Merge pull request #37 from kbinani/win-GetDisplayBounds-202501

Pin the argument object before calling enumDisplayMonitors

Co-authored-by: NanoRed <[email protected]>

Author: kbinani

windows.go

@@ -95,22 +95,6 @@ func Capture(x, y, width, height int) (*image.RGBA, error) {
 	return img, nil
 }
 
-func NumActiveDisplays() int {
-	var count int = 0
-	enumDisplayMonitors(win.HDC(0), nil, syscall.NewCallback(countupMonitorCallback), uintptr(unsafe.Pointer(&count)))
-	return count
-}
-
-func GetDisplayBounds(displayIndex int) image.Rectangle {
-	var ctx getMonitorBoundsContext
-	ctx.Index = displayIndex
-	ctx.Count = 0
-	enumDisplayMonitors(win.HDC(0), nil, syscall.NewCallback(getMonitorBoundsCallback), uintptr(unsafe.Pointer(&ctx)))
-	return image.Rect(
-		int(ctx.Rect.Left), int(ctx.Rect.Top),
-		int(ctx.Rect.Right), int(ctx.Rect.Bottom))
-}
-
 func getDesktopWindow() win.HWND {
 	ret, _, _ := syscall.Syscall(funcGetDesktopWindow, 0, 0, 0, 0)
 	return win.HWND(ret)

windows_ge1.21.go

@@ -0,0 +1,37 @@
+//go:build windows && go1.21
+
+package screenshot
+
+import (
+	"image"
+	"runtime"
+	"syscall"
+	"unsafe"
+
+	"github.com/lxn/win"
+)
+
+func NumActiveDisplays() int {
+	count := new(int)
+	pinner := new(runtime.Pinner)
+	pinner.Pin(count)
+	defer pinner.Unpin()
+	*count = 0
+	ptr := unsafe.Pointer(count)
+	enumDisplayMonitors(win.HDC(0), nil, syscall.NewCallback(countupMonitorCallback), uintptr(ptr))
+	return *count
+}
+
+func GetDisplayBounds(displayIndex int) image.Rectangle {
+	ctx := new(getMonitorBoundsContext)
+	pinner := new(runtime.Pinner)
+	pinner.Pin(ctx)
+	defer pinner.Unpin()
+	ctx.Index = displayIndex
+	ctx.Count = 0
+	ptr := unsafe.Pointer(ctx)
+	enumDisplayMonitors(win.HDC(0), nil, syscall.NewCallback(getMonitorBoundsCallback), uintptr(ptr))
+	return image.Rect(
+		int(ctx.Rect.Left), int(ctx.Rect.Top),
+		int(ctx.Rect.Right), int(ctx.Rect.Bottom))
+}

windows_lt1.21.go

@@ -0,0 +1,30 @@
+//go:build windows && !go1.21
+
+package screenshot
+
+import (
+	"image"
+	"syscall"
+	"unsafe"
+
+	"github.com/lxn/win"
+)
+
+func NumActiveDisplays() int {
+	var count int
+	count = 0
+	ptr := unsafe.Pointer(&count)
+	enumDisplayMonitors(win.HDC(0), nil, syscall.NewCallback(countupMonitorCallback), uintptr(ptr))
+	return count
+}
+
+func GetDisplayBounds(displayIndex int) image.Rectangle {
+	var ctx getMonitorBoundsContext
+	ctx.Index = displayIndex
+	ctx.Count = 0
+	ptr := unsafe.Pointer(&ctx)
+	enumDisplayMonitors(win.HDC(0), nil, syscall.NewCallback(getMonitorBoundsCallback), uintptr(ptr))
+	return image.Rect(
+		int(ctx.Rect.Left), int(ctx.Rect.Top),
+		int(ctx.Rect.Right), int(ctx.Rect.Bottom))
+}