Add gwinClearInit() and gwinWidgetClearInit() to clear gwin initialisation structures.

Incorporate into demo's

4 files changed, 49 insertions, 1 deletions

diff --git a/src/gwin/gwidget.c b/src/gwin/gwidget.c
index 181b7425..c46520ea 100644
--- a/src/gwin/gwidget.c
+++ b/src/gwin/gwidget.c
@@ -297,6 +297,14 @@ void _gwidgetRedraw(GHandle gh) {
 	gw->fnDraw(gw, gw->fnParam);
 }
 
+void gwinWidgetClearInit(GWidgetInit *pwi) {
+	char		*p;
+	unsigned	len;
+
+	for(p = (char *)pwi, len = sizeof(GWidgetInit); len; len--)
+		*p++ = 0;
+}
+
 void gwinSetDefaultStyle(const GWidgetStyle *pstyle, bool_t updateAll) {
 	if (!pstyle)
 		pstyle = &BlackWidgetStyle;
diff --git a/src/gwin/gwidget.h b/src/gwin/gwidget.h
index 96832fe3..8373e2d0 100644
--- a/src/gwin/gwidget.h
+++ b/src/gwin/gwidget.h
@@ -78,6 +78,10 @@ typedef void (*CustomWidgetDrawFunction)(struct GWidgetObject *gw, void *param);
  * @brief	The structure to initialise a widget.
  *
  * @note	Some widgets may have extra parameters.
+ * @note	If you create this structure on the stack, you should always memset
+ * 			it to all zero's first in case a future version of the software
+ * 			add's extra fields. Alternatively you can use @p gwinWidgetClearInit()
+ * 			to clear it.
  * @note	The text element must be static string (not stack allocated). If you want to use
  * 			a dynamic string (eg a stack allocated string) use NULL for this member and then call
  * 			@p gwinSetText() with useAlloc set to TRUE.
@@ -127,6 +131,18 @@ extern "C" {
 #endif
 
 /**
+ * @brief	Clear a GWidgetInit structure to all zero's
+ * @note	This function is provided just to prevent problems
+ * 			on operating systems where using memset() causes issues
+ * 			in the users application.
+ *
+ * @param[in] pwi	The GWidgetInit structure to clear
+ *
+ * @api
+ */
+void gwinWidgetClearInit(GWidgetInit *pwi);
+
+/**
  * @brief   Set the default style for widgets created hereafter.
  *
  * @param[in] pstyle	The default style. Passing NULL uses the system compiled style.
diff --git a/src/gwin/gwin.c b/src/gwin/gwin.c
index 54f42077..93c17f3a 100644
--- a/src/gwin/gwin.c
+++ b/src/gwin/gwin.c
@@ -149,6 +149,14 @@ GHandle _gwindowCreate(GDisplay *g, GWindowObject *pgw, const GWindowInit *pInit
  * Routines that affect all windows
  *-----------------------------------------------*/
 
+void gwinClearInit(GWindowInit *pwi) {
+	char		*p;
+	unsigned	len;
+
+	for(p = (char *)pwi, len = sizeof(GWindowInit); len; len--)
+		*p++ = 0;
+}
+
 void gwinSetDefaultColor(color_t clr) {
 	defaultFgColor = clr;
 }
diff --git a/src/gwin/sys_defs.h b/src/gwin/sys_defs.h
index f4e1c2f7..fa5084a3 100644
--- a/src/gwin/sys_defs.h
+++ b/src/gwin/sys_defs.h
@@ -34,7 +34,7 @@
  */
 typedef struct GWindowObject {
 	#if GWIN_NEED_WINDOWMANAGER
-		// This MUST be the first member of the struct
+		// This MUST be the first member of the structure
 		gfxQueueASyncItem	wmq;				// @< The next window (for the window manager)
 	#endif
 	const struct gwinVMT	*vmt;				// @< The VMT for this GWIN
@@ -54,6 +54,10 @@ typedef struct GWindowObject {
  *
  * @note	Some gwin's will need extra parameters.
  * @note	The dimensions and position may be changed to fit on the real screen.
+ * @note	If you create this structure on the stack, you should always memset
+ * 			it to all zero's first in case a future version of the software
+ * 			add's extra fields. Alternatively you can use @p gwinClearInit()
+ * 			to clear it.
  *
  * @{
  */
@@ -103,6 +107,18 @@ extern "C" {
  *-------------------------------------------------*/
 
 	/**
+	 * @brief	Clear a GWindowInit structure to all zero's
+	 * @note	This function is provided just to prevent problems
+	 * 			on operating systems where using memset() causes issues
+	 * 			in the users application.
+	 *
+	 * @param[in] pwi	The GWindowInit structure to clear
+	 *
+	 * @api
+	 */
+	void gwinClearInit(GWindowInit *pwi);
+
+	/**
 	 * @brief	Set the default foreground color for all new GWIN windows
 	 *
 	 * @param[in] clr	The color to be set