HISI OSD

HI_MPI_RGN_GetCanvasInfo(i, &stCanvasInfo);
stBitmap.pData   = (HI_VOID *)stCanvasInfo.u32VirtAddr;
stSize.u32Width  = stCanvasInfo.stSize.u32Width;
stSize.u32Height = stCanvasInfo.stSize.u32Height;


static HI_S32 SAMPLE_RGN_UpdateCharCanvas(char *ptext, BITMAP_S *pstBitmap, HI_BOOL bFil,HI_U32 u16FilColor, SIZE_S *pstSize, HI_U32 u32Stride, PIXEL_FORMAT_E enPixelFmt)
{
  sdl_text = TTF_RenderUTF8_Solid(font, ptext, forecol);
  pst_temp = SDL_CreateRGBSurface(SDL_SWSURFACE, sdl_text->w, sdl_text->h, 16,0x00000000, 0x00000000, 0x00000000,0);

  SDL_LowerBlit(sdl_text, &st_rect, pst_temp, &st_rect);

  SDL_Rect st_rect;
  st_rect.x = 0;
  st_rect.y = 0;
  st_rect.w = sdl_text->w;
  st_rect.h = sdl_text->h;
  SDL_LowerBlit(sdl_text, &st_rect, pst_temp, &st_rect);
  pstBitmap->u32Width  = pst_temp->pitch/2;
  pstBitmap->u32Height = pst_temp->h;
  pstBitmap->pData =pst_temp->pixels;
  pstBitmap->enPixelFormat = PIXEL_FORMAT_RGB_1555;
}
HI_MPI_RGN_UpdateCanvas(i);

保存下来的图片上显示字符，在OSD上显示不出来,请大神指点下，谢谢