When doing a sketch, you often want to adjust the position and size of your character's mouth. You can use the lasso tool to change the placement or size of a part of the drawing.
Since we have a picture like this, let's try changing the position of the mouth. First of all, tap the ① Lasso tool from the Tool Selection window.
Tap the ② Lasso tool from the ① Tool Selection window. The lasso tool selects the portion of the image surrounded by your stroke.
At the bottom of the screen there are a mode selection and three commands. The three modes are ① Set, ② Add, and ③ Subtract. In Set Mode you create a selection with one stroke. In such a case, the previous selection disappears and a new one is created. Add Mode keeps the current selection and adds a new selection as defined by your stroke. Subtract Mode subtracts the region defined by your stroke from the current selection.
While you are still a beginner, using just the Add Mode is a good idea.
In Add mode, try drawing around the mouth. A selection region will be displayed with a dashed line. The inside of this dashed line is the portion of the drawing that you have selected.
Open the Layer window and you will see a small blue dot on the ① Selection Layer at the top (the layer with the pink background). On the Selection Layer, the part of the image that is selected is shown in blue. Looking just at the dashed line it is not possible to tell whether the inside or outside of the line is selected, but it is easy to check in the Layer window. Now, close the Layer window.
Tap the ① Invert Selection button (just tap it once). Tapping it does not change anything that you can see on the screen, but now re-open the Layer window.
Can you see that the selection layer at the top has been inverted? This shows that the area outside of the dashed line is now selected. Now, close the Layer window.
Tap the ① Invert Selection button again to change the selection back to the inside of the dashed line.
Now, try tapping the ② Clear button. The dashed line that shows the selection will disappear. Applying color while the selection region remains will only apply color to the selection. Forgetting to clear the selection can make it feel like you can't apply color anywhere. This is a common mistake, so always remember to clear the selection after you have finished working on it.
Go back to the subject and adjust the position of the mouth.
Once again, in Add mode draw around the mouth to select it.
Zoom out the view to make the face fit in. Next, switch to ①Transform tool .
Use ① one finger to drag and ② two fingers (pinch) to scale the selection.
To rotate, turn ③ Rotate ON and use a two-fingered drag to rotate.
When you are satisfied with the position of the mouth tap the ④ Done button to close the Transform tool.
After tapping the Done button clear the selection.
Finish the line drawing using the brush, eraser, undo, lasso tool, etc.
Hide your sketched draft after you have finished the line drawing. Tap the ① Eye Icon to hide the layer.
If the lower toolbar is in the way, tap ① Full Screen button to hide the Quick Slider bar and make the Main toolbar transparent. If you want to be able to see your whole drawing it is a good idea to use full screen mode.