make beginDraw return a boolean so can abort

When a gtk3 window's shutting down it appears we can't get a cairo_t*
for it. This change makes it possible to turn that fact into aborting
the whole draw operation.

xwords4/android/XWords4/jni/drawwrapper.c

@@ -349,7 +349,7 @@ and_draw_drawTimer( DrawCtx* dctx, const XP_Rect* rect, XP_U16 player,
 }
 
 /* Not used on android yet */
-static void and_draw_beginDraw( DrawCtx* XP_UNUSED(dctx) ) {}
+static XP_Bool and_draw_beginDraw( DrawCtx* XP_UNUSED(dctx) ) {return XP_TRUE;}
 static void and_draw_endDraw( DrawCtx* XP_UNUSED(dctx) ) {}
 
 static XP_Bool

xwords4/common/boarddrw.c

@@ -624,13 +624,14 @@ XP_Bool
 board_draw( BoardCtxt* board )
 {
     if ( !!board->draw && board->boardBounds.width > 0 ) {
-        draw_beginDraw( board->draw );
+        if ( draw_beginDraw( board->draw ) ) {
 
-        drawScoreBoard( board );
-        drawTray( board );
-        drawBoard( board );
+            drawScoreBoard( board );
+            drawTray( board );
+            drawBoard( board );
 
-        draw_endDraw( board->draw );
+            draw_endDraw( board->draw );
+        }
     }
     return !board->needsDrawing && 0 == board->trayInvalBits;
 } /* board_draw */

xwords4/common/draw.h

@@ -116,7 +116,7 @@ typedef struct DrawCtxVTable {
     void DRAW_VTABLE_NAME(dictChanged)( DrawCtx* dctx, XP_S16 playerNum,
                                         const DictionaryCtxt* dict );
 
-    void DRAW_VTABLE_NAME(beginDraw) ( DrawCtx* dctx );
+    XP_Bool DRAW_VTABLE_NAME(beginDraw) ( DrawCtx* dctx );
     void DRAW_VTABLE_NAME(endDraw) ( DrawCtx* dctx );
 
     XP_Bool DRAW_VTABLE_NAME(boardBegin) ( DrawCtx* dctx, 

xwords4/linux/cursesdraw.c

@@ -78,6 +78,12 @@ curses_draw_dictChanged( DrawCtx* XP_UNUSED(p_dctx),
 {
 }
 
+static XP_Bool
+curses_draw_beginDraw( DrawCtx* XP_UNUSED(p_dctx) )
+{
+    return XP_TRUE;
+}
+
 static XP_Bool
 curses_draw_boardBegin( DrawCtx* XP_UNUSED(p_dctx), 
                         const XP_Rect* XP_UNUSED(rect), 
@@ -582,6 +588,7 @@ curses_draw_frameTray( DrawCtx* p_dctx, XP_Rect* rect )
 static XP_Bool
 draw_doNothing( DrawCtx* XP_UNUSED(dctx), ... )
 {
+    LOG_FUNC();
     return XP_FALSE;
 } /* draw_doNothing */
 
@@ -593,18 +600,19 @@ cursesDrawCtxtMake( WINDOW* boardWin )
     dctx->vtable = malloc( sizeof(*(((CursesDrawCtx*)dctx)->vtable)) );
 
     for ( int ii = 0;
-          ii < sizeof(*dctx->vtable)/sizeof(draw_doNothing);
+          ii < sizeof(*dctx->vtable)/sizeof(dctx->vtable->m_draw_destroyCtxt);
           ++ii ) {
         ((void**)(dctx->vtable))[ii] = draw_doNothing;
     }
 
     SET_VTABLE_ENTRY( dctx->vtable, draw_destroyCtxt, curses );
     SET_VTABLE_ENTRY( dctx->vtable, draw_dictChanged, curses );
-        
+
+    SET_VTABLE_ENTRY( dctx->vtable, draw_beginDraw, curses );
     SET_VTABLE_ENTRY( dctx->vtable, draw_boardBegin, curses );
-    SET_VTABLE_ENTRY( dctx->vtable, draw_objFinished, curses );
     SET_VTABLE_ENTRY( dctx->vtable, draw_trayBegin, curses );
     SET_VTABLE_ENTRY( dctx->vtable, draw_scoreBegin, curses );
+    SET_VTABLE_ENTRY( dctx->vtable, draw_objFinished, curses );
 
 #ifdef XWFEATURE_SCOREONEPASS
     SET_VTABLE_ENTRY( dctx->vtable, draw_drawRemText, curses );

xwords4/linux/gtkdraw.c

@@ -82,15 +82,20 @@ gtkInsetRect( XP_Rect* r, short i )
 # define GDKCOLORMAP GdkColormap
 #endif
 
-static void
+static XP_Bool
 initCairo( GtkDrawCtx* dctx )
 {
     /* XP_LOGF( "%s(dctx=%p)", __func__, dctx ); */
     XP_ASSERT( !dctx->_cairo );
-    dctx->_cairo = gdk_cairo_create( gtk_widget_get_window(dctx->drawing_area) );
-    /* XP_LOGF( "dctx->cairo=%p", dctx->_cairo ); */
-    cairo_set_line_width( dctx->_cairo, 1.0 );
-    cairo_set_line_cap( dctx->_cairo, CAIRO_LINE_CAP_SQUARE );
+    cairo_t* cairo = gdk_cairo_create( gtk_widget_get_window(dctx->drawing_area) );
+    XP_Bool inited = !!cairo;
+    if ( inited ) {
+        dctx->_cairo = cairo;
+        /* XP_LOGF( "dctx->cairo=%p", dctx->_cairo ); */
+        cairo_set_line_width( cairo, 1.0 );
+        cairo_set_line_cap( cairo, CAIRO_LINE_CAP_SQUARE );
+    }
+    return inited;
 }
 
 static void
@@ -435,12 +440,12 @@ gtk_draw_dictChanged( DrawCtx* XP_UNUSED(p_dctx),
 {
 }
 
-static void
+static XP_Bool
 gtk_draw_beginDraw( DrawCtx* p_dctx )
 {
 #ifdef USE_CAIRO
     GtkDrawCtx* dctx = (GtkDrawCtx*)p_dctx;
-    initCairo( dctx );
+    return initCairo( dctx );
 #endif
 }
 
@@ -1482,24 +1487,24 @@ gtkDrawCtxtMake( GtkWidget* drawing_area, GtkGameGlobals* globals )
 void
 draw_gtk_status( GtkDrawCtx* dctx, char ch )
 {
-    initCairo( dctx );
+    if ( initCairo( dctx ) ) {
+        GtkGameGlobals* globals = dctx->globals;
 
-    GtkGameGlobals* globals = dctx->globals;
+        XP_Rect rect = {
+            .left = globals->netStatLeft,
+            .top = globals->netStatTop,
+            .width = GTK_NETSTAT_WIDTH,
+            .height = GTK_HOR_SCORE_HEIGHT
+        };
+        gtkEraseRect( dctx, &rect );
 
-    XP_Rect rect = {
-        .left = globals->netStatLeft,
-        .top = globals->netStatTop,
-        .width = GTK_NETSTAT_WIDTH,
-        .height = GTK_HOR_SCORE_HEIGHT
-    };
-    gtkEraseRect( dctx, &rect );
+        const XP_UCHAR str[2] = { ch, '\0' };
+        draw_string_at( dctx, NULL, str, GTKMIN_W_HT,
+                        &rect, XP_GTK_JUST_CENTER,
+                        &dctx->black, NULL );
 
-    const XP_UCHAR str[2] = { ch, '\0' };
-    draw_string_at( dctx, NULL, str, GTKMIN_W_HT,
-                    &rect, XP_GTK_JUST_CENTER,
-                    &dctx->black, NULL );
-
-    destroyCairo( dctx );
+        destroyCairo( dctx );
+    }
 }
 
 void