flutter_charts 0.1.4 flutter_charts: ^0.1.4 copied to clipboard
Charts Library for Flutter, written in Dart with Flutter.
Table of Contents #
- Flutter Charts - introduction
- Flutter Charts - data, options, classes
- Experimenting with Flutter Charts: Using the included sample app flutter_charts_sample_app.dart
- Flutter Charts: LineChart and VerticalBarChart samples: Code and resulting charts
- Random Data (Y values), Random X Labels, Random Colors, Random Data Rows Legends, Data-Generated Y Labels.
- User-Provided Data (Y values), User-Provided X Labels, Random Colors, User-Provided Data Rows Legends, Data-Generated Y Labels,
- User-Provided Data (Y values), User-Provided X Labels, Random Colors, User-Provided Data Rows Legends, User-Provided Y Labels
- VerticalBar Chart - one more example, showing positive/negative stacks:
- Known bugs
- Future enhancements and work
- Terminology and Selected Classes
Flutter Charts - introduction #
Flutter Charts is a charting library for Flutter, written in Flutter. Currently, column chart and line chart are supported.
You may want to study the included sample app flutter_charts_sample_app.dart
to build your application using Flutter Charts. The sample app shows how a Flutter Chart can be included in a Flutter application.
Flutter Charts - data, options, classes #
Before we show several examples of charts, a few notes.
- The
ChartData
class: allows to define data - X labels, Y values, (optional) Y labels, each-dataRow (series) legends, each-dataRow (series) color. The list below provides a summary description of each item- X labels:
ChartData.xLabels
allow to define X labels. SettingxLabels
is required, but client can set them to empty strings. - Y values:
ChartData.dataRows
allow to define Y values in rows. Assumption: size of each data row inChartData.dataRows
is the same, and each data row size ==ChartData.xLabels.size
- Y labels (optional): Normally, Y labels are generated from data. The option
ChartOptions.useUserProvidedYLabels
(default true), asks flutter_charts to data-generate Y labels. If this option is set to false, thenChartData.yLabels
must be set. Any number of such user-provided Y labels is allowed. - Each-dataRow (each series) legends:
ChartData.dataRowsLegends
allow to define a legend for each data row inChartData.dataRows
. Assumption:ChartData.dataRows.size
==ChartData.dataRowsLegends.size
- Each-dataRow (each series) color:
ChartData.dataRowsColors
allow to define a color for each data row inChartData.dataRows
. Assumption:ChartData.dataRows.size
==ChartData.dataRowsColors.size
- X labels:
- The
ChartOptions
class: allows to define options, by using it's defaults, or setting some options to non default values. There are alsoLineChartOptions
andVerticalBarChartOptions
classes. - Support for randomly generated data, colors, labels: Flutter Charts also provides randomly generated data, in the class
RandomChartData
. This class generates:- Y values data,
- X labels,
- Series colors,
- Series legends
- Currently the only purpose of
RandomChartData
is for use in the examples below. To be clear,RandomChartData
Y values, series colors, and series legends are not completely random - they hardcode some demoable label, legends, color values, and data ranges (data random within the range).
Experimenting with Flutter Charts: Using the included sample app flutter_charts_sample_app.dart #
There are multiple ways to experiment with Flutter Charts from your computer. We describe running Flutter Charts in development mode on your device (Android, iOS - follow 1, 2 or 3, 4 and 6), or alternatively on a device emulator (device emulator running from an IDE such as IntelliJ with Android Studio installed - follow 1, 2 or 3, 5, 6 or 7).
-
Install Flutter on your computer. See https://flutter.io/ installation section.
-
Clone flutter_charts code from Github to your computer. Needs git client.
cd DIRECTORY_OF_CHOICE git clone https://github.com/mzimmerm/flutter_charts.git # clone will create directory flutter_charts cd flutter_charts
-
(Alternative to 2.): Download and unzip flutter_charts code from Github
- Browse to https://github.com/mzimmerm/flutter_charts.git
- On the righ top, click on the "Clone or Download" button, then select save Zip, save and extract to DIRECTORY_OF_CHOICE
- cd flutter_charts
-
Prepare a physical device (must be set to Development Mode) to run applications from your computer. Then connect a android device in development mode to your computer. See https://www.kingoapp.com/root-tutorials/how-to-enable-usb-debugging-mode-on-android.htm
-
(Alternative to 4.): Prepare and start an Android device emulator on your computer.
-
Install Android Studio: see https://developer.android.com/studio/index.html
-
Install an IDE such as IntelliJ with Flutter plugin. See https://flutter.io/intellij-setup/
-
-
Run Flutter Charts demo app from command line (this will work in both method 4. and method 5.)
cd DIRECTORY_OF_CHOICE/flutter_charts flutter run example/chart/flutter_charts_sample_app.dart
-
(Alternative to 6.) Run Flutter Charts demo app from IDE. This will work only with method 5.
- Start IntelliJ IDE, create a project in the
DIRECTORY_OF_CHOICE/flutter_charts
start an Android emulator, then click on the Run button in Intellij (which should see the flutter_charts_sample_app)
- Start IntelliJ IDE, create a project in the
Sample Flutter Charts application output #
As described above, there is one sample application in flutter_charts: example/chart/chart_usage_example.dart. You can run the application using one of the methods (6, 7) above.
This application is also used as a base to show several possible sample charts in the paragraphs below. Two samples:
Vertical Bar Chart (Column Chart)
Point and Line Chart (Line Chart)
Output uses semi-random data. Click the blue + button to rerun chart with a different dataset.
Flutter Charts: LineChart and VerticalBarChart samples: Code and resulting charts #
Flutter Charts code allow to define the following data elements:
*Data (Y values)* | User-Provided or Random |
*X Labels* | User-Provided or Random |
*Options including Colors* | User-Provided or Random |
*Data Rows Legends* | User-Provided or Random |
*Y Labels* | User-Provided or Data-Generated |
The samples below show a few alternative code snippets (User-Provided or Random data, labels, option) and the resulting charts.
The chart images were obtained by substituting the code snippet to the example/chart/flutter_charts_sample_app.dart
code.
Random Data (Y values), Random X Labels, Random Colors, Random Data Rows Legends, Data-Generated Y Labels. #
This example shows that Data-Generated Y labels is the default.
Flutter Charts support reasonably intelligently generated Y Labels from data, including dealing with negatives.
The example charts in this section are equivalent to those shown in "Sample Flutter Charts Application Output".
Code in defineOptionsAndData()
:
void defineOptionsAndData() {
_lineChartOptions = new LineChartOptions();
_verticalBarChartOptions = new VerticalBarChartOptions();
_chartData = new RandomChartData(useUserProvidedYLabels: _lineChartOptions.useUserProvidedYLabels);
}
Result line chart:
Result vertical bar chart:
User-Provided Data (Y values), User-Provided X Labels, Random Colors, User-Provided Data Rows Legends, Data-Generated Y Labels, #
Code in defineOptionsAndData()
:
void defineOptionsAndData() {
_lineChartOptions = new LineChartOptions();
_verticalBarChartOptions = new VerticalBarChartOptions();
_chartData = new ChartData();
_chartData.dataRowsLegends = [
"Spring",
"Summer",
"Fall",
"Winter"];
_chartData.dataRows = [
[10.0, 20.0, 5.0, 30.0, 5.0, 20.0, ],
[30.0, 60.0, 16.0, 100.0, 12.0, 120.0, ],
[25.0, 40.0, 20.0, 80.0, 12.0, 90.0, ],
[12.0, 30.0, 18.0, 40.0, 10.0, 30.0, ],
];
_chartData.xLabels = ["Wolf", "Deer", "Owl", "Mouse", "Hawk", "Vole"];
_chartData.assignDataRowsDefaultColors();
// Note: ChartOptions.useUserProvidedYLabels default is still used (false);
}
Result line chart:
Result vertical bar chart:
User-Provided Data (Y values), User-Provided X Labels, Random Colors, User-Provided Data Rows Legends, User-Provided Y Labels #
This example show how to use the option useUserProvidedYLabels
, and scaling of data to the Y labels range.
Code in defineOptionsAndData()
:
void defineOptionsAndData() {
// This example shows user defined Y Labels.
// When setting Y labels by user, the dataRows value scale
// is irrelevant. User can use for example interval <0, 1>,
// <0, 10>, or any other, even negative ranges. Here we use <0-10>.
// The only thing that matters is the relative values in the data Rows.
// Note that current implementation sets
// the minimum of dataRows range (1.0 in this example)
// on the level of the first Y Label ("Ok" in this example),
// and the maximum of dataRows range (10.0 in this example)
// on the level of the last Y Label ("High" in this example).
// This is not desirable, we need to add a userProvidedYLabelsBoundaryMin/Max.
_lineChartOptions = new LineChartOptions();
_verticalBarChartOptions = new VerticalBarChartOptions();
_chartData = new ChartData();
_chartData.dataRowsLegends = [
"Java",
"Dart",
"Python",
"Newspeak"];
_chartData.dataRows = [
[9.0, 4.0, 3.0, 9.0, ],
[7.0, 6.0, 7.0, 6.0, ],
[4.0, 9.0, 6.0, 8.0, ],
[3.0, 9.0, 10.0, 1.0, ],
];
_chartData.xLabels = ["Fast", "Readable", "Novel", "Use"];
_chartData.dataRowsColors = [
Colors.blue,
Colors.yellow,
Colors.green,
Colors.amber,
];
_lineChartOptions.useUserProvidedYLabels = true; // use the labels below on Y axis
_chartData.yLabels = [
"Ok",
"Higher",
"High",
];
}
Result line chart:
(Disclaimer: Not actually measured)
Result vertical bar chart: Here the Y values should be numeric (if any) as manual labeling "Ok", "Higher", High" does not make sense for stacked type charts.
(Disclaimer: Not actually measured)
VerticalBar Chart - one more example, showing positive/negative stacks: #
User-Provided Data (Y values), User-Provided X Labels, User-Provided Colors, User-Provided Data Rows Legends, User-Provided Y Labels #
This example has again user defined Y Labels, with a bar chart, using the smart auto-layout of user defined Y Labels. The chart shows negative and positive values similar to %down/%up stock charts.
Code in defineOptionsAndData()
:
void defineOptionsAndData() {
// This example shows user defined Y Labels with
// a bar chart, showing negative and positive values
// similar to %down/%up stock charts.
_lineChartOptions = new LineChartOptions();
_verticalBarChartOptions = new VerticalBarChartOptions();
_chartData = new ChartData();
_chartData.dataRowsLegends = [
"-2%_0%",
"<-2%",
"0%_+2%",
">+2%"];
// each column absolute values should add to same number todo - 100 would make more sense, to represent 100% of stocks in each category
_chartData.dataRows = [
[-9.0, -8.0, -8.0, -5.0, -8.0, ],
[-1.0, -2.0, -4.0, -1.0, -1.0, ],
[7.0, 8.0, 7.0, 11.0, 9.0, ],
[3.0, 2.0, 1.0, 3.0, 3.0, ],
];
_chartData.xLabels = ["Energy", "Health", "Finance", "Chips", "Oil"];
_chartData.dataRowsColors = [
Colors.grey,
Colors.red,
Colors.greenAccent,
Colors.black,
];
_lineChartOptions.useUserProvidedYLabels = false; // use labels below
//_chartData.yLabels = [
// "Ok",
// "Higher",
// "High",
//];
}
Result vertical bar chart:
(there is a bug here,see Known Bugs)
Known bugs #
- Chart area needs clipping in the application
- Take a look at the stock charts example. There is a bug reverting series on the negative values - both negative dataRows, and dataRowsColors must be reverted for the chart stacks to show in intended order (black, green grey red from top). But even then, dataRowsLegends are incorrect.
Future enhancements and work #
Bug fixes:
- Clip chart to not paint outside area provided by Flutter app.
- Clip labels and legends not to run into the neighbor, if too long.
On the boundary of bug and enhancement:
- For ChartOptions.useUserProvidedYLabels = true. See example with User defined YLabels: Current implementation sets the minimum of dataRows range (1.0 in the example) on the level of the first Y Label ("Ok" in this example), and the maximum of dataRows range (10.0 in this example) on the level of the last Y Label ("High" in this example). This is not desirable, we need to add a userProvidedYLabelsBoundaryMin/Max.
Enhancements:
- Create document / image showing layout and spacing - show option variables on image
- Simple:
- Add options to hide the grid (keep axes)
- Add options to hide axes (if axes not shown, labels should not show?)
- Decrease option for default spacing around the Y axis.
- First, probably need to provide tooltips
- Next, a few more chart types: Spline line chart (stacked line chart), Grouped VerticalBar chart,
- Next, re-implement the layout more generically and clearly. Space saving changes such as tilting labels.
- Next, add ability to invert X and Y axis (values on horizontal axis)
TODO Terminology and Selected Classes #
- (Presenter)Leaf : The finest visual element presented in each "column of view" in chart - that is, all widgets representing series of data displayed above each X label. For example, for Line chart, the leaf would be one line and dot representing one Y value at one X label. For the bar chart, the leaf would be one bar representing one (stacked) Y value at one X label.
- Classes: Presenter, LineAndHotspotPresenter, VerticalBarPresenter, PresenterCreator
- Painter : Class which paints to chart to canvas. Terminology and class structure taken from Flutter's Painter and Painting classes.
- Classes: todo