I'm working with the sample code - http://developer.anscamobile.com/content/pinch-zoom-gesture and can't figure out where you'd set it up to limit the minimum/maximum scale of the background. Here's the code from the sample:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 | -- activate multitouch system.activate( "multitouch" ) -- add bkgd image to screen local background = display.newImage( "aquariumbackgroundIPhone.jpg", 0, 0 ) local function calculateDelta( previousTouches, event ) local id,touch = next( previousTouches ) if event.id == id then id,touch = next( previousTouches, id ) assert( id ~= event.id ) end local dx = touch.x - event.x local dy = touch.y - event.y return dx, dy end -- create a table listener object for the bkgd image function background:touch( event ) local result = true local phase = event.phase local previousTouches = self.previousTouches local numTotalTouches = 1 if ( previousTouches ) then -- add in total from previousTouches, subtract one if event is already in the array numTotalTouches = numTotalTouches + self.numPreviousTouches if previousTouches[event.id] then numTotalTouches = numTotalTouches - 1 end end if "began" == phase then -- Very first "began" event if ( not self.isFocus ) then -- Subsequent touch events will target button even if they are outside the stageBounds of button display.getCurrentStage():setFocus( self ) self.isFocus = true previousTouches = {} self.previousTouches = previousTouches self.numPreviousTouches = 0 elseif ( not self.distance ) then local dx,dy if previousTouches and ( numTotalTouches ) >= 2 then dx,dy = calculateDelta( previousTouches, event ) end -- initialize to distance between two touches if ( dx and dy ) then local d = math.sqrt( dx*dx + dy*dy ) if ( d > 0 ) then self.distance = d self.xScaleOriginal = self.xScale self.yScaleOriginal = self.yScale print( "distance = " .. self.distance ) end end end if not previousTouches[event.id] then self.numPreviousTouches = self.numPreviousTouches + 1 end previousTouches[event.id] = event elseif self.isFocus then if "moved" == phase then if ( self.distance ) then local dx,dy if previousTouches and ( numTotalTouches ) >= 2 then dx,dy = calculateDelta( previousTouches, event ) end if ( dx and dy ) then local newDistance = math.sqrt( dx*dx + dy*dy ) local scale = newDistance / self.distance print( "newDistance(" ..newDistance .. ") / distance(" .. self.distance .. ") = scale(".. scale ..")" ) if ( scale > 0 ) then self.xScale = self.xScaleOriginal * scale self.yScale = self.yScaleOriginal * scale end end end if not previousTouches[event.id] then self.numPreviousTouches = self.numPreviousTouches + 1 end previousTouches[event.id] = event elseif "ended" == phase or "cancelled" == phase then if previousTouches[event.id] then self.numPreviousTouches = self.numPreviousTouches - 1 previousTouches[event.id] = nil end if ( #previousTouches > 0 ) then -- must be at least 2 touches remaining to pinch/zoom self.distance = nil else -- previousTouches is empty so no more fingers are touching the screen -- Allow touch events to be sent normally to the objects they "hit" display.getCurrentStage():setFocus( nil ) self.isFocus = false self.distance = nil self.xScaleOriginal = nil self.yScaleOriginal = nil -- reset array self.previousTouches = nil self.numPreviousTouches = nil end end end return result end -- Determine if running on Corona Simulator -- local isSimulator = "simulator" == system.getInfo("environment") -- Multitouch Events not supported on Simulator -- if isSimulator then msg = display.newText( "Multitouch not supported on Simulator!", 0, 20, "Verdana-Bold", 14 ) msg.x = display.contentWidth/2 -- center title msg.y = display.contentHeight/2 -- center title msg:setTextColor( 255,255,0 ) end -- register table listener background:addEventListener( "touch", background ) |
I've got the same question. Any advice?
I would just like to know when a pinch and un-pinch occurs. I do not need to know the values
The sample code looks overly complexed, can someone show me how to just detect a pinch and un-pinch. I will be zooming and unzoom to a fixed value.
Keep in mind that the pinch/zoom is completely fluid, meaning the user can go either way and switch direction anytime.
In lines 55-60, the original distance between the first and second touch is discovered, but the magic happens in lines 79-86 where it changes the scale based on the change in the distance.
When it's calculating the distance between the two points and assigning it to newDistance, and if it's less than the original distance stored in self.distance, it's a pinch. If it's greater, it's a zoom.
I agree it can look a little convoluted, but multitouch is much more complicated than detecting a single touch, since you have to track multiple fingers, and if one lets go or one gets added, the program has to know how to handle them individually.
Has anyone gotten this to work, iDesperately need a solution, i've basically tried everything I could think of, so if anyone can point me in the direction or provide code it'd be greatly appreciated.
Hi,
I've made a pinch zoom module easier then in the pinch zoom sample.
I think it may help you, you only have to set an
1 2 3 | if image.contentWidth < yourMaximumWidth then --the zoom in code end |
Go to this part of the pinch-zoom-gesture code sample: starting from line 82
82 if ( scale > 0 ) then
83 self.xScale = self.xScaleOriginal * scale
84 self.yScale = self.yScaleOriginal * scale
85 end
and make the following changes:
if ( scale > 0) then
if ( ( self.xScaleOriginal * scale ) > 0.5 and ( self.xScaleOriginal * scale ) <2.0 ) then
self.xScale = self.xScaleOriginal * scale
self.yScale = self.yScaleOriginal * scale
end
end
here the limits are >0.5 and <2.0
meaning that the ZOOM OUT stop when the image (or stage or whatever you are zooming on) become scaled at 50% of its original size, and the ZOOM IN also stop when the image become scaled at 200% of its original size. Of course you can change these limits.
views:1893 update：2012/1/2 12:52:55