Best practise approach for artwork for iOS and Android?

Mark Waddingham mark at livecode.com
Tue Jun 12 16:44:50 EDT 2018


Just one thing to add here based on what Trevor mentioned - these are images which you have complete control over so...

If you can upscale them (perhaps using the tool Lagi suggests) with a good degree of visual improvement then you can use the multi-resolution aware feature of referenced (filename) image objects to improve the display of your images on high resolution screens.

Modern devices have screens which are 2-3x the dpi of screens we have lived with for decades - so more pixel data means better quality display.

When you use the filename property such as 'foo.png' the image object will look for images which have name 'foo@<n>x.png' first where x is 1,1.5,2 or 4 based on the number of device pixels available. E.g. On a 2x retina device - it will look for the 2x image and fit it to the logical (the rect) size.

Note: the base size is taken from the 1x image size and the file actually used is based on the 'effective scale' of the total transform from image text to device pixels - so the dpi setting in the images don't matter and it's much more competent than just using the type of screen.

TL;DR: if you can find a tool which can upscale your images acceptably to 2x or even 4x - do so - keep the original
image as foo.png and the upscale ones as foo at 2x/4x.png and set the filename of the image with foo.png. The engine should do the rest (from the using as much as it can pixel data wise at least point of view).

Warmest Regards,

Mark.

Sent from my iPhone

> On 12 Jun 2018, at 17:23, Trevor DeVore via use-livecode <use-livecode at lists.runrev.com> wrote:
> 
> On Tue, Jun 12, 2018 at 2:01 AM, Tiemo Hollmann TB via use-livecode <
> use-livecode at lists.runrev.com> wrote:
> 
>> 
>> I thought the dpi only reflects at print, because any screen has it's fixed
>> pixels. I think an image 800x600 with 144 dpi looks identical on any
>> screen,
>> as an image 800x600 with 72 dpi because in both cases 800x600 screen pixels
>> are being used and there is nothing between the pixels. Or don't I see
>> anything here?
>> 
> 
> Changing the DPI setting in the image may affect display in image viewing
> applications. If you were to change the DDPI setting of an 800x600 image
> from 72 to 144 then the image would be displayed as a 400x300 image in an
> application like Preview on macOS or Photoshop. LiveCode will display an
> image using the natural dimensions by default. That means an image with
> 800x600 pixels will be displayed as an 800x600 image.
> 
> As a developer you could get the `metadata` of an image and check the
> `density` key in the resulting array to determine if you should resize the
> image based on the density setting. Depending on your application you may
> face a new dilemma, however. You have to decide what the base DPI is for
> the image. An image with 144 DPI could be a 2x image if created on macOS
> (base of 72 DPI) or a 1.5x image if created on Windows (base of 96 DPI).
> So that image may need to be displayed at 400x300 or 533x400.
> 
> -- 
> Trevor DeVore
> ScreenSteps
> www.screensteps.com
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