3.wxWidgets – Windowing Basics

December 12, 2021 amit C/C++, wxWidgets 1

OVERVIEW

Now we can actually start using wxWidgets for building GUI screens. The example code in this section will show how to create windows and panels and use of common controls like labels and buttons. We are not going to look at layout management as that is dealt with in later sections. The objective here is to get familiar with creating basic GUI applications.

If you have followed the posts in the Introduction page on how to setup wxWidgets and run a sample program, then you now know how to build an application which has a single cpp source file.

In later examples in this series, you will have to work with multiple cpp files. We first look at how to build an executable with multiple source files before we go into the windowing examples.

We have two files simple.cpp which is the wxWidget GUI window and main.cpp which is the main wxApp that calls the Window object in simple.cpp. As per standard C++ practice , we define header files for each class.

SAMPLE CODE

simple.h
#include <wx/wxprec.h>
#ifndef WX_PRECOMP
	#include <wx/wx.h>
#endif

class Simple: public wxFrame {
	public:
		Simple(const wxString& title);
};

simple.cpp

#include "simple.h"

Simple::Simple(const wxString& title):
	wxFrame(NULL, -1, title, wxDefaultPosition, wxSize(700,300)) {

	Centre();
}

main.h

#include <wx/wxprec.h>
#ifndef WX_PRECOMP
	#include <wx/wx.h>
#endif

class MyApp: public wxApp {
	public:
	  virtual bool OnInit();
};

main.cpp

#include "main.h"
#include "simple.h"

IMPLEMENT_APP(MyApp)

bool MyApp::OnInit() {
	Simple *simple = new Simple(wxT("Simple Window test"));
	simple->Show(true);

	return 	true;
}

To build the executable under Linux use the command

g++ main.cpp simple.cpp ``wx-config --cxxflags --libs`` -o simple

Use only single surrounding backticks in the command above and not the double backticks as shown .This will create an executable called simple which you can run via ./simple

To build the executable under Windows , make the following changes to the sample makefile from the earlier post:

# =========================================================================
#     This makefile was generated by
#     Bakefile 0.2.12 (http://www.bakefile.org)
#     Do not modify, all changes will be overwritten!
# =========================================================================




prefix = /mingw64
exec_prefix = ${prefix}
datarootdir = ${prefix}/share
INSTALL = /usr/bin/install -c
EXEEXT = .exe
WINDRES = windres
NM = nm
BK_DEPS = /d/wxWidgets/build-debug/bk-deps
srcdir = .
top_srcdir = ..
LIBS = -lz -lrpcrt4 -loleaut32 -lole32 -luuid -llzma -luxtheme -lwinspool -lwinmm -lshell32 -lshlwapi -lcomctl32 -lcomdlg32 -ladvapi32 -lversion -lwsock32 -lgdi32 -loleacc -lwinhttp
LDFLAGS_GUI = -mwindows
CXX = g++
CXXFLAGS = 
CPPFLAGS = 
LDFLAGS = 
USE_DPI_AWARE_MANIFEST = 2
WX_LIB_FLAVOUR = 
TOOLKIT = MSW
TOOLKIT_LOWERCASE = msw
TOOLKIT_VERSION = 
TOOLCHAIN_FULLNAME = msw-unicode-static-3.1
EXTRALIBS =    -lz -lrpcrt4 -loleaut32 -lole32 -luuid -llzma -luxtheme -lwinspool -lwinmm -lshell32 -lshlwapi -lcomctl32 -lcomdlg32 -ladvapi32 -lversion -lwsock32 -lgdi32 -loleacc -lwinhttp 
EXTRALIBS_XML =  -lexpat
EXTRALIBS_GUI = -llzma
WX_CPPFLAGS = -I${wx_top_builddir}/lib/wx/include/msw-unicode-static-3.1 -I${top_srcdir}/include -D_FILE_OFFSET_BITS=64 
WX_CXXFLAGS = -Wall -Wundef -Wunused-parameter -Wno-ctor-dtor-privacy -Woverloaded-virtual -g -O0   
WX_LDFLAGS =  
HOST_SUFFIX = 
SAMPLES_RPATH_FLAG = 
SAMPLES_CXXFLAGS =  
wx_top_builddir = D:/wxWidgets/build-debug

### Variables: ###

DESTDIR = 
WX_RELEASE = 3.1
WX_VERSION = $(WX_RELEASE).5
LIBDIRNAME = $(wx_top_builddir)/lib
MAINAPP_CXXFLAGS = $(WX_CPPFLAGS) -D__WX$(TOOLKIT)__ $(__WXUNIV_DEFINE_p) \
	$(__DEBUG_DEFINE_p) $(__EXCEPTIONS_DEFINE_p) $(__RTTI_DEFINE_p) \
	$(__THREAD_DEFINE_p) -I$(srcdir) $(__DLLFLAG_p) -I$(srcdir). \
	$(WX_CXXFLAGS) $(CPPFLAGS) $(CXXFLAGS)
MAINAPP_OBJECTS =  \
	$(__MAINAPP___win32rc) \
	MAINAPP_main.o \
	MAINAPP_simple.o

### Conditionally set variables: ###

#CXXC = $(CXX)
CXXC = $(BK_DEPS) $(CXX)
#PORTNAME = base
PORTNAME = $(TOOLKIT_LOWERCASE)$(TOOLKIT_VERSION)
#WXBASEPORT = _carbon
#WXDEBUGFLAG = d
WXUNICODEFLAG = u
#WXUNIVNAME = univ
EXTRALIBS_FOR_BASE = $(EXTRALIBS)
#EXTRALIBS_FOR_BASE = $(EXTRALIBS) \
#	$(EXTRALIBS_XML) $(EXTRALIBS_GUI)
EXTRALIBS_FOR_GUI = $(EXTRALIBS_GUI)
#EXTRALIBS_FOR_GUI = 
#__WXUNIV_DEFINE_p = -D__WXUNIVERSAL__
#__WXUNIV_DEFINE_p_1 = --define __WXUNIVERSAL__
#__DEBUG_DEFINE_p = -DwxDEBUG_LEVEL=0
#__DEBUG_DEFINE_p_1 = --define wxDEBUG_LEVEL=0
#__EXCEPTIONS_DEFINE_p = -DwxNO_EXCEPTIONS
#__EXCEPTIONS_DEFINE_p_1 = --define wxNO_EXCEPTIONS
#__RTTI_DEFINE_p = -DwxNO_RTTI
#__RTTI_DEFINE_p_1 = --define wxNO_RTTI
#__THREAD_DEFINE_p = -DwxNO_THREADS
#__THREAD_DEFINE_p_1 = --define wxNO_THREADS
#__DLLFLAG_p = -DWXUSINGDLL
#__DLLFLAG_p_1 = --define WXUSINGDLL
__WIN32_DPI_MANIFEST_p = \
	--define \
	wxUSE_DPI_AWARE_MANIFEST=$(USE_DPI_AWARE_MANIFEST)
COND_PLATFORM_OS2_1___MAINAPP___os2_emxbindcmd = $(NM) simplewindow$(EXEEXT) \
	| if grep -q pmwin.763 ; then emxbind -ep simplewindow$(EXEEXT) ; fi
#__MAINAPP___os2_emxbindcmd = $(COND_PLATFORM_OS2_1___MAINAPP___os2_emxbindcmd)
__RCDEFDIR_p = --include-dir \
	$(LIBDIRNAME)/wx/include/$(TOOLCHAIN_FULLNAME)
#__MAINAPP___win32rc = MAINAPP_MAINAPP_rc.o
#__MAINAPP_app_Contents_PkgInfo___depname \
#	= simplewindow.app/Contents/PkgInfo
#__MAINAPP_bundle___depname = MAINAPP_bundle
#____MAINAPP_BUNDLE_TGT_REF_DEP = \
#	$(__MAINAPP_app_Contents_PkgInfo___depname)
#____MAINAPP_BUNDLE_TGT_REF_DEP \
#	= $(__MAINAPP_app_Contents_PkgInfo___depname)
#____MAINAPP_BUNDLE_TGT_REF_DEP \
#	= $(__MAINAPP_app_Contents_PkgInfo___depname)
#____MAINAPP_BUNDLE_TGT_REF_DEP \
#	= $(__MAINAPP_app_Contents_PkgInfo___depname)
#____MAINAPP_BUNDLE_TGT_REF_DEP = \
#	$(__MAINAPP_app_Contents_PkgInfo___depname)
COND_MONOLITHIC_0___WXLIB_CORE_p = \
	-lwx_$(PORTNAME)$(WXUNIVNAME)$(WXUNICODEFLAG)$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)_core-$(WX_RELEASE)$(HOST_SUFFIX)
__WXLIB_CORE_p = $(COND_MONOLITHIC_0___WXLIB_CORE_p)
COND_MONOLITHIC_0___WXLIB_BASE_p = \
	-lwx_base$(WXBASEPORT)$(WXUNICODEFLAG)$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)-$(WX_RELEASE)$(HOST_SUFFIX)
__WXLIB_BASE_p = $(COND_MONOLITHIC_0___WXLIB_BASE_p)
COND_MONOLITHIC_1___WXLIB_MONO_p = \
	-lwx_$(PORTNAME)$(WXUNIVNAME)$(WXUNICODEFLAG)$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)-$(WX_RELEASE)$(HOST_SUFFIX)
#__WXLIB_MONO_p = $(COND_MONOLITHIC_1___WXLIB_MONO_p)
#__LIB_SCINTILLA_IF_MONO_p \
#	= \
#	-lwxscintilla$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)-$(WX_RELEASE)$(HOST_SUFFIX)
__LIB_TIFF_p \
	= \
	-lwxtiff$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)-$(WX_RELEASE)$(HOST_SUFFIX)
__LIB_JPEG_p \
	= \
	-lwxjpeg$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)-$(WX_RELEASE)$(HOST_SUFFIX)
__LIB_PNG_p \
	= \
	-lwxpng$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)-$(WX_RELEASE)$(HOST_SUFFIX)
#__LIB_ZLIB_p = \
#	-lwxzlib$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)-$(WX_RELEASE)$(HOST_SUFFIX)
COND_wxUSE_REGEX_builtin___LIB_REGEX_p = \
	-lwxregex$(WXUNICODEFLAG)$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)-$(WX_RELEASE)$(HOST_SUFFIX)
__LIB_REGEX_p = $(COND_wxUSE_REGEX_builtin___LIB_REGEX_p)
#__LIB_EXPAT_p = \
#	-lwxexpat$(WXDEBUGFLAG)$(WX_LIB_FLAVOUR)-$(WX_RELEASE)$(HOST_SUFFIX)

### Targets: ###

all: mainapp$(EXEEXT) $(__MAINAPP_bundle___depname)

install: 

uninstall: 

install-strip: install

clean: 
	rm -rf ./.deps ./.pch
	rm -f ./*.o
	rm -f mainapp$(EXEEXT)
	rm -rf mainapp.app

distclean: clean
	rm -f config.cache config.log config.status bk-deps bk-make-pch shared-ld-sh Makefile

mainapp$(EXEEXT): $(MAINAPP_OBJECTS) 
	$(CXX) -o $@ $(MAINAPP_OBJECTS)    -L$(LIBDIRNAME)  $(LDFLAGS_GUI) $(LDFLAGS)  $(WX_LDFLAGS) $(__WXLIB_CORE_p)  $(__WXLIB_BASE_p)  $(__WXLIB_MONO_p) $(__LIB_SCINTILLA_IF_MONO_p) $(__LIB_TIFF_p) $(__LIB_JPEG_p) $(__LIB_PNG_p)  $(EXTRALIBS_FOR_GUI) $(__LIB_REGEX_p) $(__LIB_EXPAT_p) $(EXTRALIBS_FOR_BASE) $(LIBS)
	$(__MAINAPP___os2_emxbindcmd)

#simplewindow.app/Contents/PkgInfo: simplewindow$(EXEEXT) $(top_srcdir)/src/osx/carbon/Info.plist.in $(top_srcdir)/src/osx/carbon/wxmac.icns
#	mkdir -p simplewindow.app/Contents
#	mkdir -p simplewindow.app/Contents/MacOS
#	mkdir -p simplewindow.app/Contents/Resources
#	
#	
#	sed -e "s/IDENTIFIER/`echo $(srcdir) | sed -e 's,\.\./,,g' | sed -e 's,/,.,g'`/" \
#	-e "s/EXECUTABLE/simplewindow/" \
#	-e "s/VERSION/$(WX_VERSION)/" \
#	$(top_srcdir)/src/osx/carbon/Info.plist.in >simplewindow.app/Contents/Info.plist
#	
#	
#	/bin/echo "APPL????" >simplewindow.app/Contents/PkgInfo
#	
#	
#	ln -f simplewindow$(EXEEXT) simplewindow.app/Contents/MacOS/simplewindow
#	
#	
#	cp -f $(top_srcdir)/src/osx/carbon/wxmac.icns simplewindow.app/Contents/Resources/wxmac.icns

#MAINAPP_bundle: $(____MAINAPP_BUNDLE_TGT_REF_DEP)

#
#MAINAPP_MAINAPP_rc.o: $(srcdir)/main.rc
#	$(WINDRES) -i$< -o$@    --define __WX$(TOOLKIT)__ $(__WXUNIV_DEFINE_p_1) $(__DEBUG_DEFINE_p_1)  $(__EXCEPTIONS_DEFINE_p_1) $(__RTTI_DEFINE_p_1) $(__THREAD_DEFINE_p_1)  --include-dir $(srcdir) $(__DLLFLAG_p_1) $(__WIN32_DPI_MANIFEST_p) --include-dir $(srcdir). $(__RCDEFDIR_p) --include-dir $(top_srcdir)/include

	
MAINAPP_simple.o: $(srcdir)/simple.cpp 
	$(CXXC) -c -o $@ $(MAINAPP_CXXFLAGS) $(srcdir)/simple.cpp


MAINAPP_main.o: $(srcdir)/main.cpp 
	$(CXXC) -c -o $@ $(MAINAPP_CXXFLAGS) $(srcdir)/main.cpp




# Include dependency info, if present:
-include ./.deps/*.d

.PHONY: all install uninstall clean distclean MAINAPP_bundle

Run the makefile within MSYS2 MingW64-bit console by typing

make

On successful completion run the executable from within MSYS2 console with ./simple

If you want to run it from outside the MSYS console, make sure you have the supporting dlls in place and double click simple.exe

This is how the app will look under Ubuntu with a Dark theme:











The following topics are covered further in this section:





	

		

			
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