Add GLFW callbacks (#81)

Closes #80

ChangeLog.md

@@ -3,6 +3,7 @@
 ## [1.1.0]
 
 - `imgui` updated to 1.84.2.
+- Added GLFW backend callbacks.
 
 ## [1.0.2]
 

dear-imgui.cabal

@@ -181,7 +181,8 @@ library
     exposed-modules:
       DearImGui.GLFW
     build-depends:
-      GLFW-b
+      GLFW-b,
+      bindings-GLFW
     cxx-sources:
       imgui/backends/imgui_impl_glfw.cpp
 

src/DearImGui/GLFW.hs

@@ -19,9 +19,33 @@ module DearImGui.GLFW (
     -- ** GLFW
     glfwNewFrame
   , glfwShutdown
+
+    -- $callbacks
+  , glfwWindowFocusCallback
+  , glfwCursorEnterCallback
+  , glfwMouseButtonCallback
+  , glfwScrollCallback
+  , glfwKeyCallback
+  , glfwCharCallback
+  , glfwMonitorCallback
   )
   where
 
+-- base
+import Foreign
+  ( Ptr, castPtr )
+import Foreign.C.Types
+  ( CInt, CDouble, CUInt )
+import Unsafe.Coerce (unsafeCoerce)
+
+-- bindings-GLFW
+import Bindings.GLFW
+  ( C'GLFWmonitor, C'GLFWwindow )
+
+-- GLFW-b
+import Graphics.UI.GLFW
+  ( Monitor, Window )
+
 -- inline-c
 import qualified Language.C.Inline as C
 
@@ -44,8 +68,121 @@ glfwNewFrame :: MonadIO m => m ()
 glfwNewFrame = liftIO do
   [C.exp| void { ImGui_ImplGlfw_NewFrame(); } |]
 
+-- $callbacks
+-- == GLFW callbacks
+-- * When calling Init with @install_callbacks=true@:
+--   GLFW callbacks will be installed for you.
+--   They will call user's previously installed callbacks, if any.
+-- * When calling Init with @install_callbacks=false@:
+--   GLFW callbacks won't be installed.
+--   You will need to call those function yourself from your own GLFW callbacks.
 
 -- | Wraps @ImGui_ImplGlfw_Shutdown@.
 glfwShutdown :: MonadIO m => m ()
 glfwShutdown = liftIO do
   [C.exp| void { ImGui_ImplGlfw_Shutdown(); } |]
+
+glfwWindowFocusCallback :: MonadIO m => Window -> CInt -> m ()
+glfwWindowFocusCallback window focused = liftIO do
+  [C.exp| void {
+    ImGui_ImplGlfw_WindowFocusCallback(
+      static_cast<GLFWwindow *>(
+        $(void * windowPtr)
+      ),
+      $(int focused)
+    );
+  } |]
+  where
+    windowPtr = castPtr $ unWindow window
+
+glfwCursorEnterCallback :: MonadIO m => Window -> CInt -> m ()
+glfwCursorEnterCallback window entered = liftIO do
+  [C.exp| void {
+    ImGui_ImplGlfw_CursorEnterCallback(
+      static_cast<GLFWwindow *>(
+        $(void * windowPtr)
+      ),
+      $(int entered)
+    );
+  } |]
+  where
+    windowPtr = castPtr $ unWindow window
+
+glfwMouseButtonCallback :: MonadIO m => Window -> CInt -> CInt -> CInt -> m ()
+glfwMouseButtonCallback window button action mods = liftIO do
+  [C.exp| void {
+    ImGui_ImplGlfw_MouseButtonCallback(
+      static_cast<GLFWwindow *>(
+        $(void * windowPtr)
+      ),
+      $(int button),
+      $(int action),
+      $(int mods)
+    );
+  } |]
+  where
+    windowPtr = castPtr $ unWindow window
+
+glfwScrollCallback :: MonadIO m => Window -> CDouble -> CDouble -> m ()
+glfwScrollCallback window xoffset yoffset = liftIO do
+  [C.exp| void {
+    ImGui_ImplGlfw_ScrollCallback(
+      static_cast<GLFWwindow *>(
+        $(void * windowPtr)
+      ),
+      $(double xoffset),
+      $(double yoffset)
+    );
+  } |]
+  where
+    windowPtr = castPtr $ unWindow window
+
+glfwKeyCallback :: MonadIO m => Window -> CInt -> CInt -> CInt -> CInt -> m ()
+glfwKeyCallback window key scancode action mods = liftIO do
+  [C.exp| void {
+    ImGui_ImplGlfw_KeyCallback(
+      static_cast<GLFWwindow *>(
+        $(void * windowPtr)
+      ),
+      $(int key),
+      $(int scancode),
+      $(int action),
+      $(int mods)
+    );
+  } |]
+  where
+    windowPtr = castPtr $ unWindow window
+
+glfwCharCallback :: MonadIO m => Window -> CUInt -> m ()
+glfwCharCallback window c = liftIO do
+  [C.exp| void {
+    ImGui_ImplGlfw_CharCallback(
+      static_cast<GLFWwindow *>(
+        $(void * windowPtr)
+      ),
+      $(unsigned int c)
+    );
+  } |]
+  where
+    windowPtr = castPtr $ unWindow window
+
+glfwMonitorCallback :: MonadIO m => Monitor -> CInt -> m ()
+glfwMonitorCallback monitor event = liftIO do
+  [C.exp| void {
+    ImGui_ImplGlfw_MonitorCallback(
+      static_cast<GLFWmonitor *>(
+        $(void * monitorPtr)
+      ),
+      $(int event)
+    );
+  } |]
+  where
+    monitorPtr = castPtr $ unMonitor monitor
+
+-- | Strip the unpublished newtype wrapper.
+unWindow :: Window -> Ptr C'GLFWwindow
+unWindow = unsafeCoerce
+
+-- | Strip the unpublished newtype wrapper.
+unMonitor :: Monitor -> Ptr C'GLFWmonitor
+unMonitor = unsafeCoerce