textium: fix a few issues in rasterization

* don't underflow bbox {x,y}
* actually specify a pack resize strategy when packing
* fix the type signature of make_atlas
* bring packer::{Packer, GrowingPacker} traits into scope

textium/src/rasterizer.rs

@@ -5,7 +5,7 @@ use std::collections::HashMap;
 use ::{FontAtlas, GlyphMetadata};
 use ::geometry::Rect;
 use ::texture::{Buffer2d, Bitmap};
-use ::packer::SkylinePacker;
+use ::packer::{Packer, GrowingPacker, SkylinePacker};
 
 pub struct Font<'a> {
     font: rusttype::Font<'a>
@@ -27,7 +27,7 @@ impl<'a> Font<'a> {
     /// `width` and `height` are the starting size of the bitmap.
     ///
     /// The packer may enlarge the bitmap beyond its initial dimensions in order to fit all glyphs.
-    pub fn make_atlas<I>(&self, chrs: I, scale: f32, margin: u32, width: usize, height: usize)
+    pub fn make_atlas<I>(&self, chrs: I, scale: f32, margin: usize, width: usize, height: usize)
         -> (FontAtlas, Bitmap<u8>, f32)
             where I: Iterator<Item=char>
     {
@@ -36,7 +36,7 @@ impl<'a> Font<'a> {
         packer.set_margin(margin);
         for chr in chrs {
             if let Some((mut info, rendered)) = self.rasterize_char(chr, scale) {
-                let r = packer.pack_resize(&rendered);
+                let r = packer.pack_resize(&rendered, |(w, h)| (w*2, h*2));
                 info.bounding_box = r;
                 atlas.glyph_data.insert(chr, info);
             } else if chr == ' ' {
@@ -83,8 +83,8 @@ impl<'a> Font<'a> {
         let data = GlyphMetadata {
             scale: scale,
             bounding_box: Rect {
-                x: bbox.min.x as usize,
-                y: bbox.min.y as usize,
+                x: 0_usize,
+                y: 0_usize,
                 w: bbox.width() as usize,
                 h: bbox.height() as usize,
             },