在限制线之间绘制背景色

Question

我试图通过扩展LineChart类并重写onDraw方法，在LineChart中绘制界限线之间的颜色。我在https://github.com/philjay/mpandroidchart/issues/485中这样做，其中彩色矩形简单地绘制在画布上：

public class CustomLineChart extends LineChart {

protected Paint mYAxisZonePaint;
protected  String[] arrayColors = {"#FFFFFF","#F4D03F","#F5B041","#EB984E","#DC7633"};

    @Override
protected void init() {
    super.init();
    mYAxisZonePaint = new Paint();
    mYAxisZonePaint.setStyle(Paint.Style.FILL);
}

@Override
protected void onDraw(Canvas canvas) {
    List<LimitLine> limitLines = mAxisLeft.getLimitLines();

    if (limitLines == null || limitLines.size() < 4){
        super.onDraw(canvas);
        return;
    }

    float[] pts = new float[2];

    float startPts = 0;

    for (int i = 0; i < limitLines.size(); i++) {
        pts[0] = limitLines.get(i).getLimit();
        pts[1] = startPts;

        mLeftAxisTransformer.pointValuesToPixel(pts);
        mYAxisZonePaint.setColor(Color.parseColor(arrayColors[i]));

        canvas.drawRect(mViewPortHandler.contentLeft(), pts[1], mViewPortHandler.contentRight(), pts[0], mYAxisZonePaint);

        startPts = limitLines.get(i).getLimit();

    }
    super.onDraw(canvas);
}
}

使用上面的代码，我可以绘制彩色矩形作为折线图数据后面的背景，如下所示

然而，当我在y轴上滚动时，矩形将“溢出”到绘制x轴标签的区域，如图所示

我应该如何绘制彩色背景，这样它就不会给绘制x轴标签的区域着色，类似于线数据和限制线在x轴上方被切断的方式？

Answer 1

看来我已经找到了解决问题的办法。在onDraw方法中，我应该限制以下绘图操作可以写入的区域。我在onDraw方法中添加了以下内容：

@Override
protected void onDraw(Canvas canvas) {
    List<LimitLine> limitLines = mAxisLeft.getLimitLines();

    // Saves current canvas
    int clipRestoreCount = canvas.save();
    // Makes sure that the colored background cannot be drawn outside the content-rect. Otherwise the colored background would be drawn above and beneath the graph "borders".
    canvas.clipRect(mViewPortHandler.getContentRect());

    if (limitLines == null || limitLines.size() < 4){
        super.onDraw(canvas);
        return;
    }

    float[] pts = new float[2];

    float startPts = 0;

    for (int i = 0; i < limitLines.size(); i++) {
        pts[0] = limitLines.get(i).getLimit();
        pts[1] = startPts;

        mLeftAxisTransformer.pointValuesToPixel(pts);
        mYAxisZonePaint.setColor(Color.parseColor(arrayColors[i]));

        canvas.drawRect(mViewPortHandler.contentLeft(), pts[1], mViewPortHandler.contentRight(), pts[0], mYAxisZonePaint);

        startPts = limitLines.get(i).getLimit();

    }

    // Removes the clipping rectangles so rest of graph elements can be drawn (like x-axis/y-axis labels)
    canvas.restoreToCount(clipRestoreCount);
    super.onDraw(canvas);
}

结果：