ExtraMaus is a tool that shows an additional mouse cursor. Useful for VLC recording. Author: Dodger Tools

extramaus.c

#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <assert.h>
#include <X11/cursorfont.h>
#include <X11/extensions/shape.h>

// Include the mouse cursor xbm directly
#define mouse_width 12
#define mouse_height 21
static unsigned char mouse_bits[] = {
   0x01, 0x00, 0x03, 0x00, 0x07, 0x00, 0x0f, 0x00, 0x1f, 0x00, 0x3f, 0x00,
   0x7f, 0x00, 0xff, 0x00, 0xff, 0x01, 0xff, 0x03, 0xff, 0x07, 0xff, 0x0f,
   0xff, 0x00, 0xff, 0x00, 0xe7, 0x01, 0xe3, 0x01, 0xc1, 0x03, 0xc0, 0x03,
   0x80, 0x07, 0x80, 0x07, 0x00, 0x03 };

/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

   Some ideas taken from oneko-1.2.sakura (http://www.daidouji.com/oneko/)
   and shape.c (http://www.edwardrosten.com/code/).
	
   @see http://dodger-tools.sourceforge.net/cms/index.php?id=100000201
   @see https://forums.gentoo.org/viewtopic-t-1040822-start-0.html
   @see https://unix.stackexchange.com/questions/152435/sharing-your-desktop-with-google-hangouts-dual-monitor-and-gnome-shell

   Compile on Fedora:
      sudo dnf install libXext-devel libX11-devel
      gcc extramaus.c -o extramaus -lX11 -lXext -g
*/


int main(argc, argv) int argc; char *argv[];
{
   Display               *display;
   int                  screenNr;
   Colormap            colorMap;
   XSetWindowAttributes   windowAttributes;
   Pixmap               mouseCursor;
   XColor               red, exact_red;
   Window                mouseWindow, QueryRoot, QueryChild;
   int                  mouseX, mouseY, winX, winY, mouseOldX, mouseOldY;
   unsigned int         mask;
   XSizeHints            *s_hints;
   XWindowChanges         windowChanges;
   unsigned long         windowMask;

   // Open the X11 display and get back a pointer to it
   display = XOpenDisplay(NULL);

   // Get the screen number
   screenNr = DefaultScreen(display);

   // Get the color map (ID)
   colorMap = DefaultColormap(display, screenNr);

   // Stop the program, if display is false (NULL)
   assert(display);

   // Get the "nearest" color matching the color name "red" and store it in the variable "red"
   //XAllocNamedColor(display, colorMap, "red", &red, &exact_red);
   XAllocNamedColor(display, colorMap, "white", &red, &exact_red);

   // Set the mouse coordinates to invalid values
   mouseOldX = -1;
   mouseOldY = -1;

   // Set some attributes
   windowAttributes.background_pixel = red.pixel;
   windowAttributes.override_redirect = True;
   windowMask = CWBackPixel | CWOverrideRedirect;

   // Create the window at position 10, 10, with width and height of the cursor
   mouseWindow = XCreateWindow(display, XRootWindow(display, screenNr), 10, 10, mouse_width, mouse_height, 0, DefaultDepth(display, screenNr), InputOutput, CopyFromParent, windowMask, &windowAttributes);
   assert(mouseWindow);

   // Create a bitmap with the size of the mouse cursor and its bits
   mouseCursor = XCreateBitmapFromData(display, mouseWindow, mouse_bits, mouse_width, mouse_height);

   // Use the mouse cursor as shape for the mouse window
   XShapeCombineMask(display, mouseWindow, ShapeBounding, 0, 0, mouseCursor, ShapeSet);

   // Show the mouse window
   XMapWindow(display, mouseWindow);
   XFlush(display);

   // Let it loop forever
   while (True)
   {
      // Get the position of the mouse and store it in the variables mouseX and mouseY
      XQueryPointer(display,DefaultRootWindow(display),&QueryRoot, &QueryChild,&mouseX,&mouseY,&winX,&winY,&mask);

      // Check, if the mouse was moved since the last time
      if ((mouseOldX != mouseX) || (mouseOldY != mouseY))
      {
         // Change the position of the mouse window to x+1 and y+1. +1 because without the normal mouse wouldn't be able to click on things anymore.
         windowChanges.x = mouseX+1;
         windowChanges.y = mouseY+1;
         XConfigureWindow(display, mouseWindow, CWX | CWY, &windowChanges);

         // Store the new mouse coordinates
         mouseOldX = mouseX;
         mouseOldY = mouseY;

         // Update the display
         XFlush(display);
      }

      // Make a pause of 1/100 seconds to save
      usleep(10000);
   }
}