ebiten/internal/jsutil/go113_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.
// +build go1.13
package jsutil
import (
"fmt"
"reflect"
"runtime"
"syscall/js"
"unsafe"
)
func Uint8ArrayToSlice(value js.Value) []byte {
s := make([]byte, value.Get("byteLength").Int())
js.CopyBytesToGo(s, value)
return s
}
func ArrayBufferToSlice(value js.Value) []byte {
return Uint8ArrayToSlice(js.Global().Get("Uint8Array").New(value))
}
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func sliceToByteSlice(s interface{}) (bs []byte) {
switch s := s.(type) {
case []int8:
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
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bs = *(*[]byte)(unsafe.Pointer(h))
runtime.KeepAlive(s)
case []int16:
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
h.Len *= 2
h.Cap *= 2
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bs = *(*[]byte)(unsafe.Pointer(h))
runtime.KeepAlive(s)
case []int32:
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
h.Len *= 4
h.Cap *= 4
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bs = *(*[]byte)(unsafe.Pointer(h))
runtime.KeepAlive(s)
case []int64:
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
h.Len *= 8
h.Cap *= 8
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bs = *(*[]byte)(unsafe.Pointer(h))
runtime.KeepAlive(s)
case []uint8:
return s
case []uint16:
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
h.Len *= 2
h.Cap *= 2
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bs = *(*[]byte)(unsafe.Pointer(h))
runtime.KeepAlive(s)
case []uint32:
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
h.Len *= 4
h.Cap *= 4
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bs = *(*[]byte)(unsafe.Pointer(h))
runtime.KeepAlive(s)
case []uint64:
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
h.Len *= 8
h.Cap *= 8
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bs = *(*[]byte)(unsafe.Pointer(h))
runtime.KeepAlive(s)
case []float32:
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
h.Len *= 4
h.Cap *= 4
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bs = *(*[]byte)(unsafe.Pointer(h))
runtime.KeepAlive(s)
case []float64:
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
h.Len *= 8
h.Cap *= 8
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bs = *(*[]byte)(unsafe.Pointer(h))
runtime.KeepAlive(s)
default:
panic(fmt.Sprintf("jsutil: unexpected value at sliceToBytesSlice: %T", s))
}
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return
}
func CopySliceToJS(dst js.Value, src interface{}) {
switch s := src.(type) {
case []uint8:
js.CopyBytesToJS(dst, s)
case []int8, []int16, []int32, []uint16, []uint32, []float32, []float64:
a := js.Global().Get("Uint8Array").New(dst.Get("buffer"), dst.Get("byteOffset"), dst.Get("byteLength"))
js.CopyBytesToJS(a, sliceToByteSlice(s))
default:
panic(fmt.Sprintf("jsutil: unexpected value at CopySliceToJS: %T", s))
}
}