internal/ui: move impls for device scale to internal/ui for desktops

This enables to remove restrictions for some functions to be called
from the main thread.

Updates #2423

internal/devicescale/devicescale.go

@@ -1,66 +0,0 @@
-// 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.
-
-//go:build !android && !ios && !js
-
-package devicescale
-
-import (
-	"sync"
-)
-
-type posAndScale struct {
-	x, y  int
-	scale float64
-}
-
-var (
-	m     sync.Mutex
-	cache []posAndScale
-)
-
-// GetAt returns the device scale at (x, y), i.e. the number of device-dependent pixels per device-independent pixel.
-// x and y are in device-dependent pixels and must be the top-left coordinate of a monitor, or 0,0 to request a "global scale".
-func GetAt(x, y int) float64 {
-	m.Lock()
-	defer m.Unlock()
-
-	for _, p := range cache {
-		if p.x == x && p.y == y {
-			return p.scale
-		}
-	}
-
-	s := impl(x, y)
-	cache = append(cache, posAndScale{
-		x:     x,
-		y:     y,
-		scale: s,
-	})
-	return s
-}
-
-// ClearCache clears the cache.
-// This should be called when monitors are changed by connecting or disconnecting.
-func ClearCache() {
-	// TODO: This should be called not only when monitors are changed but also a monitor's scales are changed.
-	// 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).
-
-	m.Lock()
-	defer m.Unlock()
-
-	cache = cache[:0]
-}

internal/devicescale/impl_desktop.go

@@ -1,51 +0,0 @@
-// Copyright 2021 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.
-
-//go:build !android && !ios && !js
-
-package devicescale
-
-import (
-	"github.com/hajimehoshi/ebiten/v2/internal/glfw"
-)
-
-func monitorAt(x, y int) *glfw.Monitor {
-	// Note: this assumes that x, y are exact monitor origins.
-	// If they're not, this arbitrarily returns the first monitor.
-	monitors := glfw.GetMonitors()
-	for _, mon := range monitors {
-		mx, my := mon.GetPos()
-		if x == mx && y == my {
-			return mon
-		}
-	}
-	return monitors[0]
-}
-
-func impl(x, y int) float64 {
-	// Keep calling GetContentScale until the returned scale is 0 (#2051).
-	// Retry this at most 5 times to avoid an infinite loop.
-	for i := 0; i < 5; i++ {
-		// An error can happen e.g. when entering a screensaver on Windows (#2488).
-		sx, _, err := monitorAt(x, y).GetContentScale()
-		if err != nil {
-			continue
-		}
-		if sx == 0 {
-			continue
-		}
-		return float64(sx)
-	}
-	return 1
-}

internal/ui/monitor_glfw.go

@@ -20,7 +20,6 @@ import (
 	"sync"
 	"sync/atomic"
 
-	"github.com/hajimehoshi/ebiten/v2/internal/devicescale"
 	"github.com/hajimehoshi/ebiten/v2/internal/glfw"
 )
 
@@ -33,6 +32,7 @@ type Monitor struct {
 	name           string
 	x              int
 	y              int
+	contentScale   float64
 	videoModeScale float64
 }
 
@@ -90,6 +90,25 @@ func (m *monitors) update() {
 	newMonitors := make([]*Monitor, 0, len(glfwMonitors))
 	for i, m := range glfwMonitors {
 		x, y := m.GetPos()
+
+		// TODO: Detect the update of the content scale by SetContentScaleCallback (#2343).
+		contentScale := 1.0
+
+		// Keep calling GetContentScale until the returned scale is 0 (#2051).
+		// Retry this at most 5 times to avoid an infinite loop.
+		for i := 0; i < 5; i++ {
+			// An error can happen e.g. when entering a screensaver on Windows (#2488).
+			sx, _, err := m.GetContentScale()
+			if err != nil {
+				continue
+			}
+			if sx == 0 {
+				continue
+			}
+			contentScale = float64(sx)
+			break
+		}
+
 		newMonitors = append(newMonitors, &Monitor{
 			m:              m,
 			videoMode:      m.GetVideoMode(),
@@ -97,6 +116,7 @@ func (m *monitors) update() {
 			name:           m.GetName(),
 			x:              x,
 			y:              y,
+			contentScale:   contentScale,
 			videoModeScale: videoModeScale(m),
 		})
 	}
@@ -105,7 +125,5 @@ func (m *monitors) update() {
 	m.monitors = newMonitors
 	m.m.Unlock()
 
-	devicescale.ClearCache()
-
 	atomic.StoreInt32(&m.updateCalled, 1)
 }

internal/ui/ui_glfw.go

@@ -27,7 +27,6 @@ import (
 	"sync/atomic"
 	"time"
 
-	"github.com/hajimehoshi/ebiten/v2/internal/devicescale"
 	"github.com/hajimehoshi/ebiten/v2/internal/file"
 	"github.com/hajimehoshi/ebiten/v2/internal/gamepad"
 	"github.com/hajimehoshi/ebiten/v2/internal/glfw"
@@ -239,12 +238,9 @@ func (u *userInterfaceImpl) Monitor() *Monitor {
 
 // getMonitorFromPosition returns a monitor for the given window x/y,
 // or returns nil if monitor is not found.
-//
-// getMonitorFromPosition must be called on the main thread.
 func getMonitorFromPosition(wx, wy int) *Monitor {
 	for _, m := range theMonitors.append(nil) {
 		// TODO: Fix incorrectness in the cases of https://github.com/glfw/glfw/issues/1961.
-		// See also internal/devicescale/impl_desktop.go for a maybe better way of doing this.
 		if m.x <= wx && wx < m.x+m.videoMode.Width && m.y <= wy && wy < m.y+m.videoMode.Height {
 			return m
 		}
@@ -759,7 +755,6 @@ func (u *userInterfaceImpl) DeviceScaleFactor() float64 {
 	return f
 }
 
-// deviceScaleFactor must be called from the main thread.
 func (u *userInterfaceImpl) deviceScaleFactor(monitor *Monitor) float64 {
 	// It is rare, but monitor can be nil when glfw.GetPrimaryMonitor returns nil.
 	// In this case, return 1 as a tentative scale (#1878).
@@ -767,7 +762,7 @@ func (u *userInterfaceImpl) deviceScaleFactor(monitor *Monitor) float64 {
 		return 1
 	}
 
-	return devicescale.GetAt(monitor.x, monitor.y)
+	return monitor.contentScale
 }
 
 func init() {

internal/ui/ui_glfw_linbsd.go

@@ -110,17 +110,14 @@ func videoModeScale(m *glfw.Monitor) float64 {
 	return 1
 }
 
-// dipFromGLFWMonitorPixel must be called from the main thread.
 func (u *userInterfaceImpl) dipFromGLFWMonitorPixel(x float64, monitor *Monitor) float64 {
 	return x / (monitor.videoModeScale * u.deviceScaleFactor(monitor))
 }
 
-// dipFromGLFWPixel must be called from the main thread.
 func (u *userInterfaceImpl) dipFromGLFWPixel(x float64, monitor *Monitor) float64 {
 	return x / u.deviceScaleFactor(monitor)
 }
 
-// dipToGLFWPixel must be called from the main thread.
 func (u *userInterfaceImpl) dipToGLFWPixel(x float64, monitor *Monitor) float64 {
 	return x * u.deviceScaleFactor(monitor)
 }

internal/ui/ui_glfw_windows.go

@@ -91,17 +91,14 @@ func videoModeScale(monitor *glfw.Monitor) float64 {
 	return 1
 }
 
-// dipFromGLFWMonitorPixel must be called from the main thread.
 func (u *userInterfaceImpl) dipFromGLFWMonitorPixel(x float64, monitor *Monitor) float64 {
 	return x / u.deviceScaleFactor(monitor)
 }
 
-// dipFromGLFWPixel must be called from the main thread.
 func (u *userInterfaceImpl) dipFromGLFWPixel(x float64, monitor *Monitor) float64 {
 	return x / u.deviceScaleFactor(monitor)
 }
 
-// dipToGLFWPixel must be called from the main thread.
 func (u *userInterfaceImpl) dipToGLFWPixel(x float64, monitor *Monitor) float64 {
 	return x * u.deviceScaleFactor(monitor)
 }