52 lines
1.2 KiB
Go
52 lines
1.2 KiB
Go
package buffer
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// Output holds the visible lines for a terminal viewport and the cursor
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// position adjusted for scrolling.
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// Unlike Cursor, Glyph and Line are 1-indexed terminal coordinates for ANSI
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// cursor positioning.
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type Output struct {
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Glyph int
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Line int
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Lines []string
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}
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// TODO: wrap lines.
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// TODO: add highlighting.
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func (b *Buffer) Render(height, width int) *Output {
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// Vertical scroll.
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if b.cursor.line < b.offset.line {
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b.offset.line = b.cursor.line
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}
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if b.cursor.line >= height+b.offset.line {
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b.offset.line = b.cursor.line - height + 1
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}
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// Horizontal scroll.
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if b.cursor.glyph < b.offset.glyph {
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b.offset.glyph = b.cursor.glyph
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}
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if b.cursor.glyph >= width+b.offset.glyph {
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b.offset.glyph = b.cursor.glyph - width + 1
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}
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// Generate lines.
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var lines = []string{}
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for i := b.offset.line; i < height+b.offset.line; i++ {
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// Return empty lines for indexes past the buffer's lines.
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if i >= len(b.lines) {
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lines = append(lines, "")
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continue
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}
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line := b.lines[i].Render(b.offset.glyph, width)
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lines = append(lines, line)
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}
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return &Output{
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// Terminals are 1-indexed.
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Glyph: b.cursor.glyph - b.offset.glyph + 1,
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Line: b.cursor.line - b.offset.line + 1,
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Lines: lines,
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}
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}
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