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Two pointers touch pinch event. Lambda Signature: (start1: Xy, start2: Xy, end1: Xy, end2: Xy) -> Unit Two fingers touch mode is enabled by performing a single pointer touch immediately followed by two pointers down, with one of the pointers close to the previous touch. "start1" param represents start of the previous position for first pointer "start2" param represents start of the previous position for second pointer "end1" param represents end of the current position for first pointer "end2" param represents end of the current position for second pointer