but why wouldn't you simply have the lock engaged from the start? I understand what you're asking, but i can't imagine ever needing to scale an object this way...
You resize proportionally by dragging a corner handle while holding down the Shift and Alt keys. This will resizer about eh centre handle wherever you place it.
If you want to get the centre to a particular position in the image window, then drag out some guides to that location, and then drag the rulers zero/zero point to the guide intersection
You can then move the centre handle precisely to that location by using Free Transform, and entering a zero in the X: and Y: fields in the Options Bar.
Even if I press the icon to lock the proportions before I attempt to resize, as soon as I click on one of the handles, the icon unlocks itself.
hmmm, i can kind of understand why you'd want to scale that way... unfortunately there's no solution to your issue. Ps always takes the scale from W and applies it to H when you click the lock and i don't think there's any way to change the behavior. It'd be great if one could opt/alt the lock and have it apply the reverse, but i think people have been requesting that for years and it's never happened...
I appreciate the response, but that is not what I am talking about. I am not talking about resizing by dragging a corner handle. I am talking about proportional vertical resizing based upon a guideline(s) as a snapping point(s)
Let me try a different explanation. Referring to my original scenario, here is the exact opposite (for whatever reason, Photoshop does not automatically resize the width when dragging the horizontal (top or bottom) handles (not the corner handles, the handles in the center).
Sorry for all the screen shots, but I don't know how else to explain this.
I want to resize the height of the black box proportionally by dragging, snapping between the two horizontal guidelines (again, the reason I am doing it this way is not material, there are plenty of reasons why I would).
I would drag the box to snap to the top-most guideline...
... then by dragging the center handle at the bottom of the box, I would snap to the second horizontal guideline...
... but when I click on the icon to lock proportions, I do not get the desired effect...
Now, compared to my original example, if I try this method by dragging the vertical handles (left or right), then Photoshop will respect the change and automatically resize the height, but for whatever reason Photoshop will not react the same when I resize the height first. I know this might be confusing, but for people that have experienced this, they should know exactly what I am talking about. This has to be an issue with Photoshop, right?
ok, here's another solution. You can drag the center nodal point to the handle you'd like to scale to or use the Location icon in the upper left and once you have that set, then all you'd need to do is opt/alt-shift from a corner and your layer will scale proportionally to that guide/node. Does that make sense?
That might work if Photoshop would accurately snap to guidelines when dragging a corner handle. Unless you are zoomed in really close to the guideline and then move your cursor slowly, Photoshop will not even come close to snapping on that guideline.
It appears that this behavior is just the way Photoshop was built (at least up to CS4). I just think it's odd that Photoshop would not result in the same behavior whether one resized vertically or horizontally.
yes, i have no idea why snapping doesn't work when dragging from a corner. It's been that way as long as i can remember and we've asked to have it fixed, but there doesn't seem to be any interest from Adobe in resolving the issue.