So I want this code to create a window with an image on it (hello world) and then quit after 5 seconds using SDL2, visual studio, and c++. I thought it should be simple enough. I wrote out the code and when I built it there were no errors, however the problem is that the window quits as soon as it's created. I thought intially that adding SDL_Delay(5000) would cause the desired effect but I guess it didn't work that way. Can anyone tell me as to why this is?
#include <SDL.h>
#include <iostream>
bool init();
bool load_media();
void close();
const int s_height = 300;
const int s_width = 400;
SDL_Window* new_window = NULL;
SDL_Surface* new_surface = NULL;
SDL_Surface* new_image = NULL;
using namespace std;
bool init()
{
bool success = true;
if (SDL_Init(SDL_INIT_VIDEO) < 0)
{
cout << "couldn't initialize" << endl;
success = false;
}
else
{
new_window = SDL_CreateWindow(
"SDL Tutorial 2",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
s_width,
s_height,
SDL_WINDOW_SHOWN);
if (new_window == NULL)
{
cout << "there's no window" << endl;
success = false;
}
else
{
new_surface = SDL_GetWindowSurface(new_window);
}
}
return success;
}
bool load_media()
{
bool success = true;
new_image = SDL_LoadBMP("SDL Tutorial 2/hello_world.bmp");
if (new_image == NULL)
{
cout << "couldn't load image" << endl;
success = false;
}
return success;
}
void close()
{
SDL_FreeSurface(new_image);
SDL_DestroyWindow(new_window);
SDL_Quit;
}
int main(int argc, char *argv[])
{
if (!init())
{
cout << "FAILED to Initialize!" << endl;
if (!load_media())
{
cout << "FAILED to Load Media!" << endl;
}
else
{
SDL_BlitSurface(new_image, NULL, new_surface, NULL);
SDL_UpdateWindowSurface(new_window);
SDL_Delay(5000);
SDL_Quit;
}
}
close();
return 0;
}
You only initialized the Video sub-system; you need to initialize the Timer sub-system if you want to use SDL_Delay
and other time-related functions.
Change your SDL_Init(SDL_INIT_VIDEO)
to SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER)
Your first line should be...
if (init())
calling 'if (!init())' continues to the rest of the code only if init() fails. I think the window briefly appears because in init(), the window is created, but the rest of your code (including timing) is skipped and the window closes right away.
I would revise to:
int main(int argc, char* argv[])
{
if( init()) {
//other code executes if init() is successful
SDL_Delay(5000);
}
else {
cout << "Failed to initialize!";
}
close();
return 0;
}
Here you have the code that works, with all the suggestions from comments and other answers:
#include <SDL.h>
#include <iostream>
int const s_height = 300;
int const s_width = 400;
SDL_Window *new_window = NULL;
SDL_Surface *new_surface = NULL;
SDL_Surface *new_image = NULL;
using namespace std;
bool init(void) {
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) < 0) {
cout << "couldn't initialize" << endl;
return false;
}
new_window = SDL_CreateWindow("SDL Tutorial 2",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
s_width,
s_height,
SDL_WINDOW_SHOWN
);
if (new_window == NULL) {
cout << "there's no window" << endl;
return false;
}
new_surface = SDL_GetWindowSurface(new_window);
if (new_surface == NULL) {
cout << "there's no surface" << endl;
return false;
}
return true;
}
bool load_media(void) {
new_image = SDL_LoadBMP("SDL Tutorial 2/hello_world.bmp");
if (new_image == NULL) {
cout << "couldn't load image" << endl;
return false;
}
return true;
}
void finish(void) {
if (new_image) {
SDL_FreeSurface(new_image);
}
if (new_window) {
SDL_DestroyWindow(new_window);
}
SDL_Quit();
}
int main(int argc, char *argv[]) {
if (init()) {
if (load_media()) {
SDL_BlitSurface(new_image, NULL, new_surface, NULL);
SDL_UpdateWindowSurface(new_window);
SDL_Delay(5000);
finish();
} else {
cout << "FAILED to Load Media!" << endl;
}
} else {
cout << "FAILED to Initialize!" << endl;
}
return 0;
}
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.