1// dear imgui: standalone example application for Android + OpenGL ES 3
2
3// Learn about Dear ImGui:
4// - FAQ https://dearimgui.com/faq
5// - Getting Started https://dearimgui.com/getting-started
6// - Documentation https://dearimgui.com/docs (same as your local docs/ folder).
7// - Introduction, links and more at the top of imgui.cpp
8
9#include "imgui.h"
10#include "imgui_impl_android.h"
11#include "imgui_impl_opengl3.h"
12#include <android/log.h>
13#include <android_native_app_glue.h>
14#include <android/asset_manager.h>
15#include <EGL/egl.h>
16#include <GLES3/gl3.h>
17#include <string>
18
19// Data
20static EGLDisplay g_EglDisplay = EGL_NO_DISPLAY;
21static EGLSurface g_EglSurface = EGL_NO_SURFACE;
22static EGLContext g_EglContext = EGL_NO_CONTEXT;
23static struct android_app* g_App = nullptr;
24static bool g_Initialized = false;
25static char g_LogTag[] = "ImGuiExample";
26static std::string g_IniFilename = "";
27
28// Forward declarations of helper functions
29static void Init(struct android_app* app);
30static void Shutdown();
31static void MainLoopStep();
32static int ShowSoftKeyboardInput();
33static int PollUnicodeChars();
34static int GetAssetData(const char* filename, void** out_data);
35
36// Main code
37static void handleAppCmd(struct android_app* app, int32_t appCmd)
38{
39 switch (appCmd)
40 {
41 case APP_CMD_SAVE_STATE:
42 break;
43 case APP_CMD_INIT_WINDOW:
44 Init(app);
45 break;
46 case APP_CMD_TERM_WINDOW:
47 Shutdown();
48 break;
49 case APP_CMD_GAINED_FOCUS:
50 case APP_CMD_LOST_FOCUS:
51 break;
52 }
53}
54
55static int32_t handleInputEvent(struct android_app* app, AInputEvent* inputEvent)
56{
57 return ImGui_ImplAndroid_HandleInputEvent(inputEvent);
58}
59
60void android_main(struct android_app* app)
61{
62 app->onAppCmd = handleAppCmd;
63 app->onInputEvent = handleInputEvent;
64
65 while (true)
66 {
67 int out_events;
68 struct android_poll_source* out_data;
69
70 // Poll all events. If the app is not visible, this loop blocks until g_Initialized == true.
71 while (ALooper_pollOnce(g_Initialized ? 0 : -1, nullptr, &out_events, (void**)&out_data) >= 0)
72 {
73 // Process one event
74 if (out_data != nullptr)
75 out_data->process(app, out_data);
76
77 // Exit the app by returning from within the infinite loop
78 if (app->destroyRequested != 0)
79 {
80 // shutdown() should have been called already while processing the
81 // app command APP_CMD_TERM_WINDOW. But we play save here
82 if (!g_Initialized)
83 Shutdown();
84
85 return;
86 }
87 }
88
89 // Initiate a new frame
90 MainLoopStep();
91 }
92}
93
94void Init(struct android_app* app)
95{
96 if (g_Initialized)
97 return;
98
99 g_App = app;
100 ANativeWindow_acquire(g_App->window);
101
102 // Initialize EGL
103 // This is mostly boilerplate code for EGL...
104 {
105 g_EglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
106 if (g_EglDisplay == EGL_NO_DISPLAY)
107 __android_log_print(ANDROID_LOG_ERROR, g_LogTag, "%s", "eglGetDisplay(EGL_DEFAULT_DISPLAY) returned EGL_NO_DISPLAY");
108
109 if (eglInitialize(dpy: g_EglDisplay, major: 0, minor: 0) != EGL_TRUE)
110 __android_log_print(ANDROID_LOG_ERROR, g_LogTag, "%s", "eglInitialize() returned with an error");
111
112 const EGLint egl_attributes[] = { EGL_BLUE_SIZE, 8, EGL_GREEN_SIZE, 8, EGL_RED_SIZE, 8, EGL_DEPTH_SIZE, 24, EGL_SURFACE_TYPE, EGL_WINDOW_BIT, EGL_NONE };
113 EGLint num_configs = 0;
114 if (eglChooseConfig(dpy: g_EglDisplay, attrib_list: egl_attributes, configs: nullptr, config_size: 0, num_config: &num_configs) != EGL_TRUE)
115 __android_log_print(ANDROID_LOG_ERROR, g_LogTag, "%s", "eglChooseConfig() returned with an error");
116 if (num_configs == 0)
117 __android_log_print(ANDROID_LOG_ERROR, g_LogTag, "%s", "eglChooseConfig() returned 0 matching config");
118
119 // Get the first matching config
120 EGLConfig egl_config;
121 eglChooseConfig(dpy: g_EglDisplay, attrib_list: egl_attributes, configs: &egl_config, config_size: 1, num_config: &num_configs);
122 EGLint egl_format;
123 eglGetConfigAttrib(dpy: g_EglDisplay, config: egl_config, EGL_NATIVE_VISUAL_ID, value: &egl_format);
124 ANativeWindow_setBuffersGeometry(g_App->window, 0, 0, egl_format);
125
126 const EGLint egl_context_attributes[] = { EGL_CONTEXT_CLIENT_VERSION, 3, EGL_NONE };
127 g_EglContext = eglCreateContext(dpy: g_EglDisplay, config: egl_config, EGL_NO_CONTEXT, attrib_list: egl_context_attributes);
128
129 if (g_EglContext == EGL_NO_CONTEXT)
130 __android_log_print(ANDROID_LOG_ERROR, g_LogTag, "%s", "eglCreateContext() returned EGL_NO_CONTEXT");
131
132 g_EglSurface = eglCreateWindowSurface(g_EglDisplay, egl_config, g_App->window, nullptr);
133 eglMakeCurrent(dpy: g_EglDisplay, draw: g_EglSurface, read: g_EglSurface, ctx: g_EglContext);
134 }
135
136 // Setup Dear ImGui context
137 IMGUI_CHECKVERSION();
138 ImGui::CreateContext();
139 ImGuiIO& io = ImGui::GetIO();
140
141 // Redirect loading/saving of .ini file to our location.
142 // Make sure 'g_IniFilename' persists while we use Dear ImGui.
143 g_IniFilename = std::string(app->activity->internalDataPath) + "/imgui.ini";
144 io.IniFilename = g_IniFilename.c_str();;
145
146 // Setup Dear ImGui style
147 ImGui::StyleColorsDark();
148 //ImGui::StyleColorsLight();
149
150 // Setup Platform/Renderer backends
151 ImGui_ImplAndroid_Init(g_App->window);
152 ImGui_ImplOpenGL3_Init(glsl_version: "#version 300 es");
153
154 // Load Fonts
155 // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
156 // - If the file cannot be loaded, the function will return a nullptr. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
157 // - Read 'docs/FONTS.md' for more instructions and details.
158 // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
159 // - Android: The TTF files have to be placed into the assets/ directory (android/app/src/main/assets), we use our GetAssetData() helper to retrieve them.
160
161 // We load the default font with increased size to improve readability on many devices with "high" DPI.
162 // FIXME: Put some effort into DPI awareness.
163 // Important: when calling AddFontFromMemoryTTF(), ownership of font_data is transferred by Dear ImGui by default (deleted is handled by Dear ImGui), unless we set FontDataOwnedByAtlas=false in ImFontConfig
164 ImFontConfig font_cfg;
165 font_cfg.SizePixels = 22.0f;
166 io.Fonts->AddFontDefault(font_cfg: &font_cfg);
167 //void* font_data;
168 //int font_data_size;
169 //ImFont* font;
170 //font_data_size = GetAssetData("segoeui.ttf", &font_data);
171 //font = io.Fonts->AddFontFromMemoryTTF(font_data, font_data_size, 16.0f);
172 //IM_ASSERT(font != nullptr);
173 //font_data_size = GetAssetData("DroidSans.ttf", &font_data);
174 //font = io.Fonts->AddFontFromMemoryTTF(font_data, font_data_size, 16.0f);
175 //IM_ASSERT(font != nullptr);
176 //font_data_size = GetAssetData("Roboto-Medium.ttf", &font_data);
177 //font = io.Fonts->AddFontFromMemoryTTF(font_data, font_data_size, 16.0f);
178 //IM_ASSERT(font != nullptr);
179 //font_data_size = GetAssetData("Cousine-Regular.ttf", &font_data);
180 //font = io.Fonts->AddFontFromMemoryTTF(font_data, font_data_size, 15.0f);
181 //IM_ASSERT(font != nullptr);
182 //font_data_size = GetAssetData("ArialUni.ttf", &font_data);
183 //font = io.Fonts->AddFontFromMemoryTTF(font_data, font_data_size, 18.0f);
184 //IM_ASSERT(font != nullptr);
185
186 // Arbitrary scale-up
187 // FIXME: Put some effort into DPI awareness
188 ImGui::GetStyle().ScaleAllSizes(scale_factor: 3.0f);
189
190 g_Initialized = true;
191}
192
193void MainLoopStep()
194{
195 ImGuiIO& io = ImGui::GetIO();
196 if (g_EglDisplay == EGL_NO_DISPLAY)
197 return;
198
199 // Our state
200 // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
201 static bool show_demo_window = true;
202 static bool show_another_window = false;
203 static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
204
205 // Poll Unicode characters via JNI
206 // FIXME: do not call this every frame because of JNI overhead
207 PollUnicodeChars();
208
209 // Open on-screen (soft) input if requested by Dear ImGui
210 static bool WantTextInputLast = false;
211 if (io.WantTextInput && !WantTextInputLast)
212 ShowSoftKeyboardInput();
213 WantTextInputLast = io.WantTextInput;
214
215 // Start the Dear ImGui frame
216 ImGui_ImplOpenGL3_NewFrame();
217 ImGui_ImplAndroid_NewFrame();
218 ImGui::NewFrame();
219
220 // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
221 if (show_demo_window)
222 ImGui::ShowDemoWindow(p_open: &show_demo_window);
223
224 // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
225 {
226 static float f = 0.0f;
227 static int counter = 0;
228
229 ImGui::Begin(name: "Hello, world!"); // Create a window called "Hello, world!" and append into it.
230
231 ImGui::Text(fmt: "This is some useful text."); // Display some text (you can use a format strings too)
232 ImGui::Checkbox(label: "Demo Window", v: &show_demo_window); // Edit bools storing our window open/close state
233 ImGui::Checkbox(label: "Another Window", v: &show_another_window);
234
235 ImGui::SliderFloat(label: "float", v: &f, v_min: 0.0f, v_max: 1.0f); // Edit 1 float using a slider from 0.0f to 1.0f
236 ImGui::ColorEdit3(label: "clear color", col: (float*)&clear_color); // Edit 3 floats representing a color
237
238 if (ImGui::Button(label: "Button")) // Buttons return true when clicked (most widgets return true when edited/activated)
239 counter++;
240 ImGui::SameLine();
241 ImGui::Text(fmt: "counter = %d", counter);
242
243 ImGui::Text(fmt: "Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
244 ImGui::End();
245 }
246
247 // 3. Show another simple window.
248 if (show_another_window)
249 {
250 ImGui::Begin(name: "Another Window", p_open: &show_another_window); // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
251 ImGui::Text(fmt: "Hello from another window!");
252 if (ImGui::Button(label: "Close Me"))
253 show_another_window = false;
254 ImGui::End();
255 }
256
257 // Rendering
258 ImGui::Render();
259 glViewport(x: 0, y: 0, width: (int)io.DisplaySize.x, height: (int)io.DisplaySize.y);
260 glClearColor(red: clear_color.x * clear_color.w, green: clear_color.y * clear_color.w, blue: clear_color.z * clear_color.w, alpha: clear_color.w);
261 glClear(GL_COLOR_BUFFER_BIT);
262 ImGui_ImplOpenGL3_RenderDrawData(draw_data: ImGui::GetDrawData());
263 eglSwapBuffers(dpy: g_EglDisplay, surface: g_EglSurface);
264}
265
266void Shutdown()
267{
268 if (!g_Initialized)
269 return;
270
271 // Cleanup
272 ImGui_ImplOpenGL3_Shutdown();
273 ImGui_ImplAndroid_Shutdown();
274 ImGui::DestroyContext();
275
276 if (g_EglDisplay != EGL_NO_DISPLAY)
277 {
278 eglMakeCurrent(dpy: g_EglDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
279
280 if (g_EglContext != EGL_NO_CONTEXT)
281 eglDestroyContext(dpy: g_EglDisplay, ctx: g_EglContext);
282
283 if (g_EglSurface != EGL_NO_SURFACE)
284 eglDestroySurface(dpy: g_EglDisplay, surface: g_EglSurface);
285
286 eglTerminate(dpy: g_EglDisplay);
287 }
288
289 g_EglDisplay = EGL_NO_DISPLAY;
290 g_EglContext = EGL_NO_CONTEXT;
291 g_EglSurface = EGL_NO_SURFACE;
292 ANativeWindow_release(g_App->window);
293
294 g_Initialized = false;
295}
296
297// Helper functions
298
299// Unfortunately, there is no way to show the on-screen input from native code.
300// Therefore, we call ShowSoftKeyboardInput() of the main activity implemented in MainActivity.kt via JNI.
301static int ShowSoftKeyboardInput()
302{
303 JavaVM* java_vm = g_App->activity->vm;
304 JNIEnv* java_env = nullptr;
305
306 jint jni_return = java_vm->GetEnv((void**)&java_env, JNI_VERSION_1_6);
307 if (jni_return == JNI_ERR)
308 return -1;
309
310 jni_return = java_vm->AttachCurrentThread(&java_env, nullptr);
311 if (jni_return != JNI_OK)
312 return -2;
313
314 jclass native_activity_clazz = java_env->GetObjectClass(g_App->activity->clazz);
315 if (native_activity_clazz == nullptr)
316 return -3;
317
318 jmethodID method_id = java_env->GetMethodID(native_activity_clazz, "showSoftInput", "()V");
319 if (method_id == nullptr)
320 return -4;
321
322 java_env->CallVoidMethod(g_App->activity->clazz, method_id);
323
324 jni_return = java_vm->DetachCurrentThread();
325 if (jni_return != JNI_OK)
326 return -5;
327
328 return 0;
329}
330
331// Unfortunately, the native KeyEvent implementation has no getUnicodeChar() function.
332// Therefore, we implement the processing of KeyEvents in MainActivity.kt and poll
333// the resulting Unicode characters here via JNI and send them to Dear ImGui.
334static int PollUnicodeChars()
335{
336 JavaVM* java_vm = g_App->activity->vm;
337 JNIEnv* java_env = nullptr;
338
339 jint jni_return = java_vm->GetEnv((void**)&java_env, JNI_VERSION_1_6);
340 if (jni_return == JNI_ERR)
341 return -1;
342
343 jni_return = java_vm->AttachCurrentThread(&java_env, nullptr);
344 if (jni_return != JNI_OK)
345 return -2;
346
347 jclass native_activity_clazz = java_env->GetObjectClass(g_App->activity->clazz);
348 if (native_activity_clazz == nullptr)
349 return -3;
350
351 jmethodID method_id = java_env->GetMethodID(native_activity_clazz, "pollUnicodeChar", "()I");
352 if (method_id == nullptr)
353 return -4;
354
355 // Send the actual characters to Dear ImGui
356 ImGuiIO& io = ImGui::GetIO();
357 jint unicode_character;
358 while ((unicode_character = java_env->CallIntMethod(g_App->activity->clazz, method_id)) != 0)
359 io.AddInputCharacter(c: unicode_character);
360
361 jni_return = java_vm->DetachCurrentThread();
362 if (jni_return != JNI_OK)
363 return -5;
364
365 return 0;
366}
367
368// Helper to retrieve data placed into the assets/ directory (android/app/src/main/assets)
369static int GetAssetData(const char* filename, void** outData)
370{
371 int num_bytes = 0;
372 AAsset* asset_descriptor = AAssetManager_open(g_App->activity->assetManager, filename, AASSET_MODE_BUFFER);
373 if (asset_descriptor)
374 {
375 num_bytes = AAsset_getLength(asset_descriptor);
376 *outData = IM_ALLOC(num_bytes);
377 int64_t num_bytes_read = AAsset_read(asset_descriptor, *outData, num_bytes);
378 AAsset_close(asset_descriptor);
379 IM_ASSERT(num_bytes_read == num_bytes);
380 }
381 return num_bytes;
382}
383

source code of imgui/examples/example_android_opengl3/main.cpp