feat: expose the renderer interface

This adds the ability to use a custom renderer using a modified version
of the existing `renderer` interface.

nil_renderer.go

@@ -2,15 +2,18 @@ package tea
 
 type nilRenderer struct{}
 
-func (nilRenderer) start()          {}
-func (nilRenderer) stop()           {}
-func (nilRenderer) kill()           {}
-func (nilRenderer) write(string)    {}
-func (nilRenderer) repaint()        {}
-func (nilRenderer) clearScreen()    {}
-func (nilRenderer) altScreen() bool { return false }
-func (nilRenderer) enterAltScreen() {}
-func (nilRenderer) exitAltScreen()  {}
-func (nilRenderer) showCursor()     {}
-func (nilRenderer) hideCursor()     {}
-func (nilRenderer) execute(string)  {}
+var _ Renderer = nilRenderer{}
+
+func (nilRenderer) Flush() error                    { return nil }
+func (nilRenderer) Close() error                    { return nil }
+func (nilRenderer) Write([]byte) (int, error)       { return 0, nil }
+func (nilRenderer) WriteString(string) (int, error) { return 0, nil }
+func (nilRenderer) Repaint()                        {}
+func (nilRenderer) ClearScreen()                    {}
+func (nilRenderer) AltScreen() bool                 { return false }
+func (nilRenderer) EnterAltScreen()                 {}
+func (nilRenderer) ExitAltScreen()                  {}
+func (nilRenderer) CursorVisibility() bool          { return false }
+func (nilRenderer) ShowCursor()                     {}
+func (nilRenderer) HideCursor()                     {}
+func (nilRenderer) Execute(string)                  {}

nil_renderer_test.go

@@ -4,18 +4,13 @@ import "testing"
 
 func TestNilRenderer(t *testing.T) {
 	r := nilRenderer{}
-	r.start()
-	r.stop()
-	r.kill()
-	r.write("a")
-	r.repaint()
-	r.enterAltScreen()
-	if r.altScreen() {
+	r.Repaint()
+	r.EnterAltScreen()
+	if r.AltScreen() {
 		t.Errorf("altScreen should always return false")
 	}
-	r.exitAltScreen()
-	r.clearScreen()
-	r.showCursor()
-	r.hideCursor()
-	r.execute("")
+	r.ExitAltScreen()
+	r.ClearScreen()
+	r.ShowCursor()
+	r.HideCursor()
 }

renderer.go

@@ -1,43 +1,46 @@
 package tea
 
-// renderer is the interface for Bubble Tea renderers.
-type renderer interface {
-	// Start the renderer.
-	start()
-
-	// Stop the renderer, but render the final frame in the buffer, if any.
-	stop()
-
-	// Stop the renderer without doing any final rendering.
-	kill()
+// Renderer is the interface for Bubble Tea renderers.
+type Renderer interface {
+	// Close closes the renderer and flushes any remaining data.
+	Close() error
 
 	// Write a frame to the renderer. The renderer can write this data to
 	// output at its discretion.
-	write(string)
+	Write([]byte) (int, error)
+
+	// WriteString a frame to the renderer. The renderer can WriteString this
+	// data to output at its discretion.
+	WriteString(string) (int, error)
+
+	// Flush flushes the renderer's buffer to the output.
+	Flush() error
 
 	// Request a full re-render. Note that this will not trigger a render
 	// immediately. Rather, this method causes the next render to be a full
-	// repaint. Because of this, it's safe to call this method multiple times
+	// Repaint. Because of this, it's safe to call this method multiple times
 	// in succession.
-	repaint()
+	Repaint()
 
-	// Clears the terminal.
-	clearScreen()
+	// ClearScreen clear the terminal screen.
+	ClearScreen()
 
 	// Whether or not the alternate screen buffer is enabled.
-	altScreen() bool
+	AltScreen() bool
 	// Enable the alternate screen buffer.
-	enterAltScreen()
+	EnterAltScreen()
 	// Disable the alternate screen buffer.
-	exitAltScreen()
+	ExitAltScreen()
 
+	// CursorVisibility returns whether the cursor is visible.
+	CursorVisibility() bool
 	// Show the cursor.
-	showCursor()
+	ShowCursor()
 	// Hide the cursor.
-	hideCursor()
+	HideCursor()
 
-	// execute writes a sequence to the terminal.
-	execute(string)
+	// Execute writes a sequence to the underlying output.
+	Execute(string)
 }
 
 // repaintMsg forces a full repaint.

screen.go

@@ -168,7 +168,7 @@ func DisabledReportFocus() Msg { return disableReportFocusMsg{} }
 // Deprecated: Use the WithAltScreen ProgramOption instead.
 func (p *Program) EnterAltScreen() {
 	if p.renderer != nil {
-		p.renderer.enterAltScreen()
+		p.renderer.EnterAltScreen()
 	} else {
 		p.startupOptions |= withAltScreen
 	}
@@ -179,7 +179,7 @@ func (p *Program) EnterAltScreen() {
 // Deprecated: The altscreen will exited automatically when the program exits.
 func (p *Program) ExitAltScreen() {
 	if p.renderer != nil {
-		p.renderer.exitAltScreen()
+		p.renderer.ExitAltScreen()
 	} else {
 		p.startupOptions &^= withAltScreen
 	}
@@ -191,7 +191,7 @@ func (p *Program) ExitAltScreen() {
 // Deprecated: Use the WithMouseCellMotion ProgramOption instead.
 func (p *Program) EnableMouseCellMotion() {
 	if p.renderer != nil {
-		p.renderer.execute(ansi.EnableMouseCellMotion)
+		p.renderer.Execute(ansi.EnableMouseCellMotion)
 	} else {
 		p.startupOptions |= withMouseCellMotion
 	}
@@ -203,7 +203,7 @@ func (p *Program) EnableMouseCellMotion() {
 // Deprecated: The mouse will automatically be disabled when the program exits.
 func (p *Program) DisableMouseCellMotion() {
 	if p.renderer != nil {
-		p.renderer.execute(ansi.DisableMouseCellMotion)
+		p.renderer.Execute(ansi.DisableMouseCellMotion)
 	} else {
 		p.startupOptions &^= withMouseCellMotion
 	}
@@ -216,7 +216,7 @@ func (p *Program) DisableMouseCellMotion() {
 // Deprecated: Use the WithMouseAllMotion ProgramOption instead.
 func (p *Program) EnableMouseAllMotion() {
 	if p.renderer != nil {
-		p.renderer.execute(ansi.EnableMouseAllMotion)
+		p.renderer.Execute(ansi.EnableMouseAllMotion)
 	} else {
 		p.startupOptions |= withMouseAllMotion
 	}
@@ -228,7 +228,7 @@ func (p *Program) EnableMouseAllMotion() {
 // Deprecated: The mouse will automatically be disabled when the program exits.
 func (p *Program) DisableMouseAllMotion() {
 	if p.renderer != nil {
-		p.renderer.execute(ansi.DisableMouseAllMotion)
+		p.renderer.Execute(ansi.DisableMouseAllMotion)
 	} else {
 		p.startupOptions &^= withMouseAllMotion
 	}
@@ -239,7 +239,7 @@ func (p *Program) DisableMouseAllMotion() {
 // Deprecated: Use the SetWindowTitle command instead.
 func (p *Program) SetWindowTitle(title string) {
 	if p.renderer != nil {
-		p.renderer.execute(ansi.SetWindowTitle(title))
+		p.renderer.Execute(ansi.SetWindowTitle(title))
 	} else {
 		p.startupTitle = title
 	}