Manual zoom on both axis(price and time)

[publine2]

Is it possible to disable automatic zoom and do manual zoom by mouse like in TradingView? Will be very appreciated for code example.

[highfestiva]

Currently you can only zoom in/out in Y by Ctrl+ScrollWheel. Apart from that it currently is not possible, as I can't imagine a case where it's better to not center around price. Do you have such a case?

[publine2]

Ctrl+ScrollWheel is good, I can live with that, but when I move the chart back and forward the automatic zooming(or scaling) still making problems for me. Is it possible to switch off this automatic stuff? Normally, if you doing technical analysis on the chart, the least thing you would like to have is the scale change on every chart move. At least for me. By the way, all financial charting systems which I have ever used in my life, all of them have options to disable automatic zooming/scaling/centering and make that manual. So, probably, that manual stuff is actually needed especially for financial charts :) But anyway, thank you for reply, I just thought it should not be much harder than just overriding couple functions with empty ones.

[highfestiva]

Probably a matter of getting used to it during TA. Please file a bug report (I currently don't have feature requests), and I'll add it for v1.8.

[publine2]

I wrote some quickfix module around your finplot to solve all that problems. And as I thought before - it's not that really hard to fix that, just couple strings of code.
-------------------------finplotypan.py----------------------

#!/usr/bin/env python3

import sys
import finplot as fplt
from finplot import *

class FinViewBoxNocsm(fplt.FinViewBox):
    def __init__(self, *args, **kwargs):
        self.y_pan=False # False = default behavior
        super().__init__(*args, **kwargs)

    def setMouseEnabled(self,x=True, y=False):
        super().setMouseEnabled(x=True, y=self.y_pan)

    def set_range(self, x0, y0, x1, y1): 
        blockedFuncs=['linkedViewChanged','refresh_all_y_zoom']
        if self.y_pan and sys._getframe(1).f_code.co_name=='update_y_zoom' and sys._getframe(2).f_code.co_name in blockedFuncs:
            vr = self.viewRect()
            y0 = vr.top()
            y1 = vr.bottom()
        super().set_range(x0,y0,x1,y1)

    def mouseLeftDrag(self, ev, axis):
        super().mouseLeftDrag(ev, None if self.y_pan else axis)

    def set_y_pan(self,state=True):
        self.y_pan = state
        self.setMouseEnabled(x=True, y=self.y_pan)

fplt.FinViewBox=FinViewBoxNocsm

#example of usage:
#import finplotypan as fplt
#ax0 = fplt.create_plot()
#ax0.vb.set_y_pan() #disable automatic zoom, enable y pan
#ax0.vb.set_y_pan(False) #revert to normal behavior

---

[highfestiva]

I suppose that'll disable x-linked panning between different views. Is that ok/desired?

[publine2]

Yes, that is what I wanted. It's not disable x-linking, i't just disable y-autocenter/autozoom... only for the chart where you do set_y_pan(), and you always can go to default behavior by set_y_pan(False). But that is just a "dirty hack" just for now. I believe you will make some kind a set_y_pan() option in normal programming way for v1.8. I tested it with your dockable.py example - works perfect, exactly how it should be.

[highfestiva]

Please supply a case where manual Y zoom/pan is preferable, as I asked for initially.

If you have such as case and like the feature included in finplot, please add it to the existing class FinViewBox. And please keep the pull request minimalistic and clean, without any sys._getframe hacks or unnecessary overrides. Perhaps a hotkey for toggling on/off, and re-rendering when turning on again? Or perhaps dragging on the Y-axis as in TradingView would be better (default off)?

The reason I want these things from you is because, at it's core, finplot is for automated backtesting and inspection, not for manual TA. If we can make it better for manual traders with minimal adjustments, that's great! If not, well then those features are for another lib — or your own fork.