update

src/xlib/image.rs

@@ -1,22 +1,19 @@
-//! XImage
-//! ======
-//!
-//! Xlib provides some structures to perform operations on images. However, because there are
-//! different in-memory representations, working with images is actually totally fucked. If you
-//! want to maintain your sanity, do NOT pry into the raw data buffer of an Image. Instead, index
-//! into the image using `PixBuffer::get_pixel` which already performs the conversion and returns a
-//! tuple of RGB values.
-//!
-//! Peeking into the raw data buffer of an Image
-//! --------------------------------------------
-//!
-//! Images consist of lines of longs in row-major form.
-
 use x11::xlib;
 
 use crate::errors::{Error, Result};
 
-/// A handle to an XImage.
+/// A handle to an XImage
+///
+/// Xlib provides some structures to perform operations on images. However, because there are
+/// different in-memory representations, working with images is actually totally fucked. If you
+/// want to maintain your sanity, do NOT pry into the raw data buffer of an Image. Instead, index
+/// into the image using `PixBuffer::get_pixel` which already performs the conversion and returns a
+/// tuple of RGB values.
+///
+/// Peeking into the raw data buffer of an Image
+/// --------------------------------------------
+///
+/// Images consist of lines of longs in row-major form.
 pub struct Image {
     pub(super) inner: *mut xlib::XImage,
 }
@@ -29,20 +26,6 @@ pub enum ImageByteOrder {
     MSBFirst,
 }
 
-/// The buffer pointed to by an XImage.
-pub struct PixBuffer<'a> {
-    /// The raw pointer to the buffer
-    pub buf: *mut u8,
-
-    /// The size of the buffer
-    pub size: usize,
-
-    /// Rgb masks
-    pub masks: (u64, u64, u64),
-
-    pub image: &'a Image,
-}
-
 impl Image {
     /// Get the size (in bytes) of the data buffer.
     pub fn get_size(&self) -> usize {
@@ -64,7 +47,7 @@ impl Image {
         unsafe { (*self.inner).depth as u32 }
     }
 
-    /// Get byte order
+    /// Get byte order (LSB or MSB)
     pub fn get_byte_order(&self) -> Result<ImageByteOrder> {
         let byte_order = unsafe { (*self.inner).byte_order };
         match byte_order {
@@ -81,7 +64,7 @@ impl Image {
         (red_mask, blue_mask, green_mask)
     }
 
-    /// Produces a PixBuffer
+    /// Produces a PixBuffer.
     pub fn buffer(&self) -> PixBuffer {
         let size = self.get_size();
         let buf = unsafe { (*self.inner).data as *mut u8 };
@@ -101,34 +84,43 @@ impl Drop for Image {
     }
 }
 
+/// The buffer pointed to by an XImage.
+pub struct PixBuffer<'a> {
+    /// The raw pointer to the buffer
+    pub buf: *mut u8,
+
+    /// The size of the buffer
+    pub size: usize,
+
+    /// Rgb masks
+    pub masks: (u64, u64, u64),
+
+    pub image: &'a Image,
+}
+
 impl<'a> PixBuffer<'a> {
-    /// Gets the byte at the index of the data buffer.
-    pub fn get_byte(&self, index: usize) -> Option<u8> {
-        if index > self.size {
-            return None;
-        }
-        Some(unsafe { *self.buf.offset(index as isize) as u8 })
+    /// Retrieve a direct reference to the internal buffer.
+    pub fn get_buffer(&self) -> &[u8] {
+        unsafe { std::slice::from_raw_parts(self.buf, self.size) }
     }
 
-    /// Gets the rgb value of a particular pixel
+    /// Gets the rgb value of a particular pixel, after performing conversion
+    ///
+    /// This uses XImage's get_pixel function to retrieve the pixel value, and then the various
+    /// red/green/blue masks to actually perform the conversions, and fails (returns `None`) if the
+    /// (x, y) coordinates given aren't actually in the image.
     pub fn get_pixel(&self, x: u32, y: u32) -> Option<(u8, u8, u8)> {
-        // let bytes_per_line = unsafe{(*self.image.inner).bytes_per_line} as u32;
-        // let bits_per_pixel=unsafe{(*self.image.inner).bits_per_pixel} as u32;
-        // let pixel_ptr = (y * bytes_per_line + x * bits_per_pixel) / 8;
-        // let pixel = unsafe{*((*self.image.inner).data.offset(pixel_ptr as isize) as *mut c_ulong)};
-
         let get_pixel = unsafe { (*self.image.inner).funcs.get_pixel }.unwrap();
         let pixel = unsafe { get_pixel(self.image.inner, x as i32, y as i32) };
 
-        // warn!("pixel: {:?} {:#b}", pixel, pixel);
         let red_mask = unsafe { (*self.image.inner).red_mask };
         let green_mask = unsafe { (*self.image.inner).green_mask };
         let blue_mask = unsafe { (*self.image.inner).blue_mask };
-        // warn!("masks: {:b} {:b} {:b}", red_mask, green_mask, blue_mask);
-        let red = ((pixel & unsafe { (*self.image.inner).red_mask }) >> 16) as u8;
-        let green = ((pixel & unsafe { (*self.image.inner).green_mask }) >> 8) as u8;
-        let blue = ((pixel & unsafe { (*self.image.inner).blue_mask }) >> 0) as u8;
-        // warn!("rgb: {:?}", (red, green, blue));
+
+        let red = ((pixel & red_mask) >> 16) as u8;
+        let green = ((pixel & green_mask) >> 8) as u8;
+        let blue = ((pixel & blue_mask) >> 0) as u8;
+
         Some((red, green, blue))
     }
 }

src/xlib/mod.rs

@@ -12,6 +12,6 @@ pub use self::cursor::Cursor;
 pub use self::display::{Display, GetDisplay};
 pub use self::drawable::Drawable;
 pub use self::event::{Event, EventKind};
-pub use self::image::{Image, ImageByteOrder};
+pub use self::image::{Image, ImageByteOrder, PixBuffer};
 pub use self::visual::Visual;
 pub use self::window::{EventMask, Window};