SDL渲染RGB数据到QT的控件中通过定时器刷新

cpp文件：

#include "sdlqtrgb.h"
#include 
static SDL_Window* sdl_win = NULL;
static SDL_Renderer* sdl_render = NULL;
static SDL_Texture* sdl_texture = NULL;
static int sdl_width = 0;
static int sdl_height = 0;
static unsigned  char* rgb = NULL;
static int pix_size = 4;
void SdlQtRGB::timerEvent(QTimerEvent* ev)
{
    static unsigned char tmp = 255;
    tmp--;
    for (int j = 0; j < sdl_height; j++)
    {
        int b = j * sdl_width * pix_size;
        for (int i = 0; i < sdl_width * pix_size; i += pix_size)
        {
            rgb[b + i] = 0;         //B
            rgb[b + i + 1] = tmp;   //G
            rgb[b + i + 2] = 0;     //R
            rgb[b + i + 3] = 0;     //A
        }
    }
    SDL_UpdateTexture(sdl_texture, NULL, rgb, sdl_width * pix_size);
    SDL_RenderClear(sdl_render);
    SDL_Rect rect