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

1. 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"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
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_DestroyWindow(win)
SDL_Quit()
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58.3 Switch between two images
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
bmp = SDL_LoadBMP("hello.bmp")
tex = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
bmp = SDL_LoadBMP("hello2.bmp")
tex2 = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
for x = 1 to 10 showtex(tex) showtex(tex2) next
SDL_DestroyTexture(tex)
SDL_DestroyTexture(tex2)
SDL_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
func showtex oTex
SDL_RenderClear(ren)
SDL_RenderCopy2(ren,oTex)
SDL_RenderPresent(ren)
SDL_Delay(200)
58.4 Draw Rectangle
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
SDL_RenderClear(ren)
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_RenderPresent(ren)
SDL_Delay(2000)
SDL_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
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58.5 Display PNG Images
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
bmp = IMG_Load("hello3.png")
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_DestroyWindow(win)
SDL_Quit()
58.6 Use TTF Fonts
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
SDL_RenderClear(ren)
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_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
58.7 Display Transparent Images
Example:
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Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
flags = IMG_INIT_JPG | IMG_INIT_PNG
IMG_Init(flags)
win = SDL_CreateWindow("Hello World!", 100, 100, 800, 600, SDL_WINDOW_SHOWN)
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC )
bmp = IMG_Load("stars.jpg")
tex = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
SDL_RenderClear(ren)
SDL_RenderCopy(ren,tex,nullpointer(),nullpointer())
SDL_DestroyTexture(tex)
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)
tex = SDL_CreateTextureFromSurface(ren,bmp)
SDL_FreeSurface(bmp)
rect = sdl_new_sdl_rect()
sdl_set_sdl_rect_x(rect,0)
sdl_set_sdl_rect_y(rect,0)
sdl_set_sdl_rect_w(rect,100)
sdl_set_sdl_rect_h(rect,100)
SDL_RenderCopy(ren,tex,nullpointer(),rect)
SDL_SetTextureBlendMode(tex,2)
SDL_SetTextureAlphaMod(tex,255)
sdl_set_sdl_rect_x(rect,200)
sdl_set_sdl_rect_y(rect,200)
sdl_set_sdl_rect_w(rect,100)
sdl_set_sdl_rect_h(rect,100)
SDL_RenderCopy(ren,tex,nullpointer(),rect)
SDL_DestroyTexture(tex)
SDL_Destroy_SDL_Rect(rect)
SDL_RenderPresent(ren)
SDL_Delay(2000)
SDL_DestroyRenderer(ren)
SDL_DestroyWindow(win)
SDL_Quit()
58.8 Close Window Event
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
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win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
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_DestroyWindow(win)
SDL_Quit()
58.9 Mouse Events
Example:
Load "libsdl.ring"
SDL_Init(SDL_INIT_EVERYTHING)
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)
myevent = sdl_new_sdl_event()
while true
cMsg = ""
sdl_pollevent(myevent)
switch sdl_get_sdl_event_type(myevent)
on SDL_QUIT
exit
on SDL_KEYDOWN
Key = SDL_GET_SDL_Event_key_keysym_sym(myevent)
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
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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_DestroyWindow(win)
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"
SDL_Init(SDL_INIT_EVERYTHING)
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN)
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)
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
Mix_FreeChunk( sound )
Mix_CloseAudio()
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Mix_Quit()
SDL_DestroyWindow(win)
SDL_Quit()
58.10. Play Sound 544

8. 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)
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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()
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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