The ornamental design for a screenmagnifier for smartphone, as shown and described.
FIG. 1 is a front and top perspective view of a screen magnifier for smartphone, showing my new design;
FIG. 2 is a rear and top perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a right side elevational view thereof;
FIG. 7 is a top plan view thereof;
FIG. 8 is a bottom plan view thereof;
FIG. 9 is a perspective view of the screen magnifier for smartphone in a folded position;
FIG. 10 is a perspective view of a screen magnifier for a smartphone; and,
FIG. 11 is an enlarged view of a portion indicated in FIG. 2.
The broken lines in the figures depict portions of the screen magnifier for smartphone and environmental subject matter that form no part of the claimed design.