The origin of this article is (again) due to a forum question: "I want to rotate a triangle around a certain point" using the Rotation effect. It is time to explain the importance of the reference or registration point for objects in Captivate. In other Adobe applications like Illustrator, InDesign, Animate you have lot of control over that point. Look at this small screenshot: it shows that reference point in two different locations. Sorry for the low resolution, it is very small in Illustrator: left image shows the reference point in the left center, the right image at the bottom right. It was that last point that was wanted by the OP in the forum, but ... Captivate doesn't allow changing the reference point.
Reference points Captivate
The Reference/registration point in Captivate is used in different situations. In some situations it is located at the top left corner of the bounding box, in other situations in the center of the bounding box. The 'bounding box' is the rectangle surrounding the object or the object group. You'll see it during editing, when selecting an object or a group. The visual presentation of that box on the stage is not looking always exact, it can look larger than it really is. The correct size (px) of that box can only be seen in the Options tab of the Properties panel.
Location, resizing, rotating
The X and Y value in the Options tab are the coordinates of one of the registration points: the top left corner of the bounding box, as you can see in this screenshot:
The red lines in this screenshot are guides. The dotted square is the bounding box. The blue circle indicates the first reference point, which is top left and has its coordinates in X and Y in the Options tab. If you uncheck the 'Constrain Proportions' option, and increase the Width (W) or the Height (H) you'll see that the reference point will not move, increasing width will move the right border of the bounding box, increasing height will move the bottom border.
However, if you use the Rotation button on the stage, or the Rotation option in the Options tab, the used reference point is no longer the one indicated by the blue circle, but the center of the bounding box, which is indicated with a white circle in the screenshot. Same point is used for Flipping and 90° rotation buttons in the Options tab. The reference point will (weirdly) not change in the X, Y coordinates when you rotate an object as is visible in the next screenshot: you see that the X/Y still references to the blue circle center, which is no longer part of the bounding box of the shape:
If you align two or more objects (use the Align Toolbar which you can open by Window menu) the result can be surprising. Have a look at this first screenshot: I kept the rotated arrow, added a rectangle with exactly the same width (300px), and having the reference point at the same X value. That means that the center point of both shapes has the same X value as well, centering the shape will not move them. In a first test, I selected the arrow first for alignment (see right image in screenshot).
The result for left align is to be seen in the left image: the most left point of the bounding box of the arrow has been used as reference. When the bounding box is turned off, there seems to be no 'alignment' between the shapes. The second image looks better.
Same alignment rules when you use grouped objects instead of single objects. The bounding box of the group is what matters.
For all effects the center point of the bounding box (white circle in the very first screenshot) is the absolute reference point. It is the case for all categories of Effects. Especially for motion effects, the new Guides are very handy to locate the start, end and intermediate points of the motion path as I showed in this post: Guides Rule!.
That was the original question which I mentioned in the introduction: how can you rotate an object, not around its center but around another point. Since version 9 it is possible to apply an effect to a group. You cannot have individual effects for objects that are grouped (which is a pity). But in this case effect on a group provided a workaround for this particular question:
- Add an object that is 'invisible' to the end user, like a shape with a Fill Alpha = 0 and a stroke = 0.
- Group that object with the object to be rotated, in such a way that the center of the group bounding box coincides with the rotation point you want to use.
This sounds more complicated than it is really. Have a look at this visual presentation: the wanted rotation point was the right bottom point of the triangle. Duplication of the triangle with rotation provided me with that 'dummy' object which I made invisible to the user (here I added a light grey border to make it visible):
The red lines are guides which will not be visible on publishing. You see in this screenshot that the bounding box looks bigger than it really is, because its exact size is indicated by the red guides.