From cfcac03df76e9ccfe81f3b8f70126ddcf2463637 Mon Sep 17 00:00:00 2001
From: Pietro Gagliardi <pietro10@mac.com>
Date: Mon, 24 Mar 2014 17:01:33 -0400
Subject: [PATCH] Added GDI+ to the package's Windows version: DLL loaded,
 initialized, and shut down. It will be used for drawing to Areas because
 using GDI itself is more complex than it needs to be.

---
 common_windows.go |  1 +
 init_windows.go   | 29 +++++++++++++++++++++++++++++
 uitask_windows.go |  1 +
 3 files changed, 31 insertions(+)

diff --git a/common_windows.go b/common_windows.go
index eaa7d34..ee09650 100644
--- a/common_windows.go
+++ b/common_windows.go
@@ -12,6 +12,7 @@ var (
 	kernel32 = syscall.NewLazyDLL("kernel32.dll")
 	gdi32 = syscall.NewLazyDLL("gdi32.dll")
 	comctl32 = syscall.NewLazyDLL("comctl32.dll")
+	gdiplus = syscall.NewLazyDLL("gdiplus.dll")
 )
 
 type _HANDLE uintptr
diff --git a/init_windows.go b/init_windows.go
index 9ccd5df..bfc7649 100644
--- a/init_windows.go
+++ b/init_windows.go
@@ -11,6 +11,7 @@ import (
 var (
 	hInstance		_HANDLE
 	nCmdShow	int
+	gdiplusToken	uintptr
 )
 
 // TODO is this trick documented in MSDN?
@@ -56,6 +57,26 @@ func getWinMainnCmdShow() {
 	}
 }
 
+func initGDIPlus() (err error) {
+	var gdiplusInit struct {
+		GdiplusVersion				uint32
+		DebugEventCallback			uintptr
+		SuppressBackgroundThread	int32		// originally BOOL
+		SuppressExternalCodecs		int32		// originally BOOL
+	}
+
+	gdiplusInit.GdiplusVersion = 1		// required
+	// TODO suppress external codecs?
+	r1, _, err := gdiplus.NewProc("GdiplusStartup").Call(
+		uintptr(unsafe.Pointer(&gdiplusToken)),
+		uintptr(unsafe.Pointer(&gdiplusInit)),
+		uintptr(0))		// we use the GDI+ thread so no need for output info
+	if r1 != 0 {			// failure
+		return fmt.Errorf("error initializing GDI+ (GDI+ error code %d; windows last error %v)", r1, err)
+	}
+	return nil
+}
+
 func doWindowsInit() (err error) {
 	err = getWinMainhInstance()
 	if err != nil {
@@ -74,6 +95,14 @@ func doWindowsInit() (err error) {
 	if err != nil {
 		return fmt.Errorf("error initializing Common Controls (comctl32.dll): %v", err)
 	}
+	err = initGDIPlus()
+	if err != nil {
+		return fmt.Errorf("error initializing GDI+ (gdiplus.dll): %v", err)
+	}
 	// TODO others
 	return nil		// all ready to go
 }
+
+func doWindowsQuitStuff() {
+	gdiplus.NewProc("GdiplusShutdown").Call(gdiplusToken)		// returns void according to MSDN
+}
diff --git a/uitask_windows.go b/uitask_windows.go
index 58d5a6b..7a4db36 100644
--- a/uitask_windows.go
+++ b/uitask_windows.go
@@ -84,6 +84,7 @@ func ui(main func()) error {
 		}
 	}
 
+	doWindowsQuitStuff()
 	return nil
 }