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Safer substractions

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Use more saturating_sub.
Fixes #148.
This commit is contained in:
Alexandre Bury 2017-08-14 15:13:32 -07:00
parent 134854e688
commit 4b59808f84
2 changed files with 17 additions and 12 deletions
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2
src/views/stack_view.rs
View File

@ -204,7 +204,7 @@ impl View for StackView {
fn take_focus(&mut self, source: Direction) -> bool { fn take_focus(&mut self, source: Direction) -> bool {
match self.layers.last_mut() { match self.layers.last_mut() {
None => false, None => false,
Some(mut v) => v.view.take_focus(source), Some(v) => v.view.take_focus(source),
} }
} }

27
src/views/text_area.rs
View File

@ -148,10 +148,10 @@ impl TextArea {
fn move_left(&mut self) { fn move_left(&mut self) {
let len = { let len = {
// We don't want to utf8-parse the entire content. // We don't want to utf8-parse the entire content.
// So restrict to the last row. // So only consider the last row.
let mut row = self.selected_row(); let mut row = self.selected_row();
if self.rows[row].start == self.cursor { if self.rows[row].start == self.cursor {
row -= 1; row = row.saturating_sub(1);
} }
let text = &self.content[self.rows[row].start..self.cursor]; let text = &self.content[self.rows[row].start..self.cursor];
@ -179,7 +179,12 @@ impl TextArea {
} }
} }
// If we are editing the text, we add a fake "space" character for the cursor to indicate
// where the next character will appear.
// If the current line is full, adding a character will overflow into the next line. To
// show that, we need to add a fake "ghost" row, just for the cursor.
fn fix_ghost_row(&mut self) { fn fix_ghost_row(&mut self) {
if self.rows.is_empty() || if self.rows.is_empty() ||
self.rows.last().unwrap().end != self.content.len() self.rows.last().unwrap().end != self.content.len()
{ {
@ -199,11 +204,13 @@ impl TextArea {
// println_stderr!("Computing! Oh yeah!"); // println_stderr!("Computing! Oh yeah!");
let mut available = size.x; let mut available = size.x;
self.rows = make_rows(&self.content, available); self.rows = make_rows(&self.content, available);
self.fix_ghost_row(); self.fix_ghost_row();
if self.rows.len() > size.y { if self.rows.len() > size.y {
available -= 1; available = available.saturating_sub(1);
// Doh :( // Apparently we'll need a scrollbar. Doh :(
self.rows = make_rows(&self.content, available); self.rows = make_rows(&self.content, available);
self.fix_ghost_row(); self.fix_ghost_row();
} }
@ -295,14 +302,12 @@ impl TextArea {
// Find affected text. // Find affected text.
// We know the damage started at this row, so it'll need to go. // We know the damage started at this row, so it'll need to go.
let mut first_row = self.selected_row(); //
// Actually, if possible, also re-compute the previous row. // Actually, if possible, also re-compute the previous row.
// Indeed, the previous row may have been cut short, and if we now // Indeed, the previous row may have been cut short, and if we now
// break apart a big word, maybe the first half can go up one level. // break apart a big word, maybe the first half can go up one level.
if first_row > 0 { let first_row = self.selected_row().saturating_sub(1);
first_row -= 1;
}
// The
let first_byte = self.rows[first_row].start; let first_byte = self.rows[first_row].start;
// We don't need to go beyond a newline. // We don't need to go beyond a newline.
@ -328,7 +333,7 @@ impl TextArea {
let scrollable = self.rows.len() > size.y; let scrollable = self.rows.len() > size.y;
if scrollable { if scrollable {
// ... not if a scrollbar is there // ... not if a scrollbar is there
available -= 1; available = available.saturating_sub(1);
} }
// First attempt, if scrollbase status didn't change. // First attempt, if scrollbase status didn't change.
@ -385,7 +390,7 @@ impl View for TextArea {
}; };
let w = if self.scrollbase.scrollable() { let w = if self.scrollbase.scrollable() {
printer.size.x - 1 printer.size.x.saturating_sub(1)
} else { } else {
printer.size.x printer.size.x
}; };