ebiten/internal/devicescale/devicescale.go
2021-04-17 18:14:26 +09:00

48 lines
1.2 KiB
Go

// 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 devicescale
import (
"sync"
)
type pos struct {
x, y int
}
var (
m sync.Mutex
cache = map[pos]float64{}
)
// GetAt returns the device scale at (x, y).
// x and y are in device-dependent pixels.
func GetAt(x, y int) float64 {
m.Lock()
defer m.Unlock()
if s, ok := cache[pos{x, y}]; ok {
return s
}
s := impl(x, y)
cache[pos{x, y}] = s
// TODO: Provide a way to invalidate the cache, or move the cache.
// The device scale can vary even for the same monitor.
// The only known case is when the application works on macOS, with OpenGL, with a wider screen mode,
// and in the fullscreen mode (#1573).
return s
}