Feature: Range Annotations

[shamilovtim]

This PR adds range annotations to line charts. Docs are updated in the linechart document.

To use:

  rangeAnnotations: RangeAnnotations(
        hasVerticalRangeAnnotations: true,
        verticalRangeAnnotations: [
          VerticalRangeAnnotation(
            x1: 2,
            x2: 4,
            color: Colors.orange
          ),
          VerticalRangeAnnotation(
            x1: 8,
            x2: 10,
            color: Colors.yellow
          ),
        ],
        hasHorizontalRangeAnnotations: true,
        horizontalRangeAnnotations: [
          HorizontalRangeAnnotation(
            y1: 1,
            y2: 2,
            color: Colors.red
          ),
          HorizontalRangeAnnotation(
            y1: 4,
            y2: 5,
            color: Colors.blue
          ),
        ]
      ),

[shamilovtim]

Closes #163

[imaNNeo]

Everything looks good and thank you for your great pull request, but there is one thing left,
please make a nice sample, and please don't add it in the first page, don't add anything in pages 1 to 4, you can add it in page 5 (line_chart_page2.dart)

[shamilovtim]

I have a suggestion about it:

if (data.extraLinesData != null && !data.extraLinesData.extraLinesOnTop) {
   drawExtraLines(canvas, size);
}

drawBarLine(canvas, size, barData);
drawDots(canvas, size, barData);
drawTouchedSpotsIndicator(canvas, size, barData);

if (data.extraLinesData != null && data.extraLinesData.extraLinesOnTop) {
   drawExtraLines(canvas, size);
}

Does it make sense?

Yes! It works. Just one thing:

drawTouchedSpotsIndicator(canvas, size, barData); should come last? I believe this part of the order might been a bug. Otherwise it looks visibly broken when the touch indicator is covered up by a chart line.

[shamilovtim]

data.extraLinesData != null not necessary we have an empty array there due to default value and no matter what it's never null.

[imaNNeo]

I have a suggestion about it:

if (data.extraLinesData != null && !data.extraLinesData.extraLinesOnTop) {
   drawExtraLines(canvas, size);
}

drawBarLine(canvas, size, barData);
drawDots(canvas, size, barData);
drawTouchedSpotsIndicator(canvas, size, barData);

if (data.extraLinesData != null && data.extraLinesData.extraLinesOnTop) {
   drawExtraLines(canvas, size);
}

Does it make sense?

Yes! It works. Just one thing:

drawTouchedSpotsIndicator(canvas, size, barData); should come last? I believe this part of the order might been a bug. Otherwise it looks visibly broken when the touch indicator is covered up by a chart line.

You're right,
drawTouchedSpotsIndicator(canvas, size, barData); should be after all things.

[imaNNeo]

data.extraLinesData != null not necessary we have an empty array there due to default value and no matter what it's never null.

we are using data.extraLinesData.extraLinesOnTop in our if statement, and for sure if data.extraLinesData is null, app crashes due to NullPointerException (this is before our draw function).

[shamilovtim]

data.extraLinesData can't be null though? I confirmed this with the debugger. it's initialized with an empty array at all times.

[imaNNeo]

extraLinesData

What about if I have this code?

LineChartData(
   extraLinesData: null,
)

[shamilovtim]

ok almost done

[shamilovtim]

all set

[imaNNeo]

Hi man, everything is well, and it's ready to merge,
but there is a last request, please make the sample more smooth, I think we just need to have some colors for annotations with opacity, current colors are too sharp,
and add this sample screenshot in the line_chart.md,
with the title: Sample 8 - range annotations

[shamilovtim]

used analogous colors

[shamilovtim]

that should be it

[imaNNeo]

Great!

[imaNNeo]

Everything looks good and thank you for your great pull request, but there is one thing left,
please make a nice sample, and please don't add it in the first page, don't add anything in pages 1 to 4, you can add it in page 5 (line_chart_page2.dart)

move your sample to the line_chart_page2.dart, please

[shamilovtim]

@imaNNeoFighT It is in page 2 already

[imaNNeo]

Okay, apologize.

[imaNNeo]

Thanks for your great PR,
hope to see your more PRs.
Cheers!