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Backends: OSX, Metal: Added multi-viewports support. (#4821, #2778)
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@stuartcarnie @ocornut
stuartcarnie authored and ocornut committed May 3, 2022
1 parent 414165d commit 6868d11
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Showing 6 changed files with 536 additions and 23 deletions.
162 changes: 160 additions & 2 deletions backends/imgui_impl_metal.mm
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Expand Up @@ -4,8 +4,7 @@
// Implemented features:
// [X] Renderer: User texture binding. Use 'MTLTexture' as ImTextureID. Read the FAQ about ImTextureID!
// [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
// Missing features:
// [ ] Renderer: Multi-viewport / platform windows.
// [X] Renderer: Multi-viewport / platform windows.

// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
Expand All @@ -14,6 +13,7 @@

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2022-05-03: Misc: Implemented support for viewports / platform windows.
// 2022-04-27: Misc: Store backend data in a per-context struct, allowing to use this backend with multiple contexts.
// 2022-01-03: Metal: Ignore ImDrawCmd where ElemCount == 0 (very rare but can technically be manufactured by user code).
// 2021-12-30: Metal: Added Metal C++ support. Enable with '#define IMGUI_IMPL_METAL_CPP' in your imconfig.h file.
Expand All @@ -32,6 +32,12 @@
#import <time.h>
#import <Metal/Metal.h>

// Forward Declarations
static void ImGui_ImplMetal_InitPlatformInterface();
static void ImGui_ImplMetal_ShutdownPlatformInterface();
static void ImGui_ImplMetal_CreateDeviceObjectsForPlatformWindows();
static void ImGui_ImplMetal_InvalidateDeviceObjectsForPlatformWindows();

#pragma mark - Support classes

// A wrapper around a MTLBuffer object that knows the last time it was reused
Expand Down Expand Up @@ -137,15 +143,20 @@ bool ImGui_ImplMetal_Init(id<MTLDevice> device)
io.BackendRendererUserData = (void*)bd;
io.BackendRendererName = "imgui_impl_metal";
io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset; // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports; // We can create multi-viewports on the Renderer side (optional)

bd->SharedMetalContext = [[MetalContext alloc] init];
bd->SharedMetalContext.device = device;

if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
ImGui_ImplMetal_InitPlatformInterface();

return true;
}

void ImGui_ImplMetal_Shutdown()
{
ImGui_ImplMetal_ShutdownPlatformInterface();
ImGui_ImplMetal_DestroyDeviceObjects();
ImGui_ImplMetal_DestroyBackendData();
}
Expand Down Expand Up @@ -189,6 +200,7 @@ bool ImGui_ImplMetal_CreateDeviceObjects(id<MTLDevice> device)
{
ImGui_ImplMetal_Data* bd = ImGui_ImplMetal_GetBackendData();
[bd->SharedMetalContext makeDeviceObjectsWithDevice:device];
ImGui_ImplMetal_CreateDeviceObjectsForPlatformWindows();
ImGui_ImplMetal_CreateFontsTexture(device);

return true;
Expand All @@ -198,9 +210,155 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
{
ImGui_ImplMetal_Data* bd = ImGui_ImplMetal_GetBackendData();
ImGui_ImplMetal_DestroyFontsTexture();
ImGui_ImplMetal_InvalidateDeviceObjectsForPlatformWindows();
[bd->SharedMetalContext emptyRenderPipelineStateCache];
}

#pragma mark - Multi-viewport support

#import <QuartzCore/CAMetalLayer.h>

#if TARGET_OS_OSX
#import <Cocoa/Cocoa.h>
#endif

//--------------------------------------------------------------------------------------------------------
// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
// This is an _advanced_ and _optional_ feature, allowing the back-end to create and handle multiple viewports simultaneously.
// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
//--------------------------------------------------------------------------------------------------------

struct ImGuiViewportDataMetal
{
CAMetalLayer* MetalLayer;
id<MTLCommandQueue> CommandQueue;
MTLRenderPassDescriptor* RenderPassDescriptor;
void* Handle = NULL;
bool FirstFrame = true;
};

static void ImGui_ImplMetal_CreateWindow(ImGuiViewport* viewport)
{
ImGui_ImplMetal_Data* bd = ImGui_ImplMetal_GetBackendData();
ImGuiViewportDataMetal* data = IM_NEW(ImGuiViewportDataMetal)();
viewport->RendererUserData = data;

// PlatformHandleRaw should always be a NSWindow*, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL_Window*).
// Some back-ends will leave PlatformHandleRaw NULL, in which case we assume PlatformHandle will contain the NSWindow*.
void* handle = viewport->PlatformHandleRaw ? viewport->PlatformHandleRaw : viewport->PlatformHandle;
IM_ASSERT(handle != NULL);

id<MTLDevice> device = [bd->SharedMetalContext.depthStencilState device];
CAMetalLayer* layer = [CAMetalLayer layer];
layer.device = device;
layer.framebufferOnly = YES;
layer.pixelFormat = MTLPixelFormatBGRA8Unorm;
#if TARGET_OS_OSX
NSWindow* window = (__bridge NSWindow*)handle;
NSView* view = window.contentView;
view.layer = layer;
view.wantsLayer = YES;
#endif
data->MetalLayer = layer;
data->CommandQueue = [device newCommandQueue];
data->RenderPassDescriptor = [[MTLRenderPassDescriptor alloc] init];
data->Handle = handle;
}

static void ImGui_ImplMetal_DestroyWindow(ImGuiViewport* viewport)
{
// The main viewport (owned by the application) will always have RendererUserData == NULL since we didn't create the data for it.
if (ImGuiViewportDataMetal* data = (ImGuiViewportDataMetal*)viewport->RendererUserData)
IM_DELETE(data);
viewport->RendererUserData = NULL;
}

inline static CGSize MakeScaledSize(CGSize size, CGFloat scale)
{
return CGSizeMake(size.width * scale, size.height * scale);
}

static void ImGui_ImplMetal_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
{
ImGuiViewportDataMetal* data = (ImGuiViewportDataMetal*)viewport->RendererUserData;
data->MetalLayer.drawableSize = MakeScaledSize(CGSizeMake(size.x, size.y), viewport->DpiScale);
}

static void ImGui_ImplMetal_RenderWindow(ImGuiViewport* viewport, void*)
{
ImGuiViewportDataMetal* data = (ImGuiViewportDataMetal*)viewport->RendererUserData;

#if TARGET_OS_OSX
void* handle = viewport->PlatformHandleRaw ? viewport->PlatformHandleRaw : viewport->PlatformHandle;
NSWindow* window = (__bridge NSWindow*)handle;

// Always render the first frame, regardless of occlusionState, to avoid an initial flicker
if ((window.occlusionState & NSWindowOcclusionStateVisible) == 0 && !data->FirstFrame)
{
// Do not render windows which are completely occluded. Calling -[CAMetalLayer nextDrawable] will hang for
// approximately 1 second if the Metal layer is completely occluded.
return;
}
data->FirstFrame = false;

viewport->DpiScale = static_cast<float>(window.backingScaleFactor);
if (data->MetalLayer.contentsScale != viewport->DpiScale)
{
data->MetalLayer.contentsScale = viewport->DpiScale;
data->MetalLayer.drawableSize = MakeScaledSize(window.frame.size, viewport->DpiScale);
}
viewport->DrawData->FramebufferScale = ImVec2(viewport->DpiScale, viewport->DpiScale);
#endif

id <CAMetalDrawable> drawable = [data->MetalLayer nextDrawable];
if (drawable == nil)
return;

MTLRenderPassDescriptor* renderPassDescriptor = data->RenderPassDescriptor;
renderPassDescriptor.colorAttachments[0].texture = drawable.texture;
renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(0, 0, 0, 0);
if ((viewport->Flags & ImGuiViewportFlags_NoRendererClear) == 0)
renderPassDescriptor.colorAttachments[0].loadAction = MTLLoadActionClear;

id <MTLCommandBuffer> commandBuffer = [data->CommandQueue commandBuffer];
id <MTLRenderCommandEncoder> renderEncoder = [commandBuffer renderCommandEncoderWithDescriptor:renderPassDescriptor];
ImGui_ImplMetal_RenderDrawData(viewport->DrawData, commandBuffer, renderEncoder);
[renderEncoder endEncoding];

[commandBuffer presentDrawable:drawable];
[commandBuffer commit];
}

static void ImGui_ImplMetal_InitPlatformInterface()
{
ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
platform_io.Renderer_CreateWindow = ImGui_ImplMetal_CreateWindow;
platform_io.Renderer_DestroyWindow = ImGui_ImplMetal_DestroyWindow;
platform_io.Renderer_SetWindowSize = ImGui_ImplMetal_SetWindowSize;
platform_io.Renderer_RenderWindow = ImGui_ImplMetal_RenderWindow;
}

static void ImGui_ImplMetal_ShutdownPlatformInterface()
{
ImGui::DestroyPlatformWindows();
}

static void ImGui_ImplMetal_CreateDeviceObjectsForPlatformWindows()
{
ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
for (int i = 1; i < platform_io.Viewports.Size; i++)
if (!platform_io.Viewports[i]->RendererUserData)
ImGui_ImplMetal_CreateWindow(platform_io.Viewports[i]);
}

static void ImGui_ImplMetal_InvalidateDeviceObjectsForPlatformWindows()
{
ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
for (int i = 1; i < platform_io.Viewports.Size; i++)
if (platform_io.Viewports[i]->RendererUserData)
ImGui_ImplMetal_DestroyWindow(platform_io.Viewports[i]);
}

#pragma mark - MetalBuffer implementation

@implementation MetalBuffer
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3 changes: 1 addition & 2 deletions backends/imgui_impl_osx.h
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Expand Up @@ -8,8 +8,7 @@
// [X] Platform: OSX clipboard is supported within core Dear ImGui (no specific code in this backend).
// [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
// [X] Platform: IME support.
// Issues:
// [ ] Platform: Multi-viewport / platform windows.
// [X] Platform: Multi-viewport / platform windows.

// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
Expand Down
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