2 files changed, 244 insertions, 0 deletions
diff --git a/gpu_display/src/gpu_display_stub.rs b/gpu_display/src/gpu_display_stub.rs
new file mode 100644
index 0000000..9b33a96
--- /dev/null
+++ b/gpu_display/src/gpu_display_stub.rs
@@ -0,0 +1,234 @@
+// Copyright 2020 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+use std::collections::BTreeMap;
+use std::num::NonZeroU32;
+use std::os::unix::io::{AsRawFd, RawFd};
+
+use crate::{DisplayT, EventDevice, GpuDisplayError, GpuDisplayFramebuffer};
+
+use data_model::VolatileSlice;
+use sys_util::EventFd;
+
+type SurfaceId = NonZeroU32;
+
+#[allow(unused_variables)]
+struct Buffer {
+    width: u32,
+    height: u32,
+    bytes_per_pixel: u32,
+    bytes_total: u64,
+    bytes: Vec<u8>,
+}
+
+impl Drop for Buffer {
+    fn drop(&mut self) {}
+}
+
+impl Buffer {
+    fn as_volatile_slice(&mut self) -> VolatileSlice {
+        unsafe { VolatileSlice::new(self.bytes.as_mut_ptr(), self.bytes_total) }
+    }
+
+    fn stride(&self) -> usize {
+        return (self.bytes_per_pixel as usize) * (self.width as usize);
+    }
+
+    fn bytes_per_pixel(&self) -> usize {
+        return self.bytes_per_pixel as usize;
+    }
+}
+
+struct Surface {
+    width: u32,
+    height: u32,
+    buffer: Option<Buffer>,
+}
+
+impl Surface {
+    fn create(width: u32, height: u32) -> Result<Surface, GpuDisplayError> {
+        Ok(Surface {
+            width,
+            height,
+            buffer: None,
+        })
+    }
+
+    /// Gets the buffer at buffer_index, allocating it if necessary.
+    fn lazily_allocate_buffer(&mut self) -> Option<&mut Buffer> {
+        if self.buffer.is_none() {
+            // XRGB8888
+            let bytes_per_pixel = 4;
+            let bytes_total = (self.width as u64) * (self.height as u64) * (bytes_per_pixel as u64);
+
+            self.buffer = Some(Buffer {
+                width: self.width,
+                height: self.height,
+                bytes_per_pixel,
+                bytes_total,
+                bytes: vec![0; bytes_total as usize],
+            });
+        }
+
+        self.buffer.as_mut()
+    }
+
+    /// Gets the next framebuffer, allocating if necessary.
+    fn framebuffer(&mut self) -> Option<GpuDisplayFramebuffer> {
+        let framebuffer = self.lazily_allocate_buffer()?;
+        let framebuffer_stride = framebuffer.stride() as u32;
+        let framebuffer_bytes_per_pixel = framebuffer.bytes_per_pixel() as u32;
+        Some(GpuDisplayFramebuffer::new(
+            framebuffer.as_volatile_slice(),
+            framebuffer_stride,
+            framebuffer_bytes_per_pixel,
+        ))
+    }
+
+    fn flip(&mut self) {}
+}
+
+impl Drop for Surface {
+    fn drop(&mut self) {}
+}
+
+struct SurfacesHelper {
+    next_surface_id: SurfaceId,
+    surfaces: BTreeMap<SurfaceId, Surface>,
+}
+
+impl SurfacesHelper {
+    fn new() -> SurfacesHelper {
+        SurfacesHelper {
+            next_surface_id: SurfaceId::new(1).unwrap(),
+            surfaces: Default::default(),
+        }
+    }
+
+    fn create_surface(&mut self, width: u32, height: u32) -> Result<u32, GpuDisplayError> {
+        let new_surface = Surface::create(width, height)?;
+        let new_surface_id = self.next_surface_id;
+
+        self.surfaces.insert(new_surface_id, new_surface);
+        self.next_surface_id = SurfaceId::new(self.next_surface_id.get() + 1).unwrap();
+
+        Ok(new_surface_id.get())
+    }
+
+    fn get_surface(&mut self, surface_id: u32) -> Option<&mut Surface> {
+        SurfaceId::new(surface_id).and_then(move |id| self.surfaces.get_mut(&id))
+    }
+
+    fn destroy_surface(&mut self, surface_id: u32) {
+        SurfaceId::new(surface_id).and_then(|id| self.surfaces.remove(&id));
+    }
+
+    fn flip_surface(&mut self, surface_id: u32) {
+        if let Some(surface) = self.get_surface(surface_id) {
+            surface.flip();
+        }
+    }
+}
+
+pub struct DisplayStub {
+    /// This eventfd is never triggered and is used solely to fulfill AsRawFd.
+    eventfd: EventFd,
+    surfaces: SurfacesHelper,
+}
+
+impl DisplayStub {
+    pub fn new() -> Result<DisplayStub, GpuDisplayError> {
+        let eventfd = EventFd::new().map_err(|_| GpuDisplayError::CreateEventFd)?;
+
+        Ok(DisplayStub {
+            eventfd,
+            surfaces: SurfacesHelper::new(),
+        })
+    }
+}
+
+impl DisplayT for DisplayStub {
+    fn dispatch_events(&mut self) {}
+
+    fn create_surface(
+        &mut self,
+        parent_surface_id: Option<u32>,
+        width: u32,
+        height: u32,
+    ) -> Result<u32, GpuDisplayError> {
+        if parent_surface_id.is_some() {
+            return Err(GpuDisplayError::Unsupported);
+        }
+        self.surfaces.create_surface(width, height)
+    }
+
+    fn release_surface(&mut self, surface_id: u32) {
+        self.surfaces.destroy_surface(surface_id);
+    }
+
+    fn framebuffer(&mut self, surface_id: u32) -> Option<GpuDisplayFramebuffer> {
+        self.surfaces
+            .get_surface(surface_id)
+            .and_then(|s| s.framebuffer())
+    }
+
+    fn next_buffer_in_use(&self, _surface_id: u32) -> bool {
+        false
+    }
+
+    fn flip(&mut self, surface_id: u32) {
+        self.surfaces.flip_surface(surface_id);
+    }
+
+    fn close_requested(&self, _surface_id: u32) -> bool {
+        false
+    }
+
+    fn import_dmabuf(
+        &mut self,
+        _fd: RawFd,
+        _offset: u32,
+        _stride: u32,
+        _modifiers: u64,
+        _width: u32,
+        _height: u32,
+        _fourcc: u32,
+    ) -> Result<u32, GpuDisplayError> {
+        Err(GpuDisplayError::Unsupported)
+    }
+
+    fn release_import(&mut self, _import_id: u32) {
+        // unsupported
+    }
+
+    fn commit(&mut self, _surface_id: u32) {
+        // unsupported
+    }
+
+    fn flip_to(&mut self, _surface_id: u32, _import_id: u32) {
+        // unsupported
+    }
+
+    fn set_position(&mut self, _surface_id: u32, _x: u32, _y: u32) {
+        // unsupported
+    }
+
+    fn import_event_device(&mut self, _event_device: EventDevice) -> Result<u32, GpuDisplayError> {
+        Err(GpuDisplayError::Unsupported)
+    }
+
+    fn release_event_device(&mut self, _event_device_id: u32) {
+        // unsupported
+    }
+
+    fn attach_event_device(&mut self, _surface_id: u32, _event_device_id: u32) {
+        // unsupported
+    }
+}
+
+impl AsRawFd for DisplayStub {
+    fn as_raw_fd(&self) -> RawFd {
+        self.eventfd.as_raw_fd()
+    }
+}
diff --git a/gpu_display/src/lib.rs b/gpu_display/src/lib.rs
index 1d9fcdc..07358a0 100644
--- a/gpu_display/src/lib.rs
+++ b/gpu_display/src/lib.rs
@@ -12,6 +12,7 @@ use data_model::VolatileSlice;
 use sys_util::Error as SysError;
 
 mod event_device;
+mod gpu_display_stub;
 mod gpu_display_wl;
 #[cfg(feature = "x")]
 mod gpu_display_x;
@@ -26,6 +27,8 @@ pub enum GpuDisplayError {
     Allocate,
     /// Connecting to the compositor failed.
     Connect,
+    /// Creating event file descriptor failed.
+    CreateEventFd,
     /// Creating shared memory failed.
     CreateShm(SysError),
     /// Setting the size of shared memory failed.
@@ -51,6 +54,7 @@ impl Display for GpuDisplayError {
         match self {
             Allocate => write!(f, "internal allocation failed"),
             Connect => write!(f, "failed to connect to compositor"),
+            CreateEventFd => write!(f, "failed to create event file descriptor"),
             CreateShm(e) => write!(f, "failed to create shared memory: {}", e),
             CreateSurface => write!(f, "failed to crate surface on the compositor"),
             FailedImport => write!(f, "failed to import a buffer to the compositor"),
@@ -197,6 +201,12 @@ impl GpuDisplay {
         Ok(GpuDisplay { inner })
     }
 
+    pub fn open_stub() -> Result<GpuDisplay, GpuDisplayError> {
+        let display = gpu_display_stub::DisplayStub::new()?;
+        let inner = Box::new(display);
+        Ok(GpuDisplay { inner })
+    }
+
     /// Imports a dmabuf to the compositor for use as a surface buffer and returns a handle to it.
     pub fn import_dmabuf(
         &mut self,