Renaissance—A Cross-Platform Development Tool for Linux and Mac OS X

<?xml version="1.0"?>
<!DOCTYPE gsmarkup>
<gsmarkup>
   <objects>
     <window id="window"
             title="Tiff Viewer"
             closable="yes">
       <hbox>
        <image id="imageView"
               scaling="toFit"
               hasFrame="yes"
               width="300" height="300"
               valign="expand" halign="expand"/>
       </hbox>
     </window>
  </objects>
  <connectors>
    <outlet source="#NSOwner"
            target="#window"
            key="window"/>
    <outlet source="#NSOwner"
            target="#imageView"
            key="imageView"/>
  </connectors>
</gsmarkup>

In Listing 1, we tell Renaissance to create a closable window with the ID window. Then, we place an image view inside this window with such initial properties as the width and height of 300 points. We also specify that we want this image view to be resizable horizontally and vertically. Renaissance understands this and propagates the information up to the window to make it automatically resizable. We then define the connections for those two UI elements. We connect the window with our window outlet and the imageView with our imageView outlet. Those two outlets previously were defined in the file AppController.h.

Once the creation of the main gsmarkup file has been finished, we create the gsmarkup file (Listing 2) to hold the application menu used under GNUstep. In Listing 2, we define three menu items: Load Image, Hide and Quit. Each of them has an associated action that is invoked if the menu item is clicked on.

<?xml version="1.0"?>
<!DOCTYPE gsmarkup>
<gsmarkup>
  <objects>
    <menu type="main">
      <menuItem title="Load Image"
                   action="loadImage:"/>
      <menuItem title="Hide"
                   key="h"
                   action="hide:"/>
      <menuItem title="Quit"
                   key="q"
                   action="terminate:"/>
    </menu>
  </objects>
</gsmarkup>

Once those two files have been created, we modify our initial GNUmakefile and replace the reference to the Gorm files with our two newly created gsmarkup files. We also add the Renaissance framework in our list of linked frameworks. The GNUmakefile now should look like Listing 3.

include $(GNUSTEP_MAKEFILES)/common.make

APP_NAME = TiffViewer

TiffViewer_OBJC_FILES = AppController.m ImageModel.m
TiffViewer_RESOURCE_FILES = TiffViewer.gsmarkup \
        GNUstep-Menu.gsmarkup
ADDITIONAL_GUI_LIBS += -lRenaissance
ADDITIONAL_OBJCFLAGS = -Wall -Wno-import

include $(GNUSTEP_MAKEFILES)/application.make

Then, we modify our initial TiffViewerInfo.plist to remove the reference to MainMenu.nib. The file now should contain the content shown in Listing 4.

{
  ApplicationName = "Tiff Viewer";
  ApplicationDescription = "A small image viewer.";
}

The last step we must take before compiling the application is to implement two delegate methods in our application's controller. Those methods are responsible for loading the main gsmarkup file (TiffViewer.gsmarkup) and the one used for the application menu (GNUstep-Menu.gsmarkup). They need to be invoked automatically upon the application's startup on both GNUstep and Mac OS X. To do so, use an editor to open the AppController.m file and modify it so it has the content shown in Listing 5.

#import "AppController.h"

#import <Renaissance/Renaissance.h>

@implementation AppController
...
- (void) dealloc
{
  [model release];
  [super dealloc];
}

- (void) applicationDidFinishLaunching:
  (NSNotification *) theNotification
{
  [NSBundle loadGSMarkupNamed: @"TiffViewer"
            owner: self];
}

- (void) applicationWillFinishLaunching:
  (NSNotification *) theNotification
{
#ifdef GNUSTEP
  [NSBundle loadGSMarkupNamed: @"GNUstep-Menu"
            owner: self];
#else
  [NSBundle loadGSMarkupNamed: @"Cocoa-Menu"
            owner: self];
#endif
}

- (void) loadImage: (id)sender
{
  NSOpenPanel *oPanel;
  int result;

  oPanel = [NSOpenPanel openPanel];
...

Here, only two methods were added, -applicationDidFinishLaunching: and -applicationWillFinishLaunching:. This shows yet another strength of Renaissance—unobtrusive integration with current code bases.

Finally, compile and start the small application:

# make
# openapp TiffViewer.app

Once the application starts, click on the Load Image menu item and select a TIFF file. It should display the image properly in the window, as shown in Figure 1.

Figure 1. The Image Viewing Application on GNUstep for Linux