From 57acc66fd45ef77045e378967ff81e09f381d439 Mon Sep 17 00:00:00 2001
From: Dan Gudmundsson <dgud@erlang.org>
Date: Tue, 3 May 2016 13:36:28 +0200
Subject: wx: Fix warnings in example

Bitmaps of size less than 1 generates asserts,
and size 0 event is before window is realized.
---
 lib/wx/examples/demo/ex_canvas.erl       | 13 ++++++++-----
 lib/wx/examples/demo/ex_canvas_paint.erl | 16 ++++++++++------
 2 files changed, 18 insertions(+), 11 deletions(-)

(limited to 'lib')

diff --git a/lib/wx/examples/demo/ex_canvas.erl b/lib/wx/examples/demo/ex_canvas.erl
index 2a95ea0777..b00ce81993 100644
--- a/lib/wx/examples/demo/ex_canvas.erl
+++ b/lib/wx/examples/demo/ex_canvas.erl
@@ -136,11 +136,14 @@ handle_event(#wx{event = #wxCommand{type = command_button_clicked}},
     {noreply, State};
 handle_event(#wx{event = #wxSize{size={W,H}}},
 	     State = #state{bitmap=Prev, canvas=Canvas}) ->
-    Bitmap = wxBitmap:new(W,H),
-    draw(Canvas, Bitmap, fun(DC) -> wxDC:clear(DC) end),
-    wxBitmap:destroy(Prev),
-    {noreply, State#state{bitmap = Bitmap}};
-
+    if W > 0 andalso H > 0 ->
+	    Bitmap = wxBitmap:new(W,H),
+	    draw(Canvas, Bitmap, fun(DC) -> wxDC:clear(DC) end),
+	    wxBitmap:destroy(Prev),
+	    {noreply, State#state{bitmap = Bitmap}};
+       true ->
+	    {noreply, State}
+    end;
 handle_event(#wx{event = #wxMouse{type=left_down, x=X, y=Y}}, State) ->
     {noreply, State#state{pos={X,Y}}};
 handle_event(#wx{event = #wxMouse{type=motion, x=X1, y=Y1}},
diff --git a/lib/wx/examples/demo/ex_canvas_paint.erl b/lib/wx/examples/demo/ex_canvas_paint.erl
index aa510f5342..75eb840b04 100644
--- a/lib/wx/examples/demo/ex_canvas_paint.erl
+++ b/lib/wx/examples/demo/ex_canvas_paint.erl
@@ -157,10 +157,15 @@ handle_event(#wx{event = #wxMouse{type = motion, x = X, y = Y}},
     {noreply, State#state{old_pos = {X,Y}}};
 %% Resize event
 handle_event(#wx{event = #wxSize{size = {W,H}}}, State = #state{bitmap=Prev}) ->
-    wxBitmap:destroy(Prev),
-    Bitmap = wxBitmap:new(W,H),
-    draw(State#state.canvas, Bitmap, fun(DC) -> wxDC:clear(DC) end),
-    {noreply, State#state{bitmap=Bitmap}};
+    case W > 0 andalso H > 0 of
+	true ->
+	    wxBitmap:destroy(Prev),
+	    Bitmap = wxBitmap:new(W,H),
+	    draw(State#state.canvas, Bitmap, fun(DC) -> wxDC:clear(DC) end),
+	    {noreply, State#state{bitmap=Bitmap}};
+	false ->
+	    {noreply, State}
+    end;
 handle_event(#wx{event = #wxMouse{type = left_dclick,x = X,y = Y}}, State = #state{}) ->
     wxPanel:connect(State#state.canvas, motion),
     {noreply, State#state{old_pos = {X,Y}}};
@@ -235,11 +240,10 @@ draw(Canvas, Bitmap, Fun) ->
     CDC = wxClientDC:new(Canvas),
 
     Fun(MemoryDC),
-    
     wxDC:blit(CDC, {0,0},
 	      {wxBitmap:getWidth(Bitmap), wxBitmap:getHeight(Bitmap)},
 	      MemoryDC, {0,0}),
-    
+
     wxClientDC:destroy(CDC),
     wxMemoryDC:destroy(MemoryDC).
 
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