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compositemode.go
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compositemode.go
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// Copyright 2018 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 driver
import (
"fmt"
)
type CompositeMode int
const (
CompositeModeUnknown CompositeMode = iota - 1
CompositeModeSourceOver // This value must be 0 (= initial value)
CompositeModeClear
CompositeModeCopy
CompositeModeDestination
CompositeModeDestinationOver
CompositeModeSourceIn
CompositeModeDestinationIn
CompositeModeSourceOut
CompositeModeDestinationOut
CompositeModeSourceAtop
CompositeModeDestinationAtop
CompositeModeXor
CompositeModeLighter
CompositeModeMax = CompositeModeLighter
)
type Operation int
const (
Zero Operation = iota
One
SrcAlpha
DstAlpha
OneMinusSrcAlpha
OneMinusDstAlpha
)
func (c CompositeMode) Operations() (src Operation, dst Operation) {
switch c {
case CompositeModeSourceOver:
return One, OneMinusSrcAlpha
case CompositeModeClear:
return Zero, Zero
case CompositeModeCopy:
return One, Zero
case CompositeModeDestination:
return Zero, One
case CompositeModeDestinationOver:
return OneMinusDstAlpha, One
case CompositeModeSourceIn:
return DstAlpha, Zero
case CompositeModeDestinationIn:
return Zero, SrcAlpha
case CompositeModeSourceOut:
return OneMinusDstAlpha, Zero
case CompositeModeDestinationOut:
return Zero, OneMinusSrcAlpha
case CompositeModeSourceAtop:
return DstAlpha, OneMinusSrcAlpha
case CompositeModeDestinationAtop:
return OneMinusDstAlpha, SrcAlpha
case CompositeModeXor:
return OneMinusDstAlpha, OneMinusSrcAlpha
case CompositeModeLighter:
return One, One
default:
panic(fmt.Sprintf("graphics: invalid composite mode: %d", c))
}
}