Re: fitting a picture to the available space

[Hans Hagen <pragma@wxs.nl>]

Thomas A. Schmitz wrote:
> Hi guys,
> 
> I'm pulling my hair out. I'm trying to set up an automatism to fit  
> pictures to the available space on a slide. I need to consider three  
> parameters:
> 
> 1. If the user supplies a value for width= or height= , use this value  
> (captured in a macro);
> 
> 2. respect the maxwidth and maxheight which must not exceed the frame;
> 
> 3. if the picture is smaller than the available space, blow it up so  
> that it reaches the maxwidth or maxheight (but doesn't exceed either).
> 
> factor=max or =fit does not work because it allows pictures to exceed  
> one of the maximum values. About a year ago Giuseppe Bilotta wrote a  
> message which I append; it describes my problem. Is there a generic  
> solution for this problem? If there is, I'll gladly take it; if there  
> isn't, I thought I had a solution but may need help with expanding and  
> conditionals, then I'll be back with more questions.
> 
> Anyway, good night all, and thanks.

\starttext

\framed[width=5cm,height4cm]{\externalfigure[mill.png][maxwidth=3cm,maxheight=4cm,width=10cm]}

\stoptext

seems to work

> Thomas
> 
>> Subject: Re: [NTG-context] factor=fit images don't fit
>> Sunday, July 22, 2007 Hans Hagen wrote:
>>
>>> the fit assumes operating on a page not in a box;
>> Ah, didn't know that. I couldn't even tell from the sources,
>> since it uses enclosing box dimensions and not page or paper
>> sizes. I suspect the logic is broken at the page level too
>> though, let me explain why.
>>
>> Currently, if I understand the code correctly, factor=fit
>> expands the figure to have its major direction fit, while
>> factor=max expands the figure to have its minor direction
>> fit.
>>
>> Instead, the behavior I would expect from fit (resp. max) is
>> for the *expansion ratio* to be the minimum (resp. maximum)
>> of the expansion ratios in the two directions (not the sizes
>> in those directions, but the ratio between the sizes of the
>> figure and the container). The difference is noticeable when
>> the container and contained have different aspect ratios.
>>
>> Consider for example a 20x30mm figure in a 50x150mm page
>> (strange numbers, just used to show what I mean): with the
>> current code, using 'fit' would consider the largest
>> dimension (30) and thus calculate a factor of 150/30 = 5,
>> but this gives us an image which is 100x150mm, i.e. an image
>> that doesn't fit! Whereas, if we computed the ratios 50/20 =
>> 2.5 and 150/30 = 5, we would know that the ratio to be
>> picked was 2.5 in 'fit' and 5 in 'max'.
>>
>> Or I misintepreting the meaning of 'fit' and 'max'?
>>
>>> an alternative is:
>>> \framed[width=5cm,height4cm]
>>>
>>> {\externalfigure[mill.png][maxwidth=4cm,maxheight=5cm,width=10cm]}
>>> i.e. setting the maximum values
>> I hadn't thought about using width and maxwidth (and
>> maxheight) at the same time, thanks. Of course, I'd rather
>> have 'fit' and 'max' usable in boxes :)
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