mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-14 06:57:27 +01:00
98 lines
2.5 KiB
Go
98 lines
2.5 KiB
Go
// Copyright 2018 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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// +build !js
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package devicescale
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import (
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"fmt"
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"syscall"
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)
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const logPixelSx = 88
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var (
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user32 = syscall.NewLazyDLL("user32")
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gdi32 = syscall.NewLazyDLL("gdi32")
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)
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var (
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procSetProcessDPIAware = user32.NewProc("SetProcessDPIAware")
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procGetWindowDC = user32.NewProc("GetWindowDC")
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procReleaseDC = user32.NewProc("ReleaseDC")
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procGetDeviceCaps = gdi32.NewProc("GetDeviceCaps")
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)
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func setProcessDPIAware() error {
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r, _, e := syscall.Syscall(procSetProcessDPIAware.Addr(), 0, 0, 0, 0)
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if e != 0 {
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return fmt.Errorf("devicescale: SetProcessDPIAware failed: error code: %d", e)
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}
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if r == 0 {
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return fmt.Errorf("devicescale: SetProcessDPIAware failed: returned value: %d", r)
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}
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return nil
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}
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func getWindowDC(hwnd uintptr) (uintptr, error) {
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r, _, e := syscall.Syscall(procGetWindowDC.Addr(), 1, hwnd, 0, 0)
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if e != 0 {
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return 0, fmt.Errorf("devicescale: GetWindowDC failed: error code: %d", e)
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}
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if r == 0 {
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return 0, fmt.Errorf("devicescale: GetWindowDC failed: returned value: %d", r)
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}
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return r, nil
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}
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func releaseDC(hwnd, hdc uintptr) error {
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r, _, e := syscall.Syscall(procReleaseDC.Addr(), 2, hwnd, hdc, 0)
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if e != 0 {
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return fmt.Errorf("devicescale: ReleaseDC failed: error code: %d", e)
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}
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if r == 0 {
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return fmt.Errorf("devicescale: ReleaseDC failed: returned value: %d", r)
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}
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return nil
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}
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func getDeviceCaps(hdc uintptr, nindex int) (int, error) {
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r, _, e := syscall.Syscall(procGetDeviceCaps.Addr(), 2, hdc, uintptr(nindex), 0)
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if e != 0 {
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return 0, fmt.Errorf("devicescale: GetDeviceCaps failed: error code: %d", e)
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}
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return int(r), nil
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}
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func impl() float64 {
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if err := setProcessDPIAware(); err != nil {
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panic(err)
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}
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dc, err := getWindowDC(0)
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if err != nil {
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panic(err)
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}
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dpi, err := getDeviceCaps(dc, logPixelSx)
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if err != nil {
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panic(err)
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}
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if err := releaseDC(0, dc); err != nil {
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panic(err)
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}
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return float64(dpi) / 96
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}
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