mirror of
https://github.com/Maks1mS/bubbles.git
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98 lines
2.2 KiB
Go
98 lines
2.2 KiB
Go
package viewport
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import (
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"bytes"
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"fmt"
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"io"
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"strings"
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te "github.com/muesli/termenv"
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)
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type renderer struct {
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// Out is the io.Writer to which we should render. Generally, this will
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// be stdout.
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Out io.Writer
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// Y is the vertical offset of the rendered area in relation to the
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// terminal window.
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Y int
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// Height is the number of rows to render.
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Height int
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// TerminalHeight is the total height of the terminal.
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TerminalHeight int
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}
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// clear clears the viewport region.
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func (r *renderer) clear() {
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buf := new(bytes.Buffer)
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moveTo(buf, r.Y, 0)
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for i := 0; i < r.Height; i++ {
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clearLine(buf)
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cursorDown(buf, 1)
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}
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r.Out.Write(buf.Bytes())
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}
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// sync paints the whole area.
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func (r *renderer) sync(lines []string) {
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r.clear()
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moveTo(r.Out, r.Y, 0)
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r.writeLines(lines)
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}
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// write writes to the set writer.
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func (r *renderer) writeLines(lines []string) {
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if len(lines) == 0 {
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return
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}
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io.WriteString(r.Out, strings.Join(lines, "\r\n"))
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}
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// Effectively scroll up. That is, insert a line at the top, pushing
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// everything else down. This is roughly how ncurses does it.
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func (r *renderer) insertTop(lines []string) {
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changeScrollingRegion(r.Out, r.Y, r.Y+r.Height)
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moveTo(r.Out, r.Y, 0)
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insertLine(r.Out, len(lines))
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r.writeLines(lines)
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changeScrollingRegion(r.Out, 0, r.TerminalHeight)
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}
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// Effectively scroll down. That is, insert a line at the bottom, pushing
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// everything else up. This is roughly how ncurses does it.
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func (r *renderer) insertBottom(lines []string) {
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changeScrollingRegion(r.Out, r.Y, r.Y+r.Height)
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moveTo(r.Out, r.Y+r.Height, 0)
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io.WriteString(r.Out, "\r\n"+strings.Join(lines, "\r\n"))
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changeScrollingRegion(r.Out, 0, r.TerminalHeight)
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}
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// Terminal Control
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func changeScrollingRegion(w io.Writer, top, bottom int) {
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fmt.Fprintf(w, te.CSI+"%d;%dr", top, bottom)
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}
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func moveTo(w io.Writer, row, col int) {
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fmt.Fprintf(w, te.CSI+te.CursorPositionSeq, row, col)
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}
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func cursorDown(w io.Writer, numLines int) {
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fmt.Fprintf(w, te.CSI+te.CursorDownSeq, numLines)
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}
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func cursorDownString(numLines int) string {
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return fmt.Sprintf(te.CSI+te.CursorDownSeq, numLines)
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}
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func clearLine(w io.Writer) {
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fmt.Fprintf(w, te.CSI+te.EraseLineSeq, 2)
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}
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func insertLine(w io.Writer, numLines int) {
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fmt.Fprintf(w, te.CSI+"%dL", numLines)
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}
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