iOS - PDF Interaction & iBooks

[DougN]

put "false" into kickSelf

That's hilarious (and probably healthy, too). I think I may need to adopt this in all my stack scripts.

Doug

[Tester2]

My fellow LiveCoders....

I have been up the mountain and received a gift from the gods...a stack that had the code for how to pinch and zoom on an image!!!

The forum won't let me upload the stack...so I'll post the long code below.

I thought it would be rude not to share....enjoy!

-Tester2

----------------------------------

Code: Select all

[
local sTouches   -- an array storing the location of all the current touches (user's fingers) on the screen
local sDist      -- if we have two tocuhes, this stores the last distance between them
local sWHRatio   -- the width height (aspect) ratio of the current image

constant kPinchScaleRatio = 0.4  -- 1 unit of pinch movement results in a kPinchScaleRatio percentage image scaling

on preOpenStack
   iphoneUseDeviceResolution true
end preOpenStack

on openCard
   
   -- cache the width height ratio of the image of this current card
   -- this is used when making sure the image fits within the current card (see validateRect)
   --
   put the effective width of image "comic" / the effective height of image "comic" into sWHRatio
   
end openCard

on touchMove pId, pX, pY
   
   if sTouches[pId] is empty then
      
      -- this is the first time we have touched, store the location of this touch
      --
      put (pX, pY) into sTouches[pId]
      
      -- if we already have another touch, then cache the distance between the two touches
      -- this means the user has placed a second finger on the screen and may be about to start a pinch motion
      -- we store the current distance between the users fingers so that we know how much the user has moved if they pinch
      --
      if the number of elements in sTouches is 2 then
         put distBetweenPts(sTouches[line 1 of the keys of sTouches], sTouches[line 2 of the keys of sTouches]) into sDist
      end if
      
   else if the number of elements in sTouches is 2 then
      
      -- store the location of this touch for future reference
      --
      put (pX, pY) into sTouches[pId]
      
      -- we have two touches, this means the user has pinched and wants to resize the image
      -- work out the distance bewtween the touches (user's fingers)
      --
      local tDist
      put distBetweenPts(sTouches[line 1 of the keys of sTouches], sTouches[line 2 of the keys of sTouches]) into tDist  
      
      -- we only want to scale the image if the distance between the two touches has changed
      -- i.e. the user has moved one or both of their fingers
      --
      if tDist is not sDist then
         
         -- work out by how much we want to scale the image based on the distance moved / pinched
         --
         local tScale
         put 1 + (tDist - sDist) / 100 * kPinchScaleRatio into tScale
         
         -- scale the image by working out its new rect
         -- the new width and height are simply calculated by multiplying by the scale
         --
         local tWidth, tHeight, tLeft, tTop
         put round(the width of image "comic" * tScale) into tWidth
         put round(the height of image "comic" * tScale) into tHeight
         
         -- the top and left are a bit trickier - we want to zoom in/out on a fixed point in the image
         -- i.e. we want the point of the image which is currently at the center of the sceen 
         -- to remain there during the scaling operation
         -- to maintain this central point we first work out the current distance between the left (and top) of the image
         -- and the center of the screen (the loc of the current card)
         -- this distance will be scaled up/down in the same way as the width and height of the image
         -- we then used this new scaled distance to calculate the new left (and top) of the image
         --
         put round(item 1 of the loc of this card + (the left of image "comic" - item 1 of the loc of this card) * tScale) into tLeft
         put round(item 2 of the loc of this card + (the top of image "comic" - item 2 of the loc of this card) * tScale) into tTop
         
         -- set the new rect of the image based on the newly calculated values
         -- making sure the rect is within the current card by calling validateRect
         -- we set the rect  rather than the width, height, left, top, loc etc as this only scales the image once
         --
         set the rect of image "comic" to validateRect((tLeft, tTop, tLeft + tWidth, tTop + tHeight), sWHRatio)
         
         -- store the new distance between the touches
         --
         put tDist into sDist
         
      end if     
      
   else
      
      -- if the user is not pinching/scaling the image then we just want to move the image
      -- calculate by how much we want to move the image based on how far the user has moved thier finger
      -- this is done by calculating the difference between the current touch x and y coords from the last
      --
      local tXOffset, tYOffset
      put pX - item 1 of sTouches[pId] into tXOffset
      put pY - item 2 of sTouches[pId] into tYOffset
      
      -- set the new position of the image remebering to make sure it is within the current card
      --
      set the rect of image "comic" to validateRect((the left of image "comic" + tXOffset, the top of image "comic" + tYOffset, the right of image "comic" + tXOffset, the bottom of image "comic" + tYOffset), sWHRatio)
      
      -- store the location of the touch so we can calculate the distance on the next move or pinch
      --
      put (pX, pY) into sTouches[pId]
      
   end if
   
end touchMove

-- on touch end and touch release remove the touch location data from our array of touches 

on touchEnd pId
   delete variable sTouches[pId]
end touchEnd

on touchRelease pId
   delete variable sTouches[pId]
end touchRelease

-- Returns the distance between two coordinates using Pythagoras theorem
--
private function distBetweenPts pPt1, pPt2
   return sqrt((item 1 of pPt1 - item 1 of pPt2) ^ 2 + (item 2 of pPt1 - item 2 of pPt2) ^ 2)
end distBetweenPts

-- Make sure the rect passed is not outwith the bounds of the current card
-- Returns a new rect that fits within the bounds of the current card
--
private function validateRect pRect, pWHRatio
   
   -- if the width of the rect is less than the width of this card
   -- then scale the rect so that it's equal to the width of the card
   -- as we are altering the width of the rect, we want to maintain its aspect ratio
   -- so also set the height based of the width height ratio passed
   --
   if (item 3 of pRect - item 1 of pRect) < the width of this card then
      put item 1 of pRect + the width of this stack into item 3 of pRect
      put item 2 of pRect + the width of this stack div pWHRatio into item 4 of pRect
   end if 
   
   -- do the same if the rect is taller than the current card
   -- set the rect to be the same height as the stack and scale the width appropriately
   --
   if (item 4 of pRect - item 2 of pRect) < the height of this card then
      put item 2 of pRect + the height of this card into item 4 of pRect
      put item 1 of pRect + the height of this card * pWHRatio into item 3 of pRect
   end if 
   
   -- make sure that there is no space around the outside of the rect
   -- for example, if there is space bewteen the left hand side of this card and the rect
   -- (the left of the rect > 0), then snap the left of the rect to the left hand side of this card
   -- remembering to adjust the right of the rect so that the width is preserved
   --  
   if item 1 of pRect > 0 then
      put (0, item 2 of pRect, item 3 of pRect - item 1 of pRect, item 4 of pRect) into pRect 
   end if
   if item 2 of pRect > 0 then
      put (item 1 of pRect, 0, item 3 of pRect, item 4 of pRect - item 2 of pRect) into pRect 
   end if
   if item 3 of pRect < the width of this card then
      put (the width of this card - (item 3 of pRect - item 1 of pRect), item 2 of pRect, the width of this card, item 4 of pRect) into pRect 
   end if
   if item 4 of pRect < the height of this card then 
      put (item 1 of pRect, the height of this card - (item 4 of pRect - item 2 of pRect) , item 3 of pRect, the height of this card) into pRect 
   end if 
   
   -- return the adjusted rect
   --
   return pRect
   
end validateRect
]

[CALL-151]

put "false" into kickSelf

That's hilarious (and probably healthy, too). I think I may need to adopt this in all my stack scripts.

Doug

Happy to see that one other person in the universe shares my stupid sense of geek humor.