mirror of
https://github.com/kevinporetti/UnrealImGui.git
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66 lines
2.6 KiB
C++
66 lines
2.6 KiB
C++
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// Distributed under the MIT License (MIT) (see accompanying LICENSE file)
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#include "ImGuiPrivatePCH.h"
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#include "SImGuiWidget.h"
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#include "ImGuiModuleManager.h"
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#include "TextureManager.h"
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#include "Utilities/ScopeGuards.h"
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BEGIN_SLATE_FUNCTION_BUILD_OPTIMIZATION
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void SImGuiWidget::Construct(const FArguments& InArgs)
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{
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checkf(InArgs._ModuleManager, TEXT("Null Module Manager argument"));
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ModuleManager = InArgs._ModuleManager;
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}
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END_SLATE_FUNCTION_BUILD_OPTIMIZATION
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int32 SImGuiWidget::OnPaint(const FPaintArgs& Args, const FGeometry& AllottedGeometry, const FSlateRect& MyClippingRect,
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FSlateWindowElementList& OutDrawElements, int32 LayerId, const FWidgetStyle& WidgetStyle, bool bParentEnabled) const
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{
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// Calculate offset that will transform vertex positions to screen space - rounded to avoid half pixel offsets.
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const FVector2D VertexPositionOffset{ FMath::RoundToFloat(MyClippingRect.Left), FMath::RoundToFloat(MyClippingRect.Top) };
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// Convert clipping rectangle to format required by Slate vertex.
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const FSlateRotatedRect VertexClippingRect{ MyClippingRect };
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for (const auto& DrawList : ModuleManager->GetContextProxy().GetDrawData())
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{
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DrawList.CopyVertexData(VertexBuffer, VertexPositionOffset, VertexClippingRect);
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// Get access to the Slate scissor rectangle defined in Slate Core API, so we can customize elements drawing.
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extern SLATECORE_API TOptional<FShortRect> GSlateScissorRect;
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auto GSlateScissorRectSaver = ScopeGuards::MakeStateSaver(GSlateScissorRect);
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int IndexBufferOffset = 0;
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for (int CommandNb = 0; CommandNb < DrawList.NumCommands(); CommandNb++)
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{
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const auto& DrawCommand = DrawList.GetCommand(CommandNb);
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DrawList.CopyIndexData(IndexBuffer, IndexBufferOffset, DrawCommand.NumElements);
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// Advance offset by number of copied elements to position it for the next command.
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IndexBufferOffset += DrawCommand.NumElements;
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// Get texture resource handle for this draw command (null index will be also mapped to a valid texture).
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const FSlateResourceHandle& Handle = ModuleManager->GetTextureManager().GetTextureHandle(DrawCommand.TextureId);
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// Transform clipping rectangle to screen space and set in Slate, to apply it to elements that we draw.
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GSlateScissorRect = FShortRect{ DrawCommand.ClippingRect.OffsetBy(MyClippingRect.GetTopLeft()).IntersectionWith(MyClippingRect) };
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// Add elements to the list.
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FSlateDrawElement::MakeCustomVerts(OutDrawElements, LayerId, Handle, VertexBuffer, IndexBuffer, nullptr, 0, 0);
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}
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}
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return LayerId;
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}
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FVector2D SImGuiWidget::ComputeDesiredSize(float) const
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{
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return FVector2D{ 3840.f, 2160.f };
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}
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