Fullscreen text viewer

main.cpp

/**  
Copyright (c) 2021 Nikolai Wuttke

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

#include "imgui.h"
#include "imgui_impl_sdl.h"
#include "imgui_impl_opengl3.h"

#include <SDL.h>
#include <GLES2/gl2.h>

#include <stdio.h>
#include <fstream>

int main(int argc, char** argv)
{
  if (argc <= 1)
  {
    printf("No input given\n");
    return 0;
  }

  if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_GAMECONTROLLER) != 0)
  {
    printf("Error: %s\n", SDL_GetError());
    return -1;
  }

  SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
  SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
  SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);

  SDL_DisplayMode displayMode;
  SDL_GetDesktopDisplayMode(0, &displayMode);

  SDL_Window* window = SDL_CreateWindow(
    "Log Viewer",
    SDL_WINDOWPOS_CENTERED,
    SDL_WINDOWPOS_CENTERED,
    displayMode.w,
    displayMode.h,
    SDL_WINDOW_OPENGL | SDL_WINDOW_FULLSCREEN | SDL_WINDOW_ALLOW_HIGHDPI);

  SDL_GLContext gl_context = SDL_GL_CreateContext(window);
  SDL_GL_MakeCurrent(window, gl_context);
  SDL_GL_SetSwapInterval(1); // Enable vsync

  // Setup Dear ImGui context
  IMGUI_CHECKVERSION();
  ImGui::CreateContext();
  ImGuiIO& io = ImGui::GetIO();
  io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
  io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;

    // Setup Dear ImGui style
  ImGui::StyleColorsDark();
  //ImGui::StyleColorsClassic();

  // Setup Platform/Renderer bindings
  ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
  ImGui_ImplOpenGL3_Init(nullptr);

  const char* inputFilename = argv[1];

  std::string inputText;

  {
    std::ifstream file(inputFilename, std::ios::ate);
    const size_t fileSize = file.tellg();
    file.seekg(0);
    inputText.resize(fileSize);
    file.read(&inputText[0], fileSize);
  }

  // Main loop
  bool running = true;
  while (running)
  {
    SDL_Event event;
    while (SDL_PollEvent(&event))
    {
        ImGui_ImplSDL2_ProcessEvent(&event);
        if (
          event.type == SDL_QUIT ||
          (event.type == SDL_WINDOWEVENT &&
           event.window.event == SDL_WINDOWEVENT_CLOSE &&
           event.window.windowID == SDL_GetWindowID(window)) ||
          (event.type == SDL_CONTROLLERBUTTONDOWN &&
           event.cbutton.button == SDL_CONTROLLER_BUTTON_B)
        ) {
          running = false;
        }
    }

    // Start the Dear ImGui frame
    ImGui_ImplOpenGL3_NewFrame();
    ImGui_ImplSDL2_NewFrame(window);
    ImGui::NewFrame();

    // Draw single window with scrollable text
    const ImVec2 windowSize = io.DisplaySize;
    ImGui::SetNextWindowSize(windowSize);
    ImGui::SetNextWindowPos(ImVec2(0, 0));
    ImGui::Begin(
      inputFilename,
      &running,
      ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoResize);

    ImGui::TextUnformatted(inputText.c_str());

    ImGui::End();

    // Rendering
    ImGui::Render();
    glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
    SDL_GL_SwapWindow(window);
  }

  // Cleanup
  ImGui_ImplOpenGL3_Shutdown();
  ImGui_ImplSDL2_Shutdown();
  ImGui::DestroyContext();

  SDL_GL_DeleteContext(gl_context);
  SDL_DestroyWindow(window);
  SDL_Quit();

  return 0;
}

Makefile

#
# Cross Platform Makefile
# Compatible with MSYS2/MINGW, Ubuntu 14.04.1 and Mac OS X
#
# You will need SDL2 (http://www.libsdl.org):
# Linux:
#   apt-get install libsdl2-dev
# Mac OS X:
#   brew install sdl2
# MSYS2:
#   pacman -S mingw-w64-i686-SDL2
#

#CXX = g++
#CXX = clang++

EXE = example_sdl_opengl3
IMGUI_DIR = ../..
SOURCES = main.cpp
SOURCES += $(IMGUI_DIR)/imgui.cpp $(IMGUI_DIR)/imgui_demo.cpp $(IMGUI_DIR)/imgui_draw.cpp $(IMGUI_DIR)/imgui_tables.cpp $(IMGUI_DIR)/imgui_widgets.cpp
SOURCES += $(IMGUI_DIR)/backends/imgui_impl_sdl.cpp $(IMGUI_DIR)/backends/imgui_impl_opengl3.cpp
OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
UNAME_S := $(shell uname -s)

CXXFLAGS = -I$(IMGUI_DIR) -I$(IMGUI_DIR)/backends
CXXFLAGS += -g -Wall -Wformat
LIBS =

##---------------------------------------------------------------------
## OPENGL LOADER
##---------------------------------------------------------------------

CXXFLAGS += -DIMGUI_IMPL_OPENGL_ES2
LIBS += -lGLESv2

## Using OpenGL loader: gl3w [default]
# SOURCES += ../libs/gl3w/GL/gl3w.c
# CXXFLAGS += -I../libs/gl3w -DIMGUI_IMPL_OPENGL_LOADER_GL3W

## Using OpenGL loader: glew
## (This assumes a system-wide installation)
# CXXFLAGS += -DIMGUI_IMPL_OPENGL_LOADER_GLEW
# LIBS += -lGLEW

## Using OpenGL loader: glad
# SOURCES += ../libs/glad/src/glad.c
# CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD

## Using OpenGL loader: glad2
# SOURCES += ../libs/glad/src/gl.c
# CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD2

## Using OpenGL loader: glbinding
## This assumes a system-wide installation
## of either version 3.0.0 (or newer)
# CXXFLAGS += -DIMGUI_IMPL_OPENGL_LOADER_GLBINDING3
# LIBS += -lglbinding
## or the older version 2.x
# CXXFLAGS += -DIMGUI_IMPL_OPENGL_LOADER_GLBINDING2
# LIBS += -lglbinding

##---------------------------------------------------------------------
## BUILD FLAGS PER PLATFORM
##---------------------------------------------------------------------

ifeq ($(UNAME_S), Linux) #LINUX
	ECHO_MESSAGE = "Linux"
	LIBS += -lGL -ldl `sdl2-config --libs`

	CXXFLAGS += `sdl2-config --cflags`
	CFLAGS = $(CXXFLAGS)
endif

ifeq ($(UNAME_S), Darwin) #APPLE
	ECHO_MESSAGE = "Mac OS X"
	LIBS += -framework OpenGL -framework Cocoa -framework IOKit -framework CoreVideo `sdl2-config --libs`
	LIBS += -L/usr/local/lib -L/opt/local/lib

	CXXFLAGS += `sdl2-config --cflags`
	CXXFLAGS += -I/usr/local/include -I/opt/local/include
	CFLAGS = $(CXXFLAGS)
endif

ifeq ($(findstring MINGW,$(UNAME_S)),MINGW)
   ECHO_MESSAGE = "MinGW"
   LIBS += -lgdi32 -lopengl32 -limm32 `pkg-config --static --libs sdl2`

   CXXFLAGS += `pkg-config --cflags sdl2`
   CFLAGS = $(CXXFLAGS)
endif

##---------------------------------------------------------------------
## BUILD RULES
##---------------------------------------------------------------------

%.o:%.cpp
	$(CXX) $(CXXFLAGS) -c -o $@ $<

%.o:$(IMGUI_DIR)/%.cpp
	$(CXX) $(CXXFLAGS) -c -o $@ $<

%.o:$(IMGUI_DIR)/backends/%.cpp
	$(CXX) $(CXXFLAGS) -c -o $@ $<

%.o:../libs/gl3w/GL/%.c
	$(CC) $(CFLAGS) -c -o $@ $<

%.o:../libs/glad/src/%.c
	$(CC) $(CFLAGS) -c -o $@ $<

all: $(EXE)
	@echo Build complete for $(ECHO_MESSAGE)

$(EXE): $(OBJS)
	$(CXX) -o $@ $^ $(CXXFLAGS) $(LIBS)

clean:
	rm -f $(EXE) $(OBJS)