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feat(bar_chart): scaled font size for value labels #789

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merged 15 commits into from
Oct 14, 2020

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wylieconlon
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This is my first attempt at creating scaled font sizes for text in the bar charts, which has similarity to the scaling logic that is implemented in partition charts by @monfera. I've applied the simplest possible logic, which is to take the maximum font size that fits these restrictions:

  1. Count the number of characters in the label
  2. Divide the available bar width by the number of characters, and take the integer value that's smaller
  3. If the font size is less than the minimum in the theme, then use the minimum size instead

It doesn't work correctly for horizontal charts because I don't know how to determine rotation.

Fixes #788

Screen Shot 2020-08-20 at 4 41 20 PM

Screen Shot 2020-08-20 at 4 41 26 PM

Screen Shot 2020-08-20 at 4 41 36 PM

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Delete any items that are not applicable to this PR.

  • Any consumer-facing exports were added to src/index.ts (and stories only import from ../src except for test data & storybook)
  • This was checked for cross-browser compatibility
  • Proper documentation or storybook story was added for features that require explanation or tutorials
  • Unit tests were updated or added to match the most common scenarios

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Thank you @wylieconlon for the PR.
I've added a suggestion to make this work to compute that target font size in a more precise way than the current proposed solution.
If you need the chart rotation parameter, unfortunately is not available at that level, but you can pass it down from computeSeriesGeometries ==> renderGeometries ==> renderBars

I've also a doubt about the readability of the text using this varying-font-size approach:
longer text (due to more decimal points or higher value) can results in smaller font sizes (see the image as an extreme example).
Screenshot 2020-08-24 at 12 19 53

On a data visualization, these font changes can be interpreted in different ways from the users, assuming more importance to bigger texts rather than the smaller ones. Uniform font sizes are preferable if we don't need to communicate any exceptional significance to that value. @monfera @nickofthyme thoughts on that?

src/chart_types/xy_chart/rendering/rendering.ts Outdated Show resolved Hide resolved
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@markov00 Thanks for the feedback! I agree that uniform font sizes would look much better. To implement your suggestion, I think we would need to calculate the formatted values for all bars, and then scale the font size based on the highest character count of the formatted values. What do you think about that approach?

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@markov00 Thanks for the feedback! I agree that uniform font sizes would look much better. To implement your suggestion, I think we would need to calculate the formatted values for all bars, and then scale the font size based on the highest character count of the formatted values. What do you think about that approach?

I think we should compute the bounding box of all the formatted values and then scale the font size based on the maximum width of these boundingboxes.

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@markov00 Do you think it makes sense to change from fontSize on the API level to minFontSize and maxFontSize?

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@markov00 Do you think it makes sense to change from fontSize on the API level to minFontSize and maxFontSize?

@wylieconlon we can have that change without introducing a breaking change if we use a union type that covers two cases: fixed font size or scaled font size. Something like this could work:

export interface TextStyle {
  fontSize: number | { min: number; max: number };
  ...
}

With that, we can handle both use cases: users that want a specific fixed font size + users that look at a scalable font size

Introduce a range size format for bar chart labels to auto scale and improve readability

Address elastic#788
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dej611 commented Sep 22, 2020

Reworked the PR to address the various feedback:

  • ✨ Add a min/max range format for DisplayValueStyle type
    • why not TextStyle? Because it has a general effect on the whole code base not affected by the change - breaking many tests as well
  • ✨ Used the scale factor approach to rescale size if a range is passed
    • 🐛 tuned isValueContainedInElement to work with the new auto scaling feature
    • ✨ tuned the size scaling based on chart rotation
    • 💄 Labels now use 70% of space width - value hardcoded
  • ⚠️ small bugfixes for linting warnings

src/chart_types/xy_chart/rendering/rendering.ts Outdated Show resolved Hide resolved
displayValueSettings,
);

const isHorizontalRotation = chartRotation == null || [0, 180].includes(chartRotation);
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Either the logic or naming is wrong, the horizontal charts are 90 and 270: https://elastic.github.io/elastic-charts/?path=/story/rotations--rotations-90-deg-ordinal

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Eheh I had a chat with @markov00 about that the other day. He explained to me that their naming reference where the bars are located (for a vertical bar chart they are located on the x axis, therefore horizontal).
I used isVertical here before which makes more sense for me as well, then changed after the chat as consitency is best when maintain the codebase.

Always show labels if enabled but stick min/max values when auto scaling go beyond them
Sync API with the new fontsize format changes for bar charts
@dej611 dej611 marked this pull request as ready for review September 28, 2020 08:28
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codecov-commenter commented Sep 28, 2020

Codecov Report

Merging #789 into master will decrease coverage by 0.02%.
The diff coverage is 55.26%.

Impacted file tree graph

@@            Coverage Diff             @@
##           master     #789      +/-   ##
==========================================
- Coverage   70.01%   69.98%   -0.03%     
==========================================
  Files         321      336      +15     
  Lines       10508    10189     -319     
  Branches     2221     2031     -190     
==========================================
- Hits         7357     7131     -226     
+ Misses       3142     2991     -151     
- Partials        9       67      +58     
Flag Coverage Δ
#unittests ?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files Coverage Δ
..._types/xy_chart/renderer/canvas/primitives/text.ts 7.52% <0.00%> (-0.17%) ⬇️
src/chart_types/xy_chart/state/utils/utils.ts 92.27% <ø> (-0.01%) ⬇️
src/mocks/geometries.ts 86.84% <ø> (ø)
src/utils/geometry.ts 100.00% <ø> (ø)
src/utils/themes/theme.ts 100.00% <ø> (ø)
...chart_types/xy_chart/renderer/canvas/values/bar.ts 12.04% <20.00%> (+0.93%) ⬆️
src/chart_types/xy_chart/rendering/rendering.ts 91.11% <74.07%> (-2.18%) ⬇️
src/utils/dimensions.ts 71.42% <0.00%> (-28.58%) ⬇️
src/utils/data_generators/data_generator.ts 45.45% <0.00%> (-9.10%) ⬇️
...rc/chart_types/xy_chart/renderer/canvas/bubbles.ts 64.70% <0.00%> (-7.52%) ⬇️
... and 187 more

Continue to review full report at Codecov.

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Looks good to me, I've checked the code and tested locally seems to work fine and scales correctly all the values. I've check also the scale with very different value lengths and seems to scale correctly per bar.
I've left a few comments to address (division by zero checks) and some other nit picks

src/chart_types/xy_chart/rendering/rendering.ts Outdated Show resolved Hide resolved
src/chart_types/xy_chart/state/utils/utils.ts Outdated Show resolved Hide resolved
stories/bar/50_simple_value_label.tsx Outdated Show resolved Hide resolved
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Looks amazing so far.

I get an error when enabling both the contain within label and alternating label options.

Screen Recording 2020-10-06 at 11 43 AM

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dej611 commented Oct 6, 2020

Yes, that's related to this bug: #786 .

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Tested locally and it looks very good!
Just a small typo on the story title

stories/bar/bars.stories.tsx Outdated Show resolved Hide resolved
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cla-checker-service bot commented Oct 12, 2020

💚 CLA has been signed

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Looking good @dej611! I can't approve since this is technically my own PR, but left some small comments.

fill: color('value color', '#000'),
offsetX: number('offsetX', 0),
offsetY: number('offsetY', 0),
alignment: {
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The alignment properties don't appear to do anything yet, maybe remove this?

h: frozenDataHighVolume,
};

export const Example = () => {
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You've created a new storybook, but I noticed that you didn't update the existing storybook for value labels. I found it a little confusing not to have these options on the "value label" storybook. Would it be worth combining into a single story?

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I've left this in here as it will probably be merged with other stories in related PRs to make an Advanced value label story.

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codecov-io commented Oct 13, 2020

Codecov Report

Merging #789 into master will increase coverage by 0.06%.
The diff coverage is 58.33%.

Impacted file tree graph

@@            Coverage Diff             @@
##           master     #789      +/-   ##
==========================================
+ Coverage   69.58%   69.64%   +0.06%     
==========================================
  Files         321      336      +15     
  Lines       10605    10269     -336     
  Branches     2187     2066     -121     
==========================================
- Hits         7379     7152     -227     
+ Misses       3217     3050     -167     
- Partials        9       67      +58     
Flag Coverage Δ
#unittests ?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files Coverage Δ
..._types/xy_chart/renderer/canvas/primitives/text.ts 7.00% <0.00%> (-0.15%) ⬇️
src/chart_types/xy_chart/state/utils/utils.ts 92.27% <ø> (-0.01%) ⬇️
src/mocks/geometries.ts 86.84% <ø> (ø)
src/utils/geometry.ts 100.00% <ø> (ø)
src/utils/themes/theme.ts 100.00% <ø> (ø)
...chart_types/xy_chart/renderer/canvas/values/bar.ts 13.60% <50.00%> (+1.90%) ⬆️
src/chart_types/xy_chart/rendering/rendering.ts 91.11% <74.07%> (-2.18%) ⬇️
src/utils/dimensions.ts 71.42% <0.00%> (-28.58%) ⬇️
src/utils/data_generators/data_generator.ts 45.45% <0.00%> (-9.10%) ⬇️
...rc/chart_types/xy_chart/renderer/canvas/bubbles.ts 64.70% <0.00%> (-7.52%) ⬇️
... and 187 more

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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@dej611 dej611 merged commit 3bdd1ee into elastic:master Oct 14, 2020
markov00 pushed a commit that referenced this pull request Oct 19, 2020
# [24.0.0](v23.2.1...v24.0.0) (2020-10-19)

### Bug Fixes

* **annotation:** annotation rendering with no yDomain or groupId ([#842](#842)) ([f173b49](f173b49)), closes [#438](#438) [#798](#798)

### Features

* **bar_chart:** add Alignment offset to value labels ([#784](#784)) ([363aeb4](363aeb4))
* **bar_chart:** add shadow prop for value labels ([#785](#785)) ([9b29392](9b29392))
* **bar_chart:** scaled font size for value labels ([#789](#789)) ([3bdd1ee](3bdd1ee)), closes [#788](#788)
* **heatmap:** allow fixed right margin ([#873](#873)) ([16cf73c](16cf73c))

### BREAKING CHANGES

* **bar_chart:** The `DisplayValueStyle` `fontSize` property can now express an upper and lower bound as size, used for the automatic scaling.
* **bar_chart:** The `DisplayValueStyle` `fill` property can now express a border color and width, or let the library pick the best match based on contrast using the textInvertible parameter.
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🎉 This PR is included in version 24.0.0 🎉

The release is available on:

Your semantic-release bot 📦🚀

@markov00 markov00 added the released Issue released publicly label Oct 19, 2020
AMoo-Miki pushed a commit to AMoo-Miki/OpenSearch-Dashboards that referenced this pull request Feb 10, 2022
# [24.0.0](elastic/elastic-charts@v23.2.1...v24.0.0) (2020-10-19)

### Bug Fixes

* **annotation:** annotation rendering with no yDomain or groupId ([opensearch-project#842](elastic/elastic-charts#842)) ([6bad0d7](elastic/elastic-charts@6bad0d7)), closes [opensearch-project#438](elastic/elastic-charts#438) [opensearch-project#798](elastic/elastic-charts#798)

### Features

* **bar_chart:** add Alignment offset to value labels ([opensearch-project#784](elastic/elastic-charts#784)) ([106d924](elastic/elastic-charts@106d924))
* **bar_chart:** add shadow prop for value labels ([opensearch-project#785](elastic/elastic-charts#785)) ([de95b44](elastic/elastic-charts@de95b44))
* **bar_chart:** scaled font size for value labels ([opensearch-project#789](elastic/elastic-charts#789)) ([8b74a9d](elastic/elastic-charts@8b74a9d)), closes [opensearch-project#788](elastic/elastic-charts#788)
* **heatmap:** allow fixed right margin ([opensearch-project#873](elastic/elastic-charts#873)) ([dd34574](elastic/elastic-charts@dd34574))

### BREAKING CHANGES

* **bar_chart:** The `DisplayValueStyle` `fontSize` property can now express an upper and lower bound as size, used for the automatic scaling.
* **bar_chart:** The `DisplayValueStyle` `fill` property can now express a border color and width, or let the library pick the best match based on contrast using the textInvertible parameter.
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Value labels could have a font size as a ratio of the bar width
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