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// SPDX-License-Identifier: Unlicense OR MIT
package window
import (
"errors"
"syscall/js"
"gioui.org/app/internal/glimpl"
"gioui.org/app/internal/srgb"
"gioui.org/gpu/backend"
"gioui.org/gpu/gl"
)
type context struct {
ctx js.Value
cnv js.Value
f *glimpl.Functions
srgbFBO *srgb.FBO
}
func newContext(w *window) (*context, error) {
args := map[string]interface{}{
// Enable low latency rendering.
// See https://developers.google.com/web/updates/2019/05/desynchronized.
"desynchronized": true,
"preserveDrawingBuffer": true,
}
version := 2
ctx := w.cnv.Call("getContext", "webgl2", args)
if ctx.IsNull() {
version = 1
ctx = w.cnv.Call("getContext", "webgl", args)
}
if ctx.IsNull() {
return nil, errors.New("app: webgl is not supported")
}
f := &glimpl.Functions{Ctx: ctx}
if err := f.Init(version); err != nil {
return nil, err
}
c := &context{
ctx: ctx,
cnv: w.cnv,
f: f,
}
return c, nil
}
func (c *context) Backend() (backend.Device, error) {
return gl.NewBackend(c.f)
}
func (c *context) Release() {
if c.srgbFBO != nil {
c.srgbFBO.Release()
c.srgbFBO = nil
}
}
func (c *context) Present() error {
if c.srgbFBO != nil {
c.srgbFBO.Blit()
}
if c.srgbFBO != nil {
c.srgbFBO.AfterPresent()
}
if c.ctx.Call("isContextLost").Bool() {
return errors.New("context lost")
}
return nil
}
func (c *context) Lock() {}
func (c *context) Unlock() {}
func (c *context) MakeCurrent() error {
if c.srgbFBO == nil {
var err error
c.srgbFBO, err = srgb.New(c.f)
if err != nil {
c.Release()
c.srgbFBO = nil
return err
}
}
w, h := c.cnv.Get("width").Int(), c.cnv.Get("height").Int()
if err := c.srgbFBO.Refresh(w, h); err != nil {
c.Release()
return err
}
return nil
}
func (w *window) NewContext() (Context, error) {
return newContext(w)
}
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