webgl: Support preserveDrawingBuffer.

This commit is contained in:
Josh Matthews 2020-07-28 13:08:32 -04:00
parent 08328c22d6
commit a5e488bc2c
6 changed files with 29 additions and 21 deletions

View file

@ -40,7 +40,7 @@ style = { path = "../style" }
style_traits = { path = "../style_traits" }
# NOTE: the sm-angle feature only enables angle on windows, not other platforms!
surfman = { version = "0.3", features = ["sm-angle","sm-angle-default"] }
surfman-chains = "0.4"
surfman-chains = "0.5"
surfman-chains-api = "0.2"
time = { version = "0.1.0", optional = true }
webrender = { git = "https://github.com/servo/webrender" }

View file

@ -827,22 +827,30 @@ impl WebGLThread {
debug!("Swapping {:?}", context_id);
swap_chain
.swap_buffers(&mut self.device, &mut data.ctx)
.swap_buffers(
&mut self.device,
&mut data.ctx,
if data.attributes.preserve_drawing_buffer {
surfman_chains::PreserveBuffer::Yes(&*data.gl)
} else {
surfman_chains::PreserveBuffer::No
},
)
.unwrap();
debug_assert_eq!(data.gl.get_error(), gl::NO_ERROR);
// TODO: if preserveDrawingBuffer is true, then blit the front buffer to the back buffer
// https://github.com/servo/servo/issues/24604
debug!("Clearing {:?}", context_id);
let alpha = data
.state
.requested_flags
.contains(ContextAttributeFlags::ALPHA);
let clear_color = [0.0, 0.0, 0.0, !alpha as i32 as f32];
swap_chain
.clear_surface(&mut self.device, &mut data.ctx, &*data.gl, clear_color)
.unwrap();
debug_assert_eq!(data.gl.get_error(), gl::NO_ERROR);
if !data.attributes.preserve_drawing_buffer {
debug!("Clearing {:?}", context_id);
let alpha = data
.state
.requested_flags
.contains(ContextAttributeFlags::ALPHA);
let clear_color = [0.0, 0.0, 0.0, !alpha as i32 as f32];
swap_chain
.clear_surface(&mut self.device, &mut data.ctx, &*data.gl, clear_color)
.unwrap();
debug_assert_eq!(data.gl.get_error(), gl::NO_ERROR);
}
// Rebind framebuffers as appropriate.
debug!("Rebinding {:?}", context_id);