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129 lines
2.2 KiB
Go
129 lines
2.2 KiB
Go
package main
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import (
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"math"
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)
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func (m *model) AtTop() bool {
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return m.offset <= 0
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}
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func (m *model) AtBottom() bool {
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return m.offset >= m.maxYOffset()
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}
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func (m *model) PastBottom() bool {
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return m.offset > m.maxYOffset()
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}
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func (m *model) ScrollPercent() float64 {
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if m.height >= len(m.lines) {
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return 1.0
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}
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y := float64(m.offset)
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h := float64(m.height)
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t := float64(len(m.lines) - 1)
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v := y / (t - h)
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return math.Max(0.0, math.Min(1.0, v))
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}
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func (m *model) maxYOffset() int {
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return max(0, len(m.lines)-m.height)
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}
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func (m *model) visibleLines() (lines []string) {
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if len(m.lines) > 0 {
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top := max(0, m.offset)
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bottom := clamp(m.offset+m.height, top, len(m.lines))
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lines = m.lines[top:bottom]
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}
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return lines
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}
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func (m *model) SetOffset(n int) {
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m.offset = clamp(n, 0, m.maxYOffset())
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}
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func (m *model) ViewDown() {
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if m.AtBottom() {
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return
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}
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m.SetOffset(m.offset + m.height)
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}
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func (m *model) ViewUp() {
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if m.AtTop() {
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return
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}
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m.SetOffset(m.offset - m.height)
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}
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func (m *model) HalfViewDown() {
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if m.AtBottom() {
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return
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}
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m.SetOffset(m.offset + m.height/2)
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}
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func (m *model) HalfViewUp() {
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if m.AtTop() {
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return
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}
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m.SetOffset(m.offset - m.height/2)
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}
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func (m *model) LineDown(n int) {
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if m.AtBottom() || n == 0 {
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return
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}
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// Make sure the Number of lines by which we're going to scroll isn't
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// greater than the Number of lines we actually have left before we reach
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// the bottom.
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m.SetOffset(m.offset + n)
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}
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func (m *model) LineUp(n int) {
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if m.AtTop() || n == 0 {
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return
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}
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// Make sure the Number of lines by which we're going to scroll isn't
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// greater than the Number of lines we are from the top.
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m.SetOffset(m.offset - n)
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}
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func (m *model) GotoTop() {
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if m.AtTop() {
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return
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}
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m.SetOffset(0)
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}
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func (m *model) GotoBottom() {
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m.SetOffset(m.maxYOffset())
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}
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func (m *model) scrollDownToCursor() {
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at := m.cursorLineNumber()
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if m.offset <= at { // cursor is lower
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m.LineDown(max(0, at-(m.offset+m.height-1))) // minus one is due to cursorLineNumber() starts from 0
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} else {
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m.SetOffset(at)
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}
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}
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func (m *model) scrollUpToCursor() {
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at := m.cursorLineNumber()
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if at < m.offset+m.height { // cursor is above
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m.LineUp(max(0, m.offset-at))
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} else {
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m.SetOffset(at)
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}
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}
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