This article explains why a watermark might exceed the boundaries of a page or appear at different positions whenever its length changes.
By default, when adding a watermark using LiveCycle Assembler invoking a DDX, it is placed in the centre of the page with no rotation. The watermark can be rotated and positioned using the following attributes:
Note: These values are examples. For full details of the syntax and a description of additional attributes to use with watermarks please see the latest Assembler Service and DDX Reference http://help.adobe.com/en_US/livecycle/11.0/ddxRef.pdf.
There are two things to keep in mind when adjusting a watermark:
(1) The watermark will be positioned first and rotated after, regardless of the order in which the attributes are listed.
(2) When applying rotation, the centre of the watermark’s bounding box is used as a fixed centre of rotation. Imagine your watermark without rotation and with a frame around it. This frame represents the bounding box. The centre of that box is the fixed point for its rotation.
For example, if you want your watermark to appear at the left border of your page and rotated by 90 degrees, set the horizontal anchor to “left”, rotation to “90”, and use the horizontal and vertical offset to fine-tune its position.
With a watermark of a fixed length, the fine-tuning is done with fixed values.
Watermarks with dynamic length, however, require the offsets to be calculated dynamically as well because of points (1) and (2) above.
The graphic below demonstrates why. When working with watermarks of dynamic length you’ll have shorter watermarks and longer watermarks. For a shorter watermark the fix point for the rotation is further left than for a longer watermark.
After rotation your watermark might exceed the page boundary. In the sample below you need to adjust the vertical offset to move it further down. Notice that you need a greater vertical offset for the longer watermark and a lesser vertical offset for the shorter one. The longer watermark appears further right than the shorter one. Use the horizontal offset to adjust that. Notice that if you want both watermarks to appear at closer to the left border of the page you need a lower horizontal offset for the shorter one than for the longer one.
To avoid the dynamic calculation of offsets when working with watermarks of dynamic length, keep them at the centre of the page.