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macOS docking and viewports
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@stuartcarnie
stuartcarnie committed Jan 18, 2022
1 parent e278277 commit 2b23adf
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Showing 5 changed files with 712 additions and 152 deletions.
218 changes: 196 additions & 22 deletions backends/imgui_impl_metal.mm
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Original file line number Diff line number Diff line change
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 @@ -28,17 +27,21 @@

#include "imgui.h"
#include "imgui_impl_metal.h"

#import <time.h>
#import <Metal/Metal.h>
// #import <QuartzCore/CAMetalLayer.h> // Not supported in XCode 9.2. Maybe a macro to detect the SDK version can be used (something like #if MACOS_SDK >= 10.13 ...)
#import <simd/simd.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
@interface MetalBuffer : NSObject
@property (nonatomic, strong) id<MTLBuffer> buffer;
@property (nonatomic, assign) NSTimeInterval lastReuseTime;
@property (nonatomic, assign) double lastReuseTime;
- (instancetype)initWithBuffer:(id<MTLBuffer>)buffer;
@end

Expand All @@ -61,7 +64,7 @@ @interface MetalContext : NSObject
@property (nonatomic, strong) NSMutableDictionary *renderPipelineStateCache; // pipeline cache; keyed on framebuffer descriptors
@property (nonatomic, strong, nullable) id<MTLTexture> fontTexture;
@property (nonatomic, strong) NSMutableArray<MetalBuffer *> *bufferCache;
@property (nonatomic, assign) NSTimeInterval lastBufferCachePurge;
@property (nonatomic, assign) double lastBufferCachePurge;
- (void)makeDeviceObjectsWithDevice:(id<MTLDevice>)device;
- (void)makeFontTextureWithDevice:(id<MTLDevice>)device;
- (MetalBuffer *)dequeueReusableBufferOfLength:(NSUInteger)length device:(id<MTLDevice>)device;
Expand All @@ -81,6 +84,11 @@ - (void)renderDrawData:(ImDrawData *)drawData

static MetalContext *g_sharedMetalContext = nil;

static inline CFTimeInterval GetMachAbsoluteTimeInSeconds()
{
return static_cast<CFTimeInterval>(static_cast<double>(clock_gettime_nsec_np(CLOCK_UPTIME_RAW)) / 1e9);
}

#ifdef IMGUI_IMPL_METAL_CPP

#pragma mark - Dear ImGui Metal C++ Backend API
Expand Down Expand Up @@ -124,6 +132,7 @@ bool ImGui_ImplMetal_Init(id<MTLDevice> device)
ImGuiIO& io = ImGui::GetIO();
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)

static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
Expand All @@ -132,11 +141,15 @@ bool ImGui_ImplMetal_Init(id<MTLDevice> device)

ImGui_ImplMetal_CreateDeviceObjects(device);

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

return true;
}

void ImGui_ImplMetal_Shutdown()
{
ImGui_ImplMetal_ShutdownPlatformInterface();
ImGui_ImplMetal_DestroyDeviceObjects();
}

Expand Down Expand Up @@ -174,6 +187,7 @@ bool ImGui_ImplMetal_CreateDeviceObjects(id<MTLDevice> device)
{
[g_sharedMetalContext makeDeviceObjectsWithDevice:device];

ImGui_ImplMetal_CreateDeviceObjectsForPlatformWindows();
ImGui_ImplMetal_CreateFontsTexture(device);

return true;
Expand All @@ -182,9 +196,163 @@ bool ImGui_ImplMetal_CreateDeviceObjects(id<MTLDevice> device)
void ImGui_ImplMetal_DestroyDeviceObjects()
{
ImGui_ImplMetal_DestroyFontsTexture();
ImGui_ImplMetal_InvalidateDeviceObjectsForPlatformWindows();

[g_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 = nullptr;
bool firstFrame = true;
};

static void ImGui_ImplMetal_CreateWindow(ImGuiViewport* viewport)
{
auto 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 != nullptr);

id<MTLDevice> device = [g_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 (auto data = (ImGuiViewportDataMetal*)viewport->RendererUserData)
{
IM_DELETE(data);
}
viewport->RendererUserData = nullptr;
}

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)
{
auto data = (ImGuiViewportDataMetal*)viewport->RendererUserData;
data->MetalLayer.drawableSize = MakeScaledSize(CGSizeMake(size.x, size.y), viewport->DpiScale);
}

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

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

// Always render the firstFrame, regardless of occlusionState, to avoid an initial flicker
if ((window.occlusionState & NSWindowOcclusionStateVisible) == 0 && !data->firstFrame)
{
// Do not render windows which are completely occluded.
// FIX: 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
Expand All @@ -193,7 +361,7 @@ - (instancetype)initWithBuffer:(id<MTLBuffer>)buffer
if ((self = [super init]))
{
_buffer = buffer;
_lastReuseTime = [NSDate date].timeIntervalSince1970;
_lastReuseTime = GetMachAbsoluteTimeInSeconds();
}
return self;
}
Expand Down Expand Up @@ -255,7 +423,7 @@ - (instancetype)init {
{
_renderPipelineStateCache = [NSMutableDictionary dictionary];
_bufferCache = [NSMutableArray array];
_lastBufferCachePurge = [NSDate date].timeIntervalSince1970;
_lastBufferCachePurge = GetMachAbsoluteTimeInSeconds();
}
return self;
}
Expand Down Expand Up @@ -283,8 +451,14 @@ - (void)makeFontTextureWithDevice:(id<MTLDevice>)device
height:(NSUInteger)height
mipmapped:NO];
textureDescriptor.usage = MTLTextureUsageShaderRead;
// Only override the storageMode for macOS with GPUs supporting unified memory,
// as the default value, per Apple docs, is already set correctly.
#if TARGET_OS_OSX || TARGET_OS_MACCATALYST
textureDescriptor.storageMode = MTLStorageModeManaged;
if (@available(macOS 10.15, macCatalyst 13.0, *)) {
if (device.hasUnifiedMemory) {
textureDescriptor.storageMode = MTLStorageModeShared;
}
}
#else
textureDescriptor.storageMode = MTLStorageModeShared;
#endif
Expand All @@ -295,32 +469,32 @@ - (void)makeFontTextureWithDevice:(id<MTLDevice>)device

- (MetalBuffer *)dequeueReusableBufferOfLength:(NSUInteger)length device:(id<MTLDevice>)device
{
NSTimeInterval now = [NSDate date].timeIntervalSince1970;
uint64_t now = GetMachAbsoluteTimeInSeconds();

// Purge old buffers that haven't been useful for a while
if (now - self.lastBufferCachePurge > 1.0)
if (now - _lastBufferCachePurge > 1.0)
{
NSMutableArray *survivors = [NSMutableArray array];
for (MetalBuffer *candidate in self.bufferCache)
for (MetalBuffer *candidate in _bufferCache)
{
if (candidate.lastReuseTime > self.lastBufferCachePurge)
if (candidate.lastReuseTime > _lastBufferCachePurge)
{
[survivors addObject:candidate];
}
}
self.bufferCache = [survivors mutableCopy];
self.lastBufferCachePurge = now;
_bufferCache = [survivors mutableCopy];
_lastBufferCachePurge = now;
}

// See if we have a buffer we can reuse
MetalBuffer *bestCandidate = nil;
for (MetalBuffer *candidate in self.bufferCache)
for (MetalBuffer *candidate in _bufferCache)
if (candidate.buffer.length >= length && (bestCandidate == nil || bestCandidate.lastReuseTime > candidate.lastReuseTime))
bestCandidate = candidate;

if (bestCandidate != nil)
{
[self.bufferCache removeObject:bestCandidate];
[_bufferCache removeObject:bestCandidate];
bestCandidate.lastReuseTime = now;
return bestCandidate;
}
Expand All @@ -332,21 +506,21 @@ - (MetalBuffer *)dequeueReusableBufferOfLength:(NSUInteger)length device:(id<MTL

- (void)enqueueReusableBuffer:(MetalBuffer *)buffer
{
[self.bufferCache addObject:buffer];
[_bufferCache addObject:buffer];
}

- (_Nullable id<MTLRenderPipelineState>)renderPipelineStateForFrameAndDevice:(id<MTLDevice>)device
{
// Try to retrieve a render pipeline state that is compatible with the framebuffer config for this frame
// The hit rate for this cache should be very near 100%.
id<MTLRenderPipelineState> renderPipelineState = self.renderPipelineStateCache[self.framebufferDescriptor];
id<MTLRenderPipelineState> renderPipelineState = _renderPipelineStateCache[_framebufferDescriptor];

if (renderPipelineState == nil)
{
// No luck; make a new render pipeline state
renderPipelineState = [self _renderPipelineStateForFramebufferDescriptor:self.framebufferDescriptor device:device];
renderPipelineState = [self _renderPipelineStateForFramebufferDescriptor:_framebufferDescriptor device:device];
// Cache render pipeline state for later reuse
self.renderPipelineStateCache[self.framebufferDescriptor] = renderPipelineState;
_renderPipelineStateCache[_framebufferDescriptor] = renderPipelineState;
}

return renderPipelineState;
Expand Down
3 changes: 1 addition & 2 deletions backends/imgui_impl_osx.h
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Original file line number Diff line number Diff line change
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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