ebiten/internal/devicescale/devicescale_windows.go
2018-01-03 16:24:53 +09:00

98 lines
2.5 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.
// +build !js
package devicescale
import (
"fmt"
"syscall"
)
const logPixelSx = 88
var (
user32 = syscall.NewLazyDLL("user32")
gdi32 = syscall.NewLazyDLL("gdi32")
)
var (
procSetProcessDPIAware = user32.NewProc("SetProcessDPIAware")
procGetWindowDC = user32.NewProc("GetWindowDC")
procReleaseDC = user32.NewProc("ReleaseDC")
procGetDeviceCaps = gdi32.NewProc("GetDeviceCaps")
)
func setProcessDPIAware() error {
r, _, e := syscall.Syscall(procSetProcessDPIAware.Addr(), 0, 0, 0, 0)
if e != 0 {
return fmt.Errorf("devicescale: SetProcessDPIAware failed: error code: %d", e)
}
if r == 0 {
return fmt.Errorf("devicescale: SetProcessDPIAware failed: returned value: %d", r)
}
return nil
}
func getWindowDC(hwnd uintptr) (uintptr, error) {
r, _, e := syscall.Syscall(procGetWindowDC.Addr(), 1, hwnd, 0, 0)
if e != 0 {
return 0, fmt.Errorf("devicescale: GetWindowDC failed: error code: %d", e)
}
if r == 0 {
return 0, fmt.Errorf("devicescale: GetWindowDC failed: returned value: %d", r)
}
return r, nil
}
func releaseDC(hwnd, hdc uintptr) error {
r, _, e := syscall.Syscall(procReleaseDC.Addr(), 2, hwnd, hdc, 0)
if e != 0 {
return fmt.Errorf("devicescale: ReleaseDC failed: error code: %d", e)
}
if r == 0 {
return fmt.Errorf("devicescale: ReleaseDC failed: returned value: %d", r)
}
return nil
}
func getDeviceCaps(hdc uintptr, nindex int) (int, error) {
r, _, e := syscall.Syscall(procGetDeviceCaps.Addr(), 2, hdc, uintptr(nindex), 0)
if e != 0 {
return 0, fmt.Errorf("devicescale: GetDeviceCaps failed: error code: %d", e)
}
return int(r), nil
}
func impl() float64 {
if err := setProcessDPIAware(); err != nil {
panic(err)
}
dc, err := getWindowDC(0)
if err != nil {
panic(err)
}
dpi, err := getDeviceCaps(dc, logPixelSx)
if err != nil {
panic(err)
}
if err := releaseDC(0, dc); err != nil {
panic(err)
}
return float64(dpi) / 96
}