You can access the Selection and Transformation tools by taping on the 3rd icon at the top right of the interface. The icon switches when you are using either the selection or the transformation tool.
You can switch between the Selection and Transformation tools in the side-bar.
The Selection tool is the second tool of the side-bar.
The Free-Hand selection allows you to draw the shape of your selection.
The rectangle selection allows you to draw a rectangle of the area you want to select.
Once you have made your selection, everything not selected is grayed out.
Tap on the Selection icon to deselect.
Once you have set your selection, you can go back to the Brush tool to draw or fill only the selected area, or switch to the Transformation Tool to move and/or resize the selected pixels.
Tap on the icon at the top of the side-bar to switch to the Transformation tool.
You then have access to the transformation UI which is a rectangle surrounding the selection with 8 handles and a rotation bar.
If nothing is selected when you switch to the transformation tool, you will transform the existing pixels on the current sheet.
The top and bottom handles allow you to resize vertically.
The right and left handles allow you to resize horizontally.
The corner handles allow you to resize both vertically and horizontally.
Touch the screen with a finger while you resize to keep the ratio.
Drag the rotation bar to rotate.
You can pinch with two fingers to shrink, and pinch them apart to enlarge and keep the ratio, and rotate by making a rotation movement.
Values are displayed at the top of the canvas during the transformation, tap on them to change them manually. Tap on the values to change them and tap on the px to switch to %. The Lock allows you to keep or change the ratio.
Besides the side-bar are different options:
Mirrors the content horizontally.
Mirrors the content vertically.
Reapplies a previous transformation. It can only be used if at least one transformation was applied before.
Resets the transformation.
Cancels the transformation and switches to Selection.
Defines the quality of the transformation to High, Medium or Low.
You can apply the transformation by taping on the Transformation icon, which switches back to Selection, or by moving to another frame. If you move to another frame where there is no pixel, it switches to Selection.
If you wish to apply the transformation to several sheets and several layers, you need to select the desired sheets in the timeline before using the transformation tool. To select several frames, double tap and drag over the sheets.