Android-MPChart,HorizontalBarChart 水平柱状图颜色渐变

1.新建color.xml文件，在res/values路径下新建color.xml文件

文件内容:

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <!--底部渐变色-->
    <color name="color1">#ffcc0000</color>
    <!--顶部渐变色-->
    <color name="color2">#ff00ddff</color>

</resources>

　　

2. 在java代码中设置颜色

//1.    找到定义的2个颜色
//底部渐变色
int bottomColor = ContextCompat.getColor(this, R.color.color1);
//顶部渐变色
int topColor = ContextCompat.getColor(this, R.color.color2);

//2.    新建List存储渐变色
List<GradientColor> gradientColors = new ArrayList<>();
gradientColors.add(new GradientColor(bottomColor, topColor));

//3.    添加颜色List到BarDataSet
//set类型是BarDataSet
set.setGradientColors(gradientColors);

4.继承HorizontalBarChart写一个新类，命名为MyHorizontalBarChart

import android.content.Context;
import android.util.AttributeSet;
import com.github.mikephil.charting.charts.HorizontalBarChart;

public class MyHorizontalBarChart extends HorizontalBarChart {
    public MyHorizontalBarChart(Context context) {
        super(context);
    }

    public MyHorizontalBarChart(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MyHorizontalBarChart(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }
    
    @Override
    protected void init() {
        super.init();
        this.mRenderer = new MyHorizontalBarChartRenderer(this, this.mAnimator, this.mViewPortHandler);
    }
}

　　

5.继承HorizontalBarChartRenderer写一个新的渲染器，调整为水平颜色渐变

import android.graphics.Canvas;
import android.graphics.LinearGradient;
import android.graphics.RectF;

import com.github.mikephil.charting.animation.ChartAnimator;
import com.github.mikephil.charting.buffer.BarBuffer;
import com.github.mikephil.charting.data.BarData;
import com.github.mikephil.charting.data.BarEntry;
import com.github.mikephil.charting.interfaces.dataprovider.BarDataProvider;
import com.github.mikephil.charting.interfaces.datasets.IBarDataSet;
import com.github.mikephil.charting.model.GradientColor;
import com.github.mikephil.charting.renderer.HorizontalBarChartRenderer;
import com.github.mikephil.charting.utils.Transformer;
import com.github.mikephil.charting.utils.Utils;
import com.github.mikephil.charting.utils.ViewPortHandler;

public class MyHorizontalBarChartRenderer extends HorizontalBarChartRenderer {
    public MyHorizontalBarChartRenderer(BarDataProvider chart, ChartAnimator animator, ViewPortHandler viewPortHandler) {
        super(chart, animator, viewPortHandler);
    }

    private RectF mBarShadowRectBuffer = new RectF();
    
    @Override
    protected void drawDataSet(Canvas c, IBarDataSet dataSet, int index) {
        super.drawDataSet(c, dataSet, index);

        Transformer trans = mChart.getTransformer(dataSet.getAxisDependency());

        mBarBorderPaint.setColor(dataSet.getBarBorderColor());
        mBarBorderPaint.setStrokeWidth(Utils.convertDpToPixel(dataSet.getBarBorderWidth()));

        final boolean drawBorder = dataSet.getBarBorderWidth() > 0.f;

        float phaseX = mAnimator.getPhaseX();
        float phaseY = mAnimator.getPhaseY();

        // draw the bar shadow before the values
        if (mChart.isDrawBarShadowEnabled()) {
            mShadowPaint.setColor(dataSet.getBarShadowColor());

            BarData barData = mChart.getBarData();

            final float barWidth = barData.getBarWidth();
            final float barWidthHalf = barWidth / 2.0f;
            float x;

            for (int i = 0, count = Math.min((int)(Math.ceil((float)(dataSet.getEntryCount()) * phaseX)), dataSet.getEntryCount());
                 i < count;
                 i++) {

                BarEntry e = dataSet.getEntryForIndex(i);

                x = e.getX();

                mBarShadowRectBuffer.left = x - barWidthHalf;
                mBarShadowRectBuffer.right = x + barWidthHalf;

                trans.rectValueToPixel(mBarShadowRectBuffer);

                if (!mViewPortHandler.isInBoundsLeft(mBarShadowRectBuffer.right))
                    continue;

                if (!mViewPortHandler.isInBoundsRight(mBarShadowRectBuffer.left))
                    break;

                mBarShadowRectBuffer.top = mViewPortHandler.contentTop();
                mBarShadowRectBuffer.bottom = mViewPortHandler.contentBottom();

                c.drawRect(mBarShadowRectBuffer, mShadowPaint);
            }
        }

        // initialize the buffer
        BarBuffer buffer = mBarBuffers[index];
        buffer.setPhases(phaseX, phaseY);
        buffer.setDataSet(index);
        buffer.setInverted(mChart.isInverted(dataSet.getAxisDependency()));
        buffer.setBarWidth(mChart.getBarData().getBarWidth());

        buffer.feed(dataSet);

        trans.pointValuesToPixel(buffer.buffer);

        final boolean isSingleColor = dataSet.getColors().size() == 1;

        if (isSingleColor) {
            mRenderPaint.setColor(dataSet.getColor());
        }

        for (int j = 0; j < buffer.size(); j += 4) {

            if (!mViewPortHandler.isInBoundsLeft(buffer.buffer[j + 2]))
                continue;

            if (!mViewPortHandler.isInBoundsRight(buffer.buffer[j]))
                break;

            if (!isSingleColor) {
                // Set the color for the currently drawn value. If the index
                // is out of bounds, reuse colors.
                mRenderPaint.setColor(dataSet.getColor(j / 4));
            }

            if (dataSet.getGradientColor() != null) {
                GradientColor gradientColor = dataSet.getGradientColor();
                mRenderPaint.setShader(
                        new LinearGradient(
                                buffer.buffer[j],
                                buffer.buffer[j + 3],
                                buffer.buffer[j],
                                buffer.buffer[j + 1],
                                gradientColor.getStartColor(),
                                gradientColor.getEndColor(),
                                android.graphics.Shader.TileMode.MIRROR));
            }

            if (dataSet.getGradientColors() != null) {
                mRenderPaint.setShader(
                        new LinearGradient(
                                buffer.buffer[j],
                                buffer.buffer[j+3],
                                buffer.buffer[j+2],
                                buffer.buffer[j+1],
                                dataSet.getGradientColor(j / 4).getEndColor(),
                                dataSet.getGradientColor(j / 4).getStartColor(),
                                android.graphics.Shader.TileMode.MIRROR));
            }


            c.drawRect(buffer.buffer[j], buffer.buffer[j + 1], buffer.buffer[j + 2],
                    buffer.buffer[j + 3], mRenderPaint);

            if (drawBorder) {
                c.drawRect(buffer.buffer[j], buffer.buffer[j + 1], buffer.buffer[j + 2],
                        buffer.buffer[j + 3], mBarBorderPaint);
            }
        }


    }
}

　　

6. 在layout文件中添加自定义的MyHorizontalBarChart

                <com.mpchart.MyHorizontalBarChart
                    android:id="@+id/bar_chart1"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_marginLeft="20dp"
                    android:layout_gravity="left|center_vertical">

                </com.mdctbcinput.main.MyHorizontalBarChart >

其他代码按照官方样例正常写既可