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@eabase
Last active December 18, 2023 07:22
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A minimal Hello World C++ example for using SDL2 to render text in a native Windows window.
//---------------------------------------------------------------------
// Name: HelloSDL2.cpp
// Author: EAML
// Date: 2021-05-16
//
// Description:
// A minimal PoC for producing a native SDL2 Windows app that can
// be ran from either Windows Explorer or from Powershell console.
// It's designed to use minimal command line, compiler options,
// and dependencies... It will display a gray window for 2 sec's.
//
// Dependencies:
// [1] LLVM Clang++ compiler package
// [2] SDL2 Libraries (DLL's) and Header files (*.h)
// [3] TTF Libraries (DLL's) and Header files (*.h)
//
// Notes:
// There is a slight variation in the bahaviour, depending on:
// (a) if you compile as a Windows GUI: the text will not show.
// (b) if you compile as a console CLI: text will show in both terminal and/or in a 2nd new window
// (c) You may need to use "main()" for console and "WinMain()" for GUI...
// (c) to install on Linux, use packages: clang, libsdl2-dev
// (d) Someone said: #define SDL_MAIN_HANDLED ...
//
// To Run:
// cp .\SDL2\lib\x64\SDL2.dll C:\Windows\. # For SDL2
// cp .\SDL2_ttf\lib\x64\*.dll C:\Windows\. # For SDL2 TTF
// cp C:\Windows\Fonts\arial.ttf . # Get a font...
//
// For a CLI version, with console output in 2nd Window:
// # clang++.exe -std=c++17 main.cpp -o main.exe -L .\SDL2\lib\x64\ -L .\SDL2_ttf\lib\x64\ -I .\SDL2_ttf\include\ -I .\SDL2\include\ -lShell32 -lSDL2main -lSDL2 -lSDL2_ttf -Wno-narrowing -Xlinker /subsystem:console
//
// For a GUI version, without any console output:
// # clang++.exe -std=c++17 main.cpp -o main.exe -L .\SDL2\lib\x64\ -L .\SDL2_ttf\lib\x64\ -I .\SDL2_ttf\include\ -I .\SDL2\include\ -lShell32 -lSDL2main -lSDL2 -lSDL2_ttf -Wno-narrowing -Xlinker /subsystem:windows
//
// References:
// [1] https://github.com/llvm/llvm-project/releases
// [2] http://www.libsdl.org/release/SDL2-devel-2.0.14-VC.zip
// [3] https://www.libsdl.org/projects/SDL_ttf/release/SDL2_ttf-devel-2.0.15-VC.zip
// [4] https://www.libsdl.org/projects/SDL_ttf/docs/SDL_ttf.html
// [5] http://www.sdltutorials.com/sdl-ttf
// [6] https://www.libsdl.org/release/SDL-1.2.15/docs/html/sdlevent.html
// [7] https://stackoverflow.com/q/67559556/
//---------------------------------------------------------------------
//#include <SDL2/SDL.h>
#include "SDL2/include/SDL.h"
#include "SDL2_ttf/include/SDL_ttf.h"
#include <stdio.h>
#include <cstdio>
#include <string>
#include <sstream>
#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480
#define WINDOW_TITLE "Hello SDL2!"
#define WINDOW_TEXT "Hello World!"
// We make a custom stream handler for brievity
inline std::ostream& operator<<(std::ostream& os, SDL_version const& v) {
os << int(v.major) << '.' << int(v.minor) << '.' << int(v.patch);
return os;
}
std::string getInfo() {
SDL_version aa, bb, cc;
SDL_VERSION(&aa);
SDL_GetVersion(&bb);
SDL_TTF_VERSION(&cc);
std::ostringstream oss;
oss << "SDL version : " << aa << '\n';
oss << "SDL linker : " << bb << '\n';
oss << "SDL_TTF ver. : " << cc << '\n';
return oss.str();
}
void drawText ( SDL_Surface* screen, char* string, int size, int x, int y, SDL_Color fgC, SDL_Color bgC) {
// Remember to call TTF_Init(), TTF_Quit(), before/after using this function.
TTF_Font* font = TTF_OpenFont("arial.ttf", size);
if(!font) {
printf("[ERROR] TTF_OpenFont() Failed with: %s\n", TTF_GetError());
exit(2);
}
TTF_SetFontStyle(font, TTF_STYLE_BOLD);
//SDL_Surface* textSurface = TTF_RenderText_Solid(font, string, fgC); // aliased glyphs
SDL_Surface* textSurface = TTF_RenderText_Shaded(font, string, fgC, bgC); // anti-aliased glyphs
SDL_Rect textLocation = { x, y, 0, 0 };
SDL_BlitSurface(textSurface, NULL, screen, &textLocation);
SDL_FreeSurface(textSurface);
TTF_CloseFont(font);
//printf("[ERROR] Unknown error in drawText(): %s\n", TTF_GetError()); return 1;
}
//---------------------------------------------------------------------
// MAIN
//---------------------------------------------------------------------
int main(int argc, char* args[]) {
SDL_Window* window = NULL; // The window we are rendering to
SDL_Surface* screenSurface = NULL; // The surface contained by the window
SDL_Event wEvent; // Enable the Window Event handler...
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
printf( "[ERROR] SDL could not initialize! SDL Error: %s\n", SDL_GetError());
return 1;
}
window = SDL_CreateWindow(WINDOW_TITLE, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
if (window == NULL) {
printf( "[ERROR] Window could not be created! SDL Error: %s\n", SDL_GetError());
return 1;
}
screenSurface = SDL_GetWindowSurface(window);
SDL_FillRect(screenSurface, NULL, SDL_MapRGB(screenSurface->format, 0x80, 0x80, 0x80)); // Set a gray background canvas
SDL_UpdateWindowSurface(window);
//-----------------------------------------------------
// Draw the Text
//-----------------------------------------------------
if(TTF_Init() == -1) {
printf("[ERROR] TTF_Init() Failed with: %s\n", TTF_GetError());
exit(2);
}
SDL_Color fgC1 = { 0xff,0xff,0xff }, bgC1 = {0x00,0x00,0xa0}; // white text on blue background
SDL_Color fgC2 = { 0x00,0x00,0x00 }, bgC2 = {0xff,0x00,0xff}; // black text on magenta background
drawText( screenSurface, (char*) "Hello World! @ (x=50, y=100)", 18, 50,100, fgC1, bgC1); // 18 pt @ (x=50,y=100)
drawText( screenSurface, (char*) "arial.ttf @ (x=200, y=150)", 16, 200,150, fgC2, bgC2); // 16 pt @ (x=200,y=150)
int i=0;
const int FSIZE = 12; // Font Size
std::string ver = getInfo();
const char *pStr = ver.c_str(); // Convert string to char array
//-----------------------------------------------------
// Split on '\n' and draw each line further down
//-----------------------------------------------------
char *tok = strtok( (char*) pStr, "\n");
while (tok != NULL) {
drawText( screenSurface, (char*) tok, FSIZE, 50, (200 + (FSIZE + 4)*i), fgC1, fgC2);
tok = strtok(NULL,"\n");
i++;
}
SDL_UpdateWindowSurface(window);
TTF_Quit();
//-----------------------------------------------------
// Wait for Events to quit & close the window
//-----------------------------------------------------
SDL_Delay(1000); // Wait 1 sec for greasy fingers
bool eQuit = false;
while (!eQuit) {
while(SDL_PollEvent(&wEvent)) {
switch (wEvent.type) {
case SDL_QUIT: eQuit = true; break;
case SDL_KEYDOWN: eQuit = true; break;
case SDL_MOUSEBUTTONDOWN: eQuit = true; break;
case SDL_WINDOWEVENT_CLOSE: eQuit = true; break;
default:
//SDL_Log("Window %d got unknown event %d\n", wEvent.window.windowID, wEvent.window.event);
break;
}
}
SDL_Delay(100); // Keep < 500 [ms]
}
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
@eabase
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eabase commented May 16, 2021

This latest version (Rev.3) require silencing some compiler deprecation warnings using: -Wno-deprecated-declarations.

 $ clang++.exe -std=c++17 main.cpp -o main.exe -L .\SDL2\lib\x64\ -L .\SDL2_ttf\lib\x64\ -I .\SDL2_ttf\include\ -I .\SDL2\include\ -lShell32 -lSDL2main -lSDL2 -lSDL2_ttf -Wno-narrowing -Wno-deprecated-declarations -Xlinker /subsystem:console

It also fixed:

  • keyboard/mouse exit event handler
  • writing on multiple lines from a character buffer
  • compacted code for printing formatted arrays only using native clang++. (No fmt library.)

The result of this code is the following:
main_2021-05-16_21-39-18

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