a patch can not use?who can do it

[yubinalice]

today the chinese input is broken.
so use english to say it.
there i download a patch to let the mupdf can continuous the PDF file that the original source cannot.
there is the patch
i use

patch -p1 < filepath

but it can not ok.
who know how to use it.

there is the return of the command :

patch -p1 < ./mupdf-continuous-scrolling.patch
can't find file to patch at input line 5
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff --git a/apps/pdfapp.c b/apps/pdfapp.c
|index 52bb4c4..dbe32f3 100644
|--- a/apps/pdfapp.c
|+++ b/apps/pdfapp.c
--------------------------
File to patch:

ok,
i do not know which file to patch
so
who know and tell me below.

thank you very much.

[poloshiao]

https://www.cyberciti.biz/faq/appy-patc ... h-command/
HowTo Apply a Patch File To My Linux / UNIX Source Code