Why is Affinity Photo moving the guides after cropping?

[TomHu]

Hi, I used the crop tool to crop the canvas size, and when I did the guides I used to snap the crop tool to the right size shifted to the upper left. Why? Here's a screen cap video of what happened. 

 

Notice how the guides, which were along the bottom and right edges of the star shape, have moved after the crop. I presume this is a bug? They shouldn't move. 

[- S -]

1 hour ago, TomHu said:

Hi, I used the crop tool to crop the canvas size, and when I did the guides I used to snap the crop tool to the right size shifted to the upper left. Why?

Notice how the guides, which were along the bottom and right edges of the star shape, have moved after the crop. I presume this is a bug? They shouldn't move. 

If you go to View > Guides Manager, it will show you the exact location of the guides from the top and left of the canvas.  

When you crop the canvas, the guides will stay at the same dimensions that you set them to.  Therefore, the horizontal guides will still be X amount of pixels from the top of the canvas and the vertical guides will still be X amount of pixels from the left of the canvas.  You can't see the other two guides (the bottom and right ones) after cropping because they end up outside of the canvas area.

 

[TomHu]

Is there a setting that will keep the guides where they were, even if it gets cropped away with part of the canvas? 

Thank you for explaining what's going on. I'm a bit flabbergasted by that to be honest.

Moving the guides to be relative to the new canvas size seems completely counterintuitive to me. It makes more sense for the guides to stay where they were originally located, like lines drawn on a piece of paper. If I chop off a piece of the paper that has a line drawn on it, that part of the line is gone. It doesn't move to a different location on the piece of paper that's left. That is so arbitrary, good lord! 

[toltec]

2 hours ago, TomHu said:

Moving the guides to be relative to the new canvas size seems completely counterintuitive to me. It makes more sense for the guides to stay where they were originally located, like lines drawn on a piece of paper. If I chop off a piece of the paper that has a line drawn on it, that part of the line is gone. It doesn't move to a different location on the piece of paper that's left. That is so arbitrary, good lord! 

Sorry, but I find your way of thinking on this really strange.

Guides are set from and applicable to page rulers. These are set relative to the top left of the page. Remember that they a based on rulers.

If you think about how you use an old fashioned ruler, (if you remember them) you line it up with the edge of the page and take a measurement. If you trim the left edge of the page by 3mm you still take a measurement by lining up from the edge of the page, even although it has now 'moved' by 3mm.

If we followed your approach and with a sheet of paper, trimmed 3.5 mm from the left, 5.7mm from the top and 16.5 from the right, how would you use the ruler? You, or (anybody you sent the document to) would need to know that the new edge of the paper was in fact 3.5mm outside the new paper edge and that the ruler needed to be 20mm shorter than standard.

All guides are page guides set relative to the top left of the page. You can't just move guides, anymore that you can change the size of a ruler just because you alter the right or bottom edges. If you set a guide to be 200mm from the left and cropped 16 mm off the page, rather than be 200mm (which is what you set it to) it would now be at 184mm. And what if you set guides at 50mm gaps. 50mm, 100mm, 150mm and 184mm ;(oops!). Should the software shift all the guides 4mm to the left? 46mm, 92mm 138mm and 184mm, or just the last two and have a very narrow gap in the middle?

Good lord, what a mess that would make of page layout. Total chaos!

If you planned to build a house 5 metres wide but the council said "Sorry, the border of your land is 1metre less than originally surveyed". According to your guides (which move to the land edges) you end up with house 4 metres wide.

 

[firstdefence]

If you just select the upper left square and the lower right star and copy, then use File > New from Clipboard you don't even need guides.

What you want is for the guides to stay relative to the objects, not the page.

[Medical Officer Bones]

The behaviour of guides after changing the document or image size in design applications fall broadly in four main categories:

1. existing guides remain in place (what the OP expected to happen): Inkscape, Gravit Designer, Photoshop, Photoline, Xara Designer Pro;
2. existing guides automatically adjust relatively to the new page size. A column grid based on guides will automatically narrow down to accommodate a smaller width canvas: InDesign, PhotoLine with formulaic %-based guides, Xara Designer Pro with Auto-fit, Affinity Photo with percentages;
3. existing guides will move in absolute units in relation to the top left origin of the canvas (Affinity Photo, Krita);
4. existing guides will move in absolute units but in four, three, two canvas edges or a single canvas edge (PhotoLine with px-based guide formulas)

...and a very few design apps allow for a combination of above methods (PhotoLine for example). I believe InDesign has multiple options as well.

(1) has its uses. (2) is incredibly handy to have, for obvious reasons. (3) is only useful when guides need to move from the left top origin only. (4) is a much better variant of (3), because the size of absolute margins defined by guides, for example, would be retained on all or defined sides of the new canvas size.

Having options (1), (2), and (4) in an design app come in handy for most practical situations in my experience. Affinity Photo supports (3) and (2). (2) is very nice, of course. In my opinion (3) is not that useful to have, because existing guides used as an absolute measure  device will move after resizing a canvas and move into one direction only. Both (1) and (4) would be preferable as an available user choice. As far as I am aware only Krita and Affinity Photo (Designer too?) behave like (3) without an option to define absolutely positioned guides relative to all canvas edges or a selection of these.

Anyway, I'd like to see more control over how guides behave in Photo in the future. (1) is very handy to have, actually.

[Medical Officer Bones]

And for those of you who doubt the veracity of option (1)'s usefulness, consider this situation: suppose an asset needs an exact white margin defined. Like the OP, we add guides that define the exact size of the asset first. Then we precisely calculate and place additional guides to set the margins. (Photo's inability to change the ruler origin irritates us while working on this last step.)

Then we crop the canvas according to the outside trim guides. Result: the inside margin guides move (or completely disappear when working on a larger canvas).

This is unwanted behaviour, of course. We defined those inner guides to remind us of the exact margins, and may have need of those at a later stage in our workflow.

But they moved, rendering our preparation phase useless.

Just a simple example of why option (1) is actually preferable over (3) as a default behaviour. If anything, Affinity Photo ought to behave like (4). Or (1) - better, the choice between the two.

[toltec]

55 minutes ago, Medical Officer Bones said:

And for those of you who doubt the veracity of option (1)'s usefulness, consider this situation: suppose an asset needs an exact white margin defined. Like the OP, we add guides that define the exact size of the asset first. Then we precisely calculate and place additional guides to set the margins. (Photo's inability to change the ruler origin irritates us while working on this last step.)

Then we crop the canvas according to the outside trim guides. Result: the inside margin guides move (or completely disappear when working on a larger canvas).

This is unwanted behaviour, of course. We defined those inner guides to remind us of the exact margins, and may have need of those at a later stage in our workflow.

But they moved, rendering our preparation phase useless.

Just a simple example of why option (1) is actually preferable over (3) as a default behaviour. If anything, Affinity Photo ought to behave like (4). Or (1) - better, the choice between the two.

I still find any settings that will move relative to the page origin very strange.

Perhaps I spent too long working with paper, laying out pages etc. To me, if I set a guide to be 200mm from the left hand page edge, I want it to stay 200mm from the page edge. If I make the page 5 mm smaller, I don't want my guide to move 5mm to the left, because then it would be 195 mm from the left, not 200mm.

To me, they are not guides, but margins.

If the guides move around, what would the design be used for? As I said before, if you have guides set at 50mm intervals, what happens if the last setting suddenly moves 5mm to the left? One 50 mm gap suddenly becomes 45 mm. Odd 

I have nothing against choice, but any software that designs pages (like A4) should default to fixed page guides, as does Designer. Perhaps less important for Photo which is not page based.

 

[TomHu]

Well I think it's really strange that Affinity Photo is moving guides that I place on the canvas to align objects on that canvas. Why do the objects on the canvas stay in place, but the guides move? Why not also move the objects to the same relative place on the canvas once it's cropped if you're going to also move the guides?

I cannot think of any situation where I want the guides I place on the canvas to shift based on the size of the canvas and a relative position. The guides are primarily used to place and align objects on a canvas, not a document. If I set up my guides like this: 

...and then crop my canvas so that the shapes are more centered horizontally on the canvas, I do NOT want my guides to remain in the same RELATIVE position like this:

Sorry, but, that just makes no sense to me whatsoever to shift the guides like that, but leave the objects in the same location.

7 hours ago, toltec said:

To me, they are not guides, but margins.

What?? A canvas is not a word processing document, where you set the margin and that margin is maintained no matter the size of the document. That's a margin, not a guide. You can use a guide to indicate a margin if you want, but if you cut away part of the canvas that has one of your margin guides, add a new guide to indicate your margin.  

AP should at least provide the option to make the guides stay where you placed them and not shift to some relative location. I've encountered some odd concepts and behavior since starting with Affinity Photo, but this, for me, is the biggest head-scratcher of all. Guides that shift around based on the canvas size are useless to me.

[toltec]

40 minutes ago, TomHu said:

AP should at least provide the option to make the guides stay where you placed them and not shift to some relative location. I've encountered some odd concepts and behavior since starting with Affinity Photo, but this, for me, is the biggest head-scratcher of all. Guides that shift around based on the canvas size are useless to me.

That's the point. The guides do stay exactly where you place them, relative to and fixed to the top left of the page. Which is exactly how I want them.

You are obviously younger and don't recognise the history of this sort of program? Starting off with Quark and Pagemaker for pages and Photoshop for images.

Guides that move around the page if you trim the page are a very odd concept and would be useless to me. But then, I mostly layout pages for printing. I have been doing that for decades and never actually used guides in Photo or Photoshop.

If you are using Photo for it's intended purpose, editing photos, why do you actually need guides ? I lay out pages in software like Quark, InDesign or even Designer where I place guides relative to the page. I then edit photos in Photoshop or Photo to drop into frames (no guides needed). This is how it has worked for over thirty years.

Still, if you have different (and more modern?) needs and want them to be fixed to and move around according to the page edges, that's fine. Choice is always good.  You can put in a feature request for them