// 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. package jsutil import ( "syscall/js" ) var ( arrayBuffer = js.Global().Get("ArrayBuffer") uint8Array = js.Global().Get("Uint8Array") float32Array = js.Global().Get("Float32Array") ) var ( // temporaryArrayBuffer 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. temporaryArrayBuffer = arrayBuffer.New(16) // temporaryUint8Array is a Uint8ArrayBuffer whose underlying buffer is always temporaryArrayBuffer. temporaryUint8Array = uint8Array.New(temporaryArrayBuffer) // temporaryFloat32Array is a Float32ArrayBuffer whose underlying buffer is always temporaryArrayBuffer. temporaryFloat32Array = float32Array.New(temporaryArrayBuffer) ) func ensureTemporaryArrayBufferSize(byteLength int) { bufl := temporaryArrayBuffer.Get("byteLength").Int() if bufl < byteLength { for bufl < byteLength { bufl *= 2 } temporaryArrayBuffer = arrayBuffer.New(bufl) } if temporaryUint8Array.Get("byteLength").Int() < bufl { temporaryUint8Array = uint8Array.New(temporaryArrayBuffer) } if temporaryFloat32Array.Get("byteLength").Int() < bufl { temporaryFloat32Array = float32Array.New(temporaryArrayBuffer) } } // TemporaryUint8Array returns a Uint8Array whose length is at least minLength. // Be careful that the length can exceed the given minLength. // data must be a slice of a numeric type for initialization, or nil if you don't need initialization. func TemporaryUint8Array(minLength int, data interface{}) js.Value { ensureTemporaryArrayBufferSize(minLength) if data != nil { copySliceToTemporaryArrayBuffer(data) } return temporaryUint8Array } // TemporaryFloat32Array returns a Float32Array whose length is at least minLength. // Be careful that the length can exceed the given minLength. // data must be a slice of a numeric type for initialization, or nil if you don't need initialization. func TemporaryFloat32Array(minLength int, data interface{}) js.Value { ensureTemporaryArrayBufferSize(minLength * 4) if data != nil { copySliceToTemporaryArrayBuffer(data) } return temporaryFloat32Array }