poc: add customized format register for darwin

See #17

clipboard.go

@@ -71,22 +71,24 @@ var (
 )
 
 // Format represents the format of clipboard data.
-type Format int
+type Format interface{}
+
+type internalFormat int
 
 // All sorts of supported clipboard data
-const (
+var (
 	// FmtText indicates plain text clipboard format
-	FmtText Format = iota
+	FmtText Format = internalFormat(0)
 	// FmtImage indicates image/png clipboard format
-	FmtImage
+	FmtImage Format = internalFormat(1)
 )
 
 var (
 	// Due to the limitation on operating systems (such as darwin),
 	// concurrent read can even cause panic, use a global lock to
 	// guarantee one read at a time.
-	lock = sync.Mutex{}
-	initOnce sync.Once
+	lock      = sync.Mutex{}
+	initOnce  sync.Once
 	initError error
 )
 
@@ -95,10 +97,10 @@ var (
 // target system lacks required dependency, such as libx11-dev in X11
 // environment. For example,
 //
-// 	err := clipboard.Init()
-// 	if err != nil {
-// 		panic(err)
-// 	}
+//	err := clipboard.Init()
+//	if err != nil {
+//		panic(err)
+//	}
 //
 // If Init returns an error, any subsequent Read/Write/Watch call
 // may result in an unrecoverable panic.
@@ -152,3 +154,14 @@ func Write(t Format, buf []byte) <-chan struct{} {
 func Watch(ctx context.Context, t Format) <-chan []byte {
 	return watch(ctx, t)
 }
+
+// Handler is a clipboard content handler.
+type Handler interface {
+	Format() interface{}
+	// TODO: add reader and writer using generics.
+}
+
+// Register allows caller to provide customized clipboard handler.
+func Register(h Handler) error {
+	return register(h)
+}

clipboard_darwin.go

@@ -15,32 +15,52 @@ package clipboard
 #import <Foundation/Foundation.h>
 #import <Cocoa/Cocoa.h>
 
-unsigned int clipboard_read_string(void **out);
-unsigned int clipboard_read_image(void **out);
-int clipboard_write_string(const void *bytes, NSInteger n);
-int clipboard_write_image(const void *bytes, NSInteger n);
+unsigned int clipboard_read(void **out, void* t);
+int clipboard_write(const void *bytes, NSInteger n, void* t);
 NSInteger clipboard_change_count();
 */
 import "C"
 import (
 	"context"
+	"sync"
 	"time"
 	"unsafe"
 )
 
 func initialize() error { return nil }
 
 func read(t Format) (buf []byte, err error) {
-	var (
-		data unsafe.Pointer
-		n    C.uint
-	)
-	switch t {
-	case FmtText:
-		n = C.clipboard_read_string(&data)
-	case FmtImage:
-		n = C.clipboard_read_image(&data)
+
+	var format unsafe.Pointer
+	switch tt := t.(type) {
+	case internalFormat:
+		switch tt {
+		case FmtText:
+			format = unsafe.Pointer(C.NSPasteboardTypeString)
+		case FmtImage:
+			format = unsafe.Pointer(C.NSPasteboardTypePNG)
+		}
+	default:
+		found := false
+		registeredFormats.Range(func(key, value interface{}) bool {
+			if t == key {
+				found = true
+				return false
+			}
+			return true
+		})
+		if !found {
+			return nil, errUnsupported
+		}
+		actualFormat, ok := t.(unsafe.Pointer)
+		if !ok {
+			return nil, errUnsupported
+		}
+		format = actualFormat
 	}
+
+	var data unsafe.Pointer
+	n := C.clipboard_read(&data, unsafe.Pointer(&format))
 	if data == nil {
 		return nil, errUnavailable
 	}
@@ -54,24 +74,40 @@ func read(t Format) (buf []byte, err error) {
 // write writes the given data to clipboard and
 // returns true if success or false if failed.
 func write(t Format, buf []byte) (<-chan struct{}, error) {
-	var ok C.int
-	switch t {
-	case FmtText:
-		if len(buf) == 0 {
-			ok = C.clipboard_write_string(unsafe.Pointer(nil), 0)
-		} else {
-			ok = C.clipboard_write_string(unsafe.Pointer(&buf[0]),
-				C.NSInteger(len(buf)))
-		}
-	case FmtImage:
-		if len(buf) == 0 {
-			ok = C.clipboard_write_image(unsafe.Pointer(nil), 0)
-		} else {
-			ok = C.clipboard_write_image(unsafe.Pointer(&buf[0]),
-				C.NSInteger(len(buf)))
+	var format unsafe.Pointer
+	switch tt := t.(type) {
+	case internalFormat:
+		switch tt {
+		case FmtText:
+			format = unsafe.Pointer(C.NSPasteboardTypeString)
+		case FmtImage:
+			format = unsafe.Pointer(C.NSPasteboardTypePNG)
+		default:
+			return nil, errUnsupported
 		}
 	default:
-		return nil, errUnsupported
+		found := false
+		registeredFormats.Range(func(key, value interface{}) bool {
+			if t == key {
+				found = true
+				return false
+			}
+			return true
+		})
+		if !found {
+			return nil, errUnsupported
+		}
+		actualFormat, ok := t.(unsafe.Pointer)
+		if !ok {
+			return nil, errUnsupported
+		}
+		format = actualFormat
+	}
+	var ok C.int
+	if len(buf) == 0 {
+		ok = C.clipboard_write(unsafe.Pointer(nil), 0, unsafe.Pointer(&format))
+	} else {
+		ok = C.clipboard_write(unsafe.Pointer(&buf[0]), C.NSInteger(len(buf)), unsafe.Pointer(&format))
 	}
 	if ok != 0 {
 		return nil, errUnavailable
@@ -121,3 +157,11 @@ func watch(ctx context.Context, t Format) <-chan []byte {
 	}()
 	return recv
 }
+
+var registeredFormats sync.Map // map[any]any
+
+func register(h Handler) error {
+	t := h.Format()
+	registeredFormats.Store(t, struct{}{})
+	return nil
+}

clipboard_darwin.m

@@ -13,21 +13,12 @@
 #import <Foundation/Foundation.h>
 #import <Cocoa/Cocoa.h>
 
-unsigned int clipboard_read_string(void **out) {
-	NSPasteboard * pasteboard = [NSPasteboard generalPasteboard];
-	NSData *data = [pasteboard dataForType:NSPasteboardTypeString];
-	if (data == nil) {
-		return 0;
-	}
-	NSUInteger siz = [data length];
-	*out = malloc(siz);
-	[data getBytes: *out length: siz];
-	return siz;
-}
+unsigned int clipboard_read(void **out, void* t) {
+    NSString *cs = *((__unsafe_unretained NSString **)(t));
+	NSPasteboardType tt = (NSPasteboardType)cs;
 
-unsigned int clipboard_read_image(void **out) {
 	NSPasteboard * pasteboard = [NSPasteboard generalPasteboard];
-	NSData *data = [pasteboard dataForType:NSPasteboardTypePNG];
+	NSData *data = [pasteboard dataForType:tt];
 	if (data == nil) {
 		return 0;
 	}
@@ -37,21 +28,13 @@ unsigned int clipboard_read_image(void **out) {
 	return siz;
 }
 
-int clipboard_write_string(const void *bytes, NSInteger n) {
-	NSPasteboard *pasteboard = [NSPasteboard generalPasteboard];
-	NSData *data = [NSData dataWithBytes: bytes length: n];
-	[pasteboard clearContents];
-	BOOL ok = [pasteboard setData: data forType:NSPasteboardTypeString];
-	if (!ok) {
-		return -1;
-	}
-	return 0;
-}
-int clipboard_write_image(const void *bytes, NSInteger n) {
+int clipboard_write(const void *bytes, NSInteger n, void* t) {
+    NSString *cs = *((__unsafe_unretained NSString **)(t));
+	NSPasteboardType tt = (NSPasteboardType)cs;
 	NSPasteboard *pasteboard = [NSPasteboard generalPasteboard];
 	NSData *data = [NSData dataWithBytes: bytes length: n];
 	[pasteboard clearContents];
-	BOOL ok = [pasteboard setData: data forType:NSPasteboardTypePNG];
+	BOOL ok = [pasteboard setData: data forType:tt];
 	if (!ok) {
 		return -1;
 	}

clipboard_nocgo.go

@@ -24,3 +24,7 @@ func write(t Format, buf []byte) (<-chan struct{}, error) {
 func watch(ctx context.Context, t Format) <-chan []byte {
 	panic("clipboard: cannot use when CGO_ENABLED=0")
 }
+
+func register(h Handler) error {
+	panic("clipboard: cannot use when CGO_ENABLED=0")
+}

cmd/customformat/main.go

@@ -0,0 +1,38 @@
+package main
+
+/*
+#cgo CFLAGS: -x objective-c
+#cgo LDFLAGS: -framework Foundation -framework Cocoa
+#import <Foundation/Foundation.h>
+#import <Cocoa/Cocoa.h>
+*/
+import "C"
+import (
+	"os"
+	"unsafe"
+
+	"golang.design/x/clipboard"
+)
+
+var f = unsafe.Pointer(C.NSPasteboardTypePDF)
+
+type audioHandler struct{}
+
+func (ah *audioHandler) Format() interface{} { return f }
+
+func main() {
+	err := clipboard.Init()
+	if err != nil {
+		panic(err)
+	}
+	clipboard.Register(&audioHandler{})
+
+	content, err := os.ReadFile("~/test.pdf")
+	if err != nil {
+		panic(err)
+	}
+
+	clipboard.Write(f, content)
+	b := clipboard.Read(clipboard.FmtText)
+	os.WriteFile("x.txt", b, os.ModePerm)
+}