Don't crash on insufficient space

src/align.rs

@@ -67,10 +67,14 @@ impl HAlign {
     /// `container`, printing at the resulting offset will align the view as
     /// desired.
     pub fn get_offset(&self, content: usize, container: usize) -> usize {
-        match *self {
-            HAlign::Left => 0,
-            HAlign::Center => (container - content) / 2,
-            HAlign::Right => (container - content),
+        if container < content {
+            0
+        } else {
+            match *self {
+                HAlign::Left => 0,
+                HAlign::Center => (container - content) / 2,
+                HAlign::Right => (container - content),
+            }
         }
     }
 }
@@ -82,10 +86,14 @@ impl VAlign {
     /// `container`, printing at the resulting offset will align the view as
     /// desired.
     pub fn get_offset(&self, content: usize, container: usize) -> usize {
-        match *self {
-            VAlign::Top => 0,
-            VAlign::Center => (container - content) / 2,
-            VAlign::Bottom => (container - content),
+        if container < content {
+            0
+        } else {
+            match *self {
+                VAlign::Top => 0,
+                VAlign::Center => (container - content) / 2,
+                VAlign::Bottom => (container - content),
+            }
         }
     }
 }

src/view/dialog.rs

@@ -127,11 +127,19 @@ impl View for Dialog {
                 .fold(0, |a, b| a + b) + self.buttons.len() - 1
         };
         let overhead = self.padding + self.borders;
+        if printer.size.x < overhead.horizontal() {
+            return;
+        }
         let mut offset = overhead.left +
                          self.align
             .h
             .get_offset(width, printer.size.x - overhead.horizontal());
-        let y = printer.size.y - self.padding.bottom - self.borders.bottom - 1;
+
+        let overhead_bottom = self.padding.bottom + self.borders.bottom + 1;
+        if overhead_bottom > printer.size.y {
+            return;
+        }
+        let y = printer.size.y - overhead_bottom;
 
         for (i, button) in self.buttons.iter().enumerate() {
             let size = button.size;
@@ -146,9 +154,13 @@ impl View for Dialog {
         }
 
         // What do we have left?
-        let inner_size = printer.size - Vec2::new(0, buttons_height) -
-                         self.borders.combined() -
+        let taken = Vec2::new(0, buttons_height) +
+                         self.borders.combined() +
                          self.padding.combined();
+        if !taken.fits_in(printer.size) {
+            return;
+        }
+        let inner_size = printer.size - taken;
 
         self.content
             .draw(&printer.sub_printer(self.borders.top_left() +
@@ -186,7 +198,13 @@ impl View for Dialog {
         }
 
         // We also remove one row for the buttons.
-        let content_req = req - (nomans_land + Vec2::new(0, buttons_size.y));
+        let taken = nomans_land + Vec2::new(0, buttons_size.y);
+        if !taken.fits_in(req) {
+            // Bad!!
+            return taken;
+        }
+        let content_req = req - taken;
+
         let content_size = self.content.get_min_size(content_req);
 
         // On the Y axis, we add buttons and content.
@@ -207,7 +225,12 @@ impl View for Dialog {
     fn layout(&mut self, mut size: Vec2) {
         // Padding and borders are taken, sorry.
         // TODO: handle border-less themes?
-        size = size - (self.borders.combined() + self.padding.combined());
+        let taken = self.borders.combined() + self.padding.combined();
+        size = if taken.fits_in(size) {
+            size - taken
+        } else {
+            Vec2::zero()
+        };
 
         // Buttons are kings, we give them everything they want.
         let mut buttons_height = 0;
@@ -218,6 +241,9 @@ impl View for Dialog {
         }
 
         // Poor content will have to make do with what's left.
+        if buttons_height > size.y {
+            buttons_height = size.y;
+        }
         self.content.layout(size - Vec2::new(0, buttons_height));
     }
 

src/view/linear_layout.rs

@@ -239,11 +239,13 @@ impl View for LinearLayout {
             // Just give up...
             // TODO: print some error message or something
             // println_stderr!("Seriously? {:?} > {:?}???", desperate, req);
-            self.cache = Some(SizeCache::build(desperate, req));
+            // self.cache = Some(SizeCache::build(desperate, req));
+            self.cache = None;
             return desperate;
         }
 
         // This here is how much we're generously offered
+        // (We just checked that req >= desperate, so the substraction is safe
         let mut available = self.orientation.get(&(req - desperate));
         // println_stderr!("Available: {:?}", available);
 
@@ -252,7 +254,11 @@ impl View for LinearLayout {
         let mut overweight: Vec<(usize, usize)> = sizes.iter()
             .map(|v| self.orientation.get(v))
             .zip(min_sizes.iter().map(|v| self.orientation.get(v)))
-            .map(|(a, b)| a - b)
+            .map(|(a, b)| if a > b {
+                a - b
+            } else {
+                0
+            })
             .enumerate()
             .collect();
         // println_stderr!("Overweight: {:?}", overweight);

src/view/position.rs

@@ -54,10 +54,16 @@ impl Offset {
     /// Computes a single-dimension offset requred to draw a view.
     pub fn compute_offset(&self, size: usize, available: usize, parent: usize)
                           -> usize {
-        match *self {
-            Offset::Center => (available - size) / 2,
-            Offset::Absolute(offset) => min(offset, available - size),
-            Offset::Parent(offset) => min(parent + offset, available - size),
+        if size > available {
+            0
+        } else {
+            match *self {
+                Offset::Center => (available - size) / 2,
+                Offset::Absolute(offset) => min(offset, available - size),
+                Offset::Parent(offset) => {
+                    min(parent + offset, available - size)
+                }
+            }
         }
     }
 }

src/view/scroll.rs

@@ -130,10 +130,14 @@ impl ScrollBase {
     pub fn draw<F>(&self, printer: &Printer, line_drawer: F)
         where F: Fn(&Printer, usize)
     {
+        if self.view_height == 0 {
+            return;
+        }
         // Print the content in a sub_printer
         let max_y = min(self.view_height,
                         self.content_height - self.start_line);
         let w = if self.scrollable() {
+            if printer.size.x < 2 { return; }
             printer.size.x - 2 + self.scrollbar_padding // TODO: 2
         } else {
             printer.size.x

src/view/shadow_view.rs

@@ -22,8 +22,9 @@ impl<T: View> ShadowView<T> {
         }
     }
 
-    fn padding(&self) -> (usize, usize) {
-        (1 + self.left_padding as usize, 1 + self.top_padding as usize)
+    fn padding(&self) -> Vec2 {
+        Vec2::new(1 + self.left_padding as usize,
+                  1 + self.top_padding as usize)
     }
 
     /// If set, adds an empty column to the left of the view.
@@ -47,17 +48,23 @@ impl<T: View> ViewWrapper for ShadowView<T> {
     wrap_impl!(&self.view);
 
     fn wrap_get_min_size(&mut self, req: Vec2) -> Vec2 {
-        let offset = self.padding();
+        // Make sure req >= offset
+        let offset = self.padding().or_min(req);
         self.view.get_min_size(req - offset) + offset
     }
 
     fn wrap_layout(&mut self, size: Vec2) {
-        let offset = self.padding();
+        let offset = self.padding().or_min(size);
         self.view.layout(size - offset);
     }
 
     fn wrap_draw(&self, printer: &Printer) {
 
+        if printer.size.y == 0 || printer.size.x == 0 {
+            // Nothing to do if there's no place to draw.
+            return;
+        }
+
         // Skip the first row/column
         let printer =
             &printer.sub_printer(Vec2::new(self.left_padding as usize,

src/view/text_view.rs

@@ -120,15 +120,30 @@ impl TextView {
 
     fn compute_rows(&mut self, size: Vec2) {
         if !self.is_cache_valid(size) {
+            self.last_size = None;
             // Recompute
+
+            if size.x == 0 {
+                // Nothing we can do at this poing.
+                return;
+            }
+
             self.rows = LinesIterator::new(&self.content, size.x).collect();
             let mut scrollbar = 0;
             if self.scrollable && self.rows.len() > size.y {
                 scrollbar = 2;
+                if size.x < scrollbar {
+                    // Again, this is a lost cause.
+                    return;
+                }
+
                 // If we're too high, include a scrollbar
                 self.rows = LinesIterator::new(&self.content,
                                                size.x - scrollbar)
                     .collect();
+                if self.rows.is_empty() && !self.content.is_empty() {
+                    return;
+                }
             }
 
             // Desired width, including the scrollbar.
@@ -148,6 +163,8 @@ impl TextView {
                 my_size.y = size.y;
             }
 
+
+            // println_stderr!("my: {:?} | si: {:?}", my_size, size);
             self.last_size = Some(SizeCache::build(my_size, size));
         }
     }
@@ -214,6 +231,12 @@ impl<'a> Iterator for LinesIterator<'a> {
                 }
             };
 
+        if head_bytes == 0 {
+            // This mean we can't even get a single char?
+            // Sucks. Let's bail.
+            return None;
+        }
+
         self.start += head_bytes;
 
         Some(Row {