Re: [Cdk-jchempaint] zoom and scale (and margin, and view resizing)

[<ra...@ar...>]

Egon, thanks,
I have copied this to:
https://github.com/JChemPaint/jchempaint/wiki/Zoom-and-scale

On Sat, May 26, 2012 at 01:51:21PM +0200, Egon Willighagen wrote:
> Ralf, others,
> 
> now the rendering/controlling development is strongly picking up
> again, I would like to point out the following...
> 
> In the original CDK-JChemPaint design now used, as set out by me and
> Niels, to replace the older rendering code, there are two principle
> concepts:
> 
> scale: this factor ensures that the world coordinates gets transformed
> into screen coordinates (pixels)
> margin: this scaling is affected by the margin: the scaling is such
> that there is this margin.
> 
> And then there is this:
> 
> zoom: given the above scaling, which makes a structure fit on screen,
> there is a zoom factor used by the user to zoom in and out, where it
> defaults to 1.0, thus 100%.
> 
> There is also view, screen size, etc. That is, each actual application
> (JChemPaint, Bioclipse, AMBIT, Cinfony, and many, many others) has an
> area where it depicts a structure. This application can have various
> options:
> 
> - fixed scale: the actual area onto which is drawn is fixed, and if
> the screen (Component, JFrame, etc) is enlarged, the scale remains the
> same, and more white space is created
> - scale-to-fit: the scale is update when the size of the actual
> drawing area is increased; the amount of whitespace remains identical
> 
> Now, both can be combined with scroll panes, of course, to further
> complicate things.
> 
> However, the current CDK-JChemPaint iteration was intended to follow
> this design, and we set out to do so, but in time workaround were
> created that invalidated this design. For example, Java is pretty bad
> at font rendering, where the font size is in pixels, and you have to
> resize the font size based on the actual zoom and scale. Moreover,
> since font rendering is at least somewhat toolkit dependent (SVG, AWT,
> SWT, ...), this problem has not been resolved yet...
> 
> Why this matters: there are several bugs because of this situation. If
> people are going to look into this, we should very clearly communicate
> the design :)
> 
> Egon
> 
> -- 
> Dr E.L. Willighagen
> Postdoctoral Researcher
> Department of Bioinformatics - BiGCaT
> Maastricht University (http://www.bigcat.unimaas.nl/)
> Homepage: http://egonw.github.com/
> LinkedIn: http://se.linkedin.com/in/egonw
> Blog: http://chem-bla-ics.blogspot.com/
> PubList: http://www.citeulike.org/user/egonw/tag/papers