Prevent negative cell dimensions (#1181)

Prevent the cell dimensions from going below 1, this bug resulted in
allocation of large amounts of memory in the scrollback PR but is also
present on master.

Currently the approach is to just `panic!`, however an `eprintln!` and
`exit` could be an alternative too. I don't think it's realistic to
check this at startup and it should have no performance impact since the
failing method is only called once at startup.

To make it a bit more clear what kind of values are accepted, the
datatypes of offsets and paddings have also been changed so that these
don't accept floats anymore and padding can never be negative.

This should allow us to be a bit more strict with the config to make
sure that errors are printed when invalid values are specified (like
negative padding).

This fixes #1167.

1 files changed, 7 insertions, 7 deletions

diff --git a/src/renderer/mod.rs b/src/renderer/mod.rs
index 5b53e70f..56ae4b14 100644
--- a/src/renderer/mod.rs
+++ b/src/renderer/mod.rs
@@ -123,8 +123,8 @@ pub struct ShaderProgram {
     /// Rendering is split into two passes; 1 for backgrounds, and one for text
     u_background: GLint,
 
-    padding_x: f32,
-    padding_y: f32,
+    padding_x: u8,
+    padding_y: u8,
 }
 
 
@@ -165,7 +165,7 @@ pub struct GlyphCache {
     font_size: font::Size,
 
     /// glyph offset
-    glyph_offset: Delta,
+    glyph_offset: Delta<i8>,
 
     metrics: ::font::Metrics,
 }
@@ -1017,8 +1017,8 @@ impl ShaderProgram {
             u_cell_dim: cell_dim,
             u_visual_bell: visual_bell,
             u_background: background,
-            padding_x: config.padding().x.floor(),
-            padding_y: config.padding().y.floor(),
+            padding_x: config.padding().x,
+            padding_y: config.padding().y,
         };
 
         shader.update_projection(*size.width as f32, *size.height as f32);
@@ -1041,8 +1041,8 @@ impl ShaderProgram {
         // NB Not sure why padding change only requires changing the vertical
         //    translation in the projection, but this makes everything work
         //    correctly.
-        let ortho = cgmath::ortho(0., width - 2. * self.padding_x, 2. * self.padding_y, height,
-            -1., 1.);
+        let ortho = cgmath::ortho(0., width - 2. * self.padding_x as f32, 2. * self.padding_y as f32,
+            height, -1., 1.);
         let projection: [[f32; 4]; 4] = ortho.into();
 
         info!("width: {}, height: {}", width, height);