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Backends: GLFW: Keep track of cross-frame state individually per glfw…
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… context. This allows users to self-manage multiple glfw contexts (ocornut#3012)
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@bear24rw
bear24rw authored and Max Thrun committed Mar 17, 2021
1 parent 7ac021a commit 2053747
Showing 1 changed file with 100 additions and 60 deletions.
160 changes: 100 additions & 60 deletions backends/imgui_impl_glfw.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@
// 2016-10-15: Misc: Added a void* user_data parameter to Clipboard function handlers.

#include "imgui.h"
#include "imgui_internal.h"
#include "imgui_impl_glfw.h"

// GLFW
Expand All @@ -58,24 +59,44 @@
#define GLFW_HAS_NEW_CURSORS (0)
#endif

// Data
enum GlfwClientApi
{
GlfwClientApi_Unknown,
GlfwClientApi_OpenGL,
GlfwClientApi_Vulkan
};
static GlfwClientApi g_ClientApi = GlfwClientApi_Unknown;
static double g_Time = 0.0;
static bool g_MouseJustPressed[ImGuiMouseButton_COUNT] = {};
static GLFWcursor* g_MouseCursors[ImGuiMouseCursor_COUNT] = {};
static bool g_InstalledCallbacks = false;

// Chain GLFW callbacks: our callbacks will call the user's previously installed callbacks, if any.
static GLFWmousebuttonfun g_PrevUserCallbackMousebutton = NULL;
static GLFWscrollfun g_PrevUserCallbackScroll = NULL;
static GLFWkeyfun g_PrevUserCallbackKey = NULL;
static GLFWcharfun g_PrevUserCallbackChar = NULL;

// State for each GLFWWindow
struct State {
GlfwClientApi ClientApi = GlfwClientApi_Unknown;
double Time = 0.0;
bool MouseJustPressed[ImGuiMouseButton_COUNT] = {};
GLFWcursor* MouseCursors[ImGuiMouseCursor_COUNT] = {};
bool InstalledCallbacks = false;

// Chain GLFW callbacks: our callbacks will call the user's previously installed callbacks, if any.
GLFWmousebuttonfun PrevUserCallbackMousebutton = NULL;
GLFWscrollfun PrevUserCallbackScroll = NULL;
GLFWkeyfun PrevUserCallbackKey = NULL;
GLFWcharfun PrevUserCallbackChar = NULL;
};

// Map GLFWwindow pointer to State
static ImGuiStorage g_StateStorage;

static State* ImGui_ImplGlfw_InitWindowState(GLFWwindow* window)
{
State* state = (State*)ImGui::MemAlloc(sizeof(State));
const ImGuiID window_hash = ImHashData(&window, sizeof(void*), 0);
g_StateStorage.SetVoidPtr(window_hash, state);
return state;
}

static State* ImGui_ImplGlfw_GetWindowState(GLFWwindow* window)
{
const ImGuiID window_hash = ImHashData(&window, sizeof(void*), 0);
return (State*)g_StateStorage.GetVoidPtr(window_hash);
}

static const char* ImGui_ImplGlfw_GetClipboardText(void* user_data)
{
Expand All @@ -89,17 +110,21 @@ static void ImGui_ImplGlfw_SetClipboardText(void* user_data, const char* text)

void ImGui_ImplGlfw_MouseButtonCallback(GLFWwindow* window, int button, int action, int mods)
{
if (g_PrevUserCallbackMousebutton != NULL)
g_PrevUserCallbackMousebutton(window, button, action, mods);
State* state = ImGui_ImplGlfw_GetWindowState(window);

if (state->PrevUserCallbackMousebutton != NULL)
state->PrevUserCallbackMousebutton(window, button, action, mods);

if (action == GLFW_PRESS && button >= 0 && button < IM_ARRAYSIZE(g_MouseJustPressed))
g_MouseJustPressed[button] = true;
if (action == GLFW_PRESS && button >= 0 && button < IM_ARRAYSIZE(state->MouseJustPressed))
state->MouseJustPressed[button] = true;
}

void ImGui_ImplGlfw_ScrollCallback(GLFWwindow* window, double xoffset, double yoffset)
{
if (g_PrevUserCallbackScroll != NULL)
g_PrevUserCallbackScroll(window, xoffset, yoffset);
State* state = ImGui_ImplGlfw_GetWindowState(window);

if (state->PrevUserCallbackScroll != NULL)
state->PrevUserCallbackScroll(window, xoffset, yoffset);

ImGuiIO& io = ImGui::GetIO();
io.MouseWheelH += (float)xoffset;
Expand All @@ -108,8 +133,10 @@ void ImGui_ImplGlfw_ScrollCallback(GLFWwindow* window, double xoffset, double yo

void ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if (g_PrevUserCallbackKey != NULL)
g_PrevUserCallbackKey(window, key, scancode, action, mods);
State* state = ImGui_ImplGlfw_GetWindowState(window);

if (state->PrevUserCallbackKey != NULL)
state->PrevUserCallbackKey(window, key, scancode, action, mods);

ImGuiIO& io = ImGui::GetIO();
if (action == GLFW_PRESS)
Expand All @@ -130,16 +157,20 @@ void ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int key, int scancode, int a

void ImGui_ImplGlfw_CharCallback(GLFWwindow* window, unsigned int c)
{
if (g_PrevUserCallbackChar != NULL)
g_PrevUserCallbackChar(window, c);
State* state = ImGui_ImplGlfw_GetWindowState(window);

if (state->PrevUserCallbackChar != NULL)
state->PrevUserCallbackChar(window, c);

ImGuiIO& io = ImGui::GetIO();
io.AddInputCharacter(c);
}

static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, GlfwClientApi client_api)
{
g_Time = 0.0;
State* state = ImGui_ImplGlfw_InitWindowState(window);

state->Time = 0.0;

// Setup backend capabilities flags
ImGuiIO& io = ImGui::GetIO();
Expand Down Expand Up @@ -183,39 +214,39 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
// GLFW will emit an error which will often be printed by the app, so we temporarily disable error reporting.
// Missing cursors will return NULL and our _UpdateMouseCursor() function will use the Arrow cursor instead.)
GLFWerrorfun prev_error_callback = glfwSetErrorCallback(NULL);
g_MouseCursors[ImGuiMouseCursor_Arrow] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
g_MouseCursors[ImGuiMouseCursor_TextInput] = glfwCreateStandardCursor(GLFW_IBEAM_CURSOR);
g_MouseCursors[ImGuiMouseCursor_ResizeNS] = glfwCreateStandardCursor(GLFW_VRESIZE_CURSOR);
g_MouseCursors[ImGuiMouseCursor_ResizeEW] = glfwCreateStandardCursor(GLFW_HRESIZE_CURSOR);
g_MouseCursors[ImGuiMouseCursor_Hand] = glfwCreateStandardCursor(GLFW_HAND_CURSOR);
state->MouseCursors[ImGuiMouseCursor_Arrow] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
state->MouseCursors[ImGuiMouseCursor_TextInput] = glfwCreateStandardCursor(GLFW_IBEAM_CURSOR);
state->MouseCursors[ImGuiMouseCursor_ResizeNS] = glfwCreateStandardCursor(GLFW_VRESIZE_CURSOR);
state->MouseCursors[ImGuiMouseCursor_ResizeEW] = glfwCreateStandardCursor(GLFW_HRESIZE_CURSOR);
state->MouseCursors[ImGuiMouseCursor_Hand] = glfwCreateStandardCursor(GLFW_HAND_CURSOR);
#if GLFW_HAS_NEW_CURSORS
g_MouseCursors[ImGuiMouseCursor_ResizeAll] = glfwCreateStandardCursor(GLFW_RESIZE_ALL_CURSOR);
g_MouseCursors[ImGuiMouseCursor_ResizeNESW] = glfwCreateStandardCursor(GLFW_RESIZE_NESW_CURSOR);
g_MouseCursors[ImGuiMouseCursor_ResizeNWSE] = glfwCreateStandardCursor(GLFW_RESIZE_NWSE_CURSOR);
g_MouseCursors[ImGuiMouseCursor_NotAllowed] = glfwCreateStandardCursor(GLFW_NOT_ALLOWED_CURSOR);
state->MouseCursors[ImGuiMouseCursor_ResizeAll] = glfwCreateStandardCursor(GLFW_RESIZE_ALL_CURSOR);
state->MouseCursors[ImGuiMouseCursor_ResizeNESW] = glfwCreateStandardCursor(GLFW_RESIZE_NESW_CURSOR);
state->MouseCursors[ImGuiMouseCursor_ResizeNWSE] = glfwCreateStandardCursor(GLFW_RESIZE_NWSE_CURSOR);
state->MouseCursors[ImGuiMouseCursor_NotAllowed] = glfwCreateStandardCursor(GLFW_NOT_ALLOWED_CURSOR);
#else
g_MouseCursors[ImGuiMouseCursor_ResizeAll] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
g_MouseCursors[ImGuiMouseCursor_ResizeNESW] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
g_MouseCursors[ImGuiMouseCursor_ResizeNWSE] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
g_MouseCursors[ImGuiMouseCursor_NotAllowed] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
state->MouseCursors[ImGuiMouseCursor_ResizeAll] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
state->MouseCursors[ImGuiMouseCursor_ResizeNESW] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
state->MouseCursors[ImGuiMouseCursor_ResizeNWSE] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
state->MouseCursors[ImGuiMouseCursor_NotAllowed] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
#endif
glfwSetErrorCallback(prev_error_callback);

// Chain GLFW callbacks: our callbacks will call the user's previously installed callbacks, if any.
g_PrevUserCallbackMousebutton = NULL;
g_PrevUserCallbackScroll = NULL;
g_PrevUserCallbackKey = NULL;
g_PrevUserCallbackChar = NULL;
state->PrevUserCallbackMousebutton = NULL;
state->PrevUserCallbackScroll = NULL;
state->PrevUserCallbackKey = NULL;
state->PrevUserCallbackChar = NULL;
if (install_callbacks)
{
g_InstalledCallbacks = true;
g_PrevUserCallbackMousebutton = glfwSetMouseButtonCallback(window, ImGui_ImplGlfw_MouseButtonCallback);
g_PrevUserCallbackScroll = glfwSetScrollCallback(window, ImGui_ImplGlfw_ScrollCallback);
g_PrevUserCallbackKey = glfwSetKeyCallback(window, ImGui_ImplGlfw_KeyCallback);
g_PrevUserCallbackChar = glfwSetCharCallback(window, ImGui_ImplGlfw_CharCallback);
state->InstalledCallbacks = true;
state->PrevUserCallbackMousebutton = glfwSetMouseButtonCallback(window, ImGui_ImplGlfw_MouseButtonCallback);
state->PrevUserCallbackScroll = glfwSetScrollCallback(window, ImGui_ImplGlfw_ScrollCallback);
state->PrevUserCallbackKey = glfwSetKeyCallback(window, ImGui_ImplGlfw_KeyCallback);
state->PrevUserCallbackChar = glfwSetCharCallback(window, ImGui_ImplGlfw_CharCallback);
}

g_ClientApi = client_api;
state->ClientApi = client_api;
return true;
}

Expand All @@ -237,33 +268,38 @@ bool ImGui_ImplGlfw_InitForOther(GLFWwindow* window, bool install_callbacks)
void ImGui_ImplGlfw_Shutdown()
{
GLFWwindow* window = glfwGetCurrentContext();
State* state = ImGui_ImplGlfw_GetWindowState(window);

if (g_InstalledCallbacks)
if (state->InstalledCallbacks)
{
glfwSetMouseButtonCallback(window, g_PrevUserCallbackMousebutton);
glfwSetScrollCallback(window, g_PrevUserCallbackScroll);
glfwSetKeyCallback(window, g_PrevUserCallbackKey);
glfwSetCharCallback(window, g_PrevUserCallbackChar);
g_InstalledCallbacks = false;
glfwSetMouseButtonCallback(window, state->PrevUserCallbackMousebutton);
glfwSetScrollCallback(window, state->PrevUserCallbackScroll);
glfwSetKeyCallback(window, state->PrevUserCallbackKey);
glfwSetCharCallback(window, state->PrevUserCallbackChar);
state->InstalledCallbacks = false;
}

for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_COUNT; cursor_n++)
{
glfwDestroyCursor(g_MouseCursors[cursor_n]);
g_MouseCursors[cursor_n] = NULL;
glfwDestroyCursor(state->MouseCursors[cursor_n]);
state->MouseCursors[cursor_n] = NULL;
}
g_ClientApi = GlfwClientApi_Unknown;
state->ClientApi = GlfwClientApi_Unknown;

ImGui::MemFree(state);
}

static void ImGui_ImplGlfw_UpdateMousePosAndButtons(GLFWwindow* window)
{
State* state = ImGui_ImplGlfw_GetWindowState(window);

// Update buttons
ImGuiIO& io = ImGui::GetIO();
for (int i = 0; i < IM_ARRAYSIZE(io.MouseDown); i++)
{
// 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[i] = g_MouseJustPressed[i] || glfwGetMouseButton(window, i) != 0;
g_MouseJustPressed[i] = false;
io.MouseDown[i] = state->MouseJustPressed[i] || glfwGetMouseButton(window, i) != 0;
state->MouseJustPressed[i] = false;
}

// Update mouse position
Expand Down Expand Up @@ -291,6 +327,8 @@ static void ImGui_ImplGlfw_UpdateMousePosAndButtons(GLFWwindow* window)

static void ImGui_ImplGlfw_UpdateMouseCursor(GLFWwindow* window)
{
State* state = ImGui_ImplGlfw_GetWindowState(window);

ImGuiIO& io = ImGui::GetIO();
if ((io.ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange) || glfwGetInputMode(window, GLFW_CURSOR) == GLFW_CURSOR_DISABLED)
return;
Expand All @@ -305,7 +343,7 @@ static void ImGui_ImplGlfw_UpdateMouseCursor(GLFWwindow* window)
{
// Show OS mouse cursor
// FIXME-PLATFORM: Unfocused windows seems to fail changing the mouse cursor with GLFW 3.2, but 3.3 works here.
glfwSetCursor(window, g_MouseCursors[imgui_cursor] ? g_MouseCursors[imgui_cursor] : g_MouseCursors[ImGuiMouseCursor_Arrow]);
glfwSetCursor(window, state->MouseCursors[imgui_cursor] ? state->MouseCursors[imgui_cursor] : state->MouseCursors[ImGuiMouseCursor_Arrow]);
glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
}
}
Expand Down Expand Up @@ -354,6 +392,8 @@ void ImGui_ImplGlfw_NewFrame()

GLFWwindow* window = glfwGetCurrentContext();

State* state = ImGui_ImplGlfw_GetWindowState(window);

// Setup display size (every frame to accommodate for window resizing)
int w, h;
int display_w, display_h;
Expand All @@ -365,8 +405,8 @@ void ImGui_ImplGlfw_NewFrame()

// Setup time step
double current_time = glfwGetTime();
io.DeltaTime = g_Time > 0.0 ? (float)(current_time - g_Time) : (float)(1.0f / 60.0f);
g_Time = current_time;
io.DeltaTime = state->Time > 0.0 ? (float)(current_time - state->Time) : (float)(1.0f / 60.0f);
state->Time = current_time;

ImGui_ImplGlfw_UpdateMousePosAndButtons(window);
ImGui_ImplGlfw_UpdateMouseCursor(window);
Expand Down

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