windows: try dib format if dibv5 is not avaliable (#21)

Author: pluveto

clipboard_windows.go

@@ -15,6 +15,8 @@ package clipboard
 import (
 	"bytes"
 	"context"
+	"encoding/binary"
+	"errors"
 	"fmt"
 	"image"
 	"image/color"
@@ -25,6 +27,8 @@ import (
 	"time"
 	"unicode/utf16"
 	"unsafe"
+
+	"golang.org/x/image/bmp"
 )
 
 func initialize() error { return nil }
@@ -107,7 +111,8 @@ func writeText(buf []byte) error {
 func readImage() ([]byte, error) {
 	hMem, _, err := getClipboardData.Call(cFmtDIBV5)
 	if hMem == 0 {
-		return nil, err
+		// second chance to try FmtDIB
+		return readImageDib()
 	}
 	p, _, err := gLock.Call(hMem)
 	if p == 0 {
@@ -154,6 +159,57 @@ func readImage() ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
+func readImageDib() ([]byte, error) {
+	const (
+		fileHeaderLen = 14
+		infoHeaderLen = 40
+		cFmtDIB       = 8
+	)
+
+	hClipDat, _, err := getClipboardData.Call(cFmtDIB)
+	if err != nil {
+		return nil, errors.New("not dib format data: " + err.Error())
+	}
+	pMemBlk, _, err := gLock.Call(hClipDat)
+	if pMemBlk == 0 {
+		return nil, errors.New("failed to call global lock: " + err.Error())
+	}
+	defer gUnlock.Call(hClipDat)
+
+	bmpHeader := (*bitmapHeader)(unsafe.Pointer(pMemBlk))
+	dataSize := bmpHeader.SizeImage + fileHeaderLen + infoHeaderLen
+
+	if bmpHeader.SizeImage == 0 && bmpHeader.Compression == 0 {
+		iSizeImage := bmpHeader.Height * ((bmpHeader.Width*uint32(bmpHeader.BitCount)/8 + 3) &^ 3)
+		dataSize += iSizeImage
+	}
+	buf := new(bytes.Buffer)
+	binary.Write(buf, binary.LittleEndian, uint16('B')|(uint16('M')<<8))
+	binary.Write(buf, binary.LittleEndian, uint32(dataSize))
+	binary.Write(buf, binary.LittleEndian, uint32(0))
+	const sizeof_colorbar = 0
+	binary.Write(buf, binary.LittleEndian, uint32(fileHeaderLen+infoHeaderLen+sizeof_colorbar))
+	j := 0
+	for i := fileHeaderLen; i < int(dataSize); i++ {
+		binary.Write(buf, binary.BigEndian, *(*byte)(unsafe.Pointer(pMemBlk + uintptr(j))))
+		j++
+	}
+	return bmpToPng(buf)
+}
+
+func bmpToPng(bmpBuf *bytes.Buffer) (buf []byte, err error) {
+	var f bytes.Buffer
+	original_image, err := bmp.Decode(bmpBuf)
+	if err != nil {
+		return nil, err
+	}
+	err = png.Encode(&f, original_image)
+	if err != nil {
+		return nil, err
+	}
+	return f.Bytes(), nil
+}
+
 func writeImage(buf []byte) error {
 	r, _, err := emptyClipboard.Call()
 	if r == 0 {
@@ -386,9 +442,9 @@ func watch(ctx context.Context, t Format) <-chan []byte {
 }
 
 const (
+	cFmtBitmap      = 2 // Win+PrintScreen
 	cFmtUnicodeText = 13
 	cFmtDIBV5       = 17
-	cFmtBitmap      = 2 // Win+PrintScreen
 	// Screenshot taken from special shortcut is in different format (why??), see:
 	// https://jpsoft.com/forums/threads/detecting-clipboard-format.5225/
 	cFmtDataObject = 49161 // Shift+Win+s, returned from enumClipboardFormats
@@ -428,6 +484,20 @@ type bitmapV5Header struct {
 	Reserved    uint32
 }
 
+type bitmapHeader struct {
+	Size          uint32
+	Width         uint32
+	Height        uint32
+	PLanes        uint16
+	BitCount      uint16
+	Compression   uint32
+	SizeImage     uint32
+	XPelsPerMeter uint32
+	YPelsPerMeter uint32
+	ClrUsed       uint32
+	ClrImportant  uint32
+}
+
 // Calling a Windows DLL, see:
 // https://github.com/golang/go/wiki/WindowsDLLs
 var (

go.mod

@@ -3,6 +3,6 @@ module golang.design/x/clipboard
 go 1.16
 
 require (
-	golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d
+	golang.org/x/image v0.0.0-20211028202545-6944b10bf410
 	golang.org/x/mobile v0.0.0-20210716004757-34ab1303b554
 )

go.sum

@@ -7,8 +7,8 @@ golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56 h1:estk1glOnSVeJ9tdEZZc5mAMD
 golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56/go.mod h1:JhuoJpWY28nO4Vef9tZUw9qufEGTyX1+7lmHxV5q5G4=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
-golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d h1:RNPAfi2nHY7C2srAV8A49jpsYr0ADedCk1wq6fTMTvs=
-golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
+golang.org/x/image v0.0.0-20211028202545-6944b10bf410 h1:hTftEOvwiOq2+O8k2D5/Q7COC7k5Qcrgc2TFURJYnvQ=
+golang.org/x/image v0.0.0-20211028202545-6944b10bf410/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
 golang.org/x/mobile v0.0.0-20190312151609-d3739f865fa6/go.mod h1:z+o9i4GpDbdi3rU15maQ/Ox0txvL9dWGYEHz965HBQE=
 golang.org/x/mobile v0.0.0-20210716004757-34ab1303b554 h1:3In5TnfvnuXTF/uflgpYxSCEGP2NdYT37KsPh3VjZYU=
 golang.org/x/mobile v0.0.0-20210716004757-34ab1303b554/go.mod h1:jFTmtFYCV0MFtXBU+J5V/+5AUeVS0ON/0WkE/KSrl6E=