Masks

A mask hides part of a shape. It uses a shape on the board to define the visible area:

• The masked shape is the one partially hidden.
• The mask shape decides which area of the masked shape stays visible.

The masked shape itself does not change: turning off or removing its masks shows it in full again.

What to expect from the mask shape:

• It stops being drawn and only does its job of hiding.
• It stays on the board, so you can still select it, move it, and edit it. The masked shape follows every change.

What can be combined:

• A shape can have several masks, and one mask can serve several shapes.
• Vector shapes and Text shapes can be masks.
• Every shape except groups, frames, and cameras can be masked. To mask the shapes in a group, select them inside the group.

A document inside a table cell can also have its own mask. Select the attachment and use Add mask in the Mask section of the Attributes panel, then choose a mask shape on the board. The mask stays on the board; moving the attachment or scrolling its cell changes which part it covers.

Giving a shape a mask

• Operation:
  1. Select the shapes to mask.
  2. Click Add mask attributes to the shape in the Actions panel. This activates masking on the shapes and shows their Mask section in the Attributes panel.
  3. Click Add mask in the Mask section.
  4. Click a shape on the board.
• Needs: a shape that can be a mask: a vector or a text shape. Clicking empty canvas or a shape that cannot be a mask ends the pick without adding anything, and the selection stays so you can try again.
• Result: the clicked shape becomes the mask of every selected shape and stops being drawn. The masked shapes show only the area outside the mask, so if the mask covers part of them, that part disappears.

After this, both shapes show a Mask section in the Attributes panel, but with different contents.

Mask section of the masked shape

• Add mask: lets you click a shape on the board to use it as a mask for the selection.
• Eyedropper, on the section header: copies the masks, mode, and type of the shape you click onto the selection.
• Mode: which side of the mask stays visible. New masks start with outside.
  • inside: only the area covered by the mask shows.
  • outside: only the area around the mask shows.
• Mask type: how the mask shape defines its area. One button shows the current type, and its tooltip names it; click it to switch to the other. New masks start with Geometry.
  • Geometry: uses the mask shape's outline. Fast, and ignores transparency.
  • Luminance: uses the mask shape's brightness, so soft edges and transparency work. Slower. A fully white mask gives the same result as Geometry; other colors reveal in between:
    • White areas of the mask shape count fully as mask, black areas do not count at all, and transparent areas count as black.
    • Greys and colors count partially: the lighter the color, the more it counts. A gradient fill makes a soft transition.
    • inside shows the masked shape where the mask counts, and outside shows it where the mask does not count. A 50% grey area shows the shape at half strength either way.
• Show or hide mask: turns all the masks of the selection on or off without removing them.
• Remove mask: removes every mask from the selection.
• Masks: the list of masks of the selection, in the order they were added. For each mask:
  • Mask name: click the name to rename it, up to 40 characters. Masks are named Mask 0, Mask 1, and so on until you rename them, and clearing the name brings that default back. The name belongs to the mask shape, so every shape that uses it sees the same name.
  • Select mask shape: selects the mask shape on the board. Hold Shift while you click to add it to the current selection. Hovering this button highlights the mask shape.
  • Show or hide mask: turns that mask on or off.
  • Remove mask: removes that mask from the selection.

Mask section of the mask shape

• Remove as mask: stops the shape from masking others, and it is drawn again like a regular shape.

Adding more masks

Each click on Add mask adds one mask shape. Repeat it to combine several.

• Operation: with the masked shapes selected, click Add mask again and click another shape.
• Result: the new shape joins the list of masks of the selection. The Mode and the mask type apply to all the masks of a shape together.
• Tip: when the selected shapes have different masks, the section shows only Add mask. Select one shape to see its masks and their controls.

Working with the mask shape

The mask shape stays a normal shape underneath: moving, rotating, scaling, or editing it updates the masked shapes right away.

• Operation: click Select mask shape next to a mask in the Mask section, or click the mask shape on the board where it used to be drawn.
• Result: the mask shape is selected and shows its own Mask section, with Remove as mask as its only control.
• Tip: hovering Select mask shape in the list highlights the mask shape on the board, which helps find a mask that is far from the shape it hides.

Turning masks off without removing them

Both the whole mask and each mask shape can be switched off and on again.

• Operation: click Show or hide mask in the section header, or the one on a single mask of the list.
• Result: the masked shape is drawn in full again while the mask is off. The mask shapes stay hidden and keep their place in the list. Turning off one mask of several leaves the others working.

Removing masks

Remove masks from the masked shape's Mask section, from the Actions panel, or from the mask shape itself.

• Operation: click Remove mask on one mask of the list to remove only that one, or Remove mask in the section header to remove all of them.
• Result: the masked shape is drawn in full again. Its Mask section stays, ready for a new mask. A mask shape that no longer masks anything is drawn again like a regular shape.

Removing the Mask section

• Operation: click Remove mask in the Actions panel.
• Result: every mask of the selection is removed and the Mask section disappears from the Attributes panel.

Releasing a mask shape

• Operation: select the mask shape and click Remove as mask in its Mask section.
• Result: the shape is drawn again like a regular shape and disappears from the mask list of every shape it was masking.

Deleting a mask shape has the same effect as removing it as a mask. Deleting a masked shape releases its masks if no other shape uses them.

Masks and other operations

• Duplicating a masked shape together with its mask gives the copy its own mask. Duplicating only the masked shape makes the copy share the original mask. Duplicating only the mask shape adds the copy as an extra mask of the shapes that used the original. Copies keep the mask name. See Duplicating.
• Grouping does not change masks: each member keeps its own, and they keep working as the group moves.
• Boolean operations leave out shapes that are masks. See Boolean operations.
• Converting an SVG image to shapes turns its clip paths and masks into masks. See Conversions.