Draw the touches as they come in

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

1 files changed, 111 insertions, 1 deletions

diff --git a/multitouch.c b/multitouch.c
index 654719c..f0a7c77 100644
--- a/multitouch.c
+++ b/multitouch.c
@@ -8,6 +8,8 @@
 #include <stdarg.h>
 #include <signal.h>
 #include <poll.h>
+#include <stdint.h>
+#include <math.h>
 
 #include <cairo.h>
 #include <cairo-xlib.h>
@@ -16,6 +18,20 @@
 #include <X11/extensions/XInput.h>
 #include <X11/extensions/XInput2.h>
 
+#define MAX_TOUCHES 10
+
+enum TouchState {
+    TSTATE_END = 0,
+    TSTATE_BEGIN,
+    TSTATE_UPDATE,
+};
+
+struct touchpoint {
+    enum TouchState state;
+    uint32_t touchid; /* 0 == unused */
+    double x, y;   /* last recorded x/y position */
+};
+
 struct multitouch {
     Display *dpy;
     int screen_no;
@@ -35,6 +51,9 @@ struct multitouch {
     cairo_t *cr_win;
     cairo_surface_t *surface;
     cairo_surface_t *surface_win;
+
+    struct touchpoint touches[MAX_TOUCHES];
+    int ntouches;
 };
 
 static void expose(struct multitouch *mt, int x1, int y1, int x2, int y2);
@@ -171,6 +190,87 @@ static void print_event(struct multitouch *mt, XIDeviceEvent* event)
     msg("\ttouchid: %d\n", event->detail);
 }
 
+static void paint_touch_begin(struct multitouch *mt, XIDeviceEvent *event)
+{
+    int i;
+    int radius = 30;
+    struct touchpoint *t = NULL;
+
+    for (i = 0; i < mt->ntouches; i++)
+    {
+        if (mt->touches[i].state == TSTATE_END)
+        {
+            t = &mt->touches[i];
+            break;
+        }
+    }
+    if (!t)
+    {
+        error("Too many touchpoints, skipping\n");
+        return;
+    }
+
+    t->touchid = event->detail;
+    t->x = event->event_x;
+    t->y = event->event_y;
+    t->state = TSTATE_BEGIN;
+
+    cairo_set_source_rgb(mt->cr, 0, 0, 0);
+    cairo_arc(mt->cr, t->x, t->y, radius, 0, 2 * M_PI);
+    cairo_stroke(mt->cr);
+    expose(mt, t->x - radius, t->y - radius, t->x + radius, t->y + radius);
+}
+
+static struct touchpoint* find_touch(struct multitouch *mt, uint32_t touchid)
+{
+    int i;
+
+    for (i = 0; i < mt->ntouches; i++)
+        if (mt->touches[i].state != TSTATE_END)
+            return &mt->touches[i];
+
+    return NULL;
+}
+
+static void paint_touch_update(struct multitouch *mt, XIDeviceEvent *event)
+{
+    struct touchpoint *t = find_touch(mt, event->detail);
+
+    cairo_move_to(mt->cr, t->x, t->y);
+    cairo_line_to(mt->cr, event->event_x, event->event_y);
+    cairo_stroke(mt->cr);
+    expose(mt, t->x, t->y, event->event_x, event->event_y);
+
+    t->x = event->event_x;
+    t->y = event->event_y;
+    t->state = TSTATE_UPDATE;
+}
+
+static void paint_touch_end(struct multitouch *mt, XIDeviceEvent *event)
+{
+    int rsize = 30;
+    struct touchpoint *t = find_touch(mt, event->detail);
+
+    t->x = event->event_x;
+    t->y = event->event_y;
+    t->state = TSTATE_END;
+
+    cairo_rectangle(mt->cr, t->x - rsize/2, t->y - rsize/2, rsize, rsize);
+    cairo_stroke(mt->cr);
+    expose(mt, t->x - rsize/2, t->y - rsize/2, t->x + rsize/2, t->y + rsize/2);
+
+}
+
+static void paint_event(struct multitouch *mt, XIDeviceEvent *event)
+{
+    switch(event->evtype)
+    {
+        case XI_TouchBegin: paint_touch_begin(mt, event); break;
+        case XI_TouchUpdate: paint_touch_update(mt, event); break;
+        case XI_TouchEnd: paint_touch_end(mt, event); break;
+    }
+}
+
 static int init_cairo(struct multitouch *mt)
 {
     cairo_surface_t *surface;
@@ -251,6 +351,7 @@ static int main_loop(struct multitouch *mt)
                 cookie->type == GenericEvent &&
                 cookie->extension == mt->xi_opcode)
             {
+                paint_event(mt, cookie->data);
                 print_event(mt, cookie->data);
             }
 
@@ -261,10 +362,19 @@ static int main_loop(struct multitouch *mt)
     return EXIT_SUCCESS;
 }
 
+static void init(struct multitouch *mt)
+{
+    memset(mt, 0, sizeof(*mt));
+
+    mt->ntouches = MAX_TOUCHES;
+}
+
 int main(int argc, char **argv)
 {
     int rc;
-    struct multitouch mt = { 0 };
+    struct multitouch mt;
+
+    init(&mt);
 
     rc = init_x11(&mt, 800, 600);
     if (rc != EXIT_SUCCESS)