Move the Renderer example to CImGui.Renderer and extend it

The Renderer is now a pretty generic bit of machinery that lets users easily
write ImGui programs using a default ImGuiApp that handles the various GL/GLFW
objects, and extend it to custom subtypes of AbstractImGuiApp.

demo/demo.jl

@@ -1,132 +1,50 @@
 using CImGui
-using CImGui.CSyntax
-using CImGui.CSyntax.CStatic
-using ImGuiGLFWBackend #CImGui.GLFWBackend
-using ImGuiOpenGLBackend #CImGui.OpenGLBackend
-using ImGuiGLFWBackend.LibGLFW # #CImGui.OpenGLBackend.GLFW
-using ImGuiOpenGLBackend.ModernGL
+using CImGui.Renderer
+import CImGui.CSyntax: @c
+import CImGui.CSyntax.CStatic: @cstatic
 using Printf
 
-@static if Sys.isapple()
-    # OpenGL 3.2 + GLSL 150
-    const glsl_version = 150
-    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3)
-    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2)
-    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE) # 3.2+ only
-    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE) # required on Mac
-else
-    # OpenGL 3.0 + GLSL 130
-    const glsl_version = 130
-    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3)
-    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0)
-    # glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE) # 3.2+ only
-    # glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE) # 3.0+ only
-end
-
-# setup GLFW error callback
-#? error_callback(err::GLFW.GLFWError) = @error "GLFW ERROR: code $(err.code) msg: $(err.description)"
-#? GLFW.SetErrorCallback(error_callback)
-
-# create window
-window = glfwCreateWindow(1280, 720, "Demo", C_NULL, C_NULL)
-@assert window != C_NULL
-glfwMakeContextCurrent(window)
-glfwSwapInterval(1)  # enable vsync
-
-# setup Dear ImGui context
-ctx = CImGui.CreateContext()
-
-# setup Dear ImGui style
-CImGui.StyleColorsDark()
-# CImGui.StyleColorsClassic()
-# CImGui.StyleColorsLight()
-
-# load Fonts
-# - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use `CImGui.PushFont/PopFont` to select them.
-# - `CImGui.AddFontFromFileTTF` will return the `Ptr{ImFont}` so you can store it if you need to select the font among multiple.
-# - If the file cannot be loaded, the function will return C_NULL. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
-# - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling `CImGui.Build()`/`GetTexDataAsXXXX()``, which `ImGui_ImplXXXX_NewFrame` below will call.
-# - Read 'fonts/README.txt' for more instructions and details.
-fonts_dir = joinpath(@__DIR__, "..", "fonts")
-fonts = unsafe_load(CImGui.GetIO().Fonts)
-# default_font = CImGui.AddFontDefault(fonts)
-# CImGui.AddFontFromFileTTF(fonts, joinpath(fonts_dir, "Cousine-Regular.ttf"), 15)
-# CImGui.AddFontFromFileTTF(fonts, joinpath(fonts_dir, "DroidSans.ttf"), 16)
-# CImGui.AddFontFromFileTTF(fonts, joinpath(fonts_dir, "Karla-Regular.ttf"), 10)
-# CImGui.AddFontFromFileTTF(fonts, joinpath(fonts_dir, "ProggyTiny.ttf"), 10)
-CImGui.AddFontFromFileTTF(fonts, joinpath(fonts_dir, "Roboto-Medium.ttf"), 16)
-# @assert default_font != C_NULL
-
-# setup Platform/Renderer bindings
-glfw_ctx = ImGuiGLFWBackend.create_context(window, install_callbacks = true)
-ImGuiGLFWBackend.init(glfw_ctx)
-opengl_ctx = ImGuiOpenGLBackend.create_context(glsl_version)
-ImGuiOpenGLBackend.init(opengl_ctx)
-
-try
+let
+    fonts_dir = joinpath(@__DIR__, "..", "fonts")
     show_demo_window = true
     show_another_window = false
     clear_color = Cfloat[0.45, 0.55, 0.60, 1.00]
-    while glfwWindowShouldClose(window) == 0
-        glfwPollEvents()
-        # start the Dear ImGui frame
-        ImGuiOpenGLBackend.new_frame(opengl_ctx) #ImGui_ImplOpenGL3_NewFrame()
-        ImGuiGLFWBackend.new_frame(glfw_ctx) #ImGui_ImplGlfw_NewFrame()
-        CImGui.NewFrame()
 
+    render(; fonts=[(joinpath(fonts_dir, "Roboto-Medium.ttf"), 16)]) do
         # show the big demo window
-        show_demo_window && @c CImGui.ShowDemoWindow(&show_demo_window)
+        if show_demo_window
+            @c CImGui.ShowDemoWindow(&show_demo_window)
+        end
 
-        # show a simple window that we create ourselves.
-        # we use a Begin/End pair to created a named window.
+        # Show a simple window that we create ourselves.
+        # We use a Begin/End pair to created a named window.
         @cstatic f=Cfloat(0.0) counter=Cint(0) begin
-            CImGui.Begin("Hello, world!")  # create a window called "Hello, world!" and append into it.
-            CImGui.Text("This is some useful text.")  # display some text
-            @c CImGui.Checkbox("Demo Window", &show_demo_window)  # edit bools storing our window open/close state
-            @c CImGui.Checkbox("Another Window", &show_another_window)
+            if CImGui.Begin("Hello, world!")  # create a window called "Hello, world!" and append into it.
+                CImGui.Text("This is some useful text.")  # display some text
+                @c CImGui.Checkbox("Demo Window", &show_demo_window)  # edit bools storing our window open/close state
+                @c CImGui.Checkbox("Another Window", &show_another_window)
+
+                @c CImGui.SliderFloat("float", &f, 0, 1)  # edit 1 float using a slider from 0 to 1
+                CImGui.ColorEdit3("clear color", clear_color)  # edit 3 floats representing a color
+                CImGui.Button("Button") && (counter += 1)
 
-            @c CImGui.SliderFloat("float", &f, 0, 1)  # edit 1 float using a slider from 0 to 1
-            CImGui.ColorEdit3("clear color", clear_color)  # edit 3 floats representing a color
-            CImGui.Button("Button") && (counter += 1)
+                CImGui.SameLine()
+                CImGui.Text("counter = $counter")
 
-            CImGui.SameLine()
-            CImGui.Text("counter = $counter")
-            CImGui.Text(@sprintf("Application average %.3f ms/frame (%.1f FPS)", 1000 / unsafe_load(CImGui.GetIO().Framerate), unsafe_load(CImGui.GetIO().Framerate)))
+                framerate = unsafe_load(CImGui.GetIO().Framerate)
+                CImGui.Text(@sprintf("Application average %.3f ms/frame (%.1f FPS)", 1000 / framerate, framerate))
 
-            CImGui.End()
+                CImGui.End()
+            end
         end
 
         # show another simple window.
         if show_another_window
-            @c CImGui.Begin("Another Window", &show_another_window)  # pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            CImGui.Text("Hello from another window!")
-            CImGui.Button("Close Me") && (show_another_window = false;)
-            CImGui.End()
+            if @c CImGui.Begin("Another Window", &show_another_window)  # pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+                CImGui.Text("Hello from another window!")
+                CImGui.Button("Close Me") && (show_another_window = false;)
+                CImGui.End()
+            end
         end
-
-        # rendering
-        CImGui.Render()
-        glfwMakeContextCurrent(window)
-
-        width, height = Ref{Cint}(), Ref{Cint}() #! need helper fcn
-        glfwGetFramebufferSize(window, width, height)
-        display_w = width[]
-        display_h = height[]
-
-        glViewport(0, 0, display_w, display_h)
-        glClearColor(clear_color...)
-        glClear(GL_COLOR_BUFFER_BIT)
-        ImGuiOpenGLBackend.render(opengl_ctx) #ImGui_ImplOpenGL3_RenderDrawData(CImGui.GetDrawData())
-
-        glfwMakeContextCurrent(window)
-        glfwSwapBuffers(window)
     end
-catch e
-    @error "Error in renderloop!" exception=e
-    Base.show_backtrace(stderr, catch_backtrace())
-finally
-    ImGuiOpenGLBackend.shutdown(opengl_ctx) #ImGui_ImplOpenGL3_Shutdown()
-    ImGuiGLFWBackend.shutdown(glfw_ctx) #ImGui_ImplGlfw_Shutdown()
-    CImGui.DestroyContext(ctx)
-    glfwDestroyWindow(window)
 end