Thank you for your inquiry.
I am Viktor, the developer from Aspose.Words Team responsible for integration with Aspose.Pdf.
From my expertise this issue can be solved using ZIndex attribute but we also need minor changes in Aspose.Pdf. I’ll explain the details.
Most probably Tommy means that we should output Zindex attribute right on the image. When I add it manually this solves the problem. But the image has no its own Z-order in the document model because it is not top-level. And this works only by coincidence.
Two overlapping objects, text and image, belong to different floating text boxes. These text boxes have identical formatting but the one containing text should overlap another because it has higher Z-order. Text box with image has “default” Z-order usually treated as zero. When I tried outputting Zindex for text boxes Aspose.Pdf seemingly ignores it. I’m attaching the XML with changes.
Tommy, please check the attachment and state whether you can properly handle this case. Next I’ll need more investigation and regression testing on the base since such kind of changes usually brings regression surprises.