.net barcode generator code project 7: Scrolling with Joy in Objective-C

Encoding DataMatrix in Objective-C 7: Scrolling with Joy

TIP: The use of the buttonRadius variable allows you to change the radius of the button in one place, instead of having to update several values in several places. This is not only extra work for a value you might want to tweak several times before you get it exactly the way you want to. It can also introduce subtle bugs, because you re a human and you tend to forget things, like changing that one value over there. Suddenly the button is offset or worse, the input doesn t match the button s location. The InputLayer class schedules the update method:

[self scheduleUpdate];

The update method is used to check if the button is touched or not:

-(void) update:(ccTime)delta { if (fireButton.active) { CCLOG(@"FIRE!!!"); } }

Instead of shooting a bullet, I wanted to keep things simple for now and simply log a successful button press. If you try the ScrollingWithJoy05 project now, you ll notice that there isn t any button drawn. Yet when you touch the screen at the lower-right corner you ll see the FIRE!!! message appear in the debugger console. So all is well and right, except that the button can t be seen which we ll need to fix.

Eeeww! No, it s not what you think. Skinning in computer graphics refers to giving an otherwise featureless object a texture or simply a different look. In this case we want to actually see our button, so we need an image for that. I also prefer to add cocos2d-style static initializers to external classes using a category, as done in the last chapter. This helps avoid potentially forgetting to send alloc or autorelease messages to a SneakyButton object. I ll start with that by adding a SneakyExtensions class to the ScrollingWithJoy06 project and then stripping the header file down to this:

#import <Foundation/Foundation.h> // SneakyInput headers #import "ColoredCircleSprite.h" #import "SneakyButton.h" #import "SneakyButtonSkinnedBase.h" #import "SneakyJoystick.h" #import "SneakyJoystickSkinnedBase.h" @interface SneakyButton (Extension) +(id) button; +(id) buttonWithRect:(CGRect)rect; @end

Once more, all the SneakyInput headers are added because I plan to make more categories for every SneakyInput class that doesn t conform to regular cocos2d initializers. In this case, a SneakyButton category named Extension is added, which adds two methods, named button and buttonWithRect. They are implemented as shown in Listing 7 8.

Listing 7 8. A Category with SneakyButton Autorelease Initializers #import "SneakyExtensions.h" @implementation SneakyButton (Extension) +(id) button { return [[[SneakyButton alloc] initWithRect:CGRectZero] autorelease]; } +(id) buttonWithRect:(CGRect)rect { return [[[SneakyButton alloc] initWithRect:rect] autorelease]; } @end

They simply wrap the alloc and autorelease calls. Also, I decided to add a simple, parameterless button initializer because the CGRect parameter isn t really used anyway. This allows me to initialize the fireButton in a straightforward manner:

fireButton = [SneakyButton button];

It s just a little extra effort for more convenience and cleaner code. I ll be adding more convenience methods to SneakyExtensions without discussing them in the book, as the principle is the same. Now my mind is at peace and I can start skinning the button. I created four button images that are 100 100 pixels in size twice the final button radius of 50 that I m going with. The button images come in four variations: Default, Pressed, Activated, and Disabled. The default state is what the button looks like when it isn t pressed, which should make it obvious what the Pressed state is. The Activated state only comes into play for toggle buttons, meaning the toggle button is active, or on. The Disabled image is used if the button currently has no function. For example, when the ship s weapons are overheated and you can t shoot for a few seconds, you could disable the button and it would show the Disabled image. For the shoot button, I only needed to use the Default and Pressed images. Listing 7 9 shows the updated addFireButton method.

Listing 7 9. Replacing Listing 7 7 with a Skinned Button float buttonRadius = 50; CGSize screenSize = [[CCDirector sharedDirector] winSize]; fireButton = [SneakyButton button]; fireButton.isHoldable = YES; SneakyButtonSkinnedBase* skinFireButton = [SneakyButtonSkinnedBase skinnedButton]; skinFireButton.position = CGPointMake(screenSize.width - buttonRadius, buttonRadius); skinFireButton.defaultSprite = [CCSprite spriteWithSpriteFrameName: @"button-default.png"];