Pure Python gestures

Anxietier

thx for share ur code, it's really useful.
i was try to overload view class, so i can zoom imageview and drag it, like photo album, here is my problem:
when i use 2 fingers to drag imageview then pinch it, it's ok,
but when i pinch it at first, the imageview's left-top corner will be fixed for a while, as i pinch more scale, the imageview would jump under my fingers, then when i drag and pinch, the experience would be ok
i dont know am i describe it clearly, here is my demo code

import gestures
import ui


class MyView(ui.View):
	def __init__(self):
		self.width, self.height = ui.get_screen_size()
		self.background_color = 'white'
		
		self.set_ui()
		self.set_label_action()
		
		self.label_init_center = self.label.center
		self.label_init_width = self.label.width
		self.label_init_height =  self.label.height
		
	def set_ui(self):
		label = ui.Label()
		self.label = label
		label.text = 'Demo'
		label.border_color = 'black'
		label.border_width = 1
		label.width, label.height = 400, 400
		label.center = self.width/2, self.height/2
		self.add_subview(label)
		
	def set_label_action(self):
		pincher = gestures.pinch(self.label, self.pinch_handler)
		panner = gestures.pan(self.label, self.pan_handler, minimum_number_of_touches=2)
		panner.together_with(pincher)
		
	def pan_handler(self, data): 
		self.label.center = self.label_init_center + data.translation
		if self.label.text == '2 fingers are pinching':
			self.label.text += 'and panning'
		if self.label.text == 'Demo':
			self.label.text = '2 fingers are panning'
		if data.state == gestures.ENDED:
			self.label.text = 'Demo'
			self.label_init_center = self.label.center

	def pinch_handler(self, data): 
		self.label.width, self.label.height = self.label_init_width * data.scale, self.label_init_height * data.scale
		if self.label.text == '2 fingers are panning':
			self.label.text += ' and pinching'
		if self.label.text == 'Demo':
			self.label.text = '2 fingers are pinching'
		if data.state == gestures.ENDED:
			self.label.text = 'Demo'
			self.label_init_width = self.label.width
			self.label_init_height = self.label.height

		
if __name__ == "__main__":
	mView = MyView()
	mView.present('fullscreen', hide_title_bar = True)```

stephen

@Anxietier hey ive never dealt with gestures before but i imagin giving each movment a delegate to register separatly then get the diference of the 'onEvent' call (sorry just made that one up lol) would this posibly help? might need separate Gesture objectsbinstead of calling all from one view. not sure how that would work

Anxietier

@stephen im not sure understand whats ur meaning (not good at eng..) :
make one label, when i swipe it up\down\left\right, or drag it, or zoom it, etc.. it can do diff things
did u mean that? if so, then yes
btw, if u wanna swipe 4 directions with one handle, u can write like this:
gestures.RIGHT|gestures.LEFT|gestures.UP|gestures.DOWN

mikael

@Anxietier, can you subclass ZoomPanView instead?

If you run pygestures.py and swipe from the right, you get the demo picture that you can pan and zoom, and that seems to work ok.

The code for it is at the end of the file.

stephen

@Anxietier okay i was in a bit of a rush before and didnt visualize fully.

I have not looked at @mikael 's module yet but givin who authored it im sure ite outstsnding. that said my first post is no longer valid.. 😅😉

as for your original issue i went to photos and played with the pinch/pan for a bit and i noticed that if i pinched from corners ↴

good

everythingbworked fine. BUT if one finger wasnt close enough to corner ↴

bad

the gester would act as though it had constraints.

if i understand your problem then possibly these are similarbin effect and that should mean increasing the "touch" target rect size would help prevent this?

Note: inused photos App givin u wanted to Mock functionality ☺️🤓

Anxietier

@mikael hi, i tested zoomPanDemo, and it works fine, thanks for advice.
btw, im trying to make an effect that when i drag down PanView, it can make me feel damping, as my finger move away, it can get back to origin pos, feel like looking website, drag down for refresh
could you provide any idea for that? thank you

Anxietier

@stephen thx for reply
ive tryed mikael's zoomPanDemo, add it to my main View, and it works fine, so the issue is on mine :(
i would subclass ZoomPanView, and try it :D

stephen

@Anxietier no problem. i looked over the moduleand it looks like all uwould need to do is run a ui.animate transgorm back yto orignal psition.if touch doesnt store the original long enough (it should) you can also store this in a var. should be straight forward butd have to run through this module a bit beore i can give an example.

Anxietier

@stephen
yeah, i made a demo, i subclass ui.view, add ui,imageview to show image, and i def a method to fix imageview_size to view_size, include view_center, when i drag down imageview and leave my finger, it can move back to origin pos,
but, i need an experience, i'd try to describe it:
'' when i drag it down shortly, imageview would move down follow my finger,
when my finger drag long way, like from top screen to bottom, the imagview wouldnt follow my finger, feel like dragging a strong
spring ''
i try to find a math function to let imageview and fingers' trave non-linear, but i failed, so ... u know :P

stephen

@Anxietier 🤓 ah math now i can help u. give me a few min to write up a friction/drag method for you

mikael

@Anxietier, please see below for something you can adjust to your needs.

I recommend and use scripter, because it makes the animations easy and includes the ease functions.

import ui
import scripter

v = ui.View(background_color='black')

class Pulled(ui.View):
    
    straight_pull = 100
    slowing_pull = 100
    
    def touch_began(self, t):
        self.start_y = ui.convert_point(t.location, from_view=self).y
        
    def touch_moved(self, t):
        delta_y = (
            ui.convert_point(t.location, from_view=self).y - 
            ui.convert_point(t.prev_location, from_view=self).y)
        if self.y < self.straight_pull:
            self.y += delta_y
            return
        if self.y < (self.straight_pull + self.slowing_pull):
            diff = self.y-self.straight_pull
            diff_fraction = diff/self.slowing_pull
            effective = 1 - min(1, diff_fraction) ** 2
            self.y += delta_y * effective
        
    def touch_ended(self, t):
        scripter.y(self, 0, ease_func=scripter.ease_out)

v.add_subview(Pulled(
    frame=v.bounds,
    flex='WH',
    background_color='green'))

v.present('fullscreen')

Anxietier

@mikael
thank you, when i ran ur code, it post me an error:
scripter.y(self, 0, ease_func=scripter.ease_out)
module 'scripter' has no attribute 'y'

then i check scripter.py, i only found the vector_class has a method called y(...)
im confused~

Anxietier

@Anxietier @mikael
oh, never mind, i restarted app, now its wording fine :D

mikael

@Anxietier, and a version with a revealed label and a refresh trigger:

import ui
import scripter

v = ui.View(background_color='black')

class Pulled(ui.View):
    
    straight_pull = 30
    slowing_pull = 80
    
    def touch_began(self, t):
        self.start_y = ui.convert_point(t.location, from_view=self).y
        
    def touch_moved(self, t):
        delta_y = (
            ui.convert_point(t.location, from_view=self).y - 
            ui.convert_point(t.prev_location, from_view=self).y)
        if self.y < self.straight_pull:
            self.y += delta_y
            return
        if self.y < (self.straight_pull + self.slowing_pull):
            diff = self.y-self.straight_pull
            diff_fraction = diff/self.slowing_pull
            try:
                self.reveal_func(diff_fraction)
            except AttributeError: pass
            effective = 1 - min(1, diff_fraction) ** 2
            self.y += delta_y * effective
            
        
    def touch_ended(self, t):
        scripter.y(self, 0, ease_func=scripter.ease_out)
        try:
            self.reveal_func(0)
        except AttributeError: pass
        if self.y > self.straight_pull:
            self.trigger_func()

label = ui.Label(text='Release to refresh',
    text_color='white',
    flex='LBR',
    alpha=0,
)
label.size_to_fit()
label.center = v.bounds.center()
label.y = 8
v.add_subview(label)

def reveal(fraction):
    label.alpha = fraction
    
def trigger():
    scripter.hide(label)
    print('refresh')

v.add_subview(Pulled(
    reveal_func=reveal,
    trigger_func=trigger,
    frame=v.bounds,
    flex='WH',
    background_color='green'))

v.present('fullscreen')

mikael

@Anxietier, oh, you can throw away the touch_began method, it’s from an earlier version.

Anxietier

@mikael thank you
and if i want to bind it with gestures, what should i do
i mean is there any conflict between gestures and touch
what i want to make is, i can use twin fingers to zoom and move picture(imageview or subclass zoompanview, later is better i guess), and when i move picture, move space and scale would be limited, as i leave my fingers, picture's edge should be forced move to superview's edge

Anxietier

@mikael ah, dont bother
i didnt read doc carefully(perhaps wrong word :P), now i can bind them together, thanks for ur help, ur codes are really amazing and helpful :D

mikael

@Anxietier, little optimization of the ”feel” and code simplification.

import ui
import scripter

v = ui.View(background_color='black')

class Pulled(ui.View):
    
    trigger_distance = 30
    pull_distance = 80
    
    def touch_moved(self, t):
        delta_y = (
            ui.convert_point(t.location, from_view=self).y - 
            ui.convert_point(t.prev_location, from_view=self).y)
        diff_fraction = self.y/self.pull_distance
        try:
            self.reveal_func(diff_fraction)
        except AttributeError: pass
        self.y += delta_y * (1 - min(0.9, diff_fraction) ** 2)
        self.y = max(0, self.y)
        
    def touch_ended(self, t):
        scripter.y(self, 0, ease_func=scripter.ease_out)
        try:
            self.reveal_func(0)
        except AttributeError: pass
        if self.y > self.trigger_distance:
            self.trigger_func()

label = ui.Label(text='Release to refresh',
    text_color='white',
    flex='LBR',
    alpha=0,
)
label.size_to_fit()
label.center = v.bounds.center()
label.y = 8
v.add_subview(label)

def reveal(fraction):
    label.alpha = fraction
    
def trigger():
    scripter.hide(label)
    print('refresh')

v.add_subview(Pulled(
    reveal_func=reveal,
    trigger_func=trigger,
    frame=v.bounds,
    flex='WH',
    background_color='green'))

v.present('fullscreen')

stephen

!!! Removed by poster to not confuse future readers with incorrect Code Examples.. 🤓😉

Anxietier

@mikael
thanks for help, i make it
but there's another problem showed up:
i make a main view, then i subclass zoomPanView and add to mainView , after that i add imageView as zoomPanView's subVIew, like what zoomPanDemo did, when i overwrite on_pan method and test it, data.began and data.changed can give me right value, but data.ended not, i dont know why