ebiten/internal/jsutil/buf_js.go

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// Copyright 2019 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
2020-04-14 17:58:14 +02:00
// +build !monogame
package jsutil
import (
"syscall/js"
)
// temporaryBuffer is a temporary buffer used at gl.readPixels or gl.texSubImage2D.
// The read data is converted to Go's byte slice as soon as possible.
// To avoid often allocating ArrayBuffer, reuse the buffer whenever possible.
var temporaryBuffer = js.Global().Get("ArrayBuffer").New(16)
func TemporaryUint8Array(byteLength int) js.Value {
if bufl := temporaryBuffer.Get("byteLength").Int(); bufl < byteLength {
for bufl < byteLength {
bufl *= 2
}
temporaryBuffer = js.Global().Get("ArrayBuffer").New(bufl)
}
return js.Global().Get("Uint8Array").New(temporaryBuffer, 0, byteLength)
}