Question

我试图通过扩展LineChart类并覆盖onDraw方法在LineChart的极限线之间绘制颜色。我在https://github.com/PhilJay/MPAndroidChart/issues/485中看到了这一点，其中在画布上仅绘制了彩色矩形：

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);
}
}

上面的代码无法在线条图的数据后面绘制彩色矩形作为背景，如此处所示

chart 1

但是，当我在Y轴上滚动时，矩形将“溢出”到绘制X轴标签的区域，如该图所示

chart2

我应该如何绘制彩色背景，以使其不着色绘制X轴标签的区域，就像如何在X轴上方截断线数据和极限线一样？

Answer 1

似乎我已经找到解决问题的方法。在onDraw方法内部，我应该限制以下绘制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);
}

Result:

在极限线之间绘制背景色

1 个答案: