I try to use two PanResponder to handle multi-touch event. One PanResponder in charge of upper half screen, and one lower. The two PanResponders work fine as long as there only one finger touch the screen. But when I put two finger on the screen, only one PanResponder works. So I only know coordinate( movement) of one finger and have no idea what status of the other finger is.
I can confirm I have this behavior and was unable to get an array of 2 touches with PanResponder.
It seems other people reported the problem in the past: https://react-native.canny.io/feature-requests/p/panresponderonpanrespondermove-not-responding-for-pinch
Related
Can someone more experienced explain how the Pan Responder differs from the Gesture Responder and when it is better to use them.
Document:
Pan Responder:
https://reactnative.dev/docs/panresponder
Gesture Responder:
https://reactnative.dev/docs/gesture-responder-system
The Gesture Responder System is the basic system of how gestures are managed in React Native.
PanResponder is built on top of it and gives you a little more comfort when working with it. It also holds an InteractionManager to prevent interruption of active gestures.
While the Gesture Reponder System only provides you the native touch events, Pan Responder also provides you a gestureState object, which contains the state of the whole gesture (from starting the touch until releasing the finger). This can make your life a lot easier, since you don't have to calculate everything on your own.
If you don't need this gestureState or the properties provided by the gestureState objects are not sufficient for your use case, you could work directly with the Gesture Responder System. Otherwise I would recommend using PanResponder.
I am using a panresponder for each item of the flat-list. I want the pan responder to respond oly when the user swipes from left to right. But pan responder is getting active also when i am scrolling . I want that there will be no interuption while scrolling
Yes i have found a solution for this problem. It basically happens because the scrollView/Flatlist itself uses one responder to sense the gesture and i am also using one pan Responder . So two pan responders cannot work at same time. So the fix for this is when my pan responder becomes active at that time i disables my flatList scrolling and when the pan responder is released or the panresponderEnd method is called i enables the flatlist scrolling . So this way i solved my problem.
I also tell about a problem that faced when i was using panresponder that sometimes panresponder release method is not called , so the card get stucks in the middle. So i used panresponderEnd method which will be called every time when you release it .
In my app, I have horizontal FlatList which is used for swiping between several sub-pages of a screen. This works great.
However, on one of the pages, I have a Slider component. On iOS it works fine, but on Android, the parent ScrollView of the FlatList seems to "steal" the swipe gesture. I am only able to adjust the Slider by clicking very precisely on its thin line, but I cannot adjust it by sliding.
What I need is something like one of these
A view that wraps the Slider component and stops swipe gestures from being propagated to the parent ScrollView
A way to make the FlatList/ScrollView not consume swipes directly on elements that responds to horizontal swipes themself
Somehow adjust the area of which the Slider component will eat the touches around it (it's very small and hard to hit directly). I already tried adding a hitSlop prop, with no luck.
Any suggestions for a solution are very appreciated :)
Check example code and result here.
https://snack.expo.io/#esbenvb/mad-yogurt
My app needs to be able to detect if the user placed 3 fingers anywhere on the screen so that it can call a method while the 3 fingers have not moved from the original position. This is my first time using multitouch in an app so can someone let me know the best way to approach this?
I would suggest using a UILongPressGestureRecognizer configured to require three touches (and minimal movement).
I have a UIView within a UIScrollView. When i want to simulate the drag event on the UIView, swipe event on the UIScrollView is being triggered.
As per the documentation , there isn't much of a difference between swipe and drag.
Swipe
1- Place the pointer at the start position.
2- Hold the mouse button.
3- Move the pointer in the swipe direction and release the mouse button.
Drag
1- Place the pointer at the start position.
2- Hold down the mouse button.
3- Move the pointer in the drag direction.
On an ipad I can use two fingers two swipe and one finger to drag. Now, how do i go about doing something similar on the simulator; drag instead of a swipe?
Edit 1:
I should have been clearer first up. Anyway, my problem is that the mouse drag is firing the swipe instead of drag, thereby scrolling the scroll view instead of passing on the drag event to the UIView contained by the scroll view.
I am on macbook pro. Two-finger swipe on the touchpad is being ignored. Touch and drag is causing the same thing as mouse-drag.
Thanks
See Jeff LaMarche's quick note on how to do this. It's documented in the same page you're reading, but Jeff's explanation is clearer.
If you want to simulate a two-finger gesture in the iPhone simulator, hold down the option key. You will get two dots on the screen instead of one. The two dots will default to pinching - if you bring the dot closer to the center of the screen, the other dot comes toward the center, making it easy to simulate a pinch in or pinch out.
If you want to do a different two-finger gesture, get the two dots the distance apart that you want them to be, then hold down the shift key, while still holding down the option key. That will lock the position of the two finger presses together so you can do, for example, a two-finger swipe.
see this documentation below:
iOS Simulator User Guide
Just use the mouse to drag the view, aka, left click the view then move the mouse
I ended up disabling the scrolling from the UI and added two buttons to scroll the scroll view. Since this is a work around only for the emulator, I have used #ifndef to hide the buttons while building for the device.