Digital Oscilloscope GUI base on SDL.

Digital Oscilloscope GUI base on SDL.

1.soure code:

 

 /* Bring up a window and play with it */ #include <stdlib.h> #include <stdio.h> #include <string.h> #include <math.h> #include "SDL.h" uint32_t wavetab[64]; void DrawHLine(SDL_Surface *screen, uint32_t x, uint32_t y, uint32_t w, uint32_t color, uint32_t flag) { uint8_t *pixel; uint32_t i; if ((x + w) > screen->w) { w = screen->w - x; } pixel = screen->pixels + y * screen->pitch + x * screen->format->BytesPerPixel; if (flag == 0) for (i = 0; i < w ; i ++) { *(uint32_t *)pixel = color; pixel += 4; } else for (i = 0; i < w/2; i ++) { *(uint32_t *)pixel = color; pixel += 8; } } void DrawVLine(SDL_Surface *screen, uint32_t x, uint32_t y, uint32_t h, uint32_t color, uint32_t flag) { uint8_t *pixel; uint32_t i; if ((y + h) > screen->h) { h = screen->h - x; } pixel = screen->pixels + y * screen->pitch + x * screen->format->BytesPerPixel; if (flag == 0) for (i = 0; i < h ; i ++) { *(uint32_t *)pixel = color; pixel += screen->pitch; } else for (i = 0; i < h/2 ; i ++) { *(uint32_t *)pixel = color; pixel += (screen->pitch) * 2; } } void Drawpoint(SDL_Surface *screen, uint32_t x, uint32_t y, uint32_t color) { uint8_t *pixel; uint32_t i; if (y >= (screen->h - 3)) { return; } pixel = screen->pixels + y * screen->pitch + x * screen->format->BytesPerPixel; *(uint32_t *)pixel = color; *(uint32_t *)(pixel + screen->pitch) = color; *(uint32_t *)(pixel + 2 * screen->pitch) = color; *(uint32_t *)(pixel + 3 * screen->pitch) = color; } void generatewave(uint32_t position) { int i = 0; for(i = 0;i < 64; i++) { wavetab[i] = (sin(2 * 3.1415 * i / 64.0 + position * 3.1415 / 128) + 1) * 25.0; } } void DrawBg(SDL_Surface *screen) { SDL_Surface *picture, *displayfmt; char *bmpfile = "logo.bmp"; uint32_t color; SDL_Rect rect; picture = SDL_LoadBMP(bmpfile); if (picture == NULL) { printf("Load logo.bmp failed!/n"); return; } displayfmt = SDL_DisplayFormat(picture); if ( displayfmt == NULL ) { fprintf(stderr, "Couldn't convert image: %s/n", SDL_GetError()); return; } SDL_FreeSurface(picture); picture = displayfmt; color = SDL_MapRGB(screen->format, 0x00, 0x00, 0xFF); rect.x = 0; rect.y = 0; rect.w = screen->w; rect.h = screen->h; SDL_FillRect(screen, &rect, color); if ( SDL_BlitSurface(picture, NULL, screen, NULL) < 0 ) { /* print Oscilloscope logo*/ fprintf(stderr, "Blit failed: %s/n", SDL_GetError()); return; } } void CreateWindow(SDL_Surface **window, uint32_t width, uint32_t height) { *window = SDL_CreateRGBSurface(SDL_SWSURFACE, width, height, 32, 0xFF << 24, 0xff << 16, 0xFF << 8, 0xFF); if (*window == NULL) { printf("Create window failed!/n"); return; } else { printf("Create window successfully!/n"); } } void DrawGrid(SDL_Surface *window) { uint32_t i = 0; uint32_t color; SDL_Rect rect; rect.x = 0; rect.y = 0; rect.w = window->w; rect.h = window->h; color = SDL_MapRGB(window->format, 0, 0, 0); SDL_FillRect(window, &rect, color); color = SDL_MapRGB(window->format, 100, 100, 100); for (i = 0; i < 7; i++) { DrawHLine(window, 0, 40 + i * 40, window->w, color, 1); } for (i = 0; i < 11; i++) { DrawVLine(window, 40 + i * 40, 0, window->h, color, 1); } for(i =0; i < 39; i++) { DrawHLine(window, 236, 8 + i * 8, 8, color, 0); } for(i =0; i < 59; i++) { DrawVLine(window, 8 + i * 8, 156, 8, color, 0); } } void DrawWave(SDL_Surface *window) { int i; uint32_t color; color = SDL_MapRGB(window->format, 0xFF,0,0); for(i = 0; i < window->w; i++) { Drawpoint(window, i, window->h/2 - wavetab[i%64], color); } } void DrawWave2(SDL_Surface *window) { int i; uint32_t color; color = SDL_MapRGB(window->format, 0xFF,0xff,0); for(i = 0; i < window->w; i++) { Drawpoint(window, i, window->h/2 - (wavetab[(i+15)%64] >> 1), color); } } void render(SDL_Surface *src, SDL_Surface *dst) { static uint32_t position = 0; position += 10; if (position == 128) position = 0; SDL_Rect update; update.x = 10; update.y = 50; DrawGrid(src); generatewave(position); DrawWave(src); DrawWave2(src); if ( SDL_BlitSurface(src, NULL, dst, &update) < 0 ) { fprintf(stderr, "Blit failed: %s/n", SDL_GetError()); } } int main(int argc, char *argv[]) { SDL_Surface *screen, *window; /* Options */ int w, h; int desired_bpp; Uint32 video_flags; uint32_t position = 0; w = 600; h = 400; desired_bpp = 0; video_flags = 0; if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) { fprintf(stderr, "Couldn't initialize SDL: %s/n", SDL_GetError()); return(1); } else { printf("SDL_Init is ok!/n"); } /* Initialize the display */ screen = SDL_SetVideoMode(w, h, 32, SDL_SWSURFACE); if ( screen == NULL ) { fprintf(stderr, "Couldn't set %dx%dx%d video mode: %s/n", w, h, desired_bpp, SDL_GetError()); return -1; } else { printf("SDL_SetVideoMode is ok!/n"); } DrawBg(screen); SDL_UpdateRect(screen, 0, 0, 0, 0); CreateWindow(&window, 480, 320); uint32_t quit = 0; //int j = 0; while (!quit) { render(window, screen); SDL_UpdateRect(screen, 10, 50, 480, 320); SDL_Event event; uint32_t ret = 0; //j = 0; while (ret = SDL_PollEvent(&event)) { //printf("j = %d,ret = %d/n", j++, ret); switch(event.type) { /*case SDL_MOUSEBUTTONDOWN: break;*/ case SDL_KEYDOWN: if (event.key.keysym.sym == SDLK_ESCAPE) { quit = SDL_TRUE; } break; case SDL_QUIT: quit = SDL_TRUE; break; } } SDL_Delay(50); } SDL_Quit(); }

 

2.X86上運行效果圖：

 

 

 

3.How to use SDL APIs:

1).SDL_Init(SDL_INIT_VIDEO) .

Initialize the Video Devices such as Framebuffer ,DireactFB,X11 or OpenGL etc.

2).Set the Video device.

SDL_Surface *screen, *window;

screen = SDL_SetVideoMode(w, h, 32, SDL_SWSURFACE);

3).Draw some graphic data on the backbuffer(SWSurface). 

    uint32_t color;
    SDL_Rect rect;
    color = SDL_MapRGB(screen->format, 0x00, 0x00, 0xFF);  /* Generate the blue color*/
    rect.x = 0;
    rect.y = 0;
    rect.w = screen->w;
    rect.h = screen->h;
    SDL_FillRect(screen, &rect, color);   /* FillRect function */

4).If you want to show some on the screen,please call

SDL_UpdateRect(screen, 30, 30, 480, 320);

5).Create a new RGB surface. 

*window = SDL_CreateRGBSurface(SDL_SWSURFACE, width, height, 32,
            0xFF << 24, 0xff << 16, 0xFF << 8, 0xFF);

6).BitBlt function(Copy source surface to destination surface).

    if ( SDL_BlitSurface(src, NULL, dst, &update) < 0 ) {
        fprintf(stderr, "Blit failed: %s/n", SDL_GetError());
    }

7).How to get input events.

    while (!quit) { 
        render(window, screen);
        SDL_UpdateRect(screen, 30, 30, 480, 320);    
        SDL_Event    event;
        uint32_t ret = 0;    
        //j = 0;    
        while (ret = SDL_PollEvent(&event)) { 

            /* when get input events,this function return 1,or 0,

                and it's not blocked function */ 
            //printf("j = %d,ret = %d/n", j++, ret);
            switch(event.type) {
                /*case SDL_MOUSEBUTTONDOWN:
                    break;*/
                case SDL_KEYDOWN:
                    if (event.key.keysym.sym == SDLK_ESCAPE) {
                        quit = SDL_TRUE;
                    }
                    break;
                case SDL_QUIT:
                    quit = SDL_TRUE;
                    break;
            }
        }    
        SDL_Delay(50);
    }