How to draw a waveform chart in the C language?

2 years ago
Sophia Anderson
2 minutes

In C language, you can use graphics libraries to draw waveforms. Some commonly used graphics libraries include SDL, OpenGL, GTK, etc. Here is an example code using the SDL library to draw a waveform.

#include <SDL2/SDL.h>

#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600

void drawWaveform(SDL_Renderer* renderer) {
    int i;
    SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255); // 设置绘制颜色为白色
    for (i = 0; i < SCREEN_WIDTH; i++) {
        int y = SCREEN_HEIGHT / 2 + 50 * sin(i / 20.0); // 根据正弦函数计算波形点的y坐标
        SDL_RenderDrawPoint(renderer, i, y); // 绘制波形点
    }
}

int main() {
    SDL_Window* window;
    SDL_Renderer* renderer;

    SDL_Init(SDL_INIT_VIDEO);
    SDL_CreateWindowAndRenderer(SCREEN_WIDTH, SCREEN_HEIGHT, 0, &window, &renderer);

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); // 设置背景颜色为黑色
    SDL_RenderClear(renderer);

    drawWaveform(renderer);

    SDL_RenderPresent(renderer);

    SDL_Delay(5000); // 延时5秒

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

The code above uses the SDL library to draw a simple sine wave graph on a window. It first initializes the SDL library and creates a window and a renderer using the SDL_Init() function. Then it draws the waveform graph on the window and finally displays it using the SDL_RenderPresent() function. Finally, it delays by 5 seconds using the SDL_Delay() function before closing the window and freeing up resources.

It is important to note that you need to link the SDL library during compilation, you can use the following command to compile:

gcc -o waveform waveform.c `sdl2-config --cflags --libs`
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