Negative BarChartRodStackItem are not drawn correctly in Flutter 3.10.5 (stable)

[large]

Describe the bug
When using stacked bars the negative values are not shown correct on flutter v3.11.xx (master channel).
Same code compiled with Flutter v3.7.12 works as expected.

I have also created an issue within Flutter, but I just wanted you to have a heads up
flutter/flutter#123123 (comment)

To Reproduce
See this reproduction code: https://github.com/large/partlyflicker
(Little messy since I used code from a bigger app that had issues)

Screenshots
Flutter 3.10.5 stable & Flutter 3.11.xx-pre

Flutter 3.7.12

Versions
Flutter 3.7.12 (as expected)
Flutter 3.10.5 stable & masterchannel 3.11.xx-pre channel (not as expected)
fl_chart v0.62.0

[imaNNeo]

we are not going to support the master channel. hopefully it will be fixed in the stable channel. Otherwise, we need to fix it.

[k0psutin]

BarChartRodStackItem is also broken on Flutter 3.10.5 stable channel.

To Reproduce
Clone @large code: https://github.com/large/partlyflicker

Use Flutter 3.10.5 from stable.

Android:

iOS:

[large]

I am AFK and did not test it on stable channel lately. But this is probably an issue related to Impeller (new render engine).

It could be interesting if some could use the stable channel that fails and try to disable Impeller https://docs.flutter.dev/perf/impeller

@imaNNeo wanna give it a try, bugs from master are now included in stable? 😁

[k0psutin]

Disabling the impeller didn't do anything. But it seems that the impeller is not activated at all?

I added:

  <meta-data
    android:name="io.flutter.embedding.android.EnableImpeller"
    android:value="true" />

To androidmanifest.xml and run @large example with flutter run --enable-impeller and the chart seemed to draw correctly:

[large]

Disabling the impeller didn't do anything. But it seems that the impeller is not activated at all?

I used a mac to develop on and impeller is enabled by default there on iOS. Impeller back then had a lot of issues so almost every gfx-related issue pointed to Impeller 😁
(Impeller ate all the memory 256 GB too, so it was a mess).

So your testing shows that Android with stable 3.10.x impeller disabled = failed and enabled = ok?
How is the framerate though. It is probably slow...

[k0psutin]

I used a mac to develop on and impeller is enabled by default there on iOS. Impeller back then had a lot of issues so almost every gfx-related issue pointed to Impeller 😁 (Impeller ate all the memory 256 GB too, so it was a mess).

So your testing shows that Android with stable 3.10.x impeller disabled = failed and enabled = ok? How is the framerate though. It is probably slow...

It is quite slow and jerky with the impeller enabled, and it seems that it is very volatile as my other project crashed a lot, when I enabled the impeller (to test it).

[large]

I have tested stable 3.10.5 on a Android emulator with same results as @k0psutin.
Impeller off = bug showing
Impeller on = bug gone (performance is really bad)

iOS emulator:
Bug is not showing, emu is eating memory though (another impeller bug)...

Downgraded to Flutter 3.7.12; Android emu (performance good), impeller is not possible to enable here.

I find it hard to find the reason for why this happens, maybe a test could be written for the canvasroutine to test?

fl_chart/lib/src/chart/bar_chart/bar_chart_painter.dart

Line 289 in c6eca89

if (barRod.rodStackItems.isNotEmpty) {

---

After looking at the canvas code I wanted to test to start drawing from outer to inner on negative numbers to.
See example code here

    //Loop through all costs
    for (int stack = 0; stack < 4; stack++) {
      double startPoint = item.barRods.last.rodStackItems.isEmpty ? 0 : item.barRods.last.rodStackItems.last.toY;
      double add = i / 3;
      if(add>0)
        {
          item.barRods.last.rodStackItems.add(BarChartRodStackItem(startPoint,
              startPoint + add, stack.isEven ? Colors.cyan : Colors.red));
        }
      else //writing from outer point against zero
        {
          item.barRods.last.rodStackItems.add(BarChartRodStackItem(add * (4-stack),
              add * (3-stack), stack.isOdd ? Colors.cyan : Colors.red));
        }
    }

It would be best if fl_chart handled it though...

[imaNNeo]

I found the bug 🎉

[deverlex]

I have same issue in version ^0.63.0 and flutter 3.10.x

[imaNNeo]

Fixed in Check it out in 0.64.0