Add basic line home/end

internal/system/textbox.go

@@ -405,12 +405,12 @@ func (this *textBox) handleKeyDown (key input.Key, numberPad bool) bool {
 	
 	switch {
 	case key == input.KeyHome || (modifiers.Alt && key == input.KeyLeft):
-		dot.End = 0
+		dot.End = lineHome(this.runes, dot.End)
 		if !sel { dot.Start = dot.End }
 		this.Select(dot)
 		return true
 	case key == input.KeyEnd || (modifiers.Alt && key == input.KeyRight):
-		dot.End = len(this.text)
+		dot.End = lineEnd(this.runes, dot.End)
 		if !sel { dot.Start = dot.End }
 		this.Select(dot)
 		return true
@@ -436,7 +436,7 @@ func (this *textBox) handleKeyDown (key input.Key, numberPad bool) bool {
 		return true
 	case key == input.Key('a') && modifiers.Control:
 		dot.Start = 0
-		dot.End   = len(this.text)
+		dot.End   = len(this.text) // FIXME
 		this.Select(dot)
 		return true
 	default:
@@ -587,6 +587,8 @@ func (this *textBox) recursiveReApply () {
 	}
 }
 
+// TODO: these two functions really could be better.
+
 func previousParagraph (text []rune, index int) int {
 	consecLF := 0
 	if index >= len(text) { index = len(text) - 1 }
@@ -615,3 +617,28 @@ func nextParagraph (text []rune, index int) int {
 	}
 	return index
 }
+
+// TODO: make functions on top of these that support soft home/end
+// FIXME: these break near the start and end of the box
+
+func lineHome (text []rune, index int) int {
+	liminal := index < len(text) && text[index] == '\n'
+	for index := index; index >= 0; index -- {
+		char := text[index]
+		if char == '\n' && !liminal {
+			return index + 1
+		}
+		liminal = false
+	}
+	return 0
+}
+
+func lineEnd (text []rune, index int) int {
+	for ; index < len(text); index ++ {
+		char := text[index]
+		if char == '\n' {
+			return index
+		}
+	}
+	return index
+}