Smarter input boxes for width and height?

[ch22]

Changing the size of an image so that it fits within a predefined W x H rectangle is a common problem, which Affinity Photo does not know how to answer. However, it would suffice, in the dialog of the "Resize document" function, to write the following expression in the width and height boxes:

         *(W/w + (H/h-W/w) * max(W/w,H/h))

 Currently, unless I'm mistaken, the input boxes for width and height  recognize the document variables w and h only in the Transform pane for the Move function. They do not  recognize them in the Resize, Crop, and Export dialogs. Why not teach them all?

 Another issue is that the max() and min() functions don't seem to work in expressions — at least I cannot run them. However, this is not too serious insofar as we can find an equivalent for them,

                  max(a,b) = a + (b-a) * roundup((b-a)/(b+a))

but it would obviously be more convenient to have these two functions at disposal

 

[ch22]

Sorry ! I  messed up  my message. What I meant is below : 

Changing the size of an image so that it fits within a predefined W x H rectangle is a common problem, which Affinity Photo does not know how to answer. However, it would suffice, in the dialog of the "Resize document" function, to write the expression   * min(W/w,H/h)   in the width and height boxes :

 Currently, unless I'm mistaken, the input boxes for width and height  recognize the document variables w and h only in the Transform pane for the Move function. They do not  recognize them in the Resize, Crop, and Export dialogs. Why not teach them all?

 Another issue is that the max() and min() functions don't seem to work in expressions — at least I cannot run them. However, this is not too serious insofar as we can find an equivalent for them,

                  min(a,b) = b + (a-b) * roundup((b-a)/(b+a))

but it would obviously be more convenient to have these two functions at disposal.