Implemented uiButton.preferredSize() on Windows. This includes adding a function to get the width of text in a control.

new/button_windows.c

@@ -23,9 +23,30 @@ static BOOL onWM_NOTIFY(uiControl *c, WPARAM wParam, LPARAM lParam, void *data,
 	return FALSE;
 }
 
+// from http://msdn.microsoft.com/en-us/library/windows/desktop/dn742486.aspx#sizingandspacing
+#define buttonHeight 14
+
 static void preferredSize(uiControl *c, int baseX, int baseY, LONG internalLeading, intmax_t *width, intmax_t *height)
 {
-	// TODO
+	HWND hwnd;
+	SIZE size;
+
+	hwnd = (HWND) uiControlHandle(c);
+
+	// try the comctl32 version 6 way
+	size.cx = 0;		// explicitly ask for ideal size
+	size.cy = 0;
+	if (SendMessageW(hwnd, BCM_GETIDEALSIZE, 0, (LPARAM) (&size)) != FALSE) {
+		*width = size.cx;
+		*height = size.cy;
+		return;
+	}
+
+	// that didn't work; fall back to using Microsoft's metrics
+	// Microsoft says to use a fixed width for all buttons; this isn't good enough
+	// use the text width instead, with some edge padding
+	*width = uiWindowsWindowTextWidth(hwnd) + (2 * GetSystemMetrics(SM_CXEDGE));
+	*height = uiDlgUnitToY(buttonHeight, baseY);
 }
 
 static void defaultOnClicked(uiControl *c, void *data)

new/ui_windows.h

@@ -41,4 +41,8 @@ void *uiWindowsControlData(uiControl *);
 #define uiDlgUnitToX(dlg, baseX) MulDiv((dlg), baseX, 4)
 #define uiDlgUnitToY(dlg, baseY) MulDiv((dlg), baseY, 8)
 
+// and use this if you need the text of the window width
+// TODO really export?
+extern intmax_t uiWindowsWindowTextWidth(HWND hwnd);
+
 #endif

new/util_windows.c

@@ -16,3 +16,34 @@ WCHAR *toUTF16(const char *str)
 		logLastError("error converting from UTF-8 to UTF-16 in toUTF16()");
 	return wstr;
 }
+
+// TODO this and resize(): initialize size and other values to avoid garbage on failure
+intmax_t uiWindowsWindowTextWidth(HWND hwnd)
+{
+	int len;
+	WCHAR *text;
+	HDC dc;
+	HFONT prevfont;
+
+	// TODO check for error
+	len = GetWindowTextLengthW(hwnd);
+	if (len == 0)		// no text; nothing to do
+		return 0;
+	text = (WCHAR *) uiAlloc((len + 1) * sizeof (WCHAR));
+	if (GetWindowText(hwnd, text, len + 1) == 0)		// should only happen on error given explicit test for len == 0 above
+		logLastError("error getting window text in uiWindowsWindowTextWidth()");
+	dc = GetDC(parent);
+	if (dc == NULL)
+		logLastError("error getting DC in uiWindowsWindowTextWidth()");
+	prevFont = (HFONT) SelectObject(dc, hMessageFont);
+	if (prevFont == NULL)
+		logLastError("error loading control font into device context in uiWindowsWindowTextWidth()");
+	if (GetTextExtentPoint32W(dc, text, len, &size) == 0)
+		logLastError("error getting text extent point in uiWindowsWindowTextWidth()");
+	if (SelectObject(dc, prevFont) != hMessageFont)
+		logLastError("error restoring previous font into device context in uiWindowsWindowTextWidth()");
+	if (ReleaseDC(parent, dc) == 0)
+		logLastError("error releasing DC in uiWindowsWindowTextWidth()");
+	uiFree(text);
+	return size.cx;
+}