mirror of
https://github.com/hajimehoshi/ebiten.git
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79 lines
2.6 KiB
Go
79 lines
2.6 KiB
Go
// Copyright 2019 The Ebiten Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package jsutil
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import (
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"syscall/js"
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)
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// isTypedArrayWritable represents whether TypedArray is writable or not.
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// TypedArray's properties are not writable in the Web standard, but are writable with go2cpp.
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// This enables to avoid unnecessary allocations of js.Value.
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var isTypedArrayWritable = js.Global().Get("go2cpp").Truthy()
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// temporaryBuffer is a temporary buffer used at gl.readPixels or gl.texSubImage2D.
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// The read data is converted to Go's byte slice as soon as possible.
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// To avoid often allocating ArrayBuffer, reuse the buffer whenever possible.
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var temporaryBuffer = js.Global().Get("ArrayBuffer").New(16)
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func ensureTemporaryBufferSize(byteLength int) {
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if bufl := temporaryBuffer.Get("byteLength").Int(); bufl < byteLength {
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for bufl < byteLength {
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bufl *= 2
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}
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temporaryBuffer = js.Global().Get("ArrayBuffer").New(bufl)
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}
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}
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func TemporaryUint8Array(byteLength int) js.Value {
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ensureTemporaryBufferSize(byteLength)
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return uint8Array(temporaryBuffer, 0, byteLength)
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}
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var uint8ArrayObj js.Value
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func uint8Array(buffer js.Value, byteOffset, byteLength int) js.Value {
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if isTypedArrayWritable {
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if Equal(uint8ArrayObj, js.Undefined()) {
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uint8ArrayObj = js.Global().Get("Uint8Array").New()
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}
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uint8ArrayObj.Set("buffer", buffer)
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uint8ArrayObj.Set("byteOffset", byteOffset)
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uint8ArrayObj.Set("byteLength", byteLength)
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return uint8ArrayObj
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}
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return js.Global().Get("Uint8Array").New(buffer, byteOffset, byteLength)
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}
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func TemporaryFloat32Array(byteLength int) js.Value {
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ensureTemporaryBufferSize(byteLength)
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return float32Array(temporaryBuffer, 0, byteLength)
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}
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var float32ArrayObj js.Value
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func float32Array(buffer js.Value, byteOffset, byteLength int) js.Value {
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if isTypedArrayWritable {
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if Equal(float32ArrayObj, js.Undefined()) {
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float32ArrayObj = js.Global().Get("Float32Array").New()
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}
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float32ArrayObj.Set("buffer", buffer)
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float32ArrayObj.Set("byteOffset", byteOffset)
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float32ArrayObj.Set("byteLength", byteLength)
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return float32ArrayObj
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}
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return js.Global().Get("Float32Array").New(buffer, byteOffset/4, byteLength/4)
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}
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