Import sources and cleanup

.gitmodules

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+[submodule "3rd_party/imgui"]
+	path = 3rd_party/imgui
+	url = https://github.com/ocornut/imgui

LICENSE

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+MIT License
+
+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.

Makefile

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+EXE = text_viewer
+IMGUI_DIR = 3rd_party/imgui
+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 $(SOURCES))))
+
+CXXFLAGS = -I$(IMGUI_DIR) -I$(IMGUI_DIR)/backends
+CXXFLAGS += -g -Wall -Wformat
+CXXFLAGS += -DIMGUI_IMPL_OPENGL_ES2
+CXXFLAGS += `sdl2-config --cflags`
+LIBS = -lGLESv2 -ldl `sdl2-config --libs`
+
+##---------------------------------------------------------------------
+## 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 $@ $<
+
+all: $(EXE)
+	@echo Build complete
+
+$(EXE): $(OBJS)
+	$(CXX) -o $@ $^ $(CXXFLAGS) $(LIBS)
+
+clean:
+	rm -f $(EXE) $(OBJS)

README.md

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+# TvTextViewer
+This is a small utility for showing text files in a full-screen window with gamepad controls.
+It's meant for showing log files, instructions, error messages etc. on devices like TV boxes or gaming handhelds
+which typically don't have a keyboard/mouse.
+
+Using OpenGL ES 2.0, SDL, and the excellent [Dear ImGui library](https://github.com/ocornut/imgui).
+Target platform is Linux only for now.
+
+## Building
+
+First, install SDL2 if you haven't already. It's available in the package managers of most Linux distros.
+On Ubuntu/Debian/Mint etc. you can grab it by running `sudo apt-get install libsdl2-dev`, for example.
+
+Next, you need an OpenGL ES 2.0 implementation (`libGLESv2.so`).
+If your system doesn't come with one out of the box,
+you can use the Mesa GLES library: `sudo apt-get install libgles2-mesa-dev`.
+
+For all remaining dependencies, this project uses git submodules.
+Before you can build, these submodules need to be initialized.
+You can either use `git clone --recursive` when cloning the repo, or run:
+
+```bash
+git submodule update --init --recursive
+```
+
+Once everything is installed and submodules are initialized,
+you can build using the supplied `Makefile` by running `make` in the repository root.
+
+## Usage
+
+Basic usage is:
+
+```bash
+text_viewer <file>
+```
+
+With `<file>` being a text file you'd like to show.
+
+While running, you can scroll up and down using the analog sticks.
+Holding LB while scrolling scrolls faster, RB makes it slower.
+Press button B to quit.

main.cpp

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+/**  
+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;
+}