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Fix panics from overflow subtraction

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This commit is contained in:
Alexandre Bury 2018-06-15 23:11:17 -07:00
parent 5cf870baaf
commit 363913c68b
1 changed files with 40 additions and 22 deletions
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58
src/views/scroll_view.rs
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@ -33,9 +33,11 @@ pub struct ScrollView<V> {
// Should we show scrollbars?
//
// Even if this is true, no scrollbar will be printed if we don't need to scroll.
// Even if this is true, no scrollbar will be printed if we don't need to
// scroll.
//
// Could be an enum {Never, Auto, Always}
// TODO: have an option to always show the scrollbar.
// TODO: have an option to show scrollbar on top/left.
show_scrollbars: bool,
// How much padding should be between content and scrollbar?
@ -126,7 +128,7 @@ impl<V> ScrollView<V> {
/// Returns the size available for the child view.
fn available_size(&self) -> Vec2 {
self.last_size - self.scrollbar_size()
self.last_size.saturating_sub(self.scrollbar_size())
}
}
@ -159,8 +161,9 @@ where
);
// On non-scrolling axis, give inner_size the available space instead.
let inner_size =
self.enabled.select_or(inner_size, size - scrollbar_size);
let inner_size = self
.enabled
.select_or(inner_size, size.saturating_sub(scrollbar_size));
let new_scrollable = inner_size.zip_map(size, |i, s| i > s);
@ -171,7 +174,7 @@ where
///
/// Returns `true` if the event was consumed.
fn start_drag(&mut self, position: Vec2) -> bool {
let scrollbar_pos = self.last_size - (1, 1);
let scrollbar_pos = self.last_size.saturating_sub((1, 1));
let grabbed = scrollbar_pos.zip_map(position, |s, p| s == p);
@ -180,17 +183,18 @@ where
// See if we grabbed one of the scrollbars
for (orientation, pos, length, offset) in
XY::zip4(Orientation::pair(), position, lengths, offsets).zip(grabbed.swap())
XY::zip4(Orientation::pair(), position, lengths, offsets)
.zip(grabbed.swap())
.into_iter()
.filter(|&(_, grab)| grab)
.map(|(x, _)| x)
{
if pos >= offset && pos < offset + length {
// We grabbed the thumb! Now scroll from that position.
self.thumb_grab = Some((orientation, pos - offset));
} else {
// We hit the scrollbar, outside of the thumb. Let's move the middle there.
// We hit the scrollbar, outside of the thumb.
// Let's move the middle there.
self.thumb_grab = Some((orientation, (length - 1) / 2));
self.drag(position);
}
@ -214,10 +218,12 @@ where
let lengths = self.scrollbar_thumb_lengths();
let available = self.available_size();
// The new offset is thumb_pos * (content + 1 - available) / (available + 1 - thumb size)
let new_offset = (self.inner_size + (1, 1) - available) * thumb_pos
/ (available + (1, 1) - lengths);
let max_offset = self.inner_size - self.available_size();
// The new offset is:
// thumb_pos * (content + 1 - available) / (available + 1 - thumb size)
let new_offset = (self.inner_size + (1, 1)).saturating_sub(available)
* thumb_pos
/ (available + (1, 1)).saturating_sub(lengths);
let max_offset = self.inner_size.saturating_sub(self.available_size());
self.offset
.set_axis_from(orientation, &new_offset.or_min(max_offset));
}
@ -235,7 +241,8 @@ where
// If we need to add scrollbars, the available size will change.
if scrollable.any() && self.show_scrollbars {
// Attempt 2: he wants to scroll? Sure! Try again with some space for the scrollbar.
// Attempt 2: he wants to scroll? Sure!
// Try again with some space for the scrollbar.
let (inner_size, size, new_scrollable) =
self.sizes_when_scrolling(constraint, scrollable);
if scrollable != new_scrollable {
@ -266,7 +273,7 @@ where
fn scrollbar_thumb_offsets(&self, lengths: Vec2) -> Vec2 {
let available = self.available_size();
// The number of steps is 1 + the "extra space"
let steps = available - lengths + (1, 1);
let steps = (available + (1, 1)).saturating_sub(lengths);
steps * self.offset / (self.inner_size + (1, 1) - available)
}
}
@ -296,12 +303,19 @@ where
XY::zip5(lengths, offsets, size, line_c, Orientation::pair()).run_if(
scrolling,
|(length, offset, size, c, orientation)| {
let start = (printer.size - (1, 1)).with_axis(orientation, 0);
let start = printer
.size
.saturating_sub((1, 1))
.with_axis(orientation, 0);
let offset = orientation.make_vec(offset, 0);
printer.print_line(orientation, start, size, c);
let thumb_c = if self.thumb_grab.map(|(o, _)| o == orientation).unwrap_or(false) {
let thumb_c = if self
.thumb_grab
.map(|(o, _)| o == orientation)
.unwrap_or(false)
{
" "
} else {
"▒"
@ -318,7 +332,7 @@ thumb_c,
);
if scrolling.both() {
printer.print((printer.size.x - 1, printer.size.y - 1), "╳");
printer.print(printer.size.saturating_sub((1, 1)), "╳");
}
// Draw content
@ -340,7 +354,8 @@ thumb_c,
EventResult::Ignored => {
// If it's an arrow, try to scroll in the given direction.
// If it's a mouse scroll, try to scroll as well.
// Also allow Ctrl+arrow to move the view without moving selection.
// Also allow Ctrl+arrow to move the view,
// but not the selection.
match event {
Event::Mouse {
event: MouseEvent::WheelUp,
@ -457,7 +472,10 @@ thumb_c,
self.inner.layout(self.inner_size);
// TODO: Refresh offset if needed!
// The offset cannot be more than content - available
self.offset = self
.offset
.or_min(inner_size.saturating_sub(self.available_size()));
}
fn needs_relayout(&self) -> bool {