Screen TutorialsTutorial: Screen events | Parent topic: Tutorial: Screen events |
The following walkthrough takes you through the process of injecting an Screen mtouch event into a specified display.
screen_context_t screen_ctx; /* a connection to the screen windowing system */ screen_display_t screen_disp; /* a screen display */ screen_display_t *screen_dlist; /* a list of all available displays */ screen_event_t screen_ev; /* a screen event to handle */ int ndisplays; /* number of available displays */ int val; /* a variable used to set/get window properties */ const char *display = "1"; /* the display type */ int rval = EXIT_FAILURE; /* the application return code*/ int rc; /* a return code */
rc = screen_create_context(&screen_ctx, SCREEN_INPUT_PROVIDER_CONTEXT);
rc = screen_get_context_property_iv(screen_ctx, SCREEN_PROPERTY_DISPLAY_COUNT, &ndisplays); if (rc) { perror("screen_get_context_property_iv(SCREEN_PROPERTY_DISPLAY_COUNT)"); goto fail2; } screen_dlist = calloc(ndisplays, sizeof(*screen_dlist)); if (screen_dlist == NULL) { fprintf(stderr, "could not allocate memory for display list\n"); goto fail2; } rc = screen_get_context_property_pv(screen_ctx, SCREEN_PROPERTY_DISPLAYS, (void **)screen_dlist); if (rc) { perror("screen_get_context_property_pv(SCREEN_PROPERTY_DISPLAYS)"); free(screen_dlist); goto fail2; } if (isdigit(*display)) { j = atoi(display) - 1; } else { int type = -1; if (strcmp(display, "internal") == 0) { type = SCREEN_DISPLAY_TYPE_INTERNAL; } else if (strcmp(display, "composite") == 0) { type = SCREEN_DISPLAY_TYPE_COMPOSITE; } else if (strcmp(display, "svideo") == 0) { type = SCREEN_DISPLAY_TYPE_SVIDEO; } else if (strcmp(display, "YPbPr") == 0) { type = SCREEN_DISPLAY_TYPE_COMPONENT_YPbPr; } else if (strcmp(display, "rgb") == 0) { type = SCREEN_DISPLAY_TYPE_COMPONENT_RGB; } else if (strcmp(display, "rgbhv") == 0) { type = SCREEN_DISPLAY_TYPE_COMPONENT_RGBHV; } else if (strcmp(display, "dvi") == 0) { type = SCREEN_DISPLAY_TYPE_DVI; } else if (strcmp(display, "hdmi") == 0) { type = SCREEN_DISPLAY_TYPE_HDMI; } else if (strcmp(display, "other") == 0) { type = SCREEN_DISPLAY_TYPE_OTHER; } else { fprintf(stderr, "unknown display type %s\n", display); free(screen_dlist); goto fail2; } for (j = 0; j < ndisplays; j++) { screen_get_display_property_iv(screen_dlist[j], SCREEN_PROPERTY_TYPE, &val); if (val == type) { break; } } } if (j >= ndisplays) { fprintf(stderr, "couldn't find display %s\n", display); free(screen_dlist); goto fail2; } screen_disp = screen_dlist[j]; free(screen_dlist);
This is the Screen mtouch event that you will be injecting into the display.
rc = screen_create_event(&screen_ev);
In this example, you will be injecting an mtouch event.
val = SCREEN_EVENT_MTOUCH_TOUCH; rc = screen_set_event_property_iv(screen_ev, SCREEN_PROPERTY_TYPE, &val);
int device = 0; rc = screen_set _event_property_iv(screen_ev, SCREEN_PROPERTY_DEVICE_INDEX, &device);
int pos[2] = {5, 5}; rc = screen_set_event_property_iv(screen_ev, SCREEN_PROPERTY_POSITION, &pos);
The sequence ID is the sequence number of the mtouch event. You need to increment this number for each new mtouch event you send.
int seq_id = 1; rc = screen_set_event_property_iv(screen_ev, SCREEN_PROPERTY_SEQUENCE_ID, &pos);
The size, width and height in pixels, of the touch area.
int size[2] = { 5, 5}; rc = screen_set_event_property_iv(screen_ev, SCREEN_PROPERTY_SIZE, &size);
In this example, we use the same position and size because the offset of the window and display are one and the same.
rc = screen_set_event_property_iv(screen_ev, SCREEN_PROPERTY_SOURCE_POSITION, &pos); rc = screen_set_event_property_iv(screen_ev, SCREEN_PROPERTY_SOURCE_SIZE, &size);
int touch_orientation = 1; rc = screen_set_event_property_iv(screen_ev, SCREEN_PROPERTY_TOUCH_ORIENTATION, &touch_orientation);
The touch point ID is the order of occurence of the mtouch event for multi-touch events; multiple mtouch events are used to describe one multi-touch event (e.g., a two-finger swipe).
int touchId = 1; rc = screen_set_event_property_iv(screen_ev, SCREEN_PROPERTY_TOUCH_ID, &touchId);
The amount of pressure on the touch point is a relative value between 0 and (232-1) where 0 represents the lightest pressure.
int touch_pressure = 1; rc = screen_set_event_property_iv(screen_ev, SCREEN_PROPERTY_TOUCH_PRESSURE, &touchId);
rc = screen_inject_event(screen_disp, screen_ev);
screen_destroy_event(screen_ev); screen_destroy_context(screen_ctx);