DXFL-DX9, .DXFL-DX11
The app can reference the image by its base name (e.g. logo.png) and the version which best matches the current scale, contrast level, language, etc. will be automatically used.
The default phone template provides scale-240 images since high-DPI phones are fairly common and it is generally better to scale down from a larger image than to scale up a small image. Best would be for you to provide multiple resolutions when you replace the stock ones with your own, especially if your images are complicated and don't scale well by default.
See How to name resources using qualifiers (XAML)
Universal apps need to be able to run on very different screens. You cannot predict up front what kind of device the user might have. Big difference if he has a cheap contract phone, an expensive slate or a desktop machine. WinRT helps by automatically scaling your app to match the screen resolution.
Supported scaling percentages for a desktop/slate app are 80, 100, 140 or 180%. For a phone it is 100, 140 or 240%.
Text can auto-scale easily but images do not. They get blurry when they get rescaled, a single pixel in the image no longer coincides with a single screen pixel. Pretty noticeable when the image contains fine line art or text. Scaling down necessarily loses pixels, details may disappear.
So the Visual Assets tab of the manifest editor allows you to select multiple images, each suitable for a specific scaling percentage. You found the -240 version in your phone project's Assets directory, the 240% scaling version that were auto-generated when you created the project. The desktop version has -100 assets by default, 100% scaling.
You may want to add your own. You don't have to.
.scale-xxx appears to refer to pre-scaled image resources.
If you are using a an image logo.png with size 100x100px then logo.scale-240.png should be an image of size 240x240px, i.e. scaled by a factor of 240 percent. The idea behind this concept is apparently to avoid potentially expensive and inaccurate rescaling by the displaying device, by supplying several prescaled images at defined scales.
In your case: 170px / 2.40 = ~71px
See also the corresponding MSDN article. (The linked article is in German, I will leave it to the interested reader to find the matching English one ;-)
I'm building a new app with this great tool and i have a question to solve.
What is the best way to handle imnage size for multiple scren and multiple devices.
Apple = retina and non-retina
Android = ldpi, mdpi, hdpi, xhdpi, xxhdpi and tablets (all this with multiple screen resolution)
BlackBerry10 = one resolution (but not equal to the others)
WindowsPhone8 = one resolution (but not equal to the others)
For this case, what is the best way ?
Use SVG images (Optimizacion, perfomance, size of app) ??
Dedicate CSS tags for device pixel ratio (CSS Image Replacement) (the designer can kill me :smile: lol ) see the list http://bjango.com/articles/min-device-pixel-ratio/
CSS Sprite sheet
Another way
Before the decision, think in what is the best to apply in all devices.
Thanks in advance
There really isn't a single way to do this since each implementation of an image will require a different approach depending on its purpose. SVGs are great but not everything works as an SVG.
Media queries will be your ally.
See this: supporting multiple resolution and density of images in phonegap
and this for an alternate approach: Angular.js data-bind background images using media queries
There are also some nice polyfills for the html5 picture element which you might find useful.
See: https://github.com/scottjehl/picturefill
...and its angularjs directive implementation https://github.com/tinacious/angular-picturefill
I'm creating a magazine to read on an iPad and am having problems with creating readable pages. What size (DPI and MB) should my files be? And I'm doing an export from InDesign, are there any suggested steps that should be taken here?
The iPad display is at 132 PPI.
The iPad display is 1024 x 768 - I'd recommend making your images that size.
That's right, the image size for iPad is by default 1024x768, but I recommend you to create your file in 1152x1536 px if you want to zoom-in in your image on iPad end keep a good quality of display.
Are you creating a pdf of the entire document or saving the pages as images? You may also want to consider the way users will be accessing the document (online, each page downloaded or as an application) If it is an application you will be able to have larger page sizes. If online, then download size will definitely become a factor in how it looks. If you shrink the quality too much, your rendered text will be the first thing on the page to suffer.
Have you done any research into what you find a comfortable to read text size (i.e., with popular science, wired, or project magazines? Another one to check is digital2.0 or the first of the RAW applications which was put out) These magazine apps use scrolling text regions in a lot of cases, but you can at least see how they use fonts and how comfortable they will be at different sizes.
This may well be a little of an open-ended question
The site I am working on requires to be optimised for performance. One of the key areas is to optimise the file sizes of the images used upon the site.
Unfortunatley these images are being created by employees who do not have the required knowledge for creating images for the web, and it is my job to produce a set of guidelines for them to use.
I was wondering whether there was any resource/guidlines/literature regarding typical images file sizes for images of different dimensions - as I would like to include something like this to aid them to ensure their images are being created properly.
Any info would be greatly appreciated.
Thanks in advance
I can't answer the opinion question, but I can suggest some guidelines that will keep your images smaller.
First off, if they're using Photoshop to edit their images, it's likely they're storing a whole bunch of crap in the headers (digital papertrail, EXIF data, and such). Also, folks will frequently save in too high a bit depth.
For novice users, trying to explain why they need to use "save for web" is more likely to confuse them. Instead, just point them at:
http://www.smushit.com/ysmush.it/
This site is rather handy - it will compress all the images on a page you specify, or you can upload the images.
You should strongly consider writing some guidelines about where images are stored as well. It's frequently very beneficial to have your static image content stored on several servers, apart from your dynamic content. Most browsers will only download a limited # of files at a time from any given website (usually it's 2).
Unless there's a good reason, all your images should be cached using one of the HTTP cache techniques (expires, etags, etc).
Good luck.
72 dpi as a resolution and either jpeg or png formats work best.
Try to use images at the exact pixel area size they will end up being displayed as. This is specified by the images height and width attributes.
You can set the output quality of a jpeg image which will also save file size although there is a trade off against image quality.
I hope this is of use.