Android Chart Heatmap Custom Palette

Android Chart - Examples

SciChart Android ships with ~90 Android Chart Examples which you can browse, play with, view the source-code and even export each SciChart Android Chart Example to a stand-alone Android Studio project. All of this is possible with the new and improved SciChart Android Examples Suite, which ships as part of our Android Charts SDK.

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Demonstrates how to use the PaletteProvider API to change an Android Heatmap Chart colors in real-time. The SeekBar is used to provide a threshold value to the IUniformHeatmapPaletteProvider instance, which updates the Heatmap accordingly.

Tips!

Using this API you can color individual data points of many chart types such as Line, Mountain, Scatter, Bubble in SciChart Android. Learn more at the PaletteProvider API Documentation!

The full source code for the Android Chart Heatmap Custom Palette example is included below (Scroll down!).

Did you know you can also view the source code from one of the following sources as well?

Clone the SciChart.Android.Examples from Github.
Or, view source and export each example to an Android Studio project from the Java version of the SciChart Android Examples app.
Also the SciChart Android Trial contains the full source for the examples (link below).

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Kotlin: HeatmapPaletteProviderFragment.kt

View source code

//******************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2021. All rights reserved.
//
// Web: http://www.scichart.com
// Support: support@scichart.com
// Sales:   sales@scichart.com
//
// HeatmapPaletteProviderFragment.kt is part of SCICHART®, High Performance Scientific Charts
// For full terms and conditions of the license, see http://www.scichart.com/scichart-eula/
//
// This source code is protected by international copyright law. Unauthorized
// reproduction, reverse-engineering, or distribution of all or any portion of
// this source code is strictly prohibited.
//
// This source code contains confidential and proprietary trade secrets of
// SciChart Ltd., and should at no time be copied, transferred, sold,
// distributed or made available without express written permission.
//******************************************************************************

package com.scichart.examples.fragments.examples2d.stylingAndTheming.kt

import android.graphics.Color
import android.view.LayoutInflater
import android.widget.SeekBar
import com.scichart.charting.visuals.axes.AxisAlignment.Bottom
import com.scichart.charting.visuals.axes.AxisAlignment.Right
import com.scichart.charting.visuals.renderableSeries.FastUniformHeatmapRenderableSeries
import com.scichart.charting.visuals.renderableSeries.data.UniformHeatmapRenderPassData
import com.scichart.charting.visuals.renderableSeries.paletteProviders.IUniformHeatmapPaletteProvider
import com.scichart.charting.visuals.renderableSeries.paletteProviders.PaletteProviderBase
import com.scichart.core.model.DoubleValues
import com.scichart.core.model.IValues
import com.scichart.examples.R
import com.scichart.examples.databinding.ExampleHeatmapPaletteFragmentBinding
import com.scichart.examples.fragments.base.ExampleBaseFragment
import com.scichart.examples.utils.scichartExtensions.*
import java.util.*
import kotlin.math.sin
import kotlin.math.sqrt

class HeatmapPaletteProviderFragment : ExampleBaseFragment<ExampleHeatmapPaletteFragmentBinding>(), SeekBar.OnSeekBarChangeListener {

    private val heatmapPaletteProvider = CustomUniformHeatMapProvider()

    override fun inflateBinding(inflater: LayoutInflater): ExampleHeatmapPaletteFragmentBinding {
        return ExampleHeatmapPaletteFragmentBinding.inflate(inflater)
    }

    override fun initExample(binding: ExampleHeatmapPaletteFragmentBinding) {
        binding.surface.theme = R.style.SciChart_NavyBlue

        binding.seekBar.run {
            setOnSeekBarChangeListener(this@HeatmapPaletteProviderFragment)
            heatmapPaletteProvider.setThresholdValue(progress.toDouble())
        }

        binding.surface.suspendUpdates {
            xAxes { numericAxis { axisAlignment = Bottom } }
            yAxes { numericAxis { axisAlignment = Right } }
            renderableSeries {
                fastUniformHeatmapRenderableSeries {
                    uniformHeatmapDataSeries<Int, Int, Double>(WIDTH, HEIGHT) {
                        updateZValues(createValues())
                    }
                    minimum = 0.0
                    maximum = 200.0
                    this.paletteProvider = heatmapPaletteProvider
                }
            }
            chartModifiers { defaultModifiers() }
        }
    }

    private fun createValues(): IValues<Double> {
        val values = DoubleValues(WIDTH * HEIGHT)

        val random = Random()
        val angle = Math.PI * 2
        val cx = 150.0
        val cy = 100.0
        for (x in 0 until WIDTH) {
            for (y in 0 until HEIGHT) {
                val v = (1 + sin(x * 0.04 + angle)) * 50 + (1 + sin(y * 0.1 + angle)) * 50 * (1 + sin(angle * 2))
                val r = sqrt((x - cx) * (x - cx) + (y - cy) * (y - cy))
                val exp = 0.0.coerceAtLeast(1 - r * 0.008)

                values.add(v * exp + random.nextDouble() * 50)
            }
        }

        return values
    }

    override fun onProgressChanged(seekBar: SeekBar?, progress: Int, fromUser: Boolean) {
        heatmapPaletteProvider.setThresholdValue(progress.toDouble())
        binding.thresholdValue.text = String.format("%d", progress)
    }

    override fun onStartTrackingTouch(seekBar: SeekBar?) {}

    override fun onStopTrackingTouch(seekBar: SeekBar?) {}

    private class CustomUniformHeatMapProvider : PaletteProviderBase<FastUniformHeatmapRenderableSeries>(FastUniformHeatmapRenderableSeries::class.java), IUniformHeatmapPaletteProvider {
        private var thresholdValue = 0.0

        fun setThresholdValue(thresholdValue: Double) {
            this.thresholdValue = thresholdValue
            renderableSeries?.invalidateElement()
        }

        override fun shouldSetColors(): Boolean = false

        override fun update() {
            val renderableSeries = renderableSeries
            val currentRenderPassData = renderableSeries!!.currentRenderPassData as UniformHeatmapRenderPassData

            val zValues = currentRenderPassData.zValues
            val zColors = currentRenderPassData.zColors

            val size = zValues.size()
            zColors.setSize(size)

            // working with array is much faster than calling set() many times
            val zValuesArray = zValues.itemsArray
            val zColorsArray = zColors.itemsArray
            for (zIndex in 0 until size) {
                val value = zValuesArray[zIndex]
                zColorsArray[zIndex] = if (value < thresholdValue) Color.BLACK else Color.WHITE
            }
        }
    }

    companion object {
        private const val WIDTH = 300
        private const val HEIGHT = 200
    }
}

Java: HeatmapPaletteProviderFragment.java

View source code

//******************************************************************************
// SCICHART® Copyright SciChart Ltd. 2011-2021. All rights reserved.
//
// Web: http://www.scichart.com
// Support: support@scichart.com
// Sales:   sales@scichart.com
//
// HeatmapPaletteProviderFragment.java is part of SCICHART®, High Performance Scientific Charts
// For full terms and conditions of the license, see http://www.scichart.com/scichart-eula/
//
// This source code is protected by international copyright law. Unauthorized
// reproduction, reverse-engineering, or distribution of all or any portion of
// this source code is strictly prohibited.
//
// This source code contains confidential and proprietary trade secrets of
// SciChart Ltd., and should at no time be copied, transferred, sold,
// distributed or made available without express written permission.
//******************************************************************************

package com.scichart.examples.fragments.examples2d.stylingAndTheming;

import android.graphics.Color;
import android.view.LayoutInflater;
import android.widget.SeekBar;

import androidx.annotation.NonNull;

import com.scichart.charting.model.dataSeries.UniformHeatmapDataSeries;
import com.scichart.charting.visuals.SciChartSurface;
import com.scichart.charting.visuals.axes.AxisAlignment;
import com.scichart.charting.visuals.axes.NumericAxis;
import com.scichart.charting.visuals.renderableSeries.paletteProviders.IUniformHeatmapPaletteProvider;
import com.scichart.charting.visuals.renderableSeries.paletteProviders.PaletteProviderBase;
import com.scichart.charting.visuals.renderableSeries.FastUniformHeatmapRenderableSeries;
import com.scichart.charting.visuals.renderableSeries.data.UniformHeatmapRenderPassData;
import com.scichart.core.model.DoubleValues;
import com.scichart.core.model.IValues;
import com.scichart.core.model.IntegerValues;
import com.scichart.examples.R;
import com.scichart.examples.databinding.ExampleHeatmapPaletteFragmentBinding;
import com.scichart.examples.fragments.base.ExampleBaseFragment;

import java.util.Collections;
import java.util.Random;

public class HeatmapPaletteProviderFragment extends ExampleBaseFragment<ExampleHeatmapPaletteFragmentBinding> implements SeekBar.OnSeekBarChangeListener {
    private static final int WIDTH = 300;
    private static final int HEIGHT = 200;

    private final CustomUniformHeatMapProvider paletteProvider = new CustomUniformHeatMapProvider();

    @NonNull
    @Override
    protected ExampleHeatmapPaletteFragmentBinding inflateBinding(@NonNull LayoutInflater inflater) {
        return ExampleHeatmapPaletteFragmentBinding.inflate(inflater);
    }

    @Override
    protected void initExample(ExampleHeatmapPaletteFragmentBinding binding) {
        binding.surface.setTheme(R.style.SciChart_NavyBlue);

        binding.seekBar.setOnSeekBarChangeListener(this);

        final NumericAxis xAxis = sciChartBuilder.newNumericAxis().withAxisAlignment(AxisAlignment.Bottom).build();
        final NumericAxis yAxis = sciChartBuilder.newNumericAxis().withAxisAlignment(AxisAlignment.Right).build();

        final UniformHeatmapDataSeries<Integer, Integer, Double> dataSeries = new UniformHeatmapDataSeries<>(Integer.class, Integer.class, Double.class, WIDTH, HEIGHT);

        paletteProvider.setThresholdValue(binding.seekBar.getProgress());

        dataSeries.updateZValues(createValues());
        final FastUniformHeatmapRenderableSeries heatmapRenderableSeries = sciChartBuilder.newUniformHeatmap()
                .withDataSeries(dataSeries)
                .withMinimum(0)
                .withMaximum(200)
                .withPaletteProvider(paletteProvider)
                .build();

        final SciChartSurface surface = binding.surface;
        Collections.addAll(surface.getXAxes(), xAxis);
        Collections.addAll(surface.getYAxes(), yAxis);
        Collections.addAll(surface.getRenderableSeries(), heatmapRenderableSeries);
        Collections.addAll(surface.getChartModifiers(), sciChartBuilder.newModifierGroupWithDefaultModifiers().build());
    }

    private static IValues<Double> createValues() {
        final DoubleValues values = new DoubleValues(WIDTH * HEIGHT);

        final Random random = new Random();
        final double angle = Math.PI * 2;
        final double cx =150, cy = 100;
        for (int x = 0; x < WIDTH; x++) {
            for (int y = 0; y < HEIGHT; y++) {
                final double v = (1 + Math.sin(x * 0.04 + angle)) * 50 + (1 + Math.sin(y * 0.1 + angle)) * 50 * (1 + Math.sin(angle * 2));
                final double r = Math.sqrt((x - cx) * (x - cx) + (y - cy) * (y - cy));
                final double exp = Math.max(0, 1 - r * 0.008);

                values.add(v * exp + random.nextDouble() * 50);
            }
        }

        return values;
    }

    @Override
    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
        paletteProvider.setThresholdValue(progress);
        binding.thresholdValue.setText(String.format("%d", progress));
    }

    @Override
    public void onStartTrackingTouch(SeekBar seekBar) { }

    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {  }

    private static class CustomUniformHeatMapProvider extends PaletteProviderBase<FastUniformHeatmapRenderableSeries> implements IUniformHeatmapPaletteProvider {
        private double thresholdValue;

        public CustomUniformHeatMapProvider() {
            super(FastUniformHeatmapRenderableSeries.class);
        }

        public void setThresholdValue(double thresholdValue) {
            this.thresholdValue = thresholdValue;

            if (renderableSeries != null) {
                renderableSeries.invalidateElement();
            }
        }

        @Override
        public boolean shouldSetColors() {
            return false;
        }

        @Override
        public void update() {
            final FastUniformHeatmapRenderableSeries renderableSeries = this.renderableSeries;
            final UniformHeatmapRenderPassData currentRenderPassData = (UniformHeatmapRenderPassData) renderableSeries.getCurrentRenderPassData();

            final DoubleValues zValues = currentRenderPassData.zValues;
            final IntegerValues zColors = currentRenderPassData.zColors;

            final int size = zValues.size();
            zColors.setSize(size);

            // working with array is much faster than calling set() many times
            final double[] zValuesArray = zValues.getItemsArray();
            final int[] zColorsArray = zColors.getItemsArray();

            for (int zIndex = 0; zIndex < size; zIndex++) {
                final double value = zValuesArray[zIndex];

                zColorsArray[zIndex] = value < thresholdValue ? Color.BLACK : Color.WHITE;
            }
        }
    }
}

Back to Android Chart Examples

Android Chart Heatmap Custom Palette

Android Chart - Examples

Kotlin: HeatmapPaletteProviderFragment.kt

Java: HeatmapPaletteProviderFragment.java

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