Here's what I came up with. It is a little slow though. It's pretty much
a port of the code that I linked. I had to adapt to the way move events
are issued in LC (particularly that a touch start does not include
coordinates). I also added the ability to continue moving when a zoom
stops (only one touch ended). I initially was calling the "updateImage"
handler using send in time (and checking pending messages to avoid calling
multiple times), but the code is fast enough to not benefit from that
(adding delay made it less smooth, the "updateImage" handler always seemed
to finish before another move event was queued).
I put the code in the graphic. I called the "initGraphic" handler from the
card preOpenCard handler.
local panning, \
zooming, \
startX0, startY0, \
startX1, startY1, \
endX0, endY0, \
endX1, endY1, \
startDistanceBetweenFingers, \
endDistanceBetweenFingers, \
pinchRatio, \
imgWidth, imgHeight, \
currentContinuousZoom, \
currentOffsetX, currentOffsetY, \
currentWidth, currentHeight, \
newContinuousZoom, \
newHeight, newWidth, \
newOffsetX, newOffsetY, \
centerPointStartX, centerPointStartY, \
centerPointEndX, centerPointEndY, \
translateFromZoomingX, translateFromZoomingY, \
translateFromTranslatingX, translateFromTranslatingY, \
translateTotalX, translateTotalY, \
percentageOfImageAtPinchPointX, \
percentageOfImageAtPinchPointY, \
sTouchArray, sTouch0, sTouch1
on initGraphic
local tLoc
put the width of graphic "square" into imgWidth
put the height of graphic "square" into imgHeight
put 1.0 into currentContinuousZoom
put the left of graphic "square" into currentOffsetX
put the top of graphic "square" into currentOffsetY
put imgWidth into currentWidth
put imgHeight into currentHeight
end initGraphic
on touchMove pID, pX, pY
-- capture current position
put pX into sTouchArray[pID]["x"]
put pY into sTouchArray[pID]["y"]
-- since the touch start doesn't include location, need to handle
-- the calculations here
if sTouchArray[pID]["started"] is empty then
put true into sTouchArray[pID]["started"]
if the number of lines of the keys of sTouchArray is 1 then
put pID into sTouch0
put pX into startX0
put pY into startY0
else if the number of lines of the keys of sTouchArray is 2 then
put pID into sTouch1
put sTouchArray[sTouch0]["x"] into startX0
put sTouchArray[sTouch0]["y"] into startY0
put pX into startX1
put pY into startY1
put ((startX0 + startX1) / 2.0) into centerPointStartX
put ((startY0 + startY1) / 2.0) into centerPointStartY
put (centerPointStartX - currentOffsetX) / currentWidth \
into percentageOfImageAtPinchPointX
put (centerPointStartY - currentOffsetY) / currentHeight \
into percentageOfImageAtPinchPointY
put sqrt((startX1-startX0)^2 + (startY1-startY0)^2) \
into startDistanceBetweenFingers
end if
updatePanZoomState
exit touchMove
end if
-- record the end touch locations for the move
if panning then
put pX into endX0
put pY into endY0
else if zooming then
put sTouchArray[sTouch0]["x"] into endX0
put sTouchArray[sTouch0]["y"] into endY0
put sTouchArray[sTouch1]["x"] into endX1
put sTouchArray[sTouch1]["y"] into endY1
end if
updateImage
end touchMove
on touchEnd pID
put true into sTouchArray[pID]["ended"]
updateImage
end touchEnd
on updateImage
lock screen
if panning then
put endX0 - startX0 into translateFromTranslatingX
put endY0 - startY0 into translateFromTranslatingY
put currentOffsetX + translateFromTranslatingX into newOffsetX
put currentOffsetY + translateFromTranslatingY into newOffsetY
else if zooming then
-- Calculate current distance between points to get new-to-old pinch
-- ratio and calc width and height
put sqrt((endX1-endX0)^2 + (endY1-endY0)^2) \
into endDistanceBetweenFingers
put endDistanceBetweenFingers/startDistanceBetweenFingers into
pinchRatio
put pinchRatio * currentContinuousZoom into newContinuousZoom
put imgWidth * newContinuousZoom into newWidth
put imgHeight * newContinuousZoom into newHeight
-- Get the point between the two touches, relative to upper-left
corner of image
put ((endX0 + endX1) / 2.0) into centerPointEndX
put ((endY0 + endY1) / 2.0) into centerPointEndY
-- This is the translation due to pinch-zooming
put (currentWidth - newWidth) * percentageOfImageAtPinchPointX into
translateFromZoomingX
put (currentHeight - newHeight) * percentageOfImageAtPinchPointY into
translateFromZoomingY
-- And this is the translation due to translation of the centerpoint
between the two fingers
put centerPointEndX - centerPointStartX into translateFromTranslatingX
put centerPointEndY - centerPointStartY into translateFromTranslatingY
-- Total translation is from two components:
-- (1) changing height and width from zooming and
-- (2) from the two fingers translating in unity
put translateFromZoomingX + translateFromTranslatingX into
translateTotalX
put translateFromZoomingY + translateFromTranslatingY into
translateTotalY
-- the new offset is the old/current one plus the total translation
component
put currentOffsetX + translateTotalX into newOffsetX
put currentOffsetY + translateTotalY into newOffsetY
-- Set the image attributes on the card
set the width of graphic "square" to newWidth
set the height of graphic "square" to newHeight
end if
set the left of graphic "square" to newOffsetX
set the top of graphic "square" to newOffsetY
-- clear touch array for ended touches after updating
repeat for each key tKey in sTouchArray
if sTouchArray[tKey]["ended"] then
if tKey is sTouch0 then
put sTouch1 into sTouch0
put endX1 into endX0
put endY1 into endY0
end if
if panning or zooming then
put newOffsetX into currentOffsetX
put newOffsetY into currentOffsetY
end if
if zooming then
put newWidth into currentWidth
put newHeight into currentHeight
put newContinuousZoom into currentContinuousZoom
put endX0 into startX0
put endY0 into startY0
end if
delete variable sTouchArray[tKey]
end if
end repeat
updatePanZoomState
unlock screen
end updateImage
on updatePanZoomState
put false into panning
put false into zooming
if the number of lines of the keys of sTouchArray is 1 then
put true into panning
else if the number of lines of the keys of sTouchArray is 2 then
put true into zooming
end if
end updatePanZoomState
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