Added OpenFile(), the first dialog to be added, and implemented it on Windows... mostly.

redo/dialog.go

@@ -0,0 +1,10 @@
+// 18 august 2014
+
+package ui
+
+// OpenFile opens a dialog box that asks the user to choose a file.
+// It returns the selected filename, or an empty string if no file was chosen.
+// All events stop while OpenFile is executing. (TODO move to doc.go)
+func OpenFile() (filename string) {
+	return openFile()
+}

redo/dialog_windows.c

@@ -0,0 +1,40 @@
+// 18 august 2014
+
+#include "winapi_windows.h"
+#include "_cgo_export.h"
+
+// this should be reasonable
+#define NFILENAME 4096
+
+WCHAR *openFile(void)
+{
+	OPENFILENAMEW ofn;
+	DWORD err;
+	WCHAR *filenameBuffer;
+
+	// freed on the Go side
+	filenameBuffer = (WCHAR *) malloc((NFILENAME + 1) * sizeof (WCHAR));
+	if (filenameBuffer == NULL)
+		xpanic("memory exhausted in OpenFile()", GetLastError());
+	filenameBuffer[0] = L'\0';			// required by GetOpenFileName() to indicate no previous filename
+	ZeroMemory(&ofn, sizeof (OPENFILENAMEW));
+	ofn.lStructSize = sizeof (OPENFILENAMEW);
+	ofn.hwndOwner = NULL;
+	ofn.hInstance = hInstance;
+	ofn.lpstrFilter = NULL;			// no filters
+	ofn.lpstrFile = filenameBuffer;
+	ofn.nMaxFile = NFILENAME + 1;	// TODO include + 1?
+	ofn.lpstrInitialDir = NULL;			// let system decide
+	ofn.lpstrTitle = NULL;			// let system decide
+	// TODO OFN_SHAREAWARE?
+	// TODO remove OFN_NODEREFERENCELINKS? or does no filters ensure that anyway?
+	ofn.Flags = OFN_EXPLORER | OFN_FILEMUSTEXIST | OFN_FORCESHOWHIDDEN | OFN_HIDEREADONLY | OFN_LONGNAMES | OFN_NOCHANGEDIR | OFN_NODEREFERENCELINKS | OFN_NOTESTFILECREATE | OFN_PATHMUSTEXIST;
+	if (GetOpenFileNameW(&ofn) == FALSE) {
+		// TODO stringify
+		err = CommDlgExtendedError();
+		if (err == 0)				// user cancelled
+			return NULL;
+		xpanic("error running open file dialog", GetLastError());
+	}
+	return filenameBuffer;
+}

redo/dialog_windows.go

@@ -0,0 +1,33 @@
+// 18 august 2014
+
+package ui
+
+import (
+	"syscall"
+	"unsafe"
+	"reflect"
+)
+
+// #include "winapi_windows.h"
+import "C"
+
+// TODO move to common_windows.go
+func wstrToString(wstr *C.WCHAR) string {
+	n := C.wcslen((*C.wchar_t)(unsafe.Pointer(wstr)))
+	xbuf := &reflect.SliceHeader{
+		Data:	uintptr(unsafe.Pointer(wstr)),
+		Len:		int(n + 1),
+		Cap:		int(n + 1),
+	}
+	buf := (*[]uint16)(unsafe.Pointer(xbuf))
+	return syscall.UTF16ToString(*buf)
+}
+
+func openFile() string {
+	name := C.openFile()
+	if name == nil {
+		return ""
+	}
+	defer C.free(unsafe.Pointer(name))
+	return wstrToString(name)
+}

redo/uitask_windows.go

@@ -9,7 +9,7 @@ import (
 )
 
 // #cgo CFLAGS: --std=c99
-// #cgo LDFLAGS: -luser32 -lkernel32 -lgdi32 -luxtheme -lmsimg32
+// #cgo LDFLAGS: -luser32 -lkernel32 -lgdi32 -luxtheme -lmsimg32 -lcomdlg32
 // #include "winapi_windows.h"
 import "C"
 

redo/winapi_windows.h

@@ -133,4 +133,7 @@ enum {
 extern HIMAGELIST checkboxImageList;
 extern void makeCheckboxImageList(HWND);
 
+// dialog_windows.c
+extern WCHAR *openFile(void);
+
 #endif

redo/zz_test.go

@@ -38,6 +38,8 @@ type testwin struct {
 	festart	Button
 	felabel	Label
 	festop	Button
+	openbtn	Button
+	fnlabel	Label
 	icons	[]icon
 	il		ImageList
 	icontbl	Table
@@ -89,7 +91,19 @@ func (tw *testwin) addfe() {
 			tw.fe = nil
 		}
 	})
-	tw.festack = NewVerticalStack(tw.festart, tw.felabel, tw.festop)
+	tw.openbtn = NewButton("Open")
+	tw.openbtn.OnClicked(func() {
+		fn := OpenFile()
+		if fn == "" {
+			fn = "<no file selected>"
+		}
+		tw.fnlabel.SetText(fn)
+	})
+	tw.fnlabel = NewStandaloneLabel("<no file selected>")
+	tw.festack = NewVerticalStack(tw.festart, tw.felabel, tw.festop,
+		Space(),
+		tw.openbtn, tw.fnlabel)
+	tw.festack.SetStretchy(3)
 	tw.t.Append("Foreign Events", tw.festack)
 }