Get object(Sprite) under the touched area ..>

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Get object(Sprite) under the touched area ..>

(14 posts) (4 voices)

Started 1 year ago by ibii
Latest reply from Daniel

Tags:

ibii
Member

Hi,

Just wondering is it possible to just have a single touch event listener that when an object(sprite) is touched it can tell you what sprite was touched.

I know you can do it with stage co-ords...

In As3 I would usually just have a generic click listener, and trace e.target, or e.target.name on clicked position to id the object under that position. then set a case statement to do fire a action.

Can this be done with sparrow?, if so please let me know if someone has a solution.

Many thanks in advance...

Posted 1 year ago #
Daniel
Primary Feather
Hm, I'm not sure I understand the question correctly. If you add a touch event listener to the stage, you will receive touch events from all objects at the stage, and the 'target' property of the event will point to the object that was touched (just the way it is in AS3).

Then you could do different things depending on the object, like this:
```
SPDispayObject *target = event.target;

if ([target isKindOfClass:[SomeClass class]])
  // do something
else if ([target isKindOfClass:[AnotherClass class]])
  // something else
// etc.
```
Is that what you meant?
Posted 1 year ago #
ibii
Member

Yes, thats it... except "event.target.name" was used so I could accurately id the object. ex. button1, button2

My guess is we maybe don't have the .name to work with but my idea was to create a SPSprite class and add a variable (string)
then when touched on that object get the string and do a case statement...

Can this be done?

Posted 1 year ago #
Daniel
Primary Feather

Yes, this could be done! You could e.g. create a custom 'NamedSprite' class that adds a name property, and then use this every time you need to have a name.

However, I'm evaluating adding a 'name' property to display objects in the next version of Sparrow, as a lot of users seem to want that functionality. So this problem might fix itself in the future

Posted 1 year ago #
ibii
Member

Thanks Daniel,

Yes the .name would be good, I look forward to that release, but in the mean time will look at variables within the custom Sprite class, as I also want to pass some x,y variables as well... will be used on that isometric grid I just created with your help, many thanks for pointing me in the right direction there.

Posted 1 year ago #
freerunnering
Moderator

But unless the object is mentioned in the .h file i don't see how .name could be implemented to work how people want?

Posted 1 year ago #
ibii
Member

I ran the following test to see what would be traced, as in as3 if you have a sprite that contains an image the resulting event will only see the image in the sprite, unless its set to non mouse enabled, or we get the target.parent of the image, resulting in targeting the holding sprite.

I think if I made a custom SPImage class with another name then I could just reference this class for select items, lets say (Grid Tiles) only...

Or is there a way to hide the child object (SPImage) from the event in the sprite, resulting in SPSprite being returned??

//----------------------------------------
//Touch event
//----------------------------------------
- (void)onTouch:(SPEvent *)event
{
if ([event.target isKindOfClass:[SPSprite class]])
{
NSLog(@"touched Sprite");
}
if ([event.target isKindOfClass:[SPImage class]])
{
NSLog(@"touched Image");
}
}

NSLOG Returned:::

2010-10-11 17:43:52.895 base_ipad[844:207] touched Image
2010-10-11 17:43:53.073 base_ipad[844:207] touched Image

Posted 1 year ago #
Daniel
Primary Feather
Ah, OK, now I see what you mean.

Hm, if you know that the image is the direct child of a certain class, you could change the query to this:
```
SPDisplayObject *target = event.target;
if ([target.parent isKindOfClass:[SomeClass class]])
  // ...
```
But I admit that it's not super-elegant

Another piece of information that could help: if you change the signature of the event handler to this:

- (void)onTouch:(SPTouchEvent *)event

then you can make us of this method:

NSSet *touches = [event touchesWithTarget:someObject];

In that case, 'someObject' could be both the sprite or the image, even though the direct 'target' of the event is always the image.

However, this only helps you if you have some reference to this object.
Posted 1 year ago #
ibii
Member

Not super elegant but works, to return x,y of the sprite under touch, Thank you.

Only issue, I am getting a single warning,
warning: incompatible Objective-C types initializing 'struct SPEventDispatcher *', expected 'struct SPDisplayObject *'

Working Code::

- (void)onTouch:(SPEvent *)event
{
SPDisplayObject *target_obj = event.target;

if ([target_obj.parent isKindOfClass:[SPSprite class]])
{
NSLog(@"touched Sprite");
NSLog(@"obj_x %f obj_y %f ",target_obj.parent.x,target_obj.parent.y);

}
if ([target_obj.parent isKindOfClass:[SPImage class]])
{
NSLog(@"touched Image");
}

}

Posted 1 year ago #
Daniel
Primary Feather

Ah, sorry, I forgot to cast the target to 'DisplayObject':

SPDisplayObject *target_obj = (SPDisplayObject *)event.target;

I think that must have been the reason for the warning.

Posted 1 year ago #
ibii
Member

Thanks Daniel, Yes that fixed it.

Just like to say this framework is really impressive, only picked it up for about a week and already got an very rapid and productive head start..

On another note:

How would I do a call to function inside that target_obj (sprite). Having real issues trying to call a function.

my iso_tile is the target_obj, I checked by just adding a tween to alpha in the touch event. works no problems.

Iso_Tile.h

#import "Sparrow.h"

@interface Iso_Tile : SPSprite

- (id)initWithX:(int)inPosX andY:(int)inPosY;

SPImage *tile_img;
SPSprite *sprite;

- (void)adapt;

@end

//---------------------------------//

Iso_Tile.m

#import "Iso_Tile.h"

@implementation Iso_Tile

- (id)initWithX:(int)inPosX andY:(int)inPosY
{
if (self = [super init])
{
tile_img = [SPImage imageWithContentsOfFile:@"map_tile.png"];
sprite = [SPSprite sprite];

[sprite addChild:tile_img];
[self addChild:sprite];
sprite.x = inPosX;
sprite.y = inPosY;
}

return self;

}
- (void)adapt
{
NSLog(@"adapt fired");

}
- (void)dealloc
{
[tile_img dealloc];
[sprite dealloc];
[super dealloc];
}
@end

//------------------------------//

The touch event in Game.m

- (void)onTouch:(SPTouchEvent*)event
{
SPTouch *touch = [[event touchesWithTarget:self andPhase:SPTouchPhaseBegan] anyObject];
if (touch)
{
//SPSprite *target_obj = event.target;
SPDisplayObject *target_obj = (SPDisplayObject *)event.target;

if ([target_obj.parent isKindOfClass:[SPSprite class]])
{
NSLog(@"touched Sprite");
NSLog(@"obj_x %f obj_y %f ",target_obj.parent.x,target_obj.parent.y);

//SPTween *tween = [SPTween tweenWithTarget:target_obj.parent time:0.5f];
//[tween animateProperty:@"alpha" targetValue:0.0f];
//[self.stage.juggler addObject:tween];

[target_obj.parent adapt]; //Here's where I'm having issues....
}
}
}

Posted 1 year ago #
Daniel
Primary Feather
Hi Ibii,

sorry for the late answer! Busy week ...

When you call a method on an object, the compiler first looks at the definition of the object. An object defined like this:

SPDisplayObject *someObject;

will only support methods of 'SPDisplayObject' and the classes it inherits from. Even if 'someObject' is really a more specific class:

SPDisplayObject *someObject = [SPSprite sprite];

Thus, if you know that an object is, say, an Iso_Tile, you have to cast it to that type:

Iso_Tile *isoTile = (Iso_Tile *)event.target;

If you're not sure about the type, you can check it at run time:
```
if ([event.target isKindOfClass:[Iso_Tile class]])
{
  Iso_Tile *isoTile = (Iso_Tile *)event.target;
  // OK to call methods like 'adapt'
}
```
I hope that helps!
Posted 1 year ago #
qoolbox
Member
It seems to me that the following can never happen:
```
if ([event.target isKindOfClass:[SPSprite class]])
```
event.target is always a child of the sprite container. I would like the children of a sprite to be non-touchable, but the sprite itself touchable (and reported as the event.target) - is there anyway to do this?
Posted 1 year ago #
Daniel
Primary Feather
You're right, your sample code will never enter the if-clause, as it's always the leaf-nodes (SPImage, SPQuad) that will be the targets.

However, it works the other way round: if you call
NSArray *touches = [[touchEvent touchesWithTarget:aSprite andPhase:SPTouchPhaseMoved] allObjects];
then you will get all touches of the children, as well. The "target" word includes, in this case, any parent of a touched leaf node.

This way, you should be able to do what you described in your question. If, for some reason, you want the "target" property of the event to be the sprite, you'd just have to create a custom event instead, and dispatch it in the touch event listener method of the sprite; when any of the children is touched, the event dispatcher will be called. Now you can dispatch your custom event, and the target will be the sprite.
Posted 1 year ago #

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