internal/d3d11: extract Direct3D API to separate package

We're about the merge the Direct3D backend into package gpu. Extract the
raw Direct3D API to its own package, just like package glimpl.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/window/d3d11_windows.go

@@ -3,45 +3,59 @@
 package window
 
 import (
+	"fmt"
 	"unsafe"
 
 	"gioui.org/gpu"
-	"gioui.org/app/internal/d3d11"
+	"gioui.org/internal/d3d11"
 )
 
 type d3d11Context struct {
-	win           *window
-	swchain       *d3d11.SwapChain
-	fbo           *d3d11.Framebuffer
-	dev           *d3d11.Device
+	win *window
+	dev *d3d11.Device
+	ctx *d3d11.DeviceContext
+
+	swchain       *d3d11.IDXGISwapChain
+	renderTarget  *d3d11.RenderTargetView
+	depthView     *d3d11.DepthStencilView
 	width, height int
 }
 
+const debug = false
+
 func init() {
 	backends = append(backends, gpuAPI{
 		priority: 1,
 		initializer: func(w *window) (Context, error) {
 			hwnd, _, _ := w.HWND()
-			dev, err := d3d11.NewDevice()
+			var flags uint32
+			if debug {
+				flags |= d3d11.CREATE_DEVICE_DEBUG
+			}
+			dev, ctx, _, err := d3d11.CreateDevice(
+				d3d11.DRIVER_TYPE_HARDWARE,
+				flags,
+			)
 			if err != nil {
+				return nil, fmt.Errorf("NewContext: %v", err)
+			}
+			swchain, err := d3d11.CreateSwapChain(dev, hwnd)
+			if err != nil {
+				d3d11.IUnknownRelease(unsafe.Pointer(ctx), ctx.Vtbl.Release)
+				d3d11.IUnknownRelease(unsafe.Pointer(dev), dev.Vtbl.Release)
 				return nil, err
 			}
-			swchain, err := dev.CreateSwapChain(hwnd)
-			if err != nil {
-				dev.Release()
-				return nil, err
-			}
-			return &d3d11Context{win: w, dev: dev, swchain: swchain}, nil
+			return &d3d11Context{win: w, dev: dev, ctx: ctx, swchain: swchain}, nil
 		},
 	})
 }
 
 func (c *d3d11Context) API() gpu.API {
-	return gpu.Direct3D11{Device: unsafe.Pointer(c.dev.Handle)}
+	return gpu.Direct3D11{Device: unsafe.Pointer(c.dev)}
 }
 
 func (c *d3d11Context) Present() error {
-	err := c.swchain.Present()
+	err := c.swchain.Present(1, 0)
 	if err == nil {
 		return nil
 	}
@@ -59,25 +73,40 @@ func (c *d3d11Context) Present() error {
 
 func (c *d3d11Context) MakeCurrent() error {
 	_, width, height := c.win.HWND()
-	if c.fbo != nil && width == c.width && height == c.height {
-		c.dev.BindFramebuffer(c.fbo)
+	if c.renderTarget != nil && width == c.width && height == c.height {
+		c.ctx.OMSetRenderTargets(c.renderTarget, c.depthView)
 		return nil
 	}
-	if c.fbo != nil {
-		c.fbo.Release()
-		c.fbo = nil
-	}
-	if err := c.swchain.Resize(); err != nil {
+	c.releaseFBO()
+	if err := c.swchain.ResizeBuffers(0, 0, 0, d3d11.DXGI_FORMAT_UNKNOWN, 0); err != nil {
 		return err
 	}
 	c.width = width
 	c.height = height
-	fbo, err := c.swchain.Framebuffer(c.dev)
+
+	desc, err := c.swchain.GetDesc()
 	if err != nil {
 		return err
 	}
-	c.fbo = fbo
-	c.dev.BindFramebuffer(c.fbo)
+	backBuffer, err := c.swchain.GetBuffer(0, &d3d11.IID_Texture2D)
+	if err != nil {
+		return err
+	}
+	texture := (*d3d11.Resource)(unsafe.Pointer(backBuffer))
+	renderTarget, err := c.dev.CreateRenderTargetView(texture)
+	d3d11.IUnknownRelease(unsafe.Pointer(backBuffer), backBuffer.Vtbl.Release)
+	if err != nil {
+		return err
+	}
+	depthView, err := d3d11.CreateDepthView(c.dev, int(desc.BufferDesc.Width), int(desc.BufferDesc.Height), 24)
+	if err != nil {
+		d3d11.IUnknownRelease(unsafe.Pointer(renderTarget), renderTarget.Vtbl.Release)
+		return err
+	}
+	c.renderTarget = renderTarget
+	c.depthView = depthView
+
+	c.ctx.OMSetRenderTargets(c.renderTarget, c.depthView)
 	return nil
 }
 
@@ -86,16 +115,26 @@ func (c *d3d11Context) Lock() {}
 func (c *d3d11Context) Unlock() {}
 
 func (c *d3d11Context) Release() {
-	if c.fbo != nil {
-		c.fbo.Release()
-	}
+	c.releaseFBO()
 	if c.swchain != nil {
-		c.swchain.Release()
+		d3d11.IUnknownRelease(unsafe.Pointer(c.swchain), c.swchain.Vtbl.Release)
+	}
+	if c.ctx != nil {
+		d3d11.IUnknownRelease(unsafe.Pointer(c.ctx), c.ctx.Vtbl.Release)
 	}
 	if c.dev != nil {
-		c.dev.Release()
+		d3d11.IUnknownRelease(unsafe.Pointer(c.dev), c.dev.Vtbl.Release)
+	}
+	*c = d3d11Context{}
+}
+
+func (c *d3d11Context) releaseFBO() {
+	if c.depthView != nil {
+		d3d11.IUnknownRelease(unsafe.Pointer(c.depthView), c.depthView.Vtbl.Release)
+		c.depthView = nil
+	}
+	if c.renderTarget != nil {
+		d3d11.IUnknownRelease(unsafe.Pointer(c.renderTarget), c.renderTarget.Vtbl.Release)
+		c.renderTarget = nil
 	}
-	c.fbo = nil
-	c.swchain = nil
-	c.dev = nil
 }