imgui-mirror/backends/imgui_impl_android.cpp
Turtle Dove 372066e249 Android: Move JNI keyboard/clipboard into backend, add display metrics (#3446)
Backend improvements (imgui_impl_android.h/.cpp):
- Moved JNI soft-keyboard and Unicode char polling from the example into
  the backend. The application no longer needs any JNI boilerplate.
- Added clipboard support via JNI to Android ClipboardManager. (#7259)
- Added display metrics (DPI, density, refresh rate, orientation) via JNI.
  Used by the example to set main_scale from actual device density instead
  of hardcoded 2.0f.
- BREAKING CHANGE: ImGui_ImplAndroid_Init() now takes additional
  asset_manager and native_activity parameters. See before/after in header.

Example (main.cpp):
- Removed ShowSoftKeyboardInput() and PollUnicodeChars() JNI helpers (~120 lines).
- Removed their forward declarations and per-frame calls.
- Updated Init() call to new signature.
- Use ImGui_ImplAndroid_GetDisplayMetrics() for main_scale.
- All other comments, EGL block, GetAssetData, APP_CMD cases unchanged.

MainActivity.kt: unchanged (same 3 JNI bridge methods, now called by backend).

docs/CHANGELOG.txt: Added entries for backend and example changes.
2026-07-18 21:05:30 -05:00

606 lines
28 KiB
C++

// dear imgui: Platform Backend for Android native app
// This needs to be used along with a Renderer Backend (e.g. OpenGL3, Vulkan)
// Implemented features:
// [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy AKEYCODE_* values are obsolete since 1.87 and not supported since 1.91.5]
// [X] Platform: Mouse support. Can discriminate Mouse/TouchScreen/Pen.
// [X] Platform: On-screen keyboard (soft input) — handled internally via JNI. No application code needed. (#3446)
// [X] Platform: Unicode character input — handled internally via JNI. No application code needed. (#3446)
// [X] Platform: Clipboard support (via JNI to Android ClipboardManager). (#7259)
// Missing features or Issues:
// [ ] Platform: Gamepad support.
// [ ] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'. FIXME: Check if this is even possible with Android.
// Important:
// - Consider using SDL or GLFW backend on Android, which will be more full-featured than this.
// - This backend uses JNI internally to handle soft keyboard, Unicode character polling, and clipboard.
// The application does NOT need any JNI code — it just calls Init/NewFrame/Shutdown.
// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
// Learn about Dear ImGui:
// - FAQ https://dearimgui.com/faq
// - Getting Started https://dearimgui.com/getting-started
// - Documentation https://dearimgui.com/docs (same as your local docs/ folder).
// - Introduction, links and more at the top of imgui.cpp
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2026-07-15: Android: Moved JNI soft-keyboard and Unicode char polling from the example into the backend. (#3446)
// Added clipboard support via JNI. (#7259)
// Added display metrics (DPI, density, refresh rate, orientation) via JNI.
// BREAKING CHANGE: ImGui_ImplAndroid_Init() now takes additional asset_manager and native_activity params.
// 2022-09-26: Inputs: Renamed ImGuiKey_ModXXX introduced in 1.87 to ImGuiMod_XXX (old names still supported).
// 2022-01-26: Inputs: replaced short-lived io.AddKeyModsEvent() (added two weeks ago) with io.AddKeyEvent() using ImGuiKey_ModXXX flags. Sorry for the confusion.
// 2022-01-17: Inputs: calling new io.AddMousePosEvent(), io.AddMouseButtonEvent(), io.AddMouseWheelEvent() API (1.87+).
// 2022-01-10: Inputs: calling new io.AddKeyEvent(), io.AddKeyModsEvent() + io.SetKeyEventNativeData() API (1.87+). Support for full ImGuiKey range.
// 2021-03-04: Initial version.
#include "imgui.h"
#ifndef IMGUI_DISABLE
#include "imgui_impl_android.h"
#include <time.h>
#include <string.h>
#include <android/native_window.h>
#include <android/input.h>
#include <android/keycodes.h>
#include <android/log.h>
#include <jni.h>
// Android data
static double g_Time = 0.0;
static ANativeWindow* g_Window = nullptr;
static AAssetManager* g_AssetManager = nullptr;
static char g_LogTag[] = "ImGuiBackend";
// JNI state (for soft keyboard, Unicode polling, clipboard, display metrics)
static JavaVM* g_JavaVM = nullptr;
static jobject g_NativeActivity = nullptr; // Global ref
static bool g_HasJni = false;
// Clipboard state
static char* g_ClipboardText = nullptr;
// Display metrics
static ImGui_ImplAndroid_DisplayMetrics g_DisplayMetrics = {};
// Forward declarations of JNI helpers
static void ImGui_ImplAndroid_JniShowSoftKeyboard();
static void ImGui_ImplAndroid_JniHideSoftKeyboard();
static void ImGui_ImplAndroid_JniPollUnicodeChars();
static void ImGui_ImplAndroid_JniSetClipboardText(const char* text);
static const char* ImGui_ImplAndroid_JniGetClipboardText();
static ImGuiKey ImGui_ImplAndroid_KeyCodeToImGuiKey(int32_t key_code)
{
switch (key_code)
{
case AKEYCODE_TAB: return ImGuiKey_Tab;
case AKEYCODE_DPAD_LEFT: return ImGuiKey_LeftArrow;
case AKEYCODE_DPAD_RIGHT: return ImGuiKey_RightArrow;
case AKEYCODE_DPAD_UP: return ImGuiKey_UpArrow;
case AKEYCODE_DPAD_DOWN: return ImGuiKey_DownArrow;
case AKEYCODE_PAGE_UP: return ImGuiKey_PageUp;
case AKEYCODE_PAGE_DOWN: return ImGuiKey_PageDown;
case AKEYCODE_MOVE_HOME: return ImGuiKey_Home;
case AKEYCODE_MOVE_END: return ImGuiKey_End;
case AKEYCODE_INSERT: return ImGuiKey_Insert;
case AKEYCODE_FORWARD_DEL: return ImGuiKey_Delete;
case AKEYCODE_DEL: return ImGuiKey_Backspace;
case AKEYCODE_SPACE: return ImGuiKey_Space;
case AKEYCODE_ENTER: return ImGuiKey_Enter;
case AKEYCODE_ESCAPE: return ImGuiKey_Escape;
case AKEYCODE_APOSTROPHE: return ImGuiKey_Apostrophe;
case AKEYCODE_COMMA: return ImGuiKey_Comma;
case AKEYCODE_MINUS: return ImGuiKey_Minus;
case AKEYCODE_PERIOD: return ImGuiKey_Period;
case AKEYCODE_SLASH: return ImGuiKey_Slash;
case AKEYCODE_SEMICOLON: return ImGuiKey_Semicolon;
case AKEYCODE_EQUALS: return ImGuiKey_Equal;
case AKEYCODE_LEFT_BRACKET: return ImGuiKey_LeftBracket;
case AKEYCODE_BACKSLASH: return ImGuiKey_Backslash;
case AKEYCODE_RIGHT_BRACKET: return ImGuiKey_RightBracket;
case AKEYCODE_GRAVE: return ImGuiKey_GraveAccent;
case AKEYCODE_CAPS_LOCK: return ImGuiKey_CapsLock;
case AKEYCODE_SCROLL_LOCK: return ImGuiKey_ScrollLock;
case AKEYCODE_NUM_LOCK: return ImGuiKey_NumLock;
case AKEYCODE_SYSRQ: return ImGuiKey_PrintScreen;
case AKEYCODE_BREAK: return ImGuiKey_Pause;
case AKEYCODE_NUMPAD_0: return ImGuiKey_Keypad0;
case AKEYCODE_NUMPAD_1: return ImGuiKey_Keypad1;
case AKEYCODE_NUMPAD_2: return ImGuiKey_Keypad2;
case AKEYCODE_NUMPAD_3: return ImGuiKey_Keypad3;
case AKEYCODE_NUMPAD_4: return ImGuiKey_Keypad4;
case AKEYCODE_NUMPAD_5: return ImGuiKey_Keypad5;
case AKEYCODE_NUMPAD_6: return ImGuiKey_Keypad6;
case AKEYCODE_NUMPAD_7: return ImGuiKey_Keypad7;
case AKEYCODE_NUMPAD_8: return ImGuiKey_Keypad8;
case AKEYCODE_NUMPAD_9: return ImGuiKey_Keypad9;
case AKEYCODE_NUMPAD_DOT: return ImGuiKey_KeypadDecimal;
case AKEYCODE_NUMPAD_DIVIDE: return ImGuiKey_KeypadDivide;
case AKEYCODE_NUMPAD_MULTIPLY: return ImGuiKey_KeypadMultiply;
case AKEYCODE_NUMPAD_SUBTRACT: return ImGuiKey_KeypadSubtract;
case AKEYCODE_NUMPAD_ADD: return ImGuiKey_KeypadAdd;
case AKEYCODE_NUMPAD_ENTER: return ImGuiKey_KeypadEnter;
case AKEYCODE_NUMPAD_EQUALS: return ImGuiKey_KeypadEqual;
case AKEYCODE_CTRL_LEFT: return ImGuiKey_LeftCtrl;
case AKEYCODE_SHIFT_LEFT: return ImGuiKey_LeftShift;
case AKEYCODE_ALT_LEFT: return ImGuiKey_LeftAlt;
case AKEYCODE_META_LEFT: return ImGuiKey_LeftSuper;
case AKEYCODE_CTRL_RIGHT: return ImGuiKey_RightCtrl;
case AKEYCODE_SHIFT_RIGHT: return ImGuiKey_RightShift;
case AKEYCODE_ALT_RIGHT: return ImGuiKey_RightAlt;
case AKEYCODE_META_RIGHT: return ImGuiKey_RightSuper;
case AKEYCODE_MENU: return ImGuiKey_Menu;
case AKEYCODE_0: return ImGuiKey_0;
case AKEYCODE_1: return ImGuiKey_1;
case AKEYCODE_2: return ImGuiKey_2;
case AKEYCODE_3: return ImGuiKey_3;
case AKEYCODE_4: return ImGuiKey_4;
case AKEYCODE_5: return ImGuiKey_5;
case AKEYCODE_6: return ImGuiKey_6;
case AKEYCODE_7: return ImGuiKey_7;
case AKEYCODE_8: return ImGuiKey_8;
case AKEYCODE_9: return ImGuiKey_9;
case AKEYCODE_A: return ImGuiKey_A;
case AKEYCODE_B: return ImGuiKey_B;
case AKEYCODE_C: return ImGuiKey_C;
case AKEYCODE_D: return ImGuiKey_D;
case AKEYCODE_E: return ImGuiKey_E;
case AKEYCODE_F: return ImGuiKey_F;
case AKEYCODE_G: return ImGuiKey_G;
case AKEYCODE_H: return ImGuiKey_H;
case AKEYCODE_I: return ImGuiKey_I;
case AKEYCODE_J: return ImGuiKey_J;
case AKEYCODE_K: return ImGuiKey_K;
case AKEYCODE_L: return ImGuiKey_L;
case AKEYCODE_M: return ImGuiKey_M;
case AKEYCODE_N: return ImGuiKey_N;
case AKEYCODE_O: return ImGuiKey_O;
case AKEYCODE_P: return ImGuiKey_P;
case AKEYCODE_Q: return ImGuiKey_Q;
case AKEYCODE_R: return ImGuiKey_R;
case AKEYCODE_S: return ImGuiKey_S;
case AKEYCODE_T: return ImGuiKey_T;
case AKEYCODE_U: return ImGuiKey_U;
case AKEYCODE_V: return ImGuiKey_V;
case AKEYCODE_W: return ImGuiKey_W;
case AKEYCODE_X: return ImGuiKey_X;
case AKEYCODE_Y: return ImGuiKey_Y;
case AKEYCODE_Z: return ImGuiKey_Z;
case AKEYCODE_F1: return ImGuiKey_F1;
case AKEYCODE_F2: return ImGuiKey_F2;
case AKEYCODE_F3: return ImGuiKey_F3;
case AKEYCODE_F4: return ImGuiKey_F4;
case AKEYCODE_F5: return ImGuiKey_F5;
case AKEYCODE_F6: return ImGuiKey_F6;
case AKEYCODE_F7: return ImGuiKey_F7;
case AKEYCODE_F8: return ImGuiKey_F8;
case AKEYCODE_F9: return ImGuiKey_F9;
case AKEYCODE_F10: return ImGuiKey_F10;
case AKEYCODE_F11: return ImGuiKey_F11;
case AKEYCODE_F12: return ImGuiKey_F12;
default: return ImGuiKey_None;
}
}
int32_t ImGui_ImplAndroid_HandleInputEvent(const AInputEvent* input_event)
{
ImGuiIO& io = ImGui::GetIO();
int32_t event_type = AInputEvent_getType(input_event);
switch (event_type)
{
case AINPUT_EVENT_TYPE_KEY:
{
int32_t event_key_code = AKeyEvent_getKeyCode(input_event);
int32_t event_scan_code = AKeyEvent_getScanCode(input_event);
int32_t event_action = AKeyEvent_getAction(input_event);
int32_t event_meta_state = AKeyEvent_getMetaState(input_event);
io.AddKeyEvent(ImGuiMod_Ctrl, (event_meta_state & AMETA_CTRL_ON) != 0);
io.AddKeyEvent(ImGuiMod_Shift, (event_meta_state & AMETA_SHIFT_ON) != 0);
io.AddKeyEvent(ImGuiMod_Alt, (event_meta_state & AMETA_ALT_ON) != 0);
io.AddKeyEvent(ImGuiMod_Super, (event_meta_state & AMETA_META_ON) != 0);
switch (event_action)
{
// FIXME: AKEY_EVENT_ACTION_DOWN and AKEY_EVENT_ACTION_UP occur at once as soon as a touch pointer
// goes up from a key. We use a simple key event queue/ and process one event per key per frame in
// ImGui_ImplAndroid_NewFrame()...or consider using IO queue, if suitable: https://github.com/ocornut/imgui/issues/2787
case AKEY_EVENT_ACTION_DOWN:
case AKEY_EVENT_ACTION_UP:
{
ImGuiKey key = ImGui_ImplAndroid_KeyCodeToImGuiKey(event_key_code);
if (key != ImGuiKey_None)
{
io.AddKeyEvent(key, event_action == AKEY_EVENT_ACTION_DOWN);
io.SetKeyEventNativeData(key, event_key_code, event_scan_code);
}
break;
}
default:
break;
}
break;
}
case AINPUT_EVENT_TYPE_MOTION:
{
int32_t event_action = AMotionEvent_getAction(input_event);
int32_t event_pointer_index = (event_action & AMOTION_EVENT_ACTION_POINTER_INDEX_MASK) >> AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT;
event_action &= AMOTION_EVENT_ACTION_MASK;
switch (AMotionEvent_getToolType(input_event, event_pointer_index))
{
case AMOTION_EVENT_TOOL_TYPE_MOUSE:
io.AddMouseSourceEvent(ImGuiMouseSource_Mouse);
break;
case AMOTION_EVENT_TOOL_TYPE_STYLUS:
case AMOTION_EVENT_TOOL_TYPE_ERASER:
io.AddMouseSourceEvent(ImGuiMouseSource_Pen);
break;
case AMOTION_EVENT_TOOL_TYPE_FINGER:
default:
io.AddMouseSourceEvent(ImGuiMouseSource_TouchScreen);
break;
}
switch (event_action)
{
case AMOTION_EVENT_ACTION_DOWN:
case AMOTION_EVENT_ACTION_UP:
{
// Physical mouse buttons (and probably other physical devices) also invoke the actions AMOTION_EVENT_ACTION_DOWN/_UP,
// but we have to process them separately to identify the actual button pressed. This is done below via
// AMOTION_EVENT_ACTION_BUTTON_PRESS/_RELEASE. Here, we only process "FINGER" input (and "UNKNOWN", as a fallback).
int tool_type = AMotionEvent_getToolType(input_event, event_pointer_index);
if (tool_type == AMOTION_EVENT_TOOL_TYPE_FINGER || tool_type == AMOTION_EVENT_TOOL_TYPE_UNKNOWN)
{
io.AddMousePosEvent(AMotionEvent_getX(input_event, event_pointer_index), AMotionEvent_getY(input_event, event_pointer_index));
io.AddMouseButtonEvent(0, event_action == AMOTION_EVENT_ACTION_DOWN);
}
break;
}
case AMOTION_EVENT_ACTION_BUTTON_PRESS:
case AMOTION_EVENT_ACTION_BUTTON_RELEASE:
{
int32_t button_state = AMotionEvent_getButtonState(input_event);
io.AddMouseButtonEvent(0, (button_state & AMOTION_EVENT_BUTTON_PRIMARY) != 0);
io.AddMouseButtonEvent(1, (button_state & AMOTION_EVENT_BUTTON_SECONDARY) != 0);
io.AddMouseButtonEvent(2, (button_state & AMOTION_EVENT_BUTTON_TERTIARY) != 0);
break;
}
case AMOTION_EVENT_ACTION_HOVER_MOVE: // Hovering: Tool moves while NOT pressed (such as a physical mouse)
case AMOTION_EVENT_ACTION_MOVE: // Touch pointer moves while DOWN
io.AddMousePosEvent(AMotionEvent_getX(input_event, event_pointer_index), AMotionEvent_getY(input_event, event_pointer_index));
break;
case AMOTION_EVENT_ACTION_SCROLL:
io.AddMouseWheelEvent(AMotionEvent_getAxisValue(input_event, AMOTION_EVENT_AXIS_HSCROLL, event_pointer_index), AMotionEvent_getAxisValue(input_event, AMOTION_EVENT_AXIS_VSCROLL, event_pointer_index));
break;
default:
break;
}
}
return 1;
default:
break;
}
return 0;
}
// --- JNI helpers ---
// These functions handle the soft keyboard, Unicode character polling, and clipboard
// entirely within the backend so the application code stays clean.
static JNIEnv* ImGui_ImplAndroid_GetEnv()
{
if (!g_JavaVM)
return nullptr;
JNIEnv* env = nullptr;
jint ret = g_JavaVM->GetEnv((void**)&env, JNI_VERSION_1_6);
if (ret == JNI_EDETACHED)
{
if (g_JavaVM->AttachCurrentThread(&env, nullptr) != JNI_OK)
return nullptr;
}
else if (ret != JNI_OK)
{
return nullptr;
}
return env;
}
static void ImGui_ImplAndroid_DetachEnv()
{
if (g_JavaVM)
g_JavaVM->DetachCurrentThread();
}
static void ImGui_ImplAndroid_JniShowSoftKeyboard()
{
if (!g_NativeActivity)
return;
JNIEnv* env = ImGui_ImplAndroid_GetEnv();
if (!env) return;
jclass cls = env->GetObjectClass(g_NativeActivity);
if (!cls) { ImGui_ImplAndroid_DetachEnv(); return; }
// Try the NativeActivity showSoftInput method via InputMethodManager
jmethodID method = env->GetMethodID(cls, "showSoftInput", "()V");
if (method)
env->CallVoidMethod(g_NativeActivity, method);
env->DeleteLocalRef(cls);
ImGui_ImplAndroid_DetachEnv();
}
static void ImGui_ImplAndroid_JniHideSoftKeyboard()
{
if (!g_NativeActivity)
return;
JNIEnv* env = ImGui_ImplAndroid_GetEnv();
if (!env) return;
jclass cls = env->GetObjectClass(g_NativeActivity);
if (!cls) { ImGui_ImplAndroid_DetachEnv(); return; }
jmethodID method = env->GetMethodID(cls, "hideSoftInput", "()V");
if (method)
env->CallVoidMethod(g_NativeActivity, method);
env->DeleteLocalRef(cls);
ImGui_ImplAndroid_DetachEnv();
}
static void ImGui_ImplAndroid_JniPollUnicodeChars()
{
if (!g_NativeActivity)
return;
JNIEnv* env = ImGui_ImplAndroid_GetEnv();
if (!env) return;
jclass cls = env->GetObjectClass(g_NativeActivity);
if (!cls) { ImGui_ImplAndroid_DetachEnv(); return; }
jmethodID method = env->GetMethodID(cls, "pollUnicodeChar", "()I");
if (!method) { env->DeleteLocalRef(cls); ImGui_ImplAndroid_DetachEnv(); return; }
ImGuiIO& io = ImGui::GetIO();
jint unicode_char;
while ((unicode_char = env->CallIntMethod(g_NativeActivity, method)) != 0)
io.AddInputCharacter(unicode_char);
env->DeleteLocalRef(cls);
ImGui_ImplAndroid_DetachEnv();
}
static void ImGui_ImplAndroid_JniSetClipboardText(const char* text)
{
if (!g_NativeActivity || !text)
return;
JNIEnv* env = ImGui_ImplAndroid_GetEnv();
if (!env) return;
// Get ClipboardManager and set text
jclass activity_cls = env->GetObjectClass(g_NativeActivity);
if (!activity_cls) { ImGui_ImplAndroid_DetachEnv(); return; }
jmethodID get_service = env->GetMethodID(activity_cls, "getSystemService", "(Ljava/lang/String;)Ljava/lang/Object;");
if (!get_service) { env->DeleteLocalRef(activity_cls); ImGui_ImplAndroid_DetachEnv(); return; }
jstring service_name = env->NewStringUTF("clipboard");
jobject clipboard = env->CallObjectMethod(g_NativeActivity, get_service, service_name);
env->DeleteLocalRef(service_name);
if (clipboard)
{
jclass clipboard_cls = env->GetObjectClass(clipboard);
jmethodID set_text = env->GetMethodID(clipboard_cls, "setText", "(Ljava/lang/CharSequence;)V");
if (set_text)
{
jstring jtext = env->NewStringUTF(text);
env->CallVoidMethod(clipboard, set_text, jtext);
env->DeleteLocalRef(jtext);
}
env->DeleteLocalRef(clipboard_cls);
env->DeleteLocalRef(clipboard);
}
env->DeleteLocalRef(activity_cls);
ImGui_ImplAndroid_DetachEnv();
}
static const char* ImGui_ImplAndroid_JniGetClipboardText()
{
if (!g_NativeActivity)
return nullptr;
JNIEnv* env = ImGui_ImplAndroid_GetEnv();
if (!env) return nullptr;
jclass activity_cls = env->GetObjectClass(g_NativeActivity);
if (!activity_cls) { ImGui_ImplAndroid_DetachEnv(); return nullptr; }
jmethodID get_service = env->GetMethodID(activity_cls, "getSystemService", "(Ljava/lang/String;)Ljava/lang/Object;");
if (!get_service) { env->DeleteLocalRef(activity_cls); ImGui_ImplAndroid_DetachEnv(); return nullptr; }
jstring service_name = env->NewStringUTF("clipboard");
jobject clipboard = env->CallObjectMethod(g_NativeActivity, get_service, service_name);
env->DeleteLocalRef(service_name);
if (g_ClipboardText) { IM_FREE(g_ClipboardText); g_ClipboardText = nullptr; }
if (clipboard)
{
jclass clipboard_cls = env->GetObjectClass(clipboard);
jmethodID get_text = env->GetMethodID(clipboard_cls, "getText", "()Ljava/lang/CharSequence;");
if (get_text)
{
jobject sequence = env->CallObjectMethod(clipboard, get_text);
if (sequence)
{
jstring text = (jstring)sequence;
const char* chars = env->GetStringUTFChars(text, nullptr);
if (chars)
{
size_t len = strlen(chars);
g_ClipboardText = (char*)IM_ALLOC(len + 1);
memcpy(g_ClipboardText, chars, len + 1);
env->ReleaseStringUTFChars(text, chars);
}
env->DeleteLocalRef(sequence);
}
}
env->DeleteLocalRef(clipboard_cls);
env->DeleteLocalRef(clipboard);
}
env->DeleteLocalRef(activity_cls);
ImGui_ImplAndroid_DetachEnv();
return g_ClipboardText;
}
void ImGui_ImplAndroid_ShowSoftKeyboard()
{
ImGui_ImplAndroid_JniShowSoftKeyboard();
}
void ImGui_ImplAndroid_HideSoftKeyboard()
{
ImGui_ImplAndroid_JniHideSoftKeyboard();
}
bool ImGui_ImplAndroid_Init(ANativeWindow* window, AAssetManager* asset_manager, jobject native_activity)
{
IMGUI_CHECKVERSION();
g_Window = window;
g_AssetManager = asset_manager;
g_Time = 0.0;
// Setup backend capabilities flags
ImGuiIO& io = ImGui::GetIO();
io.BackendPlatformName = "imgui_impl_android";
// Setup JNI for soft keyboard, Unicode polling, clipboard, and display metrics
if (native_activity)
{
JNIEnv* env = ImGui_ImplAndroid_GetEnv();
if (env)
{
g_NativeActivity = env->NewGlobalRef(native_activity);
g_HasJni = true;
ImGui_ImplAndroid_DetachEnv();
}
}
// Setup clipboard handlers if JNI is available
if (g_HasJni)
{
io.SetClipboardTextFn = [](void* /*user_data*/, const char* text) { ImGui_ImplAndroid_JniSetClipboardText(text); };
io.GetClipboardTextFn = [](void* /*user_data*/) -> const char* { return ImGui_ImplAndroid_JniGetClipboardText(); };
}
}
// Query display metrics via JNI (if activity available)
if (g_HasJni)
{
JNIEnv* env = ImGui_ImplAndroid_GetEnv();
if (env)
{
jclass activity_cls = env->GetObjectClass(g_NativeActivity);
if (activity_cls)
{
jmethodID get_metrics = env->GetMethodID(activity_cls, "getWindowManager", "()Landroid/view/WindowManager;");
if (get_metrics)
{
jobject wm = env->CallObjectMethod(g_NativeActivity, get_metrics);
if (wm)
{
jclass wm_cls = env->GetObjectClass(wm);
jmethodID get_default_display = env->GetMethodID(wm_cls, "getDefaultDisplay", "()Landroid/view/Display;");
if (get_default_display)
{
jobject display = env->CallObjectMethod(wm, get_default_display);
if (display)
{
jclass display_cls = env->GetObjectClass(display);
// Refresh rate
jmethodID get_refresh = env->GetMethodID(display_cls, "getRefreshRate", "()F");
if (get_refresh)
g_DisplayMetrics.RefreshRate = env->CallFloatMethod(display, get_refresh);
// Orientation (getRotation: 0=portrait, 1=landscape, 2=rev portrait, 3=rev landscape)
jmethodID get_rotation = env->GetMethodID(display_cls, "getRotation", "()I");
if (get_rotation)
g_DisplayMetrics.Orientation = env->CallIntMethod(display, get_rotation);
env->DeleteLocalRef(display_cls);
env->DeleteLocalRef(display);
}
}
env->DeleteLocalRef(wm_cls);
env->DeleteLocalRef(wm);
}
}
// Display metrics (DPI, density)
jmethodID get_resources = env->GetMethodID(activity_cls, "getResources", "()Landroid/content/res/Resources;");
if (get_resources)
{
jobject res = env->CallObjectMethod(g_NativeActivity, get_resources);
if (res)
{
jclass res_cls = env->GetObjectClass(res);
jmethodID get_metrics = env->GetMethodID(res_cls, "getDisplayMetrics", "()Landroid/util/DisplayMetrics;");
if (get_metrics)
{
jobject dm = env->CallObjectMethod(res, get_metrics);
if (dm)
{
jclass dm_cls = env->GetObjectClass(dm);
jfieldID density_dpi = env->GetFieldID(dm_cls, "densityDpi", "I");
jfieldID density = env->GetFieldID(dm_cls, "density", "F");
jfieldID xdpi = env->GetFieldID(dm_cls, "xdpi", "F");
jfieldID ydpi = env->GetFieldID(dm_cls, "ydpi", "F");
jfieldID w_pixels = env->GetFieldID(dm_cls, "widthPixels", "I");
jfieldID h_pixels = env->GetFieldID(dm_cls, "heightPixels", "I");
if (density_dpi) g_DisplayMetrics.DensityDpi = env->GetIntField(dm, density_dpi);
if (density) g_DisplayMetrics.Density = env->GetFloatField(dm, density);
if (xdpi) g_DisplayMetrics.Xdpi = env->GetFloatField(dm, xdpi);
if (ydpi) g_DisplayMetrics.Ydpi = env->GetFloatField(dm, ydpi);
if (w_pixels) g_DisplayMetrics.WidthPixels = env->GetIntField(dm, w_pixels);
if (h_pixels) g_DisplayMetrics.HeightPixels = env->GetIntField(dm, h_pixels);
env->DeleteLocalRef(dm_cls);
env->DeleteLocalRef(dm);
}
}
env->DeleteLocalRef(res_cls);
env->DeleteLocalRef(res);
}
}
env->DeleteLocalRef(activity_cls);
}
ImGui_ImplAndroid_DetachEnv();
}
}
// Fallback display metrics from ANativeWindow if JNI didn't provide them
if (g_Window)
{
int32_t w = ANativeWindow_getWidth(g_Window);
int32_t h = ANativeWindow_getHeight(g_Window);
if (g_DisplayMetrics.WidthPixels == 0) g_DisplayMetrics.WidthPixels = w;
if (g_DisplayMetrics.HeightPixels == 0) g_DisplayMetrics.HeightPixels = h;
if (g_DisplayMetrics.DensityDpi == 0) g_DisplayMetrics.DensityDpi = 160; // Default to mdpi
if (g_DisplayMetrics.Density == 0.0f) g_DisplayMetrics.Density = (float)g_DisplayMetrics.DensityDpi / 160.0f;
if (g_DisplayMetrics.RefreshRate == 0.0f) g_DisplayMetrics.RefreshRate = 60.0f;
}
return true;
}
void ImGui_ImplAndroid_Shutdown()
{