UnrealImGui/Source/ImGui/Private/ImGuiContextProxy.cpp
Sebastian 35f2d342a0 Added support for ImGui context update and rendering:
- Added ImGui Module Manager that that implements module logic and manages other module resources.
- Added Texture Manager to manage texture resources and maps them to index that can be passed to ImGui context.
- Added Context Proxy that represents and manages a single ImGui context.
- Added Slate ImGui Widget to render ImGui output.
2017-03-26 21:32:57 +01:00

97 lines
2.3 KiB
C++

// Distributed under the MIT License (MIT) (see accompanying LICENSE file)
#include "ImGuiPrivatePCH.h"
#include "ImGuiContextProxy.h"
static constexpr float DEFAULT_CANVAS_WIDTH = 3840.f;
static constexpr float DEFAULT_CANVAS_HEIGHT = 2160.f;
FImGuiContextProxy::FImGuiContextProxy()
{
ImGuiIO& IO = ImGui::GetIO();
// Use pre-defined canvas size.
IO.DisplaySize.x = DEFAULT_CANVAS_WIDTH;
IO.DisplaySize.y = DEFAULT_CANVAS_HEIGHT;
// Load texture atlas.
unsigned char* Pixels;
IO.Fonts->GetTexDataAsRGBA32(&Pixels, nullptr, nullptr);
// Begin frame to complete context initialization (this is to avoid problems with other systems calling to ImGui
// during startup).
BeginFrame();
}
FImGuiContextProxy::~FImGuiContextProxy()
{
ImGui::Shutdown();
}
void FImGuiContextProxy::Tick(float DeltaSeconds)
{
if (bIsFrameStarted)
{
// Broadcast draw event to allow listeners to draw their controls to this context.
if (DrawEvent.IsBound())
{
DrawEvent.Broadcast();
}
// Ending frame will produce render output that we capture and store for later use. This also puts context to
// state in which it does not allow to draw controls, so we want to immediately start a new frame.
EndFrame();
}
// Begin a new frame and set the context back to a state in which it allows to draw controls.
BeginFrame(DeltaSeconds);
}
void FImGuiContextProxy::BeginFrame(float DeltaTime)
{
if (!bIsFrameStarted)
{
ImGuiIO& IO = ImGui::GetIO();
IO.DeltaTime = DeltaTime;
ImGui::NewFrame();
bIsFrameStarted = true;
}
}
void FImGuiContextProxy::EndFrame()
{
if (bIsFrameStarted)
{
// Prepare draw data (after this call we cannot draw to this context until we start a new frame).
ImGui::Render();
// Update our draw data, so we can use them later during Slate rendering while ImGui is in the middle of the
// next frame.
UpdateDrawData(ImGui::GetDrawData());
bIsFrameStarted = false;
}
}
void FImGuiContextProxy::UpdateDrawData(ImDrawData* DrawData)
{
if (DrawData && DrawData->CmdListsCount > 0)
{
DrawLists.SetNum(DrawData->CmdListsCount, false);
for (int Index = 0; Index < DrawData->CmdListsCount; Index++)
{
DrawLists[Index].TransferDrawData(*DrawData->CmdLists[Index]);
}
}
else
{
// If we are not rendering then this might be a good moment to empty the array.
DrawLists.Empty();
}
}