Make framebuffer an optional feature

Some users of libremarkable might want to use it only for its input
handling, but not for its framebuffer functionality. By disabling the
framebuffer feature, users can also avoid lots of dependencies (73
instead of 151 dependencies to install), some of which (e.g., zstd) even
need a C compiler.

The default features will build everything as before, so this will not
cause any compatibility issues.

Cargo.toml

@@ -12,25 +12,39 @@ edition = "2018"
 [dependencies]
 log = "0.4.8"
 env_logger = "0.7.1"
-ioctl-gen = "0.1.1"
+lazy_static = "1.4.0"
+atomic = "0.5.0"
+cgmath = "0.17.0"
 libc = "0.2.69"
-mmap = "0.1.1"
-rusttype = "0.8.2"
+
+# input
 evdev = "0.10.2"
 epoll = "4.1.0"
-image = "0.21.3"
-line_drawing = "0.8.0"
-hlua = "0.4.1"
-aabb-quadtree = "0.1.0"
-zstd = "0.5.1"
-stopwatch = "0.0.7"
-atomic = { version = "0.5.0" }
-cgmath = "0.17.0"
 fxhash = "0.2.1"
-lazy_static = "1.4.0"
+
+# framebuffer
+rusttype = { version = "0.8.2", optional = true }
+mmap = { version = "0.1.1", optional = true }
+image = { version = "0.21.3", optional = true }
+ioctl-gen = { version = "0.1.1", optional = true }
+line_drawing = { version = "0.8.0", optional = true }
+zstd = { version = "0.5.1", optional = true }
+
+# appctx
+aabb-quadtree = { version = "0.1.0", optional = true }
+hlua = { version = "0.4.1", optional = true }
+
+# runtime benchmarking
+stopwatch = { version = "0.0.7", optional = true }
+
 
 [features]
-enable-runtime-benchmarking = []
+default = ["framebuffer", "appctx"]
+
+framebuffer = ["rusttype", "mmap", "image", "ioctl-gen", "line_drawing", "zstd"]
+appctx = ["aabb-quadtree", "hlua"]
+
+enable-runtime-benchmarking = ["stopwatch"]
 
 [profile.release]
 debug = true

src/dimensions.rs

@@ -0,0 +1,16 @@
+use crate::input::scan::SCANNED;
+
+pub const DISPLAYWIDTH: u16 = 1404;
+pub const DISPLAYHEIGHT: u16 = 1872;
+
+lazy_static! {
+    /// Will be 767 rM1 and 1403 on the rM2
+    pub static ref MTWIDTH: u16 = SCANNED.mt_width;
+    /// Will be 1023 the rM1 and 1871 on the rM2
+    pub static ref MTHEIGHT: u16 = SCANNED.mt_height;
+
+    /// Will be 15725 on both the rM1 and rM2
+    pub static ref WACOMWIDTH: u16 = SCANNED.wacom_width;
+    /// Will be 20967 on the rM1 and 20966 on the rM2
+    pub static ref WACOMHEIGHT: u16 = SCANNED.wacom_height;
+}

src/framebuffer/common.rs

@@ -1,7 +1,9 @@
 #![allow(non_camel_case_types)]
 use crate::framebuffer::cgmath;
 use crate::framebuffer::mxcfb::*;
-use crate::input::scan::SCANNED;
+
+// Compatibility re-exports
+pub use crate::dimensions::{DISPLAYWIDTH, DISPLAYHEIGHT, MTWIDTH, MTHEIGHT, WACOMWIDTH, WACOMHEIGHT};
 
 /// This is to allow tests to run on systems with 64bit pointer types.
 /// It doesn't make a difference since we will be mocking the ioctl calls.
@@ -12,21 +14,6 @@ pub type NativeWidthType = i32;
 #[cfg(all(target_pointer_width = "32", target_env = "gnu"))]
 pub type NativeWidthType = u32;
 
-pub const DISPLAYWIDTH: u16 = 1404;
-pub const DISPLAYHEIGHT: u16 = 1872;
-
-lazy_static! {
-    /// Will be 767 rM1 and 1403 on the rM2
-    pub static ref MTWIDTH: u16 = SCANNED.mt_width;
-    /// Will be 1023 the rM1 and 1871 on the rM2
-    pub static ref MTHEIGHT: u16 = SCANNED.mt_height;
-
-    /// Will be 15725 on both the rM1 and rM2
-    pub static ref WACOMWIDTH: u16 = SCANNED.wacom_width;
-    /// Will be 20967 on the rM1 and 20966 on the rM2
-    pub static ref WACOMHEIGHT: u16 = SCANNED.wacom_height;
-}
-
 pub const MXCFB_SET_AUTO_UPDATE_MODE: NativeWidthType =
     iow!(b'F', 0x2D, std::mem::size_of::<u32>()) as NativeWidthType;
 pub const MXCFB_SET_UPDATE_SCHEME: NativeWidthType =

src/input/multitouch.rs

@@ -1,7 +1,7 @@
 use super::ecodes;
 use crate::device::CURRENT_DEVICE;
-use crate::framebuffer::cgmath;
-use crate::framebuffer::common::{DISPLAYHEIGHT, DISPLAYWIDTH, MTHEIGHT, MTWIDTH};
+use crate::cgmath;
+use crate::dimensions::{DISPLAYHEIGHT, DISPLAYWIDTH, MTHEIGHT, MTWIDTH};
 use crate::input::rotate::CoordinatePart;
 use crate::input::scan::SCANNED;
 use crate::input::{InputDeviceState, InputEvent};

src/input/wacom.rs

@@ -8,8 +8,8 @@ use evdev::raw::input_event;
 use log::debug;
 use std::sync::atomic::{AtomicU16, Ordering};
 
-use crate::framebuffer::cgmath;
-use crate::framebuffer::common::{DISPLAYHEIGHT, DISPLAYWIDTH, WACOMHEIGHT, WACOMWIDTH};
+use crate::cgmath;
+use crate::dimensions::{DISPLAYHEIGHT, DISPLAYWIDTH, WACOMHEIGHT, WACOMWIDTH};
 
 lazy_static! {
     static ref WACOM_HSCALAR: f32 = (DISPLAYWIDTH as f32) / (*WACOMWIDTH as f32);

src/lib.rs

@@ -31,6 +31,7 @@ macro_rules! end_bench {
     };
 }
 
+#[cfg(feature = "framebuffer")]
 #[macro_use]
 extern crate ioctl_gen;
 #[macro_use]
@@ -39,16 +40,23 @@ extern crate lazy_static;
 pub use cgmath;
 pub use epoll;
 pub use evdev;
+#[cfg(feature = "framebuffer")]
 pub use image;
+#[cfg(feature = "framebuffer")]
 pub use line_drawing;
+#[cfg(feature = "enable-runtime-benchmarking")]
 pub use stopwatch;
 
 /// One of the core components, allowing output and refresh of the EInk display
+#[cfg(feature = "framebuffer")]
 pub mod framebuffer;
 
 /// The other core component, allowing decoding of the three input devices present on the tablet
 pub mod input;
 
+/// Device dimensions.
+pub mod dimensions;
+
 /// Simple battery and charging status provider
 pub mod battery;
 
@@ -60,5 +68,7 @@ pub mod device;
 /// to a scene after wrapping them in `UIElementWrapper`. None of these are mandatory to be used.
 /// You can choose to entirely ignore the `ApplicationContext` and `ui_extensions` and interact
 /// with the `framebuffer` and `input` devices directly.
+#[cfg(all(feature = "framebuffer", feature = "appctx"))]
 pub mod appctx;
+#[cfg(all(feature = "framebuffer", feature = "appctx"))]
 pub mod ui_extensions;