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// +build windows
package cwriter
import (
"io"
"strings"
"syscall"
"unsafe"
"github.com/mattn/go-isatty"
)
var kernel32 = syscall.NewLazyDLL("kernel32.dll")
var (
procGetConsoleScreenBufferInfo = kernel32.NewProc("GetConsoleScreenBufferInfo")
procSetConsoleCursorPosition = kernel32.NewProc("SetConsoleCursorPosition")
procFillConsoleOutputCharacter = kernel32.NewProc("FillConsoleOutputCharacterW")
procFillConsoleOutputAttribute = kernel32.NewProc("FillConsoleOutputAttribute")
)
type (
short int16
word uint16
dword uint32
coord struct {
x short
y short
}
smallRect struct {
left short
top short
right short
bottom short
}
consoleScreenBufferInfo struct {
size coord
cursorPosition coord
attributes word
window smallRect
maximumWindowSize coord
}
)
// FdWriter is a writer with a file descriptor.
type FdWriter interface {
io.Writer
Fd() uintptr
}
func (w *Writer) clearLines() error {
f, ok := w.out.(FdWriter)
if ok && !isatty.IsTerminal(f.Fd()) {
_, err := io.WriteString(w.out, strings.Repeat(clearCursorAndLine, w.lineCount))
return err
}
fd := f.Fd()
var info consoleScreenBufferInfo
procGetConsoleScreenBufferInfo.Call(fd, uintptr(unsafe.Pointer(&info)))
for i := 0; i < w.lineCount; i++ {
// move the cursor up
info.cursorPosition.y--
procSetConsoleCursorPosition.Call(fd, uintptr(*(*int32)(unsafe.Pointer(&info.cursorPosition))))
// clear the line
cursor := coord{
x: info.window.left,
y: info.window.top + info.cursorPosition.y,
}
var count, w dword
count = dword(info.size.x)
procFillConsoleOutputCharacter.Call(fd, uintptr(' '), uintptr(count), *(*uintptr)(unsafe.Pointer(&cursor)), uintptr(unsafe.Pointer(&w)))
}
return nil
}
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