Android simulate fast swipe

Please note that this answer pertains to circa-2013 versions of Android and may not apply to current ones. Jellybean was contemporary at the time, Kitkat came out a few weeks after the question was asked

Your delay is likely a result of inefficiently having to repeatedly launch a new sendevent process, parse the textual event record, and open the device node - for each individual event. If you instead do everything from within a single process, opening the device file only once, it will be much more efficient.

If we look at the source for sendevent in toolbox contemporary with the date of the question (for example, https://android.googlesource.com/platform/system/core/+/jb-release/toolbox/sendevent.c ) we see that the core of what it is doing is encoding the events into binary records

struct input_event {
    struct timeval time;
    __u16 type;
    __u16 code;
    __s32 value;
};

and writing them to the appropriate device

memset(&event, 0, sizeof(event));
event.type = atoi(argv[2]);
event.code = atoi(argv[3]);
event.value = atoi(argv[4]);
ret = write(fd, &event, sizeof(event));

Provided that you are executing something as the shell userid or another in the input unix group, you should be able to accomplish the same thing that sendevent does from your own custom program, or using other command line tools like cat, thus efficiently pushing a binary file of event records.

For example

adb shell
cd /mnt/sdcard
cat /dev/input/event2 > events

Do a few touch screen events, then ctrl-C to kill cat

Now you can play back the captured file of binary events:

cat events > /dev/input/event2 

(Note: sendevent is zeroing the timeval part of each record; recording and playback may not do that; you'll have to see, and if it matters zero those portions of each record from the file before you write it back)

If you just want to produce linear swipes, you can use input swipe command on shell.

$ adb shell input
usage: input ...
       input text <string>
       input keyevent <key code number or name>
       input [touchscreen|touchpad|touchnavigation] tap <x> <y>
       input [touchscreen|touchpad|touchnavigation] swipe <x1> <y1> <x2> <y2> [duration(ms)]
       input trackball press
       input trackball roll <dx> <dy>

Command below draws a nice line for me in a drawing application

$ adb shell input swipe 300 300 500 1000

and a quicker one

$ adb shell input touchscreen swipe 300 300 500 1000 100