fixes pixel ration on macos

Author: pchampio

application.go

@@ -320,6 +320,9 @@ func (a *Application) Run() error {
 			})
 		})
 	})
+	a.window.SetContentScaleCallback(func(window *glfw.Window, x float32, y float32) {
+		windowManager.glfwRefreshCallback(window)
+	})
 
 	// Attach glfw window callbacks for text input
 	a.window.SetKeyCallback(

glfw.go

@@ -1,9 +1,7 @@
 package flutter
 
 import (
-	"encoding/json"
 	"fmt"
-	"sync"
 	"unsafe"
 
 	"github.com/go-flutter-desktop/go-flutter/embedder"
@@ -21,9 +19,6 @@ type windowManager struct {
 	// forcedPixelRatio forces the pixelRatio to given value, when value is not zero.
 	forcedPixelRatio float64
 
-	// sync.Once to limit pixelRatio warning messages.
-	oncePrintPixelRatioLimit sync.Once
-
 	// current pointer state
 	pointerPhase          embedder.PointerPhase
 	pointerButton         embedder.PointerButtonMouse
@@ -207,70 +202,10 @@ func (m *windowManager) glfwRefreshCallback(window *glfw.Window) {
 	if m.forcedPixelRatio != 0 {
 		pixelRatio = m.forcedPixelRatio
 	} else {
-		var selectedMonitor *glfw.Monitor
-		winX, winY := window.GetPos()
-		winCenterX, winCenterY := winX+widthPx/2, winY+heightPx/2
-
-		monitors := glfw.GetMonitors()
-		for _, monitor := range monitors {
-			monX1, monY1 := monitor.GetPos()
-			monMode := monitor.GetVideoMode()
-			if monMode == nil {
-				continue
-			}
-			monX2, monY2 := monX1+monMode.Width, monY1+monMode.Height
-			if (monX1 <= winCenterX && winCenterX <= monX2) &&
-				(monY1 <= winCenterY && winCenterY <= monY2) {
-				selectedMonitor = monitor
-				break
-			}
-		}
-
-		if selectedMonitor == nil {
-			// when no monitor was selected, try fallback to primary monitor
-			// TODO: ? perhaps select monitor that is "closest" to the window ?
-			selectedMonitor = glfw.GetPrimaryMonitor()
-		}
-		if selectedMonitor == nil {
-			pixelRatio = 1.0
-			goto SendWindowMetricsEvent
-		}
-		selectedMonitorMode := selectedMonitor.GetVideoMode()
-		if selectedMonitorMode == nil {
-			pixelRatio = 1.0
-			goto SendWindowMetricsEvent
-		}
-		selectedMonitorWidthMM, _ := selectedMonitor.GetPhysicalSize()
-		if selectedMonitorWidthMM == 0 {
-			pixelRatio = 1.0
-			goto SendWindowMetricsEvent
-		}
-		monitorScreenCoordinatesPerInch := float64(selectedMonitorMode.Width) / (float64(selectedMonitorWidthMM) / 25.4)
-
-		dpi := m.pixelsPerScreenCoordinate * monitorScreenCoordinatesPerInch
-		pixelRatio = dpi / dpPerInch
-
-		// Limit the ratio to 1 to avoid rendering a smaller UI in standard resolution monitors.
-		if pixelRatio < 1.0 {
-			m.oncePrintPixelRatioLimit.Do(func() {
-				metrics := map[string]interface{}{
-					"ppsc":           m.pixelsPerScreenCoordinate,
-					"windowWidthPx":  widthPx,
-					"windowWidthSc":  width,
-					"mscpi":          monitorScreenCoordinatesPerInch,
-					"dpi":            dpi,
-					"pixelRatio":     pixelRatio,
-					"monitorWidthMm": selectedMonitorWidthMM,
-					"monitorWidthSc": selectedMonitorMode.Width,
-				}
-				metricsBytes, _ := json.Marshal(metrics)
-				fmt.Println("go-flutter: calculated pixelRatio limited to a minimum of 1.0. metrics: " + string(metricsBytes))
-			})
-			pixelRatio = 1.0
-		}
+		xscale, _ := window.GetContentScale()
+		pixelRatio = float64(xscale)
 	}
 
-SendWindowMetricsEvent:
 	event := embedder.WindowMetricsEvent{
 		Width:      widthPx,
 		Height:     heightPx,