Recently XD made image fills easier to create and manage than masking. Drag the image from the Desktop into a box, and it's easy to adjust the cropping. Double-click on the box and you can move/size the image. Way more flexible than copying and pasting part of an image in my opinion.
If the image is already in XD and you want to crop it, then:
- Cut it by using Edit > Cut or Cmd–X (Mac) or Ctrl–X (Windows).
- Select a box.
- Edit > Paste Appearance (Mac) or Right-click > Paste Appearance (Windows).
- Double-click on the box and you can move/size the image.
I hope that helps.
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