AHK Active Window Rounded Border (Win11 24H2)

FocusBorder.ahk

; ================================
; Active Window Rounded Border Overlay
; For Windows 11 (24H2)
; Runs continuously in the background.
; Adjust the border color, thickness, and corner roundness below.
; ================================

#NoEnv
#SingleInstance, Force
#Persistent
SetBatchLines, -1
SendMode, Input
SetWorkingDir, %A_ScriptDir%

; ------------- User Settings -------------
borderColor    := 0x357EC7   ; Hex color (0xRRGGBB)
borderThickness:= 4          ; Border thickness in pixels
cornerRadius   := 12         ; Corner roundness in pixels
updateInterval := 20         ; How often (ms) to check/update active window
; ------------- End Settings -------------

; --- Create one overlay GUI that will be re‑shaped to form a hollow border ---
Gui, Overlay: +AlwaysOnTop +ToolWindow -Caption +E0x20  ; +E0x20 makes it click‑through.
; Set the background color of the overlay (it will only be visible in its “region”)
; Convert the numeric color (0xRRGGBB) to a 6‑digit hex string (without “0x”)
bgColor := Format("{:06X}", borderColor & 0xFFFFFF)
Gui, Overlay: Color, %bgColor%
Gui, Overlay: Show, NoActivate, ActiveWindowBorder
hOverlay := WinExist("ActiveWindowBorder")
; Add layered style so that SetWindowRgn is applied smoothly.
WinSet, ExStyle, +0x80000, ahk_id %hOverlay%

; Global variables to track the last active window’s position & size.
global prevHWND := "", prevAx, prevAy, prevAw, prevAh

; Set up a timer to update the overlay border.
SetTimer, UpdateBorder, %updateInterval%
Return

; -------------------------------
; UpdateBorder: Positions/resizes and re‑shapes the overlay border
; -------------------------------
UpdateBorder:
    ; Get the currently active window.
    WinGet, activeHWND, ID, A
    ; (Ignore the overlay itself if it somehow becomes active)
    if (activeHWND = hOverlay)
    {
        WinGet, activeHWND, ID, A
    }
    ; If no active window found or if the window is minimized, hide the overlay.
    if (!activeHWND) {
        Gui, Overlay: Hide
        Return
    }
    WinGet, style, Style, ahk_id %activeHWND%
    if (style & 0x20000000) {  ; WS_MINIMIZE flag
        Gui, Overlay: Hide
        Return
    }
    
    ; --- Get the window's true bounds using DWM (works better for Windows 11) ---
    VarSetCapacity(rect, 16, 0)
    if (DllCall("dwmapi\DwmGetWindowAttribute", "ptr", activeHWND, "uint", 9, "ptr", &rect, "uint", 16) = 0)
    {
        ax := NumGet(rect, 0, "int")
        ay := NumGet(rect, 4, "int")
        right := NumGet(rect, 8, "int")
        bottom := NumGet(rect, 12, "int")
        aw := right - ax
        ah := bottom - ay
    }
    else {
        ; Fallback in case DWM fails.
        WinGetPos, ax, ay, aw, ah, ahk_id %activeHWND%
    }
    
    ; Only update if something changed.
    if (activeHWND = prevHWND && ax = prevAx && ay = prevAy && aw = prevAw && ah = prevAh)
        Return
    prevHWND := activeHWND, prevAx := ax, prevAy := ay, prevAw := aw, prevAh := ah

    ; Calculate overlay position and size.
    ; The overlay is expanded by borderThickness on all sides so that its inner edge aligns
    ; exactly with the active window’s border.
    ox := ax - borderThickness
    oy := ay - borderThickness
    ow := aw + (2 * borderThickness)
    oh := ah + (2 * borderThickness)
    
    ; (Re)position the overlay window.
    Gui, Overlay: Show, x%ox% y%oy% w%ow% h%oh% NoActivate

    ; ----- Build a hollow (donut‑shaped) region with rounded corners -----
    ; Outer region: a rounded rectangle covering the full overlay.
    hRgnOuter := DllCall("CreateRoundRectRgn", "Int", 0, "Int", 0, "Int", ow, "Int", oh, "Int", cornerRadius*2, "Int", cornerRadius*2, "Ptr")
    ; Inner region: same shape, inset by borderThickness.
    innerCorner := (cornerRadius > borderThickness) ? (cornerRadius - borderThickness) : 0
    hRgnInner := DllCall("CreateRoundRectRgn", "Int", borderThickness, "Int", borderThickness, "Int", ow - borderThickness, "Int", oh - borderThickness, "Int", innerCorner*2, "Int", innerCorner*2, "Ptr")
    ; Create a region for the border by subtracting the inner region from the outer.
    ; First, create an empty region.
    hRgnBorder := DllCall("CreateRectRgn", "Int", 0, "Int", 0, "Int", 0, "Int", 0, "Ptr")
    ; RGN_DIFF = 4: hRgnBorder = hRgnOuter - hRgnInner.
    DllCall("CombineRgn", "Ptr", hRgnBorder, "Ptr", hRgnOuter, "Ptr", hRgnInner, "Int", 4)
    ; Apply the computed region to the overlay window.
    ; (After calling SetWindowRgn, the system owns hRgnBorder, so DO NOT free it.)
    DllCall("SetWindowRgn", "Ptr", hOverlay, "Ptr", hRgnBorder, "Int", True)
    ; Clean up the temporary region handles.
    DllCall("DeleteObject", "Ptr", hRgnOuter)
    DllCall("DeleteObject", "Ptr", hRgnInner)
Return

This is what it looks like with a different border color