Shift the focal point per image style

Hi Alex, thanks for your response.

There are several reasons for not moving the focal point.

1)
For one, I would be marking the wrong part of the picture as important with Focal Point. As an editor, I would be compensating for shortcomings in the site configuration by tweaking the focal point in order to make it crop the image the way I need, which would be bad path to follow.
Also, what if the image is reused in another context, with another image style that also uses focal point cropping and presents it differently? The way I had shifted the focal point might adversely affect every other instance of the image.

2)
Also, it's really not the responsibility of the editor who uploads content imagery to muck around with the cropping of the image - that's the whole point (no pun intended) of Focal Point.

3)
Most importantly, this feature lets the site builder/frontend developer/whoever knows the design actually *use* the information that will be set by editors in the future about the important part of an uploaded image. Use that information to push the focal point into an area of the cropped picture that makes sense according to the design and layout.

TL;DR:
I feel very strongly about the benefits of this module for content editors out there. They should not have to "pixel push" in order to achieve their tasks, that's the whole point of this feature.

Cheers,
Achton

Thanks for the feedback, I'll definitely work more on this and treat the feature as an "advanced feature" accordingly.

@bleen18: I did initially have this described in the UI and code as an "offset", until - as you mention - I discovered that offset is in use internally already.
Other suggestions: "Focal Point Offset X/Y" (would be `fp_offset` in code), or "Shift X/Y"?

I totally agree with the need for simplicity here, I'll try hard to retain that in the next patch.

Here's a new version of the patch, now using the term "shift" instead of "displacement". I felt that any use of "offset" would muddle the in-code terminology unnecessarily, so I did not go that route. I think "shift" works better. I also added an "Advanced settings" fieldset for the config, and added the information to the effects overview page.
To summarize the patch, it now:

• uses focal_point_crop_form() for both the crop and the scale+crop effects
• adds input fields for entering the shift x+y values for each effect, with a helpful description
• put those fields in a collapsed "Advanced" fieldset
• extends focal_point_effect_calculate_anchor() to use the shift values to "push" the user-configured focal point before cropping
• adds a few theme functions to focal_point.theme.inc for summarizing the effect (based on image.module)