Avocado/src/imgui/imgui_impl_sdl.cpp

// dear imgui: Platform Binding for SDL2
// This needs to be used along with a Renderer (e.g. DirectX11, OpenGL3, Vulkan..)
// (Info: SDL2 is a cross-platform general purpose library for handling windows, inputs, graphics context creation, etc.)
// (Requires: SDL 2.0. Prefer SDL 2.0.4+ for full feature support.)

// Implemented features:
//  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
//  [X] Platform: Clipboard support.
//  [X] Platform: Keyboard arrays indexed using SDL_SCANCODE_* codes, e.g. ImGui::IsKeyPressed(SDL_SCANCODE_SPACE).
//  [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
// Missing features:
//  [ ] Platform: SDL2 handling of IME under Windows appears to be broken and it explicitly disable the regular Windows IME. You can restore
//  Windows IME by compiling SDL with SDL_DISABLE_WINDOWS_IME.

// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
// If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp.
// https://github.com/ocornut/imgui

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
//  2020-05-25: Misc: Report a zero display-size when window is minimized, to be consistent with other backends.
//  2020-02-20: Inputs: Fixed mapping for ImGuiKey_KeyPadEnter (using SDL_SCANCODE_KP_ENTER instead of SDL_SCANCODE_RETURN2).
//  2019-12-17: Inputs: On Wayland, use SDL_GetMouseState (because there is no global mouse state).
//  2019-12-05: Inputs: Added support for ImGuiMouseCursor_NotAllowed mouse cursor.
//  2019-07-21: Inputs: Added mapping for ImGuiKey_KeyPadEnter.
//  2019-04-23: Inputs: Added support for SDL_GameController (if ImGuiConfigFlags_NavEnableGamepad is set by user application).
//  2019-03-12: Misc: Preserve DisplayFramebufferScale when main window is minimized.
//  2018-12-21: Inputs: Workaround for Android/iOS which don't seem to handle focus related calls.
//  2018-11-30: Misc: Setting up io.BackendPlatformName so it can be displayed in the About Window.
//  2018-11-14: Changed the signature of ImGui_ImplSDL2_ProcessEvent() to take a 'const SDL_Event*'.
//  2018-08-01: Inputs: Workaround for Emscripten which doesn't seem to handle focus related calls.
//  2018-06-29: Inputs: Added support for the ImGuiMouseCursor_Hand cursor.
//  2018-06-08: Misc: Extracted imgui_impl_sdl.cpp/.h away from the old combined SDL2+OpenGL/Vulkan examples.
//  2018-06-08: Misc: ImGui_ImplSDL2_InitForOpenGL() now takes a SDL_GLContext parameter.
//  2018-05-09: Misc: Fixed clipboard paste memory leak (we didn't call SDL_FreeMemory on the data returned by SDL_GetClipboardText).
//  2018-03-20: Misc: Setup io.BackendFlags ImGuiBackendFlags_HasMouseCursors flag + honor ImGuiConfigFlags_NoMouseCursorChange flag.
//  2018-02-16: Inputs: Added support for mouse cursors, honoring ImGui::GetMouseCursor() value.
//  2018-02-06: Misc: Removed call to ImGui::Shutdown() which is not available from 1.60 WIP, user needs to call
//  CreateContext/DestroyContext themselves. 2018-02-06: Inputs: Added mapping for ImGuiKey_Space. 2018-02-05: Misc: Using
//  SDL_GetPerformanceCounter() instead of SDL_GetTicks() to be able to handle very high framerate (1000+ FPS). 2018-02-05: Inputs: Keyboard
//  mapping is using scancodes everywhere instead of a confusing mixture of keycodes and scancodes. 2018-01-20: Inputs: Added Horizontal
//  Mouse Wheel support. 2018-01-19: Inputs: When available (SDL 2.0.4+) using SDL_CaptureMouse() to retrieve coordinates outside of client
//  area when dragging. Otherwise (SDL 2.0.3 and before) testing for SDL_WINDOW_INPUT_FOCUS instead of SDL_WINDOW_MOUSE_FOCUS. 2018-01-18:
//  Inputs: Added mapping for ImGuiKey_Insert. 2017-08-25: Inputs: MousePos set to -FLT_MAX,-FLT_MAX when mouse is unavailable/missing
//  (instead of -1,-1). 2016-10-15: Misc: Added a void* user_data parameter to Clipboard function handlers.

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

// SDL
#include <SDL.h>
#include <SDL_syswm.h>
#if defined(__APPLE__)
#include "TargetConditionals.h"
#endif

#define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE SDL_VERSION_ATLEAST(2, 0, 4)
#define SDL_HAS_VULKAN SDL_VERSION_ATLEAST(2, 0, 6)

// Data
static SDL_Window* g_Window = NULL;
static Uint64 g_Time = 0;
static bool g_MousePressed[3] = {false, false, false};
static SDL_Cursor* g_MouseCursors[ImGuiMouseCursor_COUNT] = {};
static char* g_ClipboardTextData = NULL;
static bool g_MouseCanUseGlobalState = true;

static const char* ImGui_ImplSDL2_GetClipboardText(void*) {
    if (g_ClipboardTextData) SDL_free(g_ClipboardTextData);
    g_ClipboardTextData = SDL_GetClipboardText();
    return g_ClipboardTextData;
}

static void ImGui_ImplSDL2_SetClipboardText(void*, const char* text) { SDL_SetClipboardText(text); }

// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
// If you have multiple SDL events and some of them are not meant to be used by dear imgui, you may need to filter events based on their
// windowID field.
bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event) {
    ImGuiIO& io = ImGui::GetIO();
    switch (event->type) {
        case SDL_MOUSEWHEEL: {
            if (event->wheel.x > 0) io.MouseWheelH += 1;
            if (event->wheel.x < 0) io.MouseWheelH -= 1;
            if (event->wheel.y > 0) io.MouseWheel += 1;
            if (event->wheel.y < 0) io.MouseWheel -= 1;
            return true;
        }
        case SDL_MOUSEBUTTONDOWN: {
            if (event->button.button == SDL_BUTTON_LEFT) g_MousePressed[0] = true;
            if (event->button.button == SDL_BUTTON_RIGHT) g_MousePressed[1] = true;
            if (event->button.button == SDL_BUTTON_MIDDLE) g_MousePressed[2] = true;
            return true;
        }
        case SDL_TEXTINPUT: {
            io.AddInputCharactersUTF8(event->text.text);
            return true;
        }
        case SDL_KEYDOWN:
        case SDL_KEYUP: {
            int key = event->key.keysym.scancode;
            IM_ASSERT(key >= 0 && key < IM_ARRAYSIZE(io.KeysDown));
            io.KeysDown[key] = (event->type == SDL_KEYDOWN);
            io.KeyShift = ((SDL_GetModState() & KMOD_SHIFT) != 0);
            io.KeyCtrl = ((SDL_GetModState() & KMOD_CTRL) != 0);
            io.KeyAlt = ((SDL_GetModState() & KMOD_ALT) != 0);
#ifdef _WIN32
            io.KeySuper = false;
#else
            io.KeySuper = ((SDL_GetModState() & KMOD_GUI) != 0);
#endif
            return true;
        }
    }
    return false;
}

static bool ImGui_ImplSDL2_Init(SDL_Window* window) {
    g_Window = window;

    // Setup back-end capabilities flags
    ImGuiIO& io = ImGui::GetIO();
    io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;  // We can honor GetMouseCursor() values (optional)
    io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;   // We can honor io.WantSetMousePos requests (optional, rarely used)
    io.BackendPlatformName = "imgui_impl_sdl";

    // Keyboard mapping. ImGui will use those indices to peek into the io.KeysDown[] array.
    io.KeyMap[ImGuiKey_Tab] = SDL_SCANCODE_TAB;
    io.KeyMap[ImGuiKey_LeftArrow] = SDL_SCANCODE_LEFT;
    io.KeyMap[ImGuiKey_RightArrow] = SDL_SCANCODE_RIGHT;
    io.KeyMap[ImGuiKey_UpArrow] = SDL_SCANCODE_UP;
    io.KeyMap[ImGuiKey_DownArrow] = SDL_SCANCODE_DOWN;
    io.KeyMap[ImGuiKey_PageUp] = SDL_SCANCODE_PAGEUP;
    io.KeyMap[ImGuiKey_PageDown] = SDL_SCANCODE_PAGEDOWN;
    io.KeyMap[ImGuiKey_Home] = SDL_SCANCODE_HOME;
    io.KeyMap[ImGuiKey_End] = SDL_SCANCODE_END;
    io.KeyMap[ImGuiKey_Insert] = SDL_SCANCODE_INSERT;
    io.KeyMap[ImGuiKey_Delete] = SDL_SCANCODE_DELETE;
    io.KeyMap[ImGuiKey_Backspace] = SDL_SCANCODE_BACKSPACE;
    io.KeyMap[ImGuiKey_Space] = SDL_SCANCODE_SPACE;
    io.KeyMap[ImGuiKey_Enter] = SDL_SCANCODE_RETURN;
    io.KeyMap[ImGuiKey_Escape] = SDL_SCANCODE_ESCAPE;
    io.KeyMap[ImGuiKey_KeyPadEnter] = SDL_SCANCODE_KP_ENTER;
    io.KeyMap[ImGuiKey_A] = SDL_SCANCODE_A;
    io.KeyMap[ImGuiKey_C] = SDL_SCANCODE_C;
    io.KeyMap[ImGuiKey_V] = SDL_SCANCODE_V;
    io.KeyMap[ImGuiKey_X] = SDL_SCANCODE_X;
    io.KeyMap[ImGuiKey_Y] = SDL_SCANCODE_Y;
    io.KeyMap[ImGuiKey_Z] = SDL_SCANCODE_Z;

    io.SetClipboardTextFn = ImGui_ImplSDL2_SetClipboardText;
    io.GetClipboardTextFn = ImGui_ImplSDL2_GetClipboardText;
    io.ClipboardUserData = NULL;

    // Load mouse cursors
    g_MouseCursors[ImGuiMouseCursor_Arrow] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_ARROW);
    g_MouseCursors[ImGuiMouseCursor_TextInput] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_IBEAM);
    g_MouseCursors[ImGuiMouseCursor_ResizeAll] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEALL);
    g_MouseCursors[ImGuiMouseCursor_ResizeNS] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENS);
    g_MouseCursors[ImGuiMouseCursor_ResizeEW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEWE);
    g_MouseCursors[ImGuiMouseCursor_ResizeNESW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENESW);
    g_MouseCursors[ImGuiMouseCursor_ResizeNWSE] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENWSE);
    g_MouseCursors[ImGuiMouseCursor_Hand] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_HAND);
    g_MouseCursors[ImGuiMouseCursor_NotAllowed] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_NO);

    // Check and store if we are on Wayland
    g_MouseCanUseGlobalState = strncmp(SDL_GetCurrentVideoDriver(), "wayland", 7) != 0;

#ifdef _WIN32
    SDL_SysWMinfo wmInfo;
    SDL_VERSION(&wmInfo.version);
    SDL_GetWindowWMInfo(window, &wmInfo);
    io.ImeWindowHandle = wmInfo.info.win.window;
#else
    (void)window;
#endif

    return true;
}

bool ImGui_ImplSDL2_InitForOpenGL(SDL_Window* window, void* sdl_gl_context) {
    (void)sdl_gl_context;  // Viewport branch will need this.
    return ImGui_ImplSDL2_Init(window);
}

bool ImGui_ImplSDL2_InitForVulkan(SDL_Window* window) {
#if !SDL_HAS_VULKAN
    IM_ASSERT(0 && "Unsupported");
#endif
    return ImGui_ImplSDL2_Init(window);
}

bool ImGui_ImplSDL2_InitForD3D(SDL_Window* window) {
#if !defined(_WIN32)
    IM_ASSERT(0 && "Unsupported");
#endif
    return ImGui_ImplSDL2_Init(window);
}

bool ImGui_ImplSDL2_InitForMetal(SDL_Window* window) { return ImGui_ImplSDL2_Init(window); }

void ImGui_ImplSDL2_Shutdown() {
    g_Window = NULL;

    // Destroy last known clipboard data
    if (g_ClipboardTextData) SDL_free(g_ClipboardTextData);
    g_ClipboardTextData = NULL;

    // Destroy SDL mouse cursors
    for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_COUNT; cursor_n++) SDL_FreeCursor(g_MouseCursors[cursor_n]);
    memset(g_MouseCursors, 0, sizeof(g_MouseCursors));
}

static void ImGui_ImplSDL2_UpdateMousePosAndButtons() {
    ImGuiIO& io = ImGui::GetIO();

    // Set OS mouse position if requested (rarely used, only when ImGuiConfigFlags_NavEnableSetMousePos is enabled by user)
    if (io.WantSetMousePos)
        SDL_WarpMouseInWindow(g_Window, (int)io.MousePos.x, (int)io.MousePos.y);
    else
        io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);

    int mx, my;
    Uint32 mouse_buttons = SDL_GetMouseState(&mx, &my);
    io.MouseDown[0]
        = g_MousePressed[0]
          || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_LEFT)) != 0;  // If a mouse press event came, always pass it as "mouse held this frame",
                                                                  // so we don't miss click-release events that are shorter than 1 frame.
    io.MouseDown[1] = g_MousePressed[1] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_RIGHT)) != 0;
    io.MouseDown[2] = g_MousePressed[2] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_MIDDLE)) != 0;
    g_MousePressed[0] = g_MousePressed[1] = g_MousePressed[2] = false;

#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE && !defined(__EMSCRIPTEN__) && !defined(__ANDROID__) && !(defined(__APPLE__) && TARGET_OS_IOS)
    SDL_Window* focused_window = SDL_GetKeyboardFocus();
    if (g_Window == focused_window) {
        if (g_MouseCanUseGlobalState) {
            // SDL_GetMouseState() gives mouse position seemingly based on the last window entered/focused(?)
            // The creation of a new windows at runtime and SDL_CaptureMouse both seems to severely mess up with that, so we retrieve that
            // position globally. Won't use this workaround when on Wayland, as there is no global mouse position.
            int wx, wy;
            SDL_GetWindowPosition(focused_window, &wx, &wy);
            SDL_GetGlobalMouseState(&mx, &my);
            mx -= wx;
            my -= wy;
        }
        io.MousePos = ImVec2((float)mx, (float)my);
    }

    // SDL_CaptureMouse() let the OS know e.g. that our imgui drag outside the SDL window boundaries shouldn't e.g. trigger the OS window
    // resize cursor. The function is only supported from SDL 2.0.4 (released Jan 2016)
    bool any_mouse_button_down = ImGui::IsAnyMouseDown();
    SDL_CaptureMouse(any_mouse_button_down ? SDL_TRUE : SDL_FALSE);
#else
    if (SDL_GetWindowFlags(g_Window) & SDL_WINDOW_INPUT_FOCUS) io.MousePos = ImVec2((float)mx, (float)my);
#endif
}

static void ImGui_ImplSDL2_UpdateMouseCursor() {
    ImGuiIO& io = ImGui::GetIO();
    if (io.ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange) return;

    ImGuiMouseCursor imgui_cursor = ImGui::GetMouseCursor();
    if (io.MouseDrawCursor || imgui_cursor == ImGuiMouseCursor_None) {
        // Hide OS mouse cursor if imgui is drawing it or if it wants no cursor
        SDL_ShowCursor(SDL_FALSE);
    } else {
        // Show OS mouse cursor
        SDL_SetCursor(g_MouseCursors[imgui_cursor] ? g_MouseCursors[imgui_cursor] : g_MouseCursors[ImGuiMouseCursor_Arrow]);
        SDL_ShowCursor(SDL_TRUE);
    }
}

static void ImGui_ImplSDL2_UpdateGamepads() {
    ImGuiIO& io = ImGui::GetIO();
    memset(io.NavInputs, 0, sizeof(io.NavInputs));
    if ((io.ConfigFlags & ImGuiConfigFlags_NavEnableGamepad) == 0) return;

    // Get gamepad
    SDL_GameController* game_controller = SDL_GameControllerOpen(0);
    if (!game_controller) {
        io.BackendFlags &= ~ImGuiBackendFlags_HasGamepad;
        return;
    }

// Update gamepad inputs
#define MAP_BUTTON(NAV_NO, BUTTON_NO) \
    { io.NavInputs[NAV_NO] = (SDL_GameControllerGetButton(game_controller, BUTTON_NO) != 0) ? 1.0f : 0.0f; }
#define MAP_ANALOG(NAV_NO, AXIS_NO, V0, V1)                                                              \
    {                                                                                                    \
        float vn = (float)(SDL_GameControllerGetAxis(game_controller, AXIS_NO) - V0) / (float)(V1 - V0); \
        if (vn > 1.0f) vn = 1.0f;                                                                        \
        if (vn > 0.0f && io.NavInputs[NAV_NO] < vn) io.NavInputs[NAV_NO] = vn;                           \
    }
    const int thumb_dead_zone = 8000;                                          // SDL_gamecontroller.h suggests using this value.
    MAP_BUTTON(ImGuiNavInput_Activate, SDL_CONTROLLER_BUTTON_A);               // Cross / A
    MAP_BUTTON(ImGuiNavInput_Cancel, SDL_CONTROLLER_BUTTON_B);                 // Circle / B
    MAP_BUTTON(ImGuiNavInput_Menu, SDL_CONTROLLER_BUTTON_X);                   // Square / X
    MAP_BUTTON(ImGuiNavInput_Input, SDL_CONTROLLER_BUTTON_Y);                  // Triangle / Y
    MAP_BUTTON(ImGuiNavInput_DpadLeft, SDL_CONTROLLER_BUTTON_DPAD_LEFT);       // D-Pad Left
    MAP_BUTTON(ImGuiNavInput_DpadRight, SDL_CONTROLLER_BUTTON_DPAD_RIGHT);     // D-Pad Right
    MAP_BUTTON(ImGuiNavInput_DpadUp, SDL_CONTROLLER_BUTTON_DPAD_UP);           // D-Pad Up
    MAP_BUTTON(ImGuiNavInput_DpadDown, SDL_CONTROLLER_BUTTON_DPAD_DOWN);       // D-Pad Down
    MAP_BUTTON(ImGuiNavInput_FocusPrev, SDL_CONTROLLER_BUTTON_LEFTSHOULDER);   // L1 / LB
    MAP_BUTTON(ImGuiNavInput_FocusNext, SDL_CONTROLLER_BUTTON_RIGHTSHOULDER);  // R1 / RB
    MAP_BUTTON(ImGuiNavInput_TweakSlow, SDL_CONTROLLER_BUTTON_LEFTSHOULDER);   // L1 / LB
    MAP_BUTTON(ImGuiNavInput_TweakFast, SDL_CONTROLLER_BUTTON_RIGHTSHOULDER);  // R1 / RB
    MAP_ANALOG(ImGuiNavInput_LStickLeft, SDL_CONTROLLER_AXIS_LEFTX, -thumb_dead_zone, -32768);
    MAP_ANALOG(ImGuiNavInput_LStickRight, SDL_CONTROLLER_AXIS_LEFTX, +thumb_dead_zone, +32767);
    MAP_ANALOG(ImGuiNavInput_LStickUp, SDL_CONTROLLER_AXIS_LEFTY, -thumb_dead_zone, -32767);
    MAP_ANALOG(ImGuiNavInput_LStickDown, SDL_CONTROLLER_AXIS_LEFTY, +thumb_dead_zone, +32767);

    io.BackendFlags |= ImGuiBackendFlags_HasGamepad;
#undef MAP_BUTTON
#undef MAP_ANALOG
}

void ImGui_ImplSDL2_NewFrame(SDL_Window* window) {
    ImGuiIO& io = ImGui::GetIO();
    IM_ASSERT(io.Fonts->IsBuilt() && "Font atlas not built! It is generally built by the renderer back-end. Missing call to renderer _NewFrame() function? e.g. ImGui_ImplOpenGL3_NewFrame().");

    // Setup display size (every frame to accommodate for window resizing)
    int w, h;
    int display_w, display_h;
    SDL_GetWindowSize(window, &w, &h);
    if (SDL_GetWindowFlags(window) & SDL_WINDOW_MINIMIZED) w = h = 0;
    SDL_GL_GetDrawableSize(window, &display_w, &display_h);
    io.DisplaySize = ImVec2((float)w, (float)h);
    if (w > 0 && h > 0) io.DisplayFramebufferScale = ImVec2((float)display_w / w, (float)display_h / h);

    // Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
    static Uint64 frequency = SDL_GetPerformanceFrequency();
    Uint64 current_time = SDL_GetPerformanceCounter();
    io.DeltaTime = g_Time > 0 ? (float)((double)(current_time - g_Time) / frequency) : (float)(1.0f / 60.0f);
    g_Time = current_time;

    ImGui_ImplSDL2_UpdateMousePosAndButtons();
    ImGui_ImplSDL2_UpdateMouseCursor();

    // Update game controllers (if enabled and available)
    ImGui_ImplSDL2_UpdateGamepads();
}