Add a Device::resize_bound_surface API

Much like #361, this change adds a `Device::resize_bound_surface` API so
that widget surfaces can be resized without introducing a spurious
`eglMakeCurrent` with `NO_SURFACE`. This will greatly improve resizing
behavior in Servo.

Signed-off-by: Martin Robinson <martin@abandonedwig.info>

Author: mrobinson

src/device.rs

@@ -224,6 +224,13 @@ where
         surface: &mut Self::Surface,
     ) -> Result<(), Error>;
 
+    /// If the currently bound surface is a widget surface, resize it,
+    fn resize_bound_surface(
+        &self,
+        context: &mut Self::Context,
+        size: Size2D<i32>,
+    ) -> Result<(), Error>;
+
     /// Resizes a widget surface.
     fn resize_surface(
         &self,

src/macros.rs

@@ -336,6 +336,15 @@ macro_rules! implement_interfaces {
                     Device::present_surface(self, context, surface)
                 }
 
+                #[inline]
+                fn resize_bound_surface(
+                    &self,
+                    context: &mut Context,
+                    size: Size2D<i32>,
+                ) -> Result<(), Error> {
+                    Device::resize_bound_surface(self, context, size)
+                }
+
                 #[inline]
                 fn resize_surface(
                     &self,

src/platform/egl/context.rs

@@ -15,6 +15,7 @@ use crate::platform::generic::egl::error::ToWindowingApiError;
 use crate::platform::generic::egl::surface::ExternalEGLSurfaces;
 use crate::surface::Framebuffer;
 use crate::{ContextAttributes, Error, Gl, SurfaceInfo};
+use euclid::default::Size2D;
 
 use std::mem;
 use std::os::raw::c_void;
@@ -317,6 +318,18 @@ impl Device {
         }
     }
 
+    /// If the currently bound surface is a widget surface, resize it,
+    pub fn resize_bound_surface(
+        &self,
+        context: &mut Context,
+        size: Size2D<i32>,
+    ) -> Result<(), Error> {
+        if let Framebuffer::Surface(surface) = &mut context.framebuffer {
+            surface.resize(size);
+        }
+        Ok(())
+    }
+
     /// Returns the attributes that the context descriptor was created with.
     pub fn context_descriptor_attributes(
         &self,

src/platform/egl/surface/android_surface.rs

@@ -209,17 +209,6 @@ impl Device {
         }
     }
 
-    /// Resizes a widget surface.
-    pub fn resize_surface(
-        &self,
-        _context: &Context,
-        surface: &mut Surface,
-        size: Size2D<i32>,
-    ) -> Result<(), Error> {
-        surface.size = size;
-        Ok(())
-    }
-
     #[allow(non_snake_case)]
     unsafe fn create_egl_image(
         &self,

src/platform/egl/surface/mod.rs

@@ -82,6 +82,12 @@ impl Drop for Surface {
     }
 }
 
+impl Surface {
+    pub(crate) fn resize(&mut self, size: Size2D<i32>) {
+        self.size = size;
+    }
+}
+
 impl Debug for SurfaceTexture {
     fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
         write!(f, "SurfaceTexture({:?})", self.surface)
@@ -119,4 +125,15 @@ impl Device {
             }
         })
     }
+
+    /// Resizes a widget surface.
+    pub fn resize_surface(
+        &self,
+        _context: &Context,
+        surface: &mut Surface,
+        size: Size2D<i32>,
+    ) -> Result<(), Error> {
+        surface.resize(size);
+        Ok(())
+    }
 }

src/platform/egl/surface/ohos_surface.rs

@@ -211,17 +211,6 @@ impl Device {
         }
     }
 
-    /// Resizes a widget surface.
-    pub fn resize_surface(
-        &self,
-        _context: &Context,
-        surface: &mut Surface,
-        size: Size2D<i32>,
-    ) -> Result<(), Error> {
-        surface.size = size;
-        Ok(())
-    }
-
     #[allow(non_snake_case)]
     unsafe fn create_egl_image(
         &self,

src/platform/generic/egl/context.rs

@@ -13,6 +13,7 @@ use crate::egl::types::{EGLConfig, EGLContext, EGLDisplay, EGLSurface, EGLint};
 use crate::surface::Framebuffer;
 use crate::{ContextAttributeFlags, ContextAttributes, ContextID, Error, GLApi, GLVersion};
 use crate::{Gl, SurfaceInfo};
+use euclid::default::Size2D;
 use glow::HasContext;
 
 use std::ffi::CString;
@@ -29,7 +30,7 @@ pub(crate) struct EGLBackedContext {
     pub(crate) egl_context: EGLContext,
     pub(crate) id: ContextID,
     pbuffer: EGLSurface,
-    framebuffer: Framebuffer<EGLBackedSurface, ExternalEGLSurfaces>,
+    pub(crate) framebuffer: Framebuffer<EGLBackedSurface, ExternalEGLSurfaces>,
     context_is_owned: bool,
 }
 
@@ -274,13 +275,20 @@ impl EGLBackedContext {
         Ok(Some(surface))
     }
 
-    pub fn present_bound_surface(&self, egl_display: EGLDisplay) -> Result<(), Error> {
+    pub(crate) fn present_bound_surface(&self, egl_display: EGLDisplay) -> Result<(), Error> {
         match &self.framebuffer {
             Framebuffer::Surface(surface) => surface.present(egl_display, self.egl_context),
             Framebuffer::None | Framebuffer::External(_) => Ok(()),
         }
     }
 
+    pub(crate) fn resize_bound_surface(&mut self, size: Size2D<i32>) -> Result<(), Error> {
+        if let Framebuffer::Surface(surface) = &mut self.framebuffer {
+            surface.resize(size);
+        }
+        Ok(())
+    }
+
     pub(crate) fn surface_info(&self) -> Result<Option<SurfaceInfo>, Error> {
         match self.framebuffer {
             Framebuffer::None => Ok(None),

src/platform/generic/egl/surface.rs

@@ -353,6 +353,10 @@ impl EGLBackedSurface {
             EGLSurfaceObjects::TextureImage { .. } => ExternalEGLSurfaces::default(),
         }
     }
+
+    pub(crate) fn resize(&mut self, size: Size2D<i32>) {
+        self.size = size;
+    }
 }
 
 impl EGLSurfaceTexture {

src/platform/generic/multi/context.rs

@@ -2,6 +2,8 @@
 //
 //! A context abstraction that allows the choice of backends dynamically.
 
+use euclid::default::Size2D;
+
 use super::device::Device;
 use super::surface::Surface;
 use crate::device::Device as DeviceInterface;
@@ -281,6 +283,23 @@ where
         }
     }
 
+    /// Resizes the currently bound surface.
+    pub fn resize_bound_surface(
+        &self,
+        context: &mut Context<Def, Alt>,
+        size: Size2D<i32>,
+    ) -> Result<(), Error> {
+        match (self, context) {
+            (Device::Default(device), Context::Default(context)) => {
+                device.resize_bound_surface(context, size)
+            }
+            (Device::Alternate(device), Context::Alternate(context)) => {
+                device.resize_bound_surface(context, size)
+            }
+            _ => Err(Error::IncompatibleContext),
+        }
+    }
+
     /// Returns the attributes that the context descriptor was created with.
     pub fn context_descriptor_attributes(
         &self,

src/platform/generic/multi/device.rs

@@ -289,6 +289,15 @@ where
         Device::present_bound_surface(self, context)
     }
 
+    #[inline]
+    fn resize_bound_surface(
+        &self,
+        context: &mut Self::Context,
+        size: Size2D<i32>,
+    ) -> Result<(), Error> {
+        Device::resize_bound_surface(&self, context, size)
+    }
+
     #[inline]
     fn present_surface(
         &self,