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1 files changed, 89 insertions, 0 deletions

diff --git a/src/platform_win/window_render_target.cpp b/src/platform_win/window_render_target.cpp
new file mode 100644
index 00000000..f4836d17
--- /dev/null
+++ b/src/platform_win/window_render_target.cpp
@@ -0,0 +1,89 @@
+#include "cru/platform/win/window_render_target.hpp"
+
+#include "cru/platform/win/exception.hpp"
+#include "cru/platform/win/graph_manager.hpp"
+#include "dpi_util.hpp"
+
+#include <cassert>
+
+namespace cru::platform::win {
+WindowRenderTarget::WindowRenderTarget(GraphManager* graph_manager, HWND hwnd) {
+  this->graph_manager_ = graph_manager;
+
+  const auto d3d11_device = graph_manager->GetD3D11Device();
+  const auto dxgi_factory = graph_manager->GetDxgiFactory();
+
+  // Allocate a descriptor.
+  DXGI_SWAP_CHAIN_DESC1 swap_chain_desc = {0};
+  swap_chain_desc.Width = 0;  // use automatic sizing
+  swap_chain_desc.Height = 0;
+  swap_chain_desc.Format =
+      DXGI_FORMAT_B8G8R8A8_UNORM;  // this is the most common swapchain format
+  swap_chain_desc.Stereo = false;
+  swap_chain_desc.SampleDesc.Count = 1;  // don't use multi-sampling
+  swap_chain_desc.SampleDesc.Quality = 0;
+  swap_chain_desc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
+  swap_chain_desc.BufferCount = 2;  // use double buffering to enable flip
+  swap_chain_desc.Scaling = DXGI_SCALING_NONE;
+  swap_chain_desc.SwapEffect =
+      DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL;  // all apps must use this SwapEffect
+  swap_chain_desc.Flags = 0;
+
+  // Get the final swap chain for this window from the DXGI factory.
+  ThrowIfFailed(dxgi_factory->CreateSwapChainForHwnd(
+      d3d11_device, hwnd, &swap_chain_desc, nullptr, nullptr,
+      &dxgi_swap_chain_));
+
+  CreateTargetBitmap();
+}
+
+void WindowRenderTarget::ResizeBuffer(const int width, const int height) {
+  const auto graph_manager = graph_manager_;
+  const auto d2d1_device_context = graph_manager->GetD2D1DeviceContext();
+
+  Microsoft::WRL::ComPtr<ID2D1Image> old_target;
+  d2d1_device_context->GetTarget(&old_target);
+  const auto target_this = old_target == this->target_bitmap_;
+  if (target_this) d2d1_device_context->SetTarget(nullptr);
+
+  old_target = nullptr;
+  target_bitmap_ = nullptr;
+
+  ThrowIfFailed(dxgi_swap_chain_->ResizeBuffers(0, width, height,
+                                                DXGI_FORMAT_UNKNOWN, 0));
+
+  CreateTargetBitmap();
+
+  if (target_this) d2d1_device_context->SetTarget(target_bitmap_.Get());
+}
+
+void WindowRenderTarget::SetAsTarget() {
+  graph_manager_->GetD2D1DeviceContext()->SetTarget(target_bitmap_.Get());
+}
+
+void WindowRenderTarget::Present() {
+  ThrowIfFailed(dxgi_swap_chain_->Present(1, 0));
+}
+
+void WindowRenderTarget::CreateTargetBitmap() {
+  assert(target_bitmap_ == nullptr);  // target bitmap must not exist.
+
+  // Direct2D needs the dxgi version of the backbuffer surface pointer.
+  Microsoft::WRL::ComPtr<IDXGISurface> dxgi_back_buffer;
+  ThrowIfFailed(
+      dxgi_swap_chain_->GetBuffer(0, IID_PPV_ARGS(&dxgi_back_buffer)));
+
+  const auto dpi = GetDpi();
+
+  auto bitmap_properties = D2D1::BitmapProperties1(
+      D2D1_BITMAP_OPTIONS_TARGET | D2D1_BITMAP_OPTIONS_CANNOT_DRAW,
+      D2D1::PixelFormat(DXGI_FORMAT_B8G8R8A8_UNORM, D2D1_ALPHA_MODE_IGNORE),
+      dpi.x, dpi.y);
+
+  // Get a D2D surface from the DXGI back buffer to use as the D2D render
+  // target.
+  ThrowIfFailed(
+      graph_manager_->GetD2D1DeviceContext()->CreateBitmapFromDxgiSurface(
+          dxgi_back_buffer.Get(), &bitmap_properties, &target_bitmap_));
+}
+}  // namespace cru::platform::win