example: add media control play/pause example

examples/README.md

@@ -0,0 +1,9 @@
+# Examples
+
+This directory contains example programs demonstrating how to use winrt-go to interact with Windows Runtime APIs.
+
+**Note:** All examples require Windows to run, as they interact with WinRT APIs.
+
+## Examples
+
+- [playpause](./playpause) - Control global media transport (get media info, toggle play/pause)

examples/playpause/main.go

@@ -0,0 +1,185 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"runtime"
+
+	"github.com/go-ole/go-ole"
+	"github.com/saltosystems/winrt-go"
+	"github.com/saltosystems/winrt-go/windows/foundation"
+	"github.com/saltosystems/winrt-go/windows/media/control"
+)
+
+var debug = flag.Bool("debug", false, "enable debug logging")
+
+func init() {
+	flag.Parse()
+	if !*debug {
+		log.SetOutput(io.Discard)
+	}
+}
+
+func main() {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	// Initialize COM and WinRT
+	log.Printf("Initializing COM/WinRT...")
+	if err := ole.RoInitialize(1); err != nil {
+		fmt.Fprintf(os.Stderr, "failed to initialize COM/WinRT: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Get session manager
+	log.Printf("Getting global system media transport controls session manager...")
+	op, err := control.GlobalSystemMediaTransportControlsSessionManagerRequestAsync()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get global system media manager: %v\n", err)
+		os.Exit(1)
+	}
+
+	log.Printf("Awaiting global system media transport controls session manager async operation...")
+	if err := awaitAsyncOperation(op, control.SignatureGlobalSystemMediaTransportControlsSessionManager); err != nil {
+		fmt.Fprintf(os.Stderr, "failed to await async operation: %v\n", err)
+		os.Exit(1)
+	}
+
+	log.Printf("Getting results from async operation...")
+	sessionManagerRes, err := op.GetResults()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get results from async operation: %v\n", err)
+		os.Exit(1)
+	}
+
+	if uintptr(sessionManagerRes) == 0 {
+		fmt.Fprintf(os.Stderr, "no media session available\n")
+		os.Exit(1)
+	}
+
+	sessionManager := (*control.GlobalSystemMediaTransportControlsSessionManager)(sessionManagerRes)
+
+	// Access current session
+	log.Printf("Getting current media session...")
+	session, err := sessionManager.GetCurrentSession()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get current session: %v\n", err)
+		os.Exit(1)
+	}
+
+	log.Printf("Getting media properties asynchronously...")
+	mediaPropsOp, err := session.TryGetMediaPropertiesAsync()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get media properties async: %v\n", err)
+		os.Exit(1)
+	}
+
+	log.Printf("Awaiting media properties async operation...")
+	if err := awaitAsyncOperation(mediaPropsOp, control.SignatureGlobalSystemMediaTransportControlsSessionMediaProperties); err != nil {
+		fmt.Fprintf(os.Stderr, "failed to await media properties async operation: %v\n", err)
+		os.Exit(1)
+	}
+
+	log.Printf("Getting results from media properties async operation...")
+	mediaPropsRes, err := mediaPropsOp.GetResults()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get results from media properties async operation: %v\n", err)
+		os.Exit(1)
+	}
+
+	mediaProps := (*control.GlobalSystemMediaTransportControlsSessionMediaProperties)(mediaPropsRes)
+	log.Printf("Retrieving artist and title from media properties...")
+	artist, err := mediaProps.GetArtist()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get artist from media properties: %v\n", err)
+		os.Exit(1)
+	}
+
+	title, err := mediaProps.GetTitle()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get title from media properties: %v\n", err)
+		os.Exit(1)
+	}
+
+	fmt.Printf("Now playing: %s - %s\n", artist, title)
+
+	// Control playback
+	log.Printf("Getting playback info...")
+	playbackInfo, err := session.GetPlaybackInfo()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get playback info: %v\n", err)
+		os.Exit(1)
+	}
+
+	log.Printf("Getting playback status...")
+	status, err := playbackInfo.GetPlaybackStatus()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get playback status: %v\n", err)
+		os.Exit(1)
+	}
+
+	var statusStr string
+	switch status {
+	case control.GlobalSystemMediaTransportControlsSessionPlaybackStatusClosed:
+		statusStr = "Closed"
+	case control.GlobalSystemMediaTransportControlsSessionPlaybackStatusOpened:
+		statusStr = "Opened"
+	case control.GlobalSystemMediaTransportControlsSessionPlaybackStatusChanging:
+		statusStr = "Changing"
+	case control.GlobalSystemMediaTransportControlsSessionPlaybackStatusStopped:
+		statusStr = "Stopped"
+	case control.GlobalSystemMediaTransportControlsSessionPlaybackStatusPlaying:
+		statusStr = "Playing"
+	case control.GlobalSystemMediaTransportControlsSessionPlaybackStatusPaused:
+		statusStr = "Paused"
+	default:
+		statusStr = "Unknown"
+	}
+
+	fmt.Printf("Current playback status before toggle: %s\n", statusStr)
+
+	log.Printf("Trying to toggle play/pause async...")
+	toggleOp, err := session.TryTogglePlayPauseAsync()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to get toggle play/pause async operation: %v\n", err)
+		os.Exit(1)
+	}
+
+	log.Printf("Awaiting toggle play/pause async operation...")
+	if err := awaitAsyncOperation(toggleOp, winrt.SignatureBool); err != nil {
+		fmt.Fprintf(os.Stderr, "failed to await toggle play/pause async operation: %v\n", err)
+		os.Exit(1)
+	}
+
+	log.Printf("Play/pause toggled successfully.")
+}
+
+func awaitAsyncOperation(asyncOperation *foundation.IAsyncOperation, genericParamSignature string) error {
+	var status foundation.AsyncStatus
+
+	// We need to obtain the GUID of the AsyncOperationCompletedHandler, but its a generic delegate
+	// so we also need the generic parameter type's signature:
+	// AsyncOperationCompletedHandler<genericParamSignature>
+	iid := winrt.ParameterizedInstanceGUID(foundation.GUIDAsyncOperationCompletedHandler, genericParamSignature)
+
+	// Wait until the async operation completes.
+	waitChan := make(chan struct{})
+	handler := foundation.NewAsyncOperationCompletedHandler(ole.NewGUID(iid), func(instance *foundation.AsyncOperationCompletedHandler, asyncInfo *foundation.IAsyncOperation, asyncStatus foundation.AsyncStatus) {
+		status = asyncStatus
+		close(waitChan)
+	})
+	defer handler.Release()
+
+	asyncOperation.SetCompleted(handler)
+
+	// Wait until async operation has stopped, and finish.
+	<-waitChan
+
+	if status != foundation.AsyncStatusCompleted {
+		return fmt.Errorf("async operation failed with status %d", status)
+	}
+	return nil
+}