fix various errors in durandal::image

src/durandal/image.rs

@@ -1,6 +1,6 @@
 //! Image and color representations.
 
-use crate::durandal::traits::*;
+use crate::durandal::{err::*, traits::*};
 use std::io;
 
 /// Creates a RGB8 color from a R5G5B5 format color.
@@ -20,7 +20,7 @@ pub fn r5g5b5_to_rgb16(rgb: u16) -> Color16
    let r = rgb >> 10 & 0x1f;
    let g = rgb >> 5  & 0x1f;
    let b = rgb       & 0x1f;
-   Color16::new(r << 3 | r >> 2, g << 11, b << 11)
+   Color16::new(r << 11, g << 11, b << 11)
 }
 
 /// Creates a RGB16 color from a RGB8 format color.
@@ -30,14 +30,13 @@ pub fn rgb8_to_rgb16(r: u8, g: u8, b: u8) -> Color16
 }
 
 /// Writes a PPM file from an image.
-pub fn write_ppm<T>(out: &mut impl io::Write, im: &T) -> io::Result<()>
-   where T: Image
+pub fn write_ppm<T: Image>(out: &mut impl io::Write, im: &T) -> ResultS<()>
 {
    write!(out, "P3\n{} {}\n{}\n", im.w(), im.h(), T::Output::MAX)?;
 
    for y in 0..im.h() {
       for x in 0..im.w() {
-         let cr = im.cr_at(x, y);
+         let cr = im.cr_at(x, y).ok_or_else(|| err_msg("no data in image"))?;
          write!(out, "{} {} {} ", cr.r(), cr.g(), cr.b())?;
       }
    }
@@ -51,7 +50,7 @@ pub trait Image
 
    fn w(&self) -> usize;
    fn h(&self) -> usize;
-   fn cr_at(&self, x: usize, y: usize) -> &Self::Output;
+   fn cr_at(&self, x: usize, y: usize) -> Option<&Self::Output>;
 }
 
 pub trait Color
@@ -78,19 +77,12 @@ impl Image for Image16
 {
    type Output = Color16;
 
-   fn w(&self) -> usize
-   {
-      self.w
-   }
+   fn w(&self) -> usize {self.w}
+   fn h(&self) -> usize {self.h}
 
-   fn h(&self) -> usize
+   fn cr_at(&self, x: usize, y: usize) -> Option<&Color16>
    {
-      self.h
-   }
-
-   fn cr_at(&self, x: usize, y: usize) -> &Color16
-   {
-      &self.cr[x + y * self.w]
+      self.cr.get(x + y * self.w)
    }
 }
 
@@ -107,19 +99,12 @@ impl Image for Image8
 {
    type Output = Color8;
 
-   fn w(&self) -> usize
-   {
-      self.w
-   }
+   fn w(&self) -> usize {self.w}
+   fn h(&self) -> usize {self.h}
 
-   fn h(&self) -> usize
+   fn cr_at(&self, x: usize, y: usize) -> Option<&Color8>
    {
-      self.h
-   }
-
-   fn cr_at(&self, x: usize, y: usize) -> &Color8
-   {
-      &self.cr[x + y * self.w]
+      self.cr.get(x + y * self.w)
    }
 }
 
@@ -127,7 +112,7 @@ impl Color16
 {
    pub const fn new(r: u16, g: u16, b: u16) -> Color16
    {
-      Color16(r, g, b, u16::max_value())
+      Color16(r, g, b)
    }
 }
 
@@ -136,32 +121,17 @@ impl Color for Color16
    type Output = u16;
    const MAX: usize = u16::max_value() as usize;
 
-   fn r(&self) -> u16
-   {
-      self.0
-   }
-
-   fn g(&self) -> u16
-   {
-      self.1
-   }
-
-   fn b(&self) -> u16
-   {
-      self.2
-   }
-
-   fn a(&self) -> u16
-   {
-      self.3
-   }
+   fn r(&self) -> u16 {self.0}
+   fn g(&self) -> u16 {self.1}
+   fn b(&self) -> u16 {self.2}
+   fn a(&self) -> u16 {u16::max_value()}
 }
 
 impl Color8
 {
    pub const fn new(r: u8, g: u8, b: u8) -> Color8
    {
-      Color8(r, g, b, u8::max_value())
+      Color8(r, g, b)
    }
 }
 
@@ -170,34 +140,19 @@ impl Color for Color8
    type Output = u8;
    const MAX: usize = u8::max_value() as usize;
 
-   fn r(&self) -> u8
-   {
-      self.0
-   }
-
-   fn g(&self) -> u8
-   {
-      self.1
-   }
-
-   fn b(&self) -> u8
-   {
-      self.2
-   }
-
-   fn a(&self) -> u8
-   {
-      self.3
-   }
+   fn r(&self) -> u8 {self.0}
+   fn g(&self) -> u8 {self.1}
+   fn b(&self) -> u8 {self.2}
+   fn a(&self) -> u8 {u8::max_value()}
 }
 
 /// A RGB16 color.
 #[derive(Clone, Debug, PartialEq)]
-pub struct Color16(u16, u16, u16, u16);
+pub struct Color16(u16, u16, u16);
 
 /// A RGB8 color.
 #[derive(Clone, Debug, PartialEq)]
-pub struct Color8(u8, u8, u8, u8);
+pub struct Color8(u8, u8, u8);
 
 /// RGB16 image.
 pub struct Image16