Image Rendering in LC 7

[Mark Waddingham]

On 2015-05-19 18:15, Peter Bogdanoff wrote:
> Hi,
> 
> Has image rendering changed in LiveCode 7?

It changed in 6.5 when we moved to Skia - at that point we changed from 
pre-scaling images to doing image transformation at 'good' and 'normal' 
quality on the fly. The 'normal' quality setting does no filtering, 
'good' uses Skia's bilinear filter.

> In LC 7, they are horrible-looking at any size smaller than full
> sized. Horizontal lines disappear. Rendered text is distorted. Is this
> because we leave QuickDraw? If so, is Cocoa that bad?

Pre-6.5 on Mac only, if you were scaling an opaque image at 'normal' 
quality, it would use the QuickDraw CopyBits call. This is not something 
we can use anymore because of needing to be AppStore compliant; and it 
also doesn't fit into the revised graphics model from 6.5 onwards.

You should try 'good' resize quality and see if that gives you what you 
need.

We're not entirely sure what algorithm CopyBits uses for scaling images 
which seems to be so good for certain image types - but if someone does 
know, and indeed has some suitably open / free source-code lying around 
which does something similar we could look to see if we could resurrect 
that kind of filtering (it does seem to be somewhat different from 
bilinear - I think it is some sort of 'box' filter, but that covers a 
fair few things).

-- 
Mark Waddingham ~ mark at livecode.com ~ http://www.livecode.com/
LiveCode: Everyone can create apps