[WIP] Viewports backend

imgui-binding/src/main/java/imgui/ImGui.java

@@ -5439,7 +5439,7 @@ public final class ImGui {
     }
 
     private static native long nGetPlatformIO(); /*
-        return (intptr_t)ImGui::GetMainViewport();
+        return (intptr_t)&ImGui::GetPlatformIO();
     */
 
     /**
@@ -5491,4 +5491,16 @@ public final class ImGui {
     private static native long nFindViewportByID(int imGuiID); /*
         return (intptr_t)ImGui::FindViewportByID(imGuiID);
     */
+
+    /**
+     * This is a helper for back-ends. The type platform_handle is decided by the back-end (e.g. HWND, MyWindow*, GLFWwindow* etc.)
+     */
+    public static ImGuiViewport findViewportByPlatformHandle(long platformHandle) {
+        FIND_VIEWPORT.ptr = nFindViewportByPlatformHandle(platformHandle);
+        return FIND_VIEWPORT;
+    }
+
+    private static native long nFindViewportByPlatformHandle(long platformHandle); /*
+        return (intptr_t)ImGui::FindViewportByPlatformHandle((void*)platformHandle);
+    */
 }

imgui-binding/src/main/java/imgui/ImGuiIO.java

@@ -390,7 +390,7 @@ public final class ImGuiIO {
      * Optional: Platform back-end name (informational only! will be displayed in About Window) + User data for back-end/wrappers to store their own stuff.
      */
     public native String getBackendPlatformName(); /*
-        return env -> NewStringUTF(ImGui::GetIO().BackendPlatformName);
+        return env->NewStringUTF(ImGui::GetIO().BackendPlatformName);
     */
 
     /**
@@ -404,7 +404,7 @@ public final class ImGuiIO {
      * Optional: Renderer back-end name (informational only! will be displayed in About Window) + User data for back-end/wrappers to store their own stuff.
      */
     public native String getBackendRendererName(); /*
-        return env -> NewStringUTF(ImGui::GetIO().BackendRendererName);
+        return env->NewStringUTF(ImGui::GetIO().BackendRendererName);
     */
 
     /**
@@ -699,6 +699,24 @@ public final class ImGuiIO {
         ImGui::GetIO().MouseWheelH = mouseDeltaX;
     */
 
+    /**
+     * (Optional) When using multiple viewports: viewport the OS mouse cursor is hovering _IGNORING_ viewports with the ImGuiViewportFlags_NoInputs flag,
+     * and _REGARDLESS_ of whether another viewport is focused. Set io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport if you can provide this info.
+     * If you don't imgui will infer the value using the rectangles and last focused time of the viewports it knows about (ignoring other OS windows).
+     */
+    public native float getMouseHoveredViewport(); /*
+        return ImGui::GetIO().MouseHoveredViewport;
+    */
+
+    /**
+     * (Optional) When using multiple viewports: viewport the OS mouse cursor is hovering _IGNORING_ viewports with the ImGuiViewportFlags_NoInputs flag,
+     * and _REGARDLESS_ of whether another viewport is focused. Set io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport if you can provide this info.
+     * If you don't imgui will infer the value using the rectangles and last focused time of the viewports it knows about (ignoring other OS windows).
+     */
+    public native void setMouseHoveredViewport(int imGuiId); /*
+        ImGui::GetIO().MouseHoveredViewport = imGuiId;
+    */
+
     /**
      * Keyboard modifier pressed: Control
      */

imgui-binding/src/main/java/imgui/ImGuiPlatformIO.java

@@ -70,6 +70,7 @@ import imgui.callback.ImPlatformFuncViewportSuppImVec2;
  *  Platform functions are typically called before their Renderer counterpart, apart from Destroy which are called the other way.
  */
 public final class ImGuiPlatformIO extends ImGuiStruct {
+    private static final ImGuiViewport MAIN_VIEWPORT = new ImGuiViewport(0);
     private static final ImGuiViewport TMP_VIEWPORT = new ImGuiViewport(0);
     private static final ImVec2 TMP_IM_VEC2 = new ImVec2();
 
@@ -307,7 +308,7 @@ public final class ImGuiPlatformIO extends ImGuiStruct {
         IMGUI_PLATFORM_IO->Platform_SetWindowTitle = PlatformStubSetWindowTitle;
     */
 
-        /*JNI
+    /*JNI
         jobject platformCallbackSetWindowAlpha = NULL;
         void PlatformStubSetWindowAlpha(ImGuiViewport* vp, float alpha) {
             if (platformCallbackSetWindowAlpha != NULL) {
@@ -485,4 +486,62 @@ public final class ImGuiPlatformIO extends ImGuiStruct {
     public native void setRendererSwapBuffers(ImPlatformFuncViewport func); /*
         IM_RENDERER_FUNC_VIEWPORT_METHOD_TMPL(SwapBuffers)
     */
+
+    // (Optional) Monitor list
+    // - Updated by: app/back-end. Update every frame to dynamically support changing monitor or DPI configuration.
+    // - Used by: dear imgui to query DPI info, clamp popups/tooltips within same monitor and not have them straddle monitors.
+
+    //------------------------------------------------------------------
+    // Output - List of viewports to render into platform windows
+    //------------------------------------------------------------------
+
+    public native void resizeMonitors(int size); /*
+        IMGUI_PLATFORM_IO->Monitors.resize(0);
+    */
+
+    public native int getMonitorsSize(); /*
+        return IMGUI_PLATFORM_IO->Monitors.Size;
+    */
+
+    public native void pushMonitors(float mainPosX, float mainPosY, float mainSizeX, float mainSizeY, float workPosX, float workPosY, float workSizeX, float workSizeY, float dpiScale); /*
+        ImGuiPlatformMonitor monitor;
+
+        monitor.MainPos = ImVec2(mainPosX, mainPosY);
+        monitor.MainSize = ImVec2(mainSizeX, mainSizeY);
+
+        monitor.WorkPos = ImVec2(workPosX, workPosY);
+        monitor.WorkSize = ImVec2(workSizeX, workSizeY);
+
+        monitor.DpiScale = dpiScale;
+
+        IMGUI_PLATFORM_IO->Monitors.push_back(monitor);
+    */
+
+    // Viewports list (the list is updated by calling ImGui::EndFrame or ImGui::Render)
+    // (in the future we will attempt to organize this feature to remove the need for a "main viewport")
+
+    /**
+     * Guaranteed to be == Viewports[0]
+     */
+    public ImGuiViewport getMainViewport() {
+        MAIN_VIEWPORT.ptr = nGetMainViewport();
+        return MAIN_VIEWPORT;
+    }
+
+    private native long nGetMainViewport(); /*
+        return (intptr_t)IMGUI_PLATFORM_IO->MainViewport;
+    */
+
+    public native int getViewportsSize(); /*
+        return IMGUI_PLATFORM_IO->Viewports.Size;
+    */
+
+    public ImGuiViewport getViewports(final int idx) {
+        TMP_VIEWPORT.ptr = nGetViewports(idx);
+        return TMP_VIEWPORT;
+    }
+
+    private native long nGetViewports(int idx); /*
+        return (intptr_t)IMGUI_PLATFORM_IO->Viewports[idx];
+    */
 }

imgui-binding/src/main/java/imgui/ImGuiViewport.java

@@ -212,7 +212,67 @@ public final class ImGuiViewport extends ImGuiStruct {
     // by the same system and you may not need to use all the UserData/Handle fields.
     // The library never uses those fields, they are merely storage to facilitate back-end implementation.
 
-    // TODO: PlatformUserData, PlatformHandle, PlatformHandleRaw
+    /**
+     * void* to hold custom data structure for the renderer (e.g. swap chain, framebuffers etc.). generally set by your Renderer_CreateWindow function.
+     */
+    public native void setRendererUserData(Object data); /*
+        if (IMGUI_VIEWPORT->RendererUserData != NULL) {
+            env->DeleteGlobalRef((jobject)IMGUI_VIEWPORT->RendererUserData);
+        }
+        IMGUI_VIEWPORT->RendererUserData = (data == NULL ? NULL : (void*)env->NewGlobalRef(data));
+    */
+
+    /**
+     * void* to hold custom data structure for the renderer (e.g. swap chain, framebuffers etc.). generally set by your Renderer_CreateWindow function.
+     */
+    public native Object getRendererUserData(); /*
+        return (jobject)IMGUI_VIEWPORT->RendererUserData;
+    */
+
+    /**
+     * void* to hold custom data structure for the OS / platform (e.g. windowing info, render context). generally set by your Platform_CreateWindow function.
+     */
+    public native void setPlatformUserData(Object data); /*
+        if (IMGUI_VIEWPORT->PlatformUserData != NULL) {
+            env->DeleteGlobalRef((jobject)IMGUI_VIEWPORT->PlatformUserData);
+        }
+        IMGUI_VIEWPORT->PlatformUserData = (data == NULL ? NULL : (void*)env->NewGlobalRef(data));
+    */
+
+    /**
+     * void* to hold custom data structure for the OS / platform (e.g. windowing info, render context). generally set by your Platform_CreateWindow function.
+     */
+    public native Object getPlatformUserData(); /*
+        return (jobject)IMGUI_VIEWPORT->PlatformUserData;
+    */
+
+    /**
+     * void* for FindViewportByPlatformHandle(). (e.g. suggested to use natural platform handle such as HWND, GLFWWindow*, SDL_Window*)
+     */
+    public native void setPlatformHandle(long data); /*
+        IMGUI_VIEWPORT->PlatformHandle = (void*)data;
+    */
+
+    /**
+     * void* for FindViewportByPlatformHandle(). (e.g. suggested to use natural platform handle such as HWND, GLFWWindow*, SDL_Window*)
+     */
+    public native long getPlatformHandle(); /*
+        return (intptr_t)IMGUI_VIEWPORT->PlatformHandle;
+    */
+
+    /**
+     * void* to hold lower-level, platform-native window handle (e.g. the HWND) when using an abstraction layer like GLFW or SDL (where PlatformHandle would be a SDL_Window*)
+     */
+    public native void setPlatformHandleRaw(long data); /*
+        IMGUI_VIEWPORT->PlatformHandleRaw = (void*)data;
+    */
+
+    /**
+     * void* to hold lower-level, platform-native window handle (e.g. the HWND) when using an abstraction layer like GLFW or SDL (where PlatformHandle would be a SDL_Window*)
+     */
+    public native long getPlatformHandleRaw(); /*
+        return (intptr_t)IMGUI_VIEWPORT->PlatformHandleRaw;
+    */
 
     /**
      * Platform window requested move (e.g. window was moved by the OS / host window manager, authoritative position will be OS window position).

imgui-binding/src/main/java/imgui/callback/ImPlatformFuncViewportFloat.java

@@ -6,5 +6,5 @@ import imgui.ImGuiViewport;
  * Callback to represent ImGuiPlatformIO function with args: (ImGuiViewport*, String)
  */
 public abstract class ImPlatformFuncViewportFloat {
-    public abstract void accept(ImGuiViewport vp, Float f);
+    public abstract void accept(ImGuiViewport vp, float f);
 }

imgui-binding/src/main/java/imgui/flag/ImGuiBackendFlags.java

@@ -24,4 +24,21 @@ public final class ImGuiBackendFlags {
      * Back-end Renderer supports ImDrawCmd::VtxOffset. This enables output of large meshes (64K+ vertices) while still using 16-bit indices.
      */
     public static final int RendererHasVtxOffset = 1 << 3;
+
+    // [BETA] Viewports
+
+    /**
+     * Back-end Platform supports multiple viewports.
+     */
+    public static final int PlatformHasViewports = 1 << 10;
+    /**
+     * Back-end Platform supports setting io.MouseHoveredViewport to the viewport directly under the mouse _IGNORING_ viewports
+     * with the ImGuiViewportFlags_NoInputs flag and _REGARDLESS_ of whether another viewport is focused and may be capturing the mouse.
+     * This information is _NOT EASY_ to provide correctly with most high-level engines! Don't set this without studying how the examples/ back-end handle it!
+     */
+    public static final int HasMouseHoveredViewport = 1 << 11;
+    /**
+     * Back-end Renderer supports multiple viewports.
+     */
+    public static final int RendererHasViewports = 1 << 12;
 }

imgui-binding/src/main/java/imgui/flag/ImGuiConfigFlags.java

@@ -43,6 +43,24 @@ public final class ImGuiConfigFlags {
      */
     public static final int DockingEnable = 1 << 6;
 
+    // [BETA] Viewports
+    // When using viewports it is recommended that your default value for ImGuiCol_WindowBg is opaque (Alpha=1.0) so transition to a viewport won't be noticeable.
+
+    /**
+     * Viewport enable flags (require both ImGuiConfigFlags_PlatformHasViewports + ImGuiConfigFlags_RendererHasViewports set by the respective back-ends)
+     */
+    public static final int ViewportsEnable = 1 << 10;
+    /**
+     * [BETA: Don't use] FIXME-DPI: Reposition and resize imgui windows when the DpiScale of a viewport changed (mostly useful for the main viewport hosting other window).
+     * Note that resizing the main window itself is up to your application.
+     */
+    public static final int DpiEnableScaleViewports = 1 << 14;
+    /**
+     * [BETA: Don't use] FIXME-DPI: Request bitmap-scaled fonts to match DpiScale. This is a very low-quality workaround.
+     * The correct way to handle DPI is _currently_ to replace the atlas and/or fonts in the Platform_OnChangedViewport callback, but this is all early work in progress.
+     */
+    public static final int DpiEnableScaleFonts = 1 << 15;
+
     // User storage (to allow your back-end/engine to communicate to code that may be shared between multiple projects. Those flags are not used by core Dear ImGui)
 
     /**