There are direct and indirect observations. For example you can count electrons or you can measure the electric potential and derive from this the approximate number of electrons. You can count bolts or knowing the weight of a bolt you can derive the number of bolts in a pile. The difference between direct and indirect measurements are sliding.
To the electron are attributed a particle like behavior as well as a wave like behavior. What do you think, which behavior is more directly observed and which more indirect? In principle this question points in the same direction as your
... suppose a photon is coming towards the slit,and think of the instant when it reaches the slit.
Shooting single photons and placing a photosensitive plate direct in front of the slit or direct behind the slits, you always observe the particle like behavior of the photon as a small point, much smaller the slits width.
A - more indirect - observation of the wave like behavior is the intensity distribution on a sensitive plate, installed away the slits. Single shooted photons arrive as particles and only after some time you observe on the screen the fringes from which is derived the wave like behavior.
Is there an alternative point of view about what happens in the interaction between the photons and the slits? No, it isn’t.
Anyway, if you want to think ahead, read this question Are there induced currents in the obstacle from the electromagnetic radiation? and Relationship between the material properties of an edge and the fringes behind this edge.