Examples: Emscripten: Demonstrating embedding fonts in Makefile and code. (#2953) [@Oipo]

docs/CHANGELOG.txt

@@ -100,12 +100,13 @@ Other Changes:
   on Windows 7. You can instead try linking with Xinput9_1_0.lib instead. (#2716)
 - Backends: Glut: Improved FreeGLUT support for MinGW. (#3004) [@podsvirov]
 - Backends: Emscripten: Avoid forcefully setting IMGUI_DISABLE_FILE_FUNCTIONS. (#3005) [@podsvirov]
-- Examples: Explicitly adding -DIMGUI_IMPL_OPENGL_LOADER_GL3W to Makefile to match linking
+- Examples: OpenGL: Explicitly adding -DIMGUI_IMPL_OPENGL_LOADER_GL3W to Makefile to match linking
   settings (otherwise if another loader such as Glew is accessible, the OpenGL3 backend might
   automatically use it). (#2919, #2798)
+- Examples: OpenGL: Added support for glbindings OpenGL loader. (#2870) [@rokups]
+- Examples: Emscripten: Demonstrating embedding fonts in Makefile and code. (#2953) [@Oipo]
 - Examples: Metal: Wrapped main loop in @autoreleasepool block to ensure allocations get freed
   even if underlying system event loop gets paused due to app nap. (#2910, #2917) [@bear24rw]
-- Examples: Added support for glbindings OpenGL loader. (#2870) [@rokups]
 
 
 -----------------------------------------------------------------------

examples/example_emscripten/Makefile

@@ -1,8 +1,10 @@
 #
 # Makefile to use with emscripten
 # See https://emscripten.org/docs/getting_started/downloads.html
-# for installation instructions. This Makefile assumes you have
-# loaded emscripten's environment.
+# for installation instructions.
+#
+# This Makefile assumes you have loaded emscripten's environment.
+# (On Windows, you may need to execute emsdk_env.bat or encmdprompt.bat ahead)
 #
 # Running `make` will produce three files:
 #  - example_emscripten.html
@@ -13,7 +15,6 @@
 
 CC = emcc
 CXX = em++
-
 EXE = example_emscripten.html
 SOURCES = main.cpp
 SOURCES += ../imgui_impl_sdl.cpp ../imgui_impl_opengl3.cpp
@@ -21,21 +22,41 @@ SOURCES += ../../imgui.cpp ../../imgui_demo.cpp ../../imgui_draw.cpp ../../imgui
 OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
 UNAME_S := $(shell uname -s)
 
-EMS = -s USE_SDL=2 -s WASM=1
+##---------------------------------------------------------------------
+## EMSCRIPTEN OPTIONS
+##---------------------------------------------------------------------
+
+EMS += -s USE_SDL=2 -s WASM=1
 EMS += -s ALLOW_MEMORY_GROWTH=1
 EMS += -s DISABLE_EXCEPTION_CATCHING=1 -s NO_EXIT_RUNTIME=0
 EMS += -s ASSERTIONS=1
-EMS += -s NO_FILESYSTEM=1 -DIMGUI_DISABLE_FILE_FUNCTIONS
-# Uncomment next line to fix possible rendering bugs with emscripten version older then 1.39.0 (https://github.com/ocornut/imgui/issues/2877)
+
+# Uncomment next line to fix possible rendering bugs with Emscripten version older then 1.39.0 (https://github.com/ocornut/imgui/issues/2877)
 #EMS += -s BINARYEN_TRAP_MODE=clamp
 #EMS += -s SAFE_HEAP=1    ## Adds overhead
 
-CPPFLAGS = -I../ -I../../
+# Emscripten allows preloading a file or folder to be accessible at runtime.
+# The Makefile for this example project suggests embedding the misc/fonts/ folder into our application, it will then be accessible as "/fonts"
+# See documentation for more details: https://emscripten.org/docs/porting/files/packaging_files.html
+# (Default value is 0. Set to 1 to enable file-system and include the misc/fonts/ folder as part of the build.)
+USE_FILE_SYSTEM ?= 0
+ifeq ($(USE_FILE_SYSTEM), 0)
+EMS += -s NO_FILESYSTEM=1 -DIMGUI_DISABLE_FILE_FUNCTIONS
+endif
+ifeq ($(USE_FILE_SYSTEM), 1)
+LDFLAGS += --no-heap-copy --preload-file ../../misc/fonts@/fonts
+endif
+
+##---------------------------------------------------------------------
+## FINAL BUILD FLAGS
+##---------------------------------------------------------------------
+
+CPPFLAGS += -I../ -I../../
 #CPPFLAGS += -g
 CPPFLAGS += -Wall -Wformat -Os
 CPPFLAGS += $(EMS)
-LIBS = $(EMS)
-LDFLAGS = --shell-file shell_minimal.html
+LIBS += $(EMS)
+LDFLAGS += --shell-file shell_minimal.html
 
 ##---------------------------------------------------------------------
 ## BUILD RULES

examples/example_emscripten/main.cpp

@@ -83,13 +83,16 @@ int main(int, char**)
     // - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
     // - Read 'docs/FONTS.txt' for more instructions and details.
     // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
+    // - Emscripten allows preloading a file or folder to be accessible at runtime. See Makefile for details.
     //io.Fonts->AddFontDefault();
-    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
-    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
-    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
-    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/ProggyTiny.ttf", 10.0f);
-    //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
+#ifndef IMGUI_DISABLE_FILE_FUNCTIONS
+    io.Fonts->AddFontFromFileTTF("fonts/Roboto-Medium.ttf", 16.0f);
+    //io.Fonts->AddFontFromFileTTF("fonts/Cousine-Regular.ttf", 15.0f);
+    //io.Fonts->AddFontFromFileTTF("fonts/DroidSans.ttf", 16.0f);
+    //io.Fonts->AddFontFromFileTTF("fonts/ProggyTiny.ttf", 10.0f);
+    //ImFont* font = io.Fonts->AddFontFromFileTTF("fonts/ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
+#endif
 
     // This function call won't return, and will engage in an infinite loop, processing events from the browser, and dispatching them.
     emscripten_set_main_loop_arg(main_loop, NULL, 0, true);