104 lines
1.9 KiB
Go
104 lines
1.9 KiB
Go
package tui
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// braillePlane is a subpixel canvas where each terminal cell maps to a 2×4
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// dot grid, rendered via Unicode braille (U+2800..U+28FF).
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type braillePlane struct {
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wCells, hCells int
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wDots, hDots int
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dots []bool
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}
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func newBraillePlane(wCells, hCells int) *braillePlane {
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wd, hd := wCells*2, hCells*4
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return &braillePlane{
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wCells: wCells, hCells: hCells,
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wDots: wd, hDots: hd,
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dots: make([]bool, wd*hd),
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}
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}
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func (p *braillePlane) set(dx, dy int) {
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if dx < 0 || dy < 0 || dx >= p.wDots || dy >= p.hDots {
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return
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}
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p.dots[dy*p.wDots+dx] = true
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}
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// line draws a Bresenham line between two dot coordinates.
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func (p *braillePlane) line(x0, y0, x1, y1 int) {
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dx := intAbs(x1 - x0)
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sx := 1
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if x0 >= x1 {
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sx = -1
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}
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dy := -intAbs(y1 - y0)
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sy := 1
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if y0 >= y1 {
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sy = -1
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}
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err := dx + dy
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for {
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p.set(x0, y0)
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if x0 == x1 && y0 == y1 {
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return
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}
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e2 := 2 * err
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if e2 >= dy {
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err += dy
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x0 += sx
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}
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if e2 <= dx {
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err += dx
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y0 += sy
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}
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}
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}
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// fillBelow fills all dots below the topmost lit dot in each column,
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// producing an area-chart effect.
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func (p *braillePlane) fillBelow() {
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for x := 0; x < p.wDots; x++ {
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topY := -1
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for y := 0; y < p.hDots; y++ {
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if p.dots[y*p.wDots+x] {
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topY = y
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break
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}
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}
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if topY >= 0 {
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for y := topY + 1; y < p.hDots; y++ {
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p.dots[y*p.wDots+x] = true
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}
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}
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}
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}
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// cellMask builds the U+2800-relative bitmask for one terminal cell.
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func (p *braillePlane) cellMask(cx, cy int) byte {
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type bit struct {
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dx, dy int
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m byte
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}
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bits := [...]bit{
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{0, 0, 0x01}, {0, 1, 0x02}, {0, 2, 0x04},
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{1, 0, 0x08}, {1, 1, 0x10}, {1, 2, 0x20},
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{0, 3, 0x40}, {1, 3, 0x80},
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}
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var mask byte
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for _, b := range bits {
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dx := cx*2 + b.dx
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dy := cy*4 + b.dy
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if dx >= 0 && dx < p.wDots && dy >= 0 && dy < p.hDots && p.dots[dy*p.wDots+dx] {
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mask |= b.m
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}
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}
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return mask
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}
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func intAbs(n int) int {
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if n < 0 {
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return -n
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}
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return n
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}
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