all: add darwin support

Author: changkun

.github/workflows/clipboard.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-latest]
+        os: [ubuntu-latest, macos-latest]
 
     steps:
     - name: install libx11-dev

README.md

@@ -27,6 +27,17 @@ clipboard.Write(clipboard.MIMEImage, []byte("image data"))
 clipboard.Read(clipboard.MIMEImage)
 ```
 
+## Notes
+
+To obtain image data to the clipboard, you can:
+
+- On macOS, Ctrl+Shift+Cmd+4
+- On Linux/Ubuntu, Ctrl+Shift+PrintScreen
+
+The package currently supports read/write plain text string or image data
+with PNG format. The other types of data are not supported, as undefined
+behavior.
+
 ## License
 
 GNU GPL-3 Copyright © 2021 The golang.design Initiative Authors, written by [Changkun Ou](https://changkun.de).

clipboard_darwin.go

@@ -4,14 +4,61 @@
 //
 // Written by Changkun Ou <changkun.de>
 
-// +build !linux,darwin
+//go:build darwin
+// +build darwin
 
 package clipboard
 
-func readAll() (buf []byte) {
-	panic("unsupported")
+/*
+#cgo CFLAGS: -x objective-c
+#cgo LDFLAGS: -framework Foundation -framework Cocoa
+#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);
+*/
+import "C"
+import "unsafe"
+
+func read(t MIMEType) (buf []byte) {
+	var (
+		data unsafe.Pointer
+		n    C.uint
+	)
+	switch t {
+	case MIMEText:
+		n = C.clipboard_read_string(&data)
+	case MIMEImage:
+		n = C.clipboard_read_image(&data)
+	}
+	if data == nil {
+		return nil
+	}
+	defer C.free(unsafe.Pointer(data))
+	if n == 0 {
+		return nil
+	}
+	return C.GoBytes(data, C.int(n))
 }
 
-func writeAll(buf []byte) {
-	panic("unsupported")
+// write writes the given data to clipboard and
+// returns true if success or false if failed.
+func write(t MIMEType, buf []byte) bool {
+	var ok C.int
+
+	switch t {
+	case MIMEText:
+		ok = C.clipboard_write_string(unsafe.Pointer(&buf[0]),
+			C.NSInteger(len(buf)))
+	case MIMEImage:
+		ok = C.clipboard_write_image(unsafe.Pointer(&buf[0]),
+			C.NSInteger(len(buf)))
+	}
+	if ok != 0 {
+		return false
+	}
+	return true
 }

clipboard_darwin.m

@@ -0,0 +1,56 @@
+// Copyright 2021 The golang.design Initiative authors.
+// All rights reserved. Use of this source code is governed
+// by a GNU GPL-3 license that can be found in the LICENSE file.
+//
+// Written by Changkun Ou <changkun.de>
+
+// Interact with NSPasteboard using Objective-C
+// https://developer.apple.com/documentation/appkit/nspasteboard?language=objc
+
+#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_image(void **out) {
+	NSPasteboard * pasteboard = [NSPasteboard generalPasteboard];
+	NSData *data = [pasteboard dataForType:NSPasteboardTypePNG];
+	if (data == nil) {
+		return 0;
+	}
+	NSUInteger siz = [data length];
+	*out = malloc(siz);
+	[data getBytes: *out length: siz];
+	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) {
+	NSPasteboard *pasteboard = [NSPasteboard generalPasteboard];
+	NSData *data = [NSData dataWithBytes: bytes length: n];
+	[pasteboard clearContents];
+	BOOL ok = [pasteboard setData: data forType:NSPasteboardTypePNG];
+	if (!ok) {
+		return -1;
+	}
+	return 0;
+}

clipboard_linux.go

@@ -4,7 +4,8 @@
 //
 // Written by Changkun Ou <changkun.de>
 
-// +build linux,!darwin
+//go:build linux
+// +build linux
 
 package clipboard
 
@@ -71,7 +72,9 @@ func readc(t string) []byte {
 	return C.GoBytes(unsafe.Pointer(data), C.int(n))
 }
 
-func write(t MIMEType, buf []byte) {
+// write writes the given data to clipboard and
+// returns true if success or false if failed.
+func write(t MIMEType, buf []byte) bool {
 	var s string
 	switch t {
 	case MIMEText:
@@ -97,6 +100,10 @@ func write(t MIMEType, buf []byte) {
 	// should use an atomic version, and use atomic_load.
 	for start == 0 {
 	}
+
+	if start < 0 {
+		return false
+	}
 	// wait until enter event loop
-	return
+	return true
 }

clipboard_test.go

@@ -15,7 +15,6 @@ import (
 )
 
 func TestClipboard(t *testing.T) {
-
 	t.Run("image", func(t *testing.T) {
 		data, err := os.ReadFile("testdata/clipboard.png")
 		if err != nil {

clipboard_others.go renamed to clipboard_windows.go

@@ -4,14 +4,17 @@
 //
 // Written by Changkun Ou <changkun.de>
 
-// +build !linux,!darwin
+//go:build windows
+// +build windows
 
 package clipboard
 
-func readAll() (buf []byte) {
+func read(t MIMEType) (buf []byte) {
 	panic("unsupported")
 }
 
-func writeAll(buf []byte) {
+// write writes the given data to clipboard and
+// returns true if success or false if failed.
+func write(t MIMEType, buf []byte) bool {
 	panic("unsupported")
 }