buf_js.go (1240B)
1 // Copyright 2019 The Ebiten Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package jsutil 16 17 import ( 18 "syscall/js" 19 ) 20 21 // temporaryBuffer is a temporary buffer used at gl.readPixels or gl.texSubImage2D. 22 // The read data is converted to Go's byte slice as soon as possible. 23 // To avoid often allocating ArrayBuffer, reuse the buffer whenever possible. 24 var temporaryBuffer = js.Global().Get("ArrayBuffer").New(16) 25 26 func TemporaryUint8Array(byteLength int) js.Value { 27 if bufl := temporaryBuffer.Get("byteLength").Int(); bufl < byteLength { 28 for bufl < byteLength { 29 bufl *= 2 30 } 31 temporaryBuffer = js.Global().Get("ArrayBuffer").New(bufl) 32 } 33 return js.Global().Get("Uint8Array").New(temporaryBuffer, 0, byteLength) 34 }