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Examples: SDL: Initial attempt at implementing the viewport/platform …
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…api. (WIP/test API) (#1542)

ImGui_ImplSDL2_Init() now takes a SDL GL context.
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@ocornut
ocornut committed Feb 27, 2018
1 parent 4cee46f commit cb601d7
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Showing 5 changed files with 257 additions and 46 deletions.
267 changes: 234 additions & 33 deletions examples/imgui_impl_sdl2.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,8 @@

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2018-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformInterface
// 2018-XX-XX: Misc: ImGui_ImplSDL2_Init() now takes a SDL_GLContext parameter.
// 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.
Expand All @@ -26,6 +28,8 @@
#include "imgui.h"
#include "imgui_impl_sdl2.h"

#include "imgui_internal.h" // FIXME-PLATFORM

// SDL
#include <SDL.h>
#include <SDL_syswm.h>
Expand All @@ -35,6 +39,10 @@ static Uint64 g_Time = 0;
static bool g_MousePressed[3] = { false, false, false };
static SDL_Cursor* g_MouseCursors[ImGuiMouseCursor_Count_] = { 0 };

// Forward Declarations
static void ImGui_ImplSDL2_InitPlatformInterface(SDL_Window* window, void* sdl_gl_context);
static void ImGui_ImplSDL2_ShutdownPlatformInterface();

static const char* ImGui_ImplSDL2_GetClipboardText(void*)
{
return SDL_GetClipboardText();
Expand Down Expand Up @@ -90,7 +98,7 @@ bool ImGui_ImplSDL2_ProcessEvent(SDL_Event* event)
return false;
}

bool ImGui_ImplSDL2_Init(SDL_Window* window)
bool ImGui_ImplSDL2_Init(SDL_Window* window, void* sdl_gl_context)
{
// Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
ImGuiIO& io = ImGui::GetIO();
Expand Down Expand Up @@ -137,17 +145,77 @@ bool ImGui_ImplSDL2_Init(SDL_Window* window)
(void)window;
#endif

// Our mouse update function expect PlatformHandle to be filled for the main viewport
ImGuiViewport* main_viewport = ImGui::GetMainViewport();
main_viewport->PlatformHandle = (void*)window;
if (io.ConfigFlags & ImGuiConfigFlags_MultiViewports)
ImGui_ImplSDL2_InitPlatformInterface(window, sdl_gl_context);

return true;
}

void ImGui_ImplSDL2_Shutdown()
{
ImGui_ImplSDL2_ShutdownPlatformInterface();

// 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_UpdateMouse()
{
ImGuiIO& io = ImGui::GetIO();
io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
io.MousePosViewport = 0;
io.MouseHoveredViewport = 0;
io.ConfigFlags &= ~ImGuiConfigFlags_PlatformHasMouseHoveredViewport; // FIXME-VIEWPORT: We can't get this info properly with SDL, capture is messing up with SDL_WINDOW_MOUSE_FOCUS report and we'd need to handle _NoInputs

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;

SDL_Window* focused_window = SDL_GetKeyboardFocus();
if (focused_window)
{
// SDL_GetMouseState() gives me mouse position seemingly based on the last window entered/focused(?)
// The creation of new window and SDL_CaptureMouse both seems to severely mess up with that, so we retrieve that position globally.
int wx, wy;
SDL_GetWindowPosition(focused_window, &wx, &wy);
SDL_GetGlobalMouseState(&mx, &my);
mx -= wx;
my -= wy;
}
if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle((void*)focused_window))
{
io.MousePos = ImVec2(viewport->Pos.x + (float)mx, viewport->Pos.y + (float)my);
io.MousePosViewport = viewport->ID;
}

// We already retrieve global mouse position, SDL_CaptureMouse() also let the OS know our drag outside boundaries shouldn't trigger, e.g.: OS window resize cursor
// The function is only supported from SDL 2.0.4 (released Jan 2016)
#if (SDL_MAJOR_VERSION >= 2) && (SDL_MINOR_VERSION >= 0) && (SDL_PATCHLEVEL >= 4)
bool any_mouse_button_down = ImGui::IsAnyMouseDown();
SDL_CaptureMouse(any_mouse_button_down ? SDL_TRUE : SDL_FALSE);
#endif

// Update OS/hardware mouse cursor if imgui isn't drawing a software cursor
ImGuiMouseCursor cursor = ImGui::GetMouseCursor();
if (io.MouseDrawCursor || cursor == ImGuiMouseCursor_None)
{
SDL_ShowCursor(SDL_FALSE);
}
else
{
SDL_SetCursor(g_MouseCursors[cursor] ? g_MouseCursors[cursor] : g_MouseCursors[ImGuiMouseCursor_Arrow]);
SDL_ShowCursor(SDL_TRUE);
}
}

void ImGui_ImplSDL2_NewFrame(SDL_Window* window)
{
ImGuiIO& io = ImGui::GetIO();
Expand All @@ -167,43 +235,176 @@ void ImGui_ImplSDL2_NewFrame(SDL_Window* window)
io.DeltaTime = g_Time > 0 ? (float)((double)(current_time - g_Time) / frequency) : (float)(1.0f / 60.0f);
g_Time = current_time;

// Setup mouse inputs (we already got mouse wheel, keyboard keys & characters from our event handler)
int mx, my;
Uint32 mouse_buttons = SDL_GetMouseState(&mx, &my);
io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
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;
ImGui_ImplSDL2_UpdateMouse();

// We need to use SDL_CaptureMouse() to easily retrieve mouse coordinates outside of the client area. This is only supported from SDL 2.0.4 (released Jan 2016)
#if (SDL_MAJOR_VERSION >= 2) && (SDL_MINOR_VERSION >= 0) && (SDL_PATCHLEVEL >= 4)
if ((SDL_GetWindowFlags(window) & (SDL_WINDOW_MOUSE_FOCUS | SDL_WINDOW_MOUSE_CAPTURE)) != 0)
io.MousePos = ImVec2((float)mx, (float)my);
bool any_mouse_button_down = false;
for (int n = 0; n < IM_ARRAYSIZE(io.MouseDown); n++)
any_mouse_button_down |= io.MouseDown[n];
if (any_mouse_button_down && (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_CAPTURE) == 0)
SDL_CaptureMouse(SDL_TRUE);
if (!any_mouse_button_down && (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_CAPTURE) != 0)
SDL_CaptureMouse(SDL_FALSE);
#else
if ((SDL_GetWindowFlags(window) & SDL_WINDOW_INPUT_FOCUS) != 0)
io.MousePos = ImVec2((float)mx, (float)my);
#endif
// Start the frame. This call will update the io.WantCaptureMouse, io.WantCaptureKeyboard flag that you can use to dispatch inputs (or not) to your application.
ImGui::NewFrame();
}

// Update OS/hardware mouse cursor if imgui isn't drawing a software cursor
ImGuiMouseCursor cursor = ImGui::GetMouseCursor();
if (io.MouseDrawCursor || cursor == ImGuiMouseCursor_None)
// --------------------------------------------------------------------------------------------------------
// Platform Windows
// --------------------------------------------------------------------------------------------------------

#include "imgui_internal.h"

#define SDL_HAS_WINDOW_OPACITY SDL_VERSION_ATLEAST(2,0,5)

struct ImGuiPlatformDataSDL2
{
SDL_Window* Window;
Uint32 WindowID;
SDL_GLContext GLContext;

ImGuiPlatformDataSDL2() { Window = NULL; WindowID = 0; GLContext = NULL; }
~ImGuiPlatformDataSDL2() { IM_ASSERT(Window == NULL && GLContext == NULL); }
};

static void ImGui_ImplSDL2_CreateViewport(ImGuiViewport* viewport)
{
ImGuiPlatformDataSDL2* data = IM_NEW(ImGuiPlatformDataSDL2)();
viewport->PlatformUserData = data;

// Share GL resources with main context
// FIXME-PLATFORM
ImGuiViewport* main_viewport = ImGui::GetMainViewport();
ImGuiPlatformDataSDL2* main_viewport_data = (ImGuiPlatformDataSDL2*)main_viewport->PlatformUserData;
SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
SDL_GL_MakeCurrent(main_viewport_data->Window, main_viewport_data->GLContext);

// We don't enable SDL_WINDOW_RESIZABLE because it enforce windows decorations
Uint32 sdl_flags = 0;
sdl_flags |= SDL_WINDOW_OPENGL; // FIXME-PLATFORM
sdl_flags |= SDL_WINDOW_HIDDEN;
sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? SDL_WINDOW_BORDERLESS : 0;
sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? 0 : SDL_WINDOW_RESIZABLE;
data->Window = SDL_CreateWindow("No Title Yet", 0, 0, (int)viewport->Size.x, (int)viewport->Size.y, sdl_flags);
data->GLContext = SDL_GL_CreateContext(data->Window);
viewport->PlatformHandle = (void*)data->Window;
}

static void ImGui_ImplSDL2_DestroyViewport(ImGuiViewport* viewport)
{
if (ImGuiPlatformDataSDL2* data = (ImGuiPlatformDataSDL2*)viewport->PlatformUserData)
{
SDL_ShowCursor(0);
if (data->GLContext)
SDL_GL_DeleteContext(data->GLContext);
data->GLContext = NULL;
if (data->Window)
SDL_DestroyWindow(data->Window);
data->Window = NULL;
IM_DELETE(data);
}
else
viewport->PlatformUserData = viewport->PlatformHandle = NULL;
}

static void ImGui_ImplSDL2_ShowWindow(ImGuiViewport* viewport)
{
ImGuiPlatformDataSDL2* data = (ImGuiPlatformDataSDL2*)viewport->PlatformUserData;
#if defined(_WIN32)
SDL_SysWMinfo info;
SDL_VERSION(&info.version);
if (SDL_GetWindowWMInfo(data->Window, &info))
{
SDL_SetCursor(g_MouseCursors[cursor] ? g_MouseCursors[cursor] : g_MouseCursors[ImGuiMouseCursor_Arrow]);
SDL_ShowCursor(1);
HWND hwnd = info.info.win.window;

// SDL hack: Hide icon from task bar
// Note: SDL 2.0.6+ has a SDL_WINDOW_SKIP_TASKBAR flag which is supported under Windows but the way it create the window breaks our seamless transition.
if (viewport->Flags & ImGuiViewportFlags_NoDecoration)
{
LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
ex_style &= ~WS_EX_APPWINDOW;
ex_style |= WS_EX_TOOLWINDOW;
::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
}

// Start the frame. This call will update the io.WantCaptureMouse, io.WantCaptureKeyboard flag that you can use to dispatch inputs (or not) to your application.
ImGui::NewFrame();
// SDL hack: SDL always activate/focus windows :/
if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
{
::ShowWindow(hwnd, SW_SHOWNA);
return;
}
}

#endif
SDL_ShowWindow(data->Window);
}

static ImVec2 ImGui_ImplSDL2_GetWindowPos(ImGuiViewport* viewport)
{
ImGuiPlatformDataSDL2* data = (ImGuiPlatformDataSDL2*)viewport->PlatformUserData;
int x = 0, y = 0;
SDL_GetWindowPosition(data->Window, &x, &y);
return ImVec2((float)x, (float)y);
}

static void ImGui_ImplSDL2_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
{
ImGuiPlatformDataSDL2* data = (ImGuiPlatformDataSDL2*)viewport->PlatformUserData;
SDL_SetWindowPosition(data->Window, (int)pos.x, (int)pos.y);
}

static ImVec2 ImGui_ImplSDL2_GetWindowSize(ImGuiViewport* viewport)
{
ImGuiPlatformDataSDL2* data = (ImGuiPlatformDataSDL2*)viewport->PlatformUserData;
int w = 0, h = 0;
SDL_GetWindowSize(data->Window, &w, &h);
return ImVec2((float)w, (float)h);
}

static void ImGui_ImplSDL2_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
{
ImGuiPlatformDataSDL2* data = (ImGuiPlatformDataSDL2*)viewport->PlatformUserData;
SDL_SetWindowSize(data->Window, (int)size.x, (int)size.y);
}

static void ImGui_ImplSDL2_SetWindowTitle(ImGuiViewport* viewport, const char* title)
{
ImGuiPlatformDataSDL2* data = (ImGuiPlatformDataSDL2*)viewport->PlatformUserData;
SDL_SetWindowTitle(data->Window, title);
}

static void ImGui_ImplSDL2_RenderViewport(ImGuiViewport* viewport)
{
ImGuiPlatformDataSDL2* data = (ImGuiPlatformDataSDL2*)viewport->PlatformUserData;
SDL_GL_MakeCurrent(data->Window, data->GLContext);
}

static void ImGui_ImplSDL2_SwapBuffers(ImGuiViewport* viewport)
{
ImGuiPlatformDataSDL2* data = (ImGuiPlatformDataSDL2*)viewport->PlatformUserData;
SDL_GL_MakeCurrent(data->Window, data->GLContext); // FIXME-PLATFORM2
SDL_GL_SwapWindow(data->Window);
}

static void ImGui_ImplSDL2_InitPlatformInterface(SDL_Window* window, void* sdl_gl_context)
{
// Register platform interface (will be coupled with a renderer interface)
ImGuiIO& io = ImGui::GetIO();
io.PlatformInterface.CreateViewport = ImGui_ImplSDL2_CreateViewport;
io.PlatformInterface.DestroyViewport = ImGui_ImplSDL2_DestroyViewport;
io.PlatformInterface.ShowWindow = ImGui_ImplSDL2_ShowWindow;
io.PlatformInterface.SetWindowPos = ImGui_ImplSDL2_SetWindowPos;
io.PlatformInterface.GetWindowPos = ImGui_ImplSDL2_GetWindowPos;
io.PlatformInterface.SetWindowSize = ImGui_ImplSDL2_SetWindowSize;
io.PlatformInterface.GetWindowSize = ImGui_ImplSDL2_GetWindowSize;
io.PlatformInterface.SetWindowTitle = ImGui_ImplSDL2_SetWindowTitle;
io.PlatformInterface.RenderViewport = ImGui_ImplSDL2_RenderViewport;
io.PlatformInterface.SwapBuffers = ImGui_ImplSDL2_SwapBuffers;

io.ConfigFlags |= SDL_HAS_WINDOW_OPACITY ? ImGuiConfigFlags_PlatformHasWindowAlpha : 0;

// Register main window handle
ImGuiViewport* main_viewport = ImGui::GetMainViewport();
ImGuiPlatformDataSDL2* data = IM_NEW(ImGuiPlatformDataSDL2)();
data->Window = window;
data->WindowID = SDL_GetWindowID(window);
data->GLContext = sdl_gl_context;
main_viewport->PlatformUserData = data;
main_viewport->PlatformHandle = data->Window;
}

static void ImGui_ImplSDL2_ShutdownPlatformInterface()
{
ImGuiIO& io = ImGui::GetIO();
memset(&io.PlatformInterface, 0, sizeof(io.PlatformInterface));
}
8 changes: 4 additions & 4 deletions examples/imgui_impl_sdl2.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@
struct SDL_Window;
typedef union SDL_Event SDL_Event;

IMGUI_API bool ImGui_ImplSDL2_Init(SDL_Window* window);
IMGUI_API void ImGui_ImplSDL2_Shutdown();
IMGUI_API void ImGui_ImplSDL2_NewFrame(SDL_Window* window);
IMGUI_API bool ImGui_ImplSDL2_ProcessEvent(SDL_Event* event);
IMGUI_API bool ImGui_ImplSDL2_Init(SDL_Window* window, void* sdl_gl_context);
IMGUI_API void ImGui_ImplSDL2_Shutdown();
IMGUI_API void ImGui_ImplSDL2_NewFrame(SDL_Window* window);
IMGUI_API bool ImGui_ImplSDL2_ProcessEvent(SDL_Event* event);
6 changes: 3 additions & 3 deletions examples/sdl_opengl2_example/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,13 +31,13 @@ int main(int, char**)
SDL_DisplayMode current;
SDL_GetCurrentDisplayMode(0, &current);
SDL_Window *window = SDL_CreateWindow("ImGui SDL2+OpenGL example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
SDL_GLContext glcontext = SDL_GL_CreateContext(window);
SDL_GLContext gl_context = SDL_GL_CreateContext(window);
SDL_GL_SetSwapInterval(1); // Enable vsync

// Setup ImGui binding
ImGui::CreateContext();
ImGuiIO& io = ImGui::GetIO(); (void)io;
ImGui_ImplSDL2_Init(window);
ImGui_ImplSDL2_Init(window, gl_context);
ImGui_ImplOpenGL2_Init();
//io.NavFlags |= ImGuiNavFlags_EnableKeyboard; // Enable Keyboard Controls

Expand Down Expand Up @@ -134,7 +134,7 @@ int main(int, char**)
ImGui_ImplSDL2_Shutdown();
ImGui::DestroyContext();

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

Expand Down
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