Android-使用MPAndroidChart在两行之间填充颜色 [英] Android - Fill the color between two lines using MPAndroidChart

问题描述

我正在使用setFillFormatter，但对我没有帮助， setfillColor()越过第二行(黑色)，因为无法将第一行(黄色)停在第二行. 我想实现这样的东西:

I am using setFillFormatter, but it's not helping me and, setfillColor() crosses the second line(black) as there is no way to stop the first line(Yellow) at Y values of the second line. I want to implement something like this:

dataSet.setFillFormatter(new IFillFormatter() {

            @Override
            public float getFillLinePosition(ILineDataSet dataSet, LineDataProvider dataProvider) {
                return //return Y value of the second line for current X of line being filled;
            }
        });

有没有办法针对第一行的每个X查找第二行的Y值?我看到 dataSet 和 dataProvider 都为每次getFillLinePosition调用返回固定值.

Is there any way to find the Y value of the second line for each X of first line? I see both dataSet and dataProvider returns fixed values for each call of getFillLinePosition.

推荐答案

感谢David Rawson将我指向LineChartRenderer.我能够为两行之间的区域着色.

Thanks David Rawson for pointing me towards LineChartRenderer. I am able to color the area between two lines.

我们需要进行两项重大更改.

We need to make two major changes.

1. 实施自定义FillFormator以返回另一行的数据集.

1. Implement a custom FillFormator to return the dataset of another line.

public class MyFillFormatter implements IFillFormatter {
private ILineDataSet boundaryDataSet;

public MyFillFormatter() {
    this(null);
}
//Pass the dataset of other line in the Constructor 
public MyFillFormatter(ILineDataSet boundaryDataSet) {
    this.boundaryDataSet = boundaryDataSet;
}

@Override
public float getFillLinePosition(ILineDataSet dataSet, LineDataProvider dataProvider) {
    return 0;
}

//Define a new method which is used in the LineChartRenderer
public List<Entry> getFillLineBoundary() {
    if(boundaryDataSet != null) {
        return ((LineDataSet) boundaryDataSet).getValues();
    }
    return null;
}}

实施自定义LineChartRenderer来绘制并填充封闭的路径.

Implement a custom LineChartRenderer to draw and fill the enclosed path.

public class MyLineLegendRenderer extends LineChartRenderer {

public MyLineLegendRenderer(LineDataProvider chart, ChartAnimator animator, ViewPortHandler viewPortHandler) {
    super(chart, animator, viewPortHandler);
}

//This method is same as it's parent implemntation
@Override
protected void drawLinearFill(Canvas c, ILineDataSet dataSet, Transformer trans, XBounds bounds) {
    final Path filled = mGenerateFilledPathBuffer;

    final int startingIndex = bounds.min;
    final int endingIndex = bounds.range + bounds.min;
    final int indexInterval = 128;

    int currentStartIndex = 0;
    int currentEndIndex = indexInterval;
    int iterations = 0;

    // Doing this iteratively in order to avoid OutOfMemory errors that can happen on large bounds sets.
    do {
        currentStartIndex = startingIndex + (iterations * indexInterval);
        currentEndIndex = currentStartIndex + indexInterval;
        currentEndIndex = currentEndIndex > endingIndex ? endingIndex : currentEndIndex;

        if (currentStartIndex <= currentEndIndex) {
            generateFilledPath(dataSet, currentStartIndex, currentEndIndex, filled);

            trans.pathValueToPixel(filled);

            final Drawable drawable = dataSet.getFillDrawable();
            if (drawable != null) {

                drawFilledPath(c, filled, drawable);
            } else {

                drawFilledPath(c, filled, dataSet.getFillColor(), dataSet.getFillAlpha());
            }
        }

        iterations++;

    } while (currentStartIndex <= currentEndIndex);
}

//This is where we define the area to be filled.
private void generateFilledPath(final ILineDataSet dataSet, final int startIndex, final int endIndex, final Path outputPath) {

    //Call the custom method to retrieve the dataset for other line
    final List<Entry> boundaryEntry = ((MyFillFormatter)dataSet.getFillFormatter()).getFillLineBoundary();

    final float phaseY = mAnimator.getPhaseY();    
    final Path filled = outputPath;
    filled.reset();

    final Entry entry = dataSet.getEntryForIndex(startIndex);

    filled.moveTo(entry.getX(), boundaryEntry.get(0).getY());
    filled.lineTo(entry.getX(), entry.getY() * phaseY);

    // create a new path
    Entry currentEntry = null;
    Entry previousEntry = null;
    for (int x = startIndex + 1; x <= endIndex; x++) {

        currentEntry = dataSet.getEntryForIndex(x);
        filled.lineTo(currentEntry.getX(), currentEntry.getY() * phaseY);

    }

    // close up
    if (currentEntry != null && previousEntry!= null) {
        filled.lineTo(currentEntry.getX(), previousEntry.getY());
    }

    //Draw the path towards the other line 
    for (int x = endIndex ; x > startIndex; x--) {
        previousEntry = boundaryEntry.get(x);
        filled.lineTo(previousEntry.getX(), previousEntry.getY() * phaseY);
    }

    filled.close();
}}

活动结束时

At the end of the activity

将MyFillFormatter设置为LineDataSet之一，并通过另一个LineDataSet作为参数.

Set the MyFillFormatter to one of the LineDataSet passing another LineDataSet as argument.

lineDataSet2.setFillFormatter(new MyFillFormatter(LineDataSet1));

mChart.setRenderer(new MyLineLegendRenderer(mChart, mChart.getAnimator(), mChart.getViewPortHandler()));

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