The Ring programming language version 1.10 book - Part 58 of 212

CHAPTER
FIFTYEIGHT
USING RINGLIBSDL
In this chapter we will learn about using RingLibSDL to create games based on the LibSDL, SDLImage, SDLTTF and
SDLMixer libraries.
Tip: RingLibSDL is not distributed with the binary releases for desktop which uses RingAllegro
Note: To use RingLibSDL, Check ring/android/ringlibsdl folder.
58.1 Create Window
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
SDL_Delay(2000)
SDL_DestroyWindow(win)
SDL_Quit()
58.2 Display Image
Example:
Load "libsdl.ring"
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
bmp = SDL_LoadBMP("hello.bmp")
tex = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
SDL_RenderClear(ren)
SDL_RenderCopy2(ren,tex)
SDL_RenderPresent(ren)
SDL_Delay(2000)
SDL_DestroyTexture(tex)
SDL_DestroyRenderer(ren)
SDL_Quit()
538

Ring Documentation, Release 1.10
58.3 Switch between two images
Example:
Load "libsdl.ring"
bmp = SDL_LoadBMP("hello.bmp")
bmp = SDL_LoadBMP("hello2.bmp")
tex2 = SDL_CreateTextureFromSurface(ren,bmp)
for x = 1 to 10 showtex(tex) showtex(tex2) next
SDL_DestroyTexture(tex2)
SDL_Quit()
func showtex oTex
SDL_RenderCopy2(ren,oTex)
SDL_Delay(200)
58.4 Draw Rectangle
Example:
Load "libsdl.ring"
rect = sdl_new_sdl_rect()
sdl_set_sdl_rect_x(rect,10)
sdl_set_sdl_rect_y(rect,10)
sdl_set_sdl_rect_w(rect,100)
sdl_set_sdl_rect_h(rect,100)
SDL_SetRenderDrawColor(ren,255,255,255,255)
SDL_RenderDrawRect(ren,rect)
sdl_destroy_sdl_rect(rect)
SDL_Delay(2000)
SDL_Quit()
58.3. Switch between two images 539

58.5 Display PNG Images
Example:
Load "libsdl.ring"
bmp = IMG_Load("hello3.png")
SDL_RenderCopy2(ren,tex)
SDL_Delay(2000)
SDL_Quit()
58.6 Use TTF Fonts
Example:
Load "libsdl.ring"
TTF_Init()
font = TTF_OpenFont("pirulen.ttf", 16)
color = sdl_new_sdl_color()
sdl_set_sdl_color_r(color,0)
sdl_set_sdl_color_g(color,255)
sdl_set_sdl_color_b(color,0)
text = TTF_RenderText_Solid(font,"Welcome to the Ring language",color)
surface = SDL_GetWindowSurface(win)
SDL_BlitSurface(text, nullpointer(), surface, nullpointer())
SDL_UpdateWindowSurface(win)
SDL_Delay(2000)
SDL_Destroy_SDL_Color(color)
SDL_FreeSurface(text)
TTF_CloseFont(font)
SDL_Quit()
58.7 Display Transparent Images
Example:
58.5. Display PNG Images 540

Load "libsdl.ring"
flags = IMG_INIT_JPG | IMG_INIT_PNG
IMG_Init(flags)
bmp = IMG_Load("stars.jpg")
SDL_RenderCopy(ren,tex,nullpointer(),nullpointer())
bmp = IMG_Load("player.png")
# Image - Set Transparent color (white)
myformat = sdl_get_sdl_surface_format(bmp)
white = SDL_MapRGB(myformat, 255, 255, 255)
SDL_SetColorKey(bmp, SDL_True, white)
rect = sdl_new_sdl_rect()
SDL_RenderCopy(ren,tex,nullpointer(),rect)
SDL_SetTextureBlendMode(tex,2)
SDL_SetTextureAlphaMod(tex,255)
SDL_RenderCopy(ren,tex,nullpointer(),rect)
SDL_Destroy_SDL_Rect(rect)
SDL_Delay(2000)
SDL_Quit()
58.8 Close Window Event
Example:
Load "libsdl.ring"
58.8. Close Window Event 541

myevent = sdl_new_sdl_event()
while true
thevent = sdl_pollevent(myevent)
switch sdl_get_sdl_event_type(myevent)
on sdl_get_sdl_quit()
exit
on sdl_get_sdl_keydown()
Key = SDL_GET_SDL_Event_key_keysym_sym(myevent)
if key = 27 exit ok
off
end
SDL_Quit()
58.9 Mouse Events
Example:
Load "libsdl.ring"
win = SDL_CreateWindow("Mouse Events ", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
TTF_Init()
font = TTF_OpenFont("pirulen.ttf", 16)
color = sdl_new_sdl_color()
sdl_set_sdl_color_r(color,0)
sdl_set_sdl_color_g(color,255)
sdl_set_sdl_color_b(color,0)
surface = SDL_GetWindowSurface(win)
while true
cMsg = ""
sdl_pollevent(myevent)
on SDL_QUIT
exit
on SDL_KEYDOWN
if key = 27 exit ok
on SDL_MOUSEBUTTONDOWN
if sdl_get_Sdl_Event_button_button(myevent) = SDL_BUTTON_LEFT
SDL_SETWINDOWTITLE(win, " Button_Left_Down " )
but sdl_get_Sdl_Event_button_button(myevent) = SDL_BUTTON_MIDDLE
SDL_SETWINDOWTITLE(win, " Button_Middle_Down " )
but sdl_get_Sdl_Event_button_button(myevent) = SDL_BUTTON_RIGHT
SDL_SETWINDOWTITLE(win, " Button_Right_Down " )
ok
on SDL_MOUSEMOTION
58.9. Mouse Events 542

sdl_fillrect(surface,nullpointer(),0)
if sdl_get_sdl_event_motion_xrel(myevent) < 0
cMsg += " Left "
else
cMsg += " Right "
ok
if sdl_get_sdl_event_motion_yrel(myevent) < 0
cMsg += " Up "
else
cMsg += " Down "
ok
cMsg += " x = " + sdl_get_sdl_event_motion_x(myevent)
cMsg += " y = " + sdl_get_sdl_event_motion_y(myevent)
showmsg(cMsg)
off
end
SDL_Destroy_SDL_Color(Color)
TTF_CloseFont(font)
SDL_Quit()
func showmsg mymsg
text = TTF_RenderText_Solid(font,mymsg,color)
SDL_BlitSurface(text, nullpointer(), surface, nullpointer())
SDL_UpdateWindowSurface(win)
SDL_FreeSurface(text)
58.10 Play Sound
Example:
Load "libsdl.ring"
Mix_OpenAudio( 44100, MIX_DEFAULT_FORMAT , 2, 10000)
Mix_AllocateChannels(4)
sound = Mix_LoadWav( "sound.wav" )
Mix_VolumeChunk(sound,1)
Mix_PlayChannel(1,sound,0)
while true
thevent = sdl_pollevent(myevent)
on sdl_get_sdl_quit()
exit
on sdl_get_sdl_keydown()
if key = 27 exit ok
off
end
Mix_FreeChunk( sound )
Mix_CloseAudio()
58.10. Play Sound 543

Mix_Quit()
SDL_Quit()
58.10. Play Sound 544

CHAPTER
FIFTYNINE
USING RINGLIBUV
In this chapter we will learn about using RingLibuv
Note: To use RingLibuv, Check ring/extensions/ringlibuv folder.
Information from the library website: http://libuv.org/
Libuv is a multi-platform support library with a focus on asynchronous I/O.
Feature highlights
• Full-featured event loop backed by epoll, kqueue, IOCP, event ports.
• Asynchronous TCP and UDP sockets
• Asynchronous DNS resolution
• Asynchronous ﬁle and ﬁle system operations
• File system events
• ANSI escape code controlled TTY
• IPC with socket sharing, using Unix domain sockets or named pipes (Windows)
• Child processes
• Thread pool
• Signal handling
• High resolution clock
• Threading and synchronization primitives
59.1 First Application using RingLibuv
Example:
load "libuv.ring"
func main
myloop = new_uv_loop_t()
uv_loop_init(myloop)
? "Now quitting"
uv_run(myloop, UV_RUN_DEFAULT)
545

uv_loop_close(myloop)
destroy_uv_loop_t(myloop)
Output:
Now quitting
59.2 The Events Loop
Example:
load "libuv.ring"
counter = 0
idler = NULL
func main
idler = new_uv_idle_t()
uv_idle_init(uv_default_loop(), idler)
uv_idle_start(idler, "wait()")
? "Idling..."
uv_run(uv_default_loop(), UV_RUN_DEFAULT);
uv_loop_close(uv_default_loop());
destroy_uv_idle_t(idler)
func wait
counter++
if counter >= 100000
uv_idle_stop(idler)
ok
Output:
Idling...
59.3 Server Example
Example:
load "libuv.ring"
? "Testing RingLibuv - Server Side"
DEFAULT_PORT = 13370
DEFAULT_BACKLOG = 1024
addr = new_sockaddr_in()
server = NULL
client = NULL
myloop = NULL
func main
myloop = uv_default_loop()
server = new_uv_tcp_t()
59.2. The Events Loop 546

uv_tcp_init(myloop, server)
uv_ip4_addr("127.0.0.1", DEFAULT_PORT, addr)
uv_tcp_bind(server, addr, 0)
r = uv_listen(server, DEFAULT_BACKLOG, "newconnection()")
if r
? "Listen error " + uv_strerror(r)
return 1
ok
uv_run(myloop, UV_RUN_DEFAULT)
destroy_uv_tcp_t(server)
destroy_uv_sockaddr_in(addr)
func newconnection
? "New Connection"
aPara = uv_Eventpara(server,:connect)
nStatus = aPara[2]
if nStatus < 0
? "New connection error : " + nStatus
return
ok
client = new_uv_tcp_t()
uv_tcp_init(myloop, client)
if uv_accept(server, client) = 0
uv_read_start(client, uv_myalloccallback(), "echo_read()")
ok
func echo_read
aPara = uv_Eventpara(client,:read)
nRead = aPara[2]
buf = aPara[3]
if nRead > 0
req = new_uv_write_t()
wrbuf = uv_buf_init(get_uv_buf_t_base(buf), nread)
uv_write(req, client, wrbuf, 1, "echo_write()")
? uv_buf2str(wrbuf)
message = "message from the server to the client"
buf = new_uv_buf_t()
set_uv_buf_t_len(buf,len(message))
set_uv_buf_t_base(buf,varptr("message","char *"))
uv_write(req, client, buf, 1, "echo_write()")
ok
func echo_write
aPara = uv_Eventpara(client,:read)
req = aPara[1]
Output:
When we run the client, We will see the message “New Connection”
Then the message “hello from the client”
Testing RingLibuv - Server Side
New Connection
hello from the client
59.3. Server Example 547

The Ring programming language version 1.10 book - Part 58 of 212

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The Ring programming language version 1.10 book - Part 58 of 212