From 7ac67006b5f3ef03f38e7d56bfe0da739579c8f3 Mon Sep 17 00:00:00 2001
From: Nuno Cruces <ncruces@users.noreply.github.com>
Date: Wed, 27 Jul 2022 00:25:18 +0100
Subject: [PATCH] Icons (windows), see #35.

---
 internal/win/user32.go           |  6 -----
 internal/win/zsyscall_windows.go | 10 --------
 util_windows.go                  | 44 +++++++++++++++++++-------------
 3 files changed, 26 insertions(+), 34 deletions(-)

diff --git a/internal/win/user32.go b/internal/win/user32.go
index 1b31505..1b4370f 100644
--- a/internal/win/user32.go
+++ b/internal/win/user32.go
@@ -231,11 +231,6 @@ const (
 	DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 = ^uintptr(4) + 1
 	DPI_AWARENESS_CONTEXT_UNAWARE_GDISCALED    = ^uintptr(5) + 1
 
-	// LoadImage type
-	IMAGE_BITMAP = 0
-	IMAGE_ICON   = 1
-	IMAGE_CURSOR = 2
-
 	// LoadIcon resources
 	IDI_APPLICATION = 32512
 	IDI_ERROR       = 32513
@@ -398,7 +393,6 @@ type CWPRETSTRUCT struct {
 //sys getWindowTextLength(wnd HWND) (ret int, err error) = user32.GetWindowTextLengthW
 //sys IsDialogMessage(wnd HWND, msg *MSG) (ok bool) = user32.IsDialogMessageW
 //sys LoadIcon(instance Handle, resource uintptr) (ret Handle, err error) = user32.LoadIconW
-//sys LoadImage(instance Handle, name *uint16, typ int, cx int, cy int, load int) (ret Handle, err error) = user32.LoadImageW
 //sys PostQuitMessage(exitCode int) = user32.PostQuitMessage
 //sys RegisterClassEx(cls *WNDCLASSEX) (err error) = user32.RegisterClassExW
 //sys ReleaseDC(wnd HWND, dc Handle) (ok bool) = user32.ReleaseDC
diff --git a/internal/win/zsyscall_windows.go b/internal/win/zsyscall_windows.go
index 34884f6..2716faa 100644
--- a/internal/win/zsyscall_windows.go
+++ b/internal/win/zsyscall_windows.go
@@ -89,7 +89,6 @@ var (
 	procGetWindowTextW               = moduser32.NewProc("GetWindowTextW")
 	procIsDialogMessageW             = moduser32.NewProc("IsDialogMessageW")
 	procLoadIconW                    = moduser32.NewProc("LoadIconW")
-	procLoadImageW                   = moduser32.NewProc("LoadImageW")
 	procPostQuitMessage              = moduser32.NewProc("PostQuitMessage")
 	procRegisterClassExW             = moduser32.NewProc("RegisterClassExW")
 	procReleaseDC                    = moduser32.NewProc("ReleaseDC")
@@ -433,15 +432,6 @@ func LoadIcon(instance Handle, resource uintptr) (ret Handle, err error) {
 	return
 }
 
-func LoadImage(instance Handle, name *uint16, typ int, cx int, cy int, load int) (ret Handle, err error) {
-	r0, _, e1 := syscall.Syscall6(procLoadImageW.Addr(), 6, uintptr(instance), uintptr(unsafe.Pointer(name)), uintptr(typ), uintptr(cx), uintptr(cy), uintptr(load))
-	ret = Handle(r0)
-	if ret == 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
 func PostQuitMessage(exitCode int) {
 	syscall.Syscall(procPostQuitMessage.Addr(), 1, uintptr(exitCode), 0, 0)
 	return
diff --git a/util_windows.go b/util_windows.go
index 6c37dd5..7f609af 100644
--- a/util_windows.go
+++ b/util_windows.go
@@ -3,6 +3,7 @@ package zenity
 import (
 	"bytes"
 	"context"
+	"io"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -13,7 +14,6 @@ import (
 	"unsafe"
 
 	"github.com/ncruces/zenity/internal/win"
-	"golang.org/x/sys/windows"
 )
 
 const (
@@ -278,39 +278,47 @@ func getIcon(i any) (icon icon, err error) {
 		return icon, nil
 	}
 
-	data, err := os.ReadFile(path)
+	file, err := os.Open(path)
+	if err != nil {
+		return icon, err
+	}
+	defer file.Close()
+
+	var peek [8]byte
+	_, err = file.ReadAt(peek[:], 0)
 	if err != nil {
 		return icon, err
 	}
 
-	switch {
-	case bytes.HasPrefix(data, []byte("\x00\x00\x01\x00")):
-		icon.handle, err = win.LoadImage(0,
-			strptr(path),
-			win.IMAGE_ICON, 0, 0,
-			win.LR_LOADFROMFILE|win.LR_DEFAULTSIZE)
-		icon.destroy = true
-	case bytes.HasPrefix(data, []byte("\x89PNG\r\n\x1a\n")):
+	if bytes.Equal(peek[:], []byte("\x89PNG\r\n\x1a\n")) {
+		data, err := io.ReadAll(file)
+		if err != nil {
+			return icon, err
+		}
 		icon.handle, err = win.CreateIconFromResourceEx(
 			data, true, 0x00030000, 0, 0,
 			win.LR_DEFAULTSIZE)
-		icon.destroy = true
-	case bytes.HasPrefix(data, []byte("MZ")):
-		var instance windows.Handle
-		instance, err = win.GetModuleHandle(nil)
 		if err != nil {
-			break
+			return icon, err
+		}
+	} else {
+		instance, err := win.GetModuleHandle(nil)
+		if err != nil {
+			return icon, err
 		}
 		path, err = filepath.Abs(path)
 		if err != nil {
-			break
+			return icon, err
 		}
 		var i uint16
 		icon.handle, err = win.ExtractAssociatedIcon(
 			instance, strptr(path), &i)
-		icon.destroy = true
+		if err != nil {
+			return icon, err
+		}
 	}
-	return icon, err
+	icon.destroy = true
+	return icon, nil
 }
 
 func (i *icon) delete() {