SDL2 cannot open any BMP files - c++

Question

Im trying to play around with SDL2 following lazyfoo's tutorials to get accustomed to it, but even the basic most program doesn't work properly. I can open a basic blank window with no image and keep it open, but as soon as I try to open a BMP file in a window, it all acts weird and doesn't work anymore. My code, that initially shows no errors:
#include <SDL2/SDL.h>
#include <cstdio>
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
SDL_Window *newWindow = nullptr;
SDL_Surface *loadedImage = nullptr;
SDL_Surface *screenSurface = nullptr;
bool quit = false;
SDL_Event event;
bool initWindow() {
bool state = true;
if (SDL_Init(SDL_INIT_VIDEO) < 0)
{
std::puts("Error init");
state = false;
}
else
{
newWindow = SDL_CreateWindow("Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
SCREEN_WIDTH,
SCREEN_HEIGHT, SDL_WINDOWEVENT_SHOWN);
if (nullptr == newWindow)
{
std::puts("Error window");
state = false;
}
else
{
screenSurface = SDL_GetWindowSurface(newWindow);
}
}
return state;
}
bool loadMedia() {
bool success = true;
loadedImage = SDL_LoadBMP("LAND3.BMP");
if (loadedImage == nullptr)
{
printf("Error image %s \n", SDL_GetError());
success = false;
}
return success;
}
void closeWindow() {
SDL_FreeSurface(loadedImage);
loadedImage = nullptr;
SDL_DestroyWindow(newWindow);
newWindow = nullptr;
SDL_Quit();
}
int main(int argc, char *args[]) {
if (!initWindow())
{
std::puts("Error init main");
}
else
{
if (!loadMedia())
{
std::puts("Error image main");
}
else
{
while (!quit)
{
if (event.type == SDL_QUIT)
{
quit = true;
}
else
{
SDL_BlitSurface(loadedImage, nullptr, screenSurface, nullptr);
SDL_UpdateWindowSurface(newWindow);
}
}
}
}
closeWindow();
return 0;
}
When running this program, I get no errors but the UI starts acting all crazy; resolution gets very small(way smaller than 480p set up by me), all windows resize and this lasts for a brief period. If I replace the while(!quit) loop with a SDL_Delay(1000), this behaviour lasts approximately as long as the delay.
Initially my suspicion was that the file I was using the first time was corrupted(I had just renamed an existing picture), but then I downloaded a sample BMP file and nothing changed.
When using the debugger I get an error from loadMedia() that the file could not be loaded, regardless of which one I use. I am using MinGW and cLion.
What might be the issue?

Answer 1

The constant SDL_WINDOWEVENT_SHOWN is not a valid flag for the function SDL_CreateWindow. That constant is not intended as a flag, but as an event ID. You probably meant to use the constant SDL_WINDOW_SHOWN instead.
The constant SDL_WINDOWEVENT_SHOWN happens to have the same value as SDL_WINDOW_FULLSCREEN (both have the value 1). Therefore, your incorrect function call
newWindow = SDL_CreateWindow("Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
SCREEN_WIDTH,
SCREEN_HEIGHT, SDL_WINDOWEVENT_SHOWN);
is equivalent to:
newWindow = SDL_CreateWindow("Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
SCREEN_WIDTH,
SCREEN_HEIGHT, SDL_WINDOW_FULLSCREEN);
In other words, you are unintentionally asking SDL to create the window in 640*480 fullscreen mode. That is probably the reason for your desktop being resized.
The reason for the file not being found is probably because the file is not in your program's current working directory. You can either ensure that the file is in that directory or you can use an absolute path to the file, for example "C:\\Users\\MyUsername\\Desktop\\LAND3.BMP".
I doubt that your problem of not being able to kill your application using the task manager is the fault of SDL. It is probably a design flaw of Microsoft Windows. See this link on how to make the task manager more accessible from a hung fullscreen application.