Trying To Get SDL2 Text Input Working

SDL Development
#1

Hi,

Trying to get SDL2 Text Input working with no success.
Here is the code:

#ifndef INPUT
#define INPUT

class Input
{
public:

	Input(void);
	virtual ~Input(void);

    bool DEBUG;

    bool EXIT_Game;

    SDL_Event Event;

    SDL_Keycode KeyOnKeyboardPressedByUser;

    char *text;

    int DelayAllUserInput;

&

while ( SDL_PollEvent(&Event) )
{
    switch (Event.type)
    {
        case SDL_QUIT:
            EXIT_Game = true;
            return;
            break;

        case SDL_WINDOWEVENT:
            if (Event.window.event == SDL_WINDOWEVENT_RESIZED || Event.window.event == SDL_WINDOWEVENT_SHOWN)
            {
                screens->ScreenIsDirty = true;
                logic->GameDisplayChanged = true;
            }
            break;

        case SDL_KEYDOWN:
            KeyOnKeyboardPressedByUser = SDL_GetKeyFromScancode(Event.key.keysym.scancode);

            if (KeyOnKeyboardPressedByUser == SDLK_LSHIFT || KeyOnKeyboardPressedByUser == SDLK_RSHIFT)
                KeyOnKeyboardPressedByUser = -1;
            break;

        case SDL_TEXTINPUT:
            strcat(text, Event.text.text);
            break;

        default:
            break;
    }
}

Pressing on a letter key now crashes my SDL2 game?
What am I doing wrong?

I don’t call:
"SDL_StartTextInput();"
until I need to use it in the new high score name input with keyboard screen function.

Any help would be appreciated, thanks!

JeZxLee

#2

Did you allocate space for the text?

#3

Thanks for the reply…

How can I fix my code above to fix the crash?
(I am new to SDL2 Text Input)

Thanks!

JeZxLee

#4

Sorry, but I tried to follow the following tutorial:
https://wiki.libsdl.org/Tutorials/TextInput

Little confused now on how to make this work…
People in the IRC room got mad and told me to use this SDL Text Input…

JeZxLee

#5

That code example is somehow missing the actual memory allocation for text.

Hey, if you’re already using C++, why not go with std::string?

Here’s a working example:

textinput.cpp 
#include <clocale>
#include <string>
#include <iostream>

#include <SDL.h>

static void Printw(std::string & txt, bool cr = false, bool flush = false) {
#if _WIN32
	const char * dstformat = "UTF-16LE";
#else
	const char * dstformat = "UTF-32";
#endif

	if (cr)
		std::wcout << L"\r";

	wchar_t * wchr = (wchar_t*)SDL_iconv_string(dstformat, "UTF-8", txt.c_str(), txt.size() + 1);
	if (wchr) {
		std::wcout << wchr;
		SDL_free(wchr);
	} else {
		std::wcout << L"\rError! Could not convert string." << std::endl;
	}

	if (flush)
		std::wcout << std::flush;
}

int main(int argc, char *argv[])
{
	int run = 1;
	std::string text;
	SDL_Window * window;

	std::setlocale(LC_ALL, "");

	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS) < 0 ) {
		return 1;
	}

	window = SDL_CreateWindow("TextInput", 50, 50, 50, 50, SDL_WINDOW_SHOWN);
	if (!window) {
		SDL_Quit();
		return 2;
	}

	while (run) {
		SDL_Event e;
		while (SDL_PollEvent(&e)) {
			if (e.type == SDL_QUIT) {
				run = 0;
			} else if (e.type == SDL_TEXTINPUT) {
				text.append(e.text.text);
				Printw(text, true, true);
			} else if (e.type == SDL_KEYDOWN) {
				if (e.key.keysym.sym == SDLK_ESCAPE) {
					run = 0;
				} else if (e.key.keysym.sym == SDLK_BACKSPACE) {
					if (text.size() > 0) {
						std::string clearstr(text.size(), ' ');
						Printw(clearstr, true);
						// Removing multi-byte characters from the UTF-8 string.
						while (text[text.size() - 1] < -64) {
							text.erase(text.size() - 1);
						}
						text.erase(text.size() - 1);
						Printw(text, true, true);
					}
				}
			} else if (e.type == SDL_KEYUP) {
				if (e.key.keysym.sym == SDLK_RETURN) {
					text.append(1, '\n');
					Printw(text, true);
					text.clear();
				}
			}
		}

		SDL_Delay(1);
	}

	SDL_DestroyWindow(window);
	SDL_Quit();

	return 0;
}