Fix incorrect position being loaded on linux when using multiple moni…

…tors

backend/utils/display.go

@@ -2,6 +2,7 @@ package utils
 
 import (
 	"image"
+	"runtime"
 
 	"github.com/kbinani/screenshot"
 )
@@ -15,5 +16,34 @@ func GetDisplayBounds() []image.Rectangle {
 		bounds = append(bounds, screenshot.GetDisplayBounds(i))
 	}
 
+	if runtime.GOOS == "linux" {
+		// gdk_monitor_get_geometry considers 0,0 to be the corner of the bounding box of all the monitors,
+		// not the 0,0 of the main monitor
+		boundingBox := bounds[0]
+		for _, b := range bounds {
+			boundingBox = boundingBox.Union(b)
+		}
+		for i := range bounds {
+			bounds[i] = bounds[i].Sub(boundingBox.Min)
+		}
+	}
+
 	return bounds
 }
+
+func GetDisplayBoundsAt(x, y int) image.Rectangle {
+	point := image.Pt(x, y)
+
+	displays := GetDisplayBounds()
+
+	curDisplay := displays[0] // use main display as fallback
+
+	for _, d := range displays {
+		if point.In(d) {
+			curDisplay = d
+			break
+		}
+	}
+
+	return curDisplay
+}

backend/wailsextras/window.go

@@ -0,0 +1,30 @@
+package wailsextras
+
+import (
+	"context"
+	"runtime"
+
+	wailsRuntime "github.com/wailsapp/wails/v2/pkg/runtime"
+
+	"github.com/satisfactorymodding/SatisfactoryModManager/backend/utils"
+)
+
+// WindowSetPosition wraps Wails's WindowSetPosition,
+// but ensures that WindowSetPosition(WindowGetPosition())
+// will result in the window remaining stationary
+// regardless of OS's behaviour with multiple displays
+func WindowSetPosition(ctx context.Context, x, y int) {
+	if runtime.GOOS == "windows" || runtime.GOOS == "linux" {
+		// WindowSetPosition expects relative to the current monitor,
+		// but WindowGetPosition returns absolute
+		curX, curY := wailsRuntime.WindowGetPosition(ctx)
+		display := utils.GetDisplayBoundsAt(curX, curY)
+		x -= display.Min.X
+		y -= display.Min.Y
+	}
+
+	// It appears that on darwin Wails gets and sets the position
+	// with values relative to the current monitor
+
+	wailsRuntime.WindowSetPosition(ctx, x, y)
+}

main.go

@@ -14,7 +14,6 @@ import (
 	"github.com/wailsapp/wails/v2"
 	"github.com/wailsapp/wails/v2/pkg/options"
 	"github.com/wailsapp/wails/v2/pkg/options/assetserver"
-	wailsRuntime "github.com/wailsapp/wails/v2/pkg/runtime"
 
 	"github.com/satisfactorymodding/SatisfactoryModManager/backend"
 	"github.com/satisfactorymodding/SatisfactoryModManager/backend/app"
@@ -25,6 +24,7 @@ import (
 	"github.com/satisfactorymodding/SatisfactoryModManager/backend/logging"
 	"github.com/satisfactorymodding/SatisfactoryModManager/backend/settings"
 	"github.com/satisfactorymodding/SatisfactoryModManager/backend/utils"
+	"github.com/satisfactorymodding/SatisfactoryModManager/backend/wailsextras"
 	"github.com/satisfactorymodding/SatisfactoryModManager/backend/websocket"
 )
 
@@ -96,7 +96,9 @@ func main() {
 			appCommon.AppContext = ctx
 
 			// Wails doesn't support setting the window position on init, so we do it here
-			loadWindowLocation(ctx)
+			if settings.Settings.WindowPosition != nil {
+				wailsextras.WindowSetPosition(ctx, settings.Settings.WindowPosition.X, settings.Settings.WindowPosition.Y)
+			}
 
 			app.App.WatchWindow() //nolint:contextcheck
 			go websocket.ListenAndServeWebsocket()
@@ -137,23 +139,6 @@ func main() {
 	}
 }
 
-func loadWindowLocation(ctx context.Context) {
-	if settings.Settings.WindowPosition != nil {
-		// Setting the window location is relative to the current monitor,
-		// but we save it as absolute position.
-
-		wailsRuntime.WindowSetPosition(ctx, 0, 0)
-
-		// Get the location the window was actually placed at
-		monitorLeft, monitorTop := wailsRuntime.WindowGetPosition(ctx)
-
-		x := settings.Settings.WindowPosition.X - monitorLeft
-		y := settings.Settings.WindowPosition.Y - monitorTop
-
-		wailsRuntime.WindowSetPosition(ctx, x, y)
-	}
-}
-
 func init() {
 	// Pass build-time variables to viper
 	if len(version) > 0 && version[0] == 'v' {