ChartsOrg/Charts

Bars not rendering or disappearing while and after dragging

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#2,240 opened on Mar 13, 2017

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help wanted★★

Description

I've created a bar chart using BarChartView. The view displays work hours per day. Unfortunately, some bars are not rendered at all - and others are disappearing while the whole chart is dragged.

Before the chart is shown the first time, it's zoomed to show only 7 bars at a time:

barChart.zoom(scaleX:ceil(CGFloat(dataSet.xMax - dataSet.xMin) / 7), scaleY: 1, x: 0, y: 0)

Then the view is animated, so the latest day is shown first:

barChart.moveViewToAnimated(xValue: dataSet.xMax, yValue: dataSet.yMin, axis: barChart.rightAxis.axisDependency, duration: 0.8, easingOption: .easeInOutSine)

This leads to the following result - so far, so good:

img_2071

As soon as I drag the chart to the right, bars begin to disappear - only the value remains visible (notice the bar of Mo. 6th - it's gone):

img_2072

Also all bars which are further left and therefore not visible immediately (because of the zoom) are not rendered at all. What I' doing wrong?

Contributor guide

Tech stack
swift
Domain
mobile
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
SwiftiOS developmentCharts library knowledge
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Investigate the rendering logic in BarChartRenderer.swift and BarChartView.swift. Focus on how bars are drawn when the chart is zoomed and animated. Check if the `moveViewToAnimated` method causes bars to be clipped or not redrawn. Look for similar issues or fixes in the repository's closed issues or pull requests.