Added calibration instructions, failure checking in c and corrected axis/abs info

Author: LinusCDE

README.md

@@ -58,6 +58,14 @@ Create a file called `/etc/X11/xorg.conf.d/10-evdev.conf` and add [this content]
 In order to work in GIMP, the device must get enabled under `Edit -> Input devices`.
 
 
+# Calibrating
+
+It also is a good idea to calibrate the tablet using xinput_calibrator because the tablet screen will be streched to match your screen. That will result in a wrong aspect ratio.
+
+When calibration using xinput_calibrator use the pdf, open it on the reMarkable and touch the points there.
+
+(I essentially just recorded the calibration screen, took a screenshot, changed the colors, added borders, and created a pdf from it.)
+
 # Credits
 
 Huge thanks to benthor's [HuionKamvasGT191LinuxDriver](https://github.com/benthor/HuionKamvasGT191LinuxDriver) (found 

tabletDriver.c

@@ -54,7 +54,10 @@ void addAbsCapability(int fd, int code, int32_t value, int32_t min, int32_t max,
    abs_setup.code = code;
    abs_setup.absinfo = abs_info;
 
-   ioctl(fd, UI_ABS_SETUP, &abs_setup); // Set abs data
+   if(ioctl(fd, UI_ABS_SETUP, &abs_setup) < 0) { // Set abs data
+      perror("Failed to absolute info to uinput-device (old kernel?)");
+      exit(1);
+   }
 }
 
 int main(int argc, char** argv)
@@ -83,14 +86,14 @@ int main(int argc, char** argv)
 
    // See https://python-evdev.readthedocs.io/en/latest/apidoc.html#evdev.device.AbsInfo.resolution
    // Resolution = max(20967, 15725) / (21*10)  # Height of display is 21cm. Format is units/mm. => ca. 100 (99.84285714285714)
-   // Tilt resolution = 12400 / ((math.pi / 180) * 140 (max angle)) (Format: units/radian) => ca. 5074 (5074.769042587292)
+   // Tilt resolution = 12600 / ((math.pi / 180) * 140 (max angle)) (Format: units/radian) => ca. 5074 (5074.769042587292)
    ioctl(fd, UI_SET_EVBIT, EV_ABS);
-   addAbsCapability(fd, ABS_PRESSURE, /*Value:*/ 0, /*Min:*/ 0, /*Max:*/ 4095,  /*Resolution:*/ 0,    /*Fuzz:*/ 0, /*Flat:*/ 0   );
-   addAbsCapability(fd, ABS_DISTANCE, /*Value:*/ 0, /*Min:*/ 0, /*Max:*/ 110,   /*Resolution:*/ 0,    /*Fuzz:*/ 0, /*Flat:*/ 0   );
-   addAbsCapability(fd, ABS_TILT_X,   /*Value:*/ 0, /*Min:*/ 0, /*Max:*/ 12400, /*Resolution:*/ 5074, /*Fuzz:*/ 0, /*Flat:*/ 6200);
-   addAbsCapability(fd, ABS_TILT_Y,   /*Value:*/ 0, /*Min:*/ 0, /*Max:*/ 12400, /*Resolution:*/ 5074, /*Fuzz:*/ 0, /*Flat:*/ 6200);
-   addAbsCapability(fd, ABS_X,        /*Value:*/ 0, /*Min:*/ 0, /*Max:*/ 20967, /*Resolution:*/ 100,  /*Fuzz:*/ 0, /*Flat:*/ 0   );
-   addAbsCapability(fd, ABS_Y,        /*Value:*/ 0, /*Min:*/ 0, /*Max:*/ 15725, /*Resolution:*/ 100,  /*Fuzz:*/ 0, /*Flat:*/ 0   );
+   addAbsCapability(fd, ABS_PRESSURE, /*Value:*/ 0,     /*Min:*/ 0,     /*Max:*/ 4095,  /*Resolution:*/ 0,   /*Fuzz:*/ 0, /*Flat:*/ 0);
+   addAbsCapability(fd, ABS_DISTANCE, /*Value:*/ 95,    /*Min:*/ 0,     /*Max:*/ 255,   /*Resolution:*/ 0,   /*Fuzz:*/ 0, /*Flat:*/ 0);
+   addAbsCapability(fd, ABS_TILT_X,   /*Value:*/ 0,     /*Min:*/ -9000, /*Max:*/ 9000, /*Resolution:*/ 5074, /*Fuzz:*/ 0, /*Flat:*/ 0);
+   addAbsCapability(fd, ABS_TILT_Y,   /*Value:*/ 0,     /*Min:*/ -9000, /*Max:*/ 9000, /*Resolution:*/ 5074, /*Fuzz:*/ 0, /*Flat:*/ 0);
+   addAbsCapability(fd, ABS_X,        /*Value:*/ 11344, /*Min:*/ 0,     /*Max:*/ 20967, /*Resolution:*/ 100, /*Fuzz:*/ 0, /*Flat:*/ 0);
+   addAbsCapability(fd, ABS_Y,        /*Value:*/ 10471, /*Min:*/ 0,     /*Max:*/ 15725, /*Resolution:*/ 100, /*Fuzz:*/ 0, /*Flat:*/ 0);
 
    struct uinput_setup usetup;
    memset(&usetup, 0, sizeof(usetup));
@@ -99,9 +102,15 @@ int main(int argc, char** argv)
    //usetup.id.product = 0x7890; /* sample product */
    usetup.id.version = 0x3;
    strcpy(usetup.name, "reMarkableTablet-FakePen");  // Has to end with "pen" to work in Krita!!!
-   ioctl(fd, UI_DEV_SETUP, &usetup);
-
-   ioctl(fd, UI_DEV_CREATE);
+   if(ioctl(fd, UI_DEV_SETUP, &usetup) < 0) {
+      perror("Failed to setup uinput-device (old kernel?)");
+      return 1;
+   }
+   
+   if(ioctl(fd, UI_DEV_CREATE) < 0) {
+      perror("Failed to create uinput-device");
+      return 1;
+   }
 
    void closeDevice() {
       ioctl(fd, UI_DEV_DESTROY);

tabletDriver.py

@@ -40,17 +40,18 @@
 # BTN_TOOL_PEN == 1 means that the pen is hovering over the tablet
 # BTN_TOUCH == 1 means that the pen is touching the tablet
 
-# This WONT'T WORK with libinput since the resolution is never actually set.
+# This WONT'T WORK with libinput since the resolution is never actually set
+# and pydev uses an old method for creating the uinput-device which can't set the resolution.
 # This is fixed in the c-version but doesn't quite work yet, too.
 capabilities = {
 	ecodes.EV_KEY: [ecodes.BTN_TOOL_PEN, ecodes.BTN_TOUCH],
 	EV_ABS: [
 		(WACOM_EVCODE_PRESSURE, AbsInfo(value=0, min=0, max=4095, fuzz=0, flat=0, resolution=0)),
-		(WACOM_EVCODE_DISTANCE, AbsInfo(value=0, min=0, max=110, fuzz=0, flat=0, resolution=0)),
-		(WACOM_EVCODE_XTILT, AbsInfo(value=0, min=0, max=12400, fuzz=0, flat=6200, resolution=5074)),
-		(WACOM_EVCODE_YTILT, AbsInfo(value=0, min=0, max=12400, fuzz=0, flat=6200, resolution=5074)),
-		(WACOM_EVCODE_XPOS, AbsInfo(value=0, min=0, max=WACOM_HEIGHT, fuzz=0, flat=0, resolution=100)),
-		(WACOM_EVCODE_YPOS, AbsInfo(value=0, min=0, max=WACOM_WIDTH, fuzz=0, flat=0, resolution=100))
+		(WACOM_EVCODE_DISTANCE, AbsInfo(value=95, min=0, max=255, fuzz=0, flat=0, resolution=0)),
+		(WACOM_EVCODE_XTILT, AbsInfo(value=0, min=-9000, max=9000, fuzz=0, flat=0, resolution=5074)),
+		(WACOM_EVCODE_YTILT, AbsInfo(value=0, min=-9000, max=9000, fuzz=0, flat=0, resolution=5074)),
+		(WACOM_EVCODE_XPOS, AbsInfo(value=11344, min=0, max=WACOM_HEIGHT, fuzz=0, flat=0, resolution=100)),
+		(WACOM_EVCODE_YPOS, AbsInfo(value=10471, min=0, max=WACOM_WIDTH, fuzz=0, flat=0, resolution=100))
 	]
 }