#195 Real buffer clearing (#246)

* #195 Real buffer clearing. Step 1

* #195 buffer clear. Clearing Windows buffer

buffer/buffer.go

@@ -883,6 +883,13 @@ func (buffer *Buffer) Clear() {
 	buffer.SetPosition(0, 0) // do we need to set position?
 }
 
+func (buffer *Buffer) ReallyClear() {
+	defer buffer.emitDisplayChange()
+	buffer.lines = []Line{}
+	buffer.terminalState.SetScrollOffset(0)
+	buffer.SetPosition(0, 0)
+}
+
 // creates if necessary
 func (buffer *Buffer) getCurrentLine() *Line {
 	return buffer.getViewLine(buffer.terminalState.cursorY)

config/actions.go

@@ -9,4 +9,5 @@ const (
 	ActionReportBug   UserAction = "report"
 	ActionToggleDebug UserAction = "debug"
 	ActionToggleSlomo UserAction = "slomo"
+	ActionBufferClear UserAction = "buffer-clear"
 )

config/defaults.go

@@ -39,6 +39,7 @@ func init() {
 	DefaultConfig.KeyMapping[string(ActionToggleDebug)] = addMod("d")
 	DefaultConfig.KeyMapping[string(ActionToggleSlomo)] = addMod(";")
 	DefaultConfig.KeyMapping[string(ActionReportBug)] = addMod("r")
+	DefaultConfig.KeyMapping[string(ActionBufferClear)] = addMod("k")
 }
 
 func addMod(keys string) string {

gui/actions.go

@@ -15,6 +15,7 @@ var actionMap = map[config.UserAction]func(gui *GUI){
 	config.ActionSearch:      actionSearchSelection,
 	config.ActionToggleSlomo: actionToggleSlomo,
 	config.ActionReportBug:   actionReportBug,
+	config.ActionBufferClear: actionBufferClear,
 }
 
 func actionCopy(gui *GUI) {
@@ -50,3 +51,7 @@ func actionToggleSlomo(gui *GUI) {
 func actionReportBug(gui *GUI) {
 	gui.launchTarget("https://github.com/liamg/aminal/issues/new/choose")
 }
+
+func actionBufferClear(gui *GUI) {
+	gui.terminal.ReallyClear()
+}

platform/interfaces.go

@@ -19,4 +19,5 @@ type Pty interface {
 	Resize(x int, y int) error
 	CreateGuestProcess(imagePath string) (Process, error)
 	GetPlatformDependentSettings() PlatformDependentSettings
+	Clear()
 }

platform/unixpty.go

@@ -86,6 +86,10 @@ func (pty *unixPty) GetPlatformDependentSettings() PlatformDependentSettings {
 	return pty.platformDependentSettings
 }
 
+func (pty *unixPty) Clear() {
+	// do nothing for unix
+}
+
 func NewPty(x, y int) (Pty, error) {
 	innerPty, innerTty, err := pty.Open()
 	if err != nil {

platform/winpty.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"fmt"
+
 	"github.com/MaxRis/w32"
 )
 
@@ -98,6 +99,7 @@ type winConPty struct {
 	innerInPipe               syscall.Handle
 	innerOutPipe              syscall.Handle
 	hcon                      uintptr
+	processID                 uint32 // required to obtain old-style console handle (for standard console functions)
 	platformDependentSettings PlatformDependentSettings
 }
 
@@ -140,6 +142,8 @@ func (pty *winConPty) CreateGuestProcess(imagePath string) (Process, error) {
 		return nil, err
 	}
 
+	pty.processID = process.processID
+
 	err = setupChildConsole(C.DWORD(process.processID), C.STD_OUTPUT_HANDLE, C.ENABLE_PROCESSED_OUTPUT|C.ENABLE_WRAP_AT_EOL_OUTPUT)
 	if err != nil {
 		process.Close()
@@ -192,6 +196,50 @@ func (pty *winConPty) GetPlatformDependentSettings() PlatformDependentSettings {
 	return pty.platformDependentSettings
 }
 
+func (pty *winConPty) Clear() {
+	C.FreeConsole()
+	defer C.AttachConsole(^C.DWORD(0)) // attach to parent process console
+
+	if C.AttachConsole(C.DWORD(pty.processID)) == 0 {
+		return
+	}
+	defer C.FreeConsole()
+	hConsole := C.GetStdHandle(C.STD_OUTPUT_HANDLE)
+
+	var coordScreen C.COORD
+	coordScreen.X = 0
+	coordScreen.Y = 0
+	var cCharsWritten C.DWORD
+	var csbi C.CONSOLE_SCREEN_BUFFER_INFO
+
+	// Get the number of character cells in the current buffer.
+	if C.GetConsoleScreenBufferInfo(hConsole, &csbi) != C.BOOL(0) {
+
+		dwConSize := C.DWORD(csbi.dwSize.X * csbi.dwSize.Y)
+
+		// Fill the entire screen with blanks.
+		C.FillConsoleOutputCharacterA(hConsole, // Handle to console screen buffer
+			' ',            // Character to write to the buffer
+			dwConSize,      // Number of cells to write
+			coordScreen,    // Coordinates of first cell
+			&cCharsWritten) // Receive number of characters written
+
+		// Get the current text attribute.
+		if C.GetConsoleScreenBufferInfo(hConsole, &csbi) != C.BOOL(0) {
+			// Set the buffer's attributes accordingly.
+
+			C.FillConsoleOutputAttribute(hConsole, // Handle to console screen buffer
+				csbi.wAttributes, // Character attributes to use
+				dwConSize,        // Number of cells to set attribute
+				coordScreen,      // Coordinates of first cell
+				&cCharsWritten)   // Receive number of characters written
+		}
+	}
+
+	// Put the cursor at its home coordinates.
+	C.SetConsoleCursorPosition(hConsole, coordScreen)
+}
+
 // NewPty creates a new instance of a Pty implementation for Windows on a newly allocated ConPTY
 func NewPty(x, y int) (pty Pty, err error) {
 	if !ptyInitSucceeded {

terminal/terminal.go

@@ -353,6 +353,11 @@ func (terminal *Terminal) Clear() {
 	terminal.ActiveBuffer().Clear()
 }
 
+func (terminal *Terminal) ReallyClear() {
+	terminal.pty.Clear()
+	terminal.ActiveBuffer().ReallyClear()
+}
+
 func (terminal *Terminal) GetSize() (int, int) {
 	return int(terminal.size.Width), int(terminal.size.Height)
 }