app/headless: implement headless windows

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

app/headless/headless_darwin.go

@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package headless
+
+import "gioui.org/app/internal/gl"
+
+/*
+#cgo CFLAGS: -DGL_SILENCE_DEPRECATION -Werror -Wno-deprecated-declarations -fmodules -fobjc-arc -x objective-c
+
+#include <CoreFoundation/CoreFoundation.h>
+#include "headless_darwin.h"
+*/
+import "C"
+
+type nsContext struct {
+	c   *gl.Functions
+	ctx C.CFTypeRef
+}
+
+func newContext() (context, error) {
+	ctx := C.gio_headless_newContext()
+	return &nsContext{ctx: ctx, c: new(gl.Functions)}, nil
+}
+
+func (c *nsContext) MakeCurrent() error {
+	C.gio_headless_makeCurrentContext(c.ctx)
+	return nil
+}
+
+func (c *nsContext) ReleaseCurrent() {
+	C.gio_headless_clearCurrentContext(c.ctx)
+}
+
+func (c *nsContext) Functions() *gl.Functions {
+	return c.c
+}
+
+func (d *nsContext) Release() {
+	if d.ctx != 0 {
+		C.gio_headless_releaseContext(d.ctx)
+		d.ctx = 0
+	}
+}