在折线图上显示图像而不是圆圈

Question

我使用 MPAndroidChart 库创建了 LineChart，一切正常。

现在我要做的是为图表上的每个条目显示一个可绘制对象（图像）而不是默认圆圈。

我尝试了 API 中的很多选项，但没有成功。

谁能告诉我该怎么做？

Answer 1

在@David Rawson 的建议和这个 post MPAndroidChart LineChart custom highlight drawable

的帮助下，尝试了很多东西之后终于

我已经成功创建了一个自定义渲染器，它将图表中的默认圆形图像替换为提供的图像。

以下是解决方案的代码片段。

class ImageLineChartRenderer extends LineChartRenderer {
private final LineChart lineChart;
private final Bitmap image;


ImageLineChartRenderer(LineChart chart, ChartAnimator animator, ViewPortHandler viewPortHandler, Bitmap image) {
    super(chart, animator, viewPortHandler);
    this.lineChart = chart;
    this.image = image;
}

private float[] mCirclesBuffer = new float[2];

@Override
protected void drawCircles(Canvas c) {
    mRenderPaint.setStyle(Paint.Style.FILL);
    float phaseY = mAnimator.getPhaseY();
    mCirclesBuffer[0] = 0;
    mCirclesBuffer[1] = 0;
    List<ILineDataSet> dataSets = mChart.getLineData().getDataSets();

    //Draw bitmap image for every data set with size as radius * 10, and store it in scaled bitmaps array
    Bitmap[] scaledBitmaps = new Bitmap[dataSets.size()];
    float[] scaledBitmapOffsets = new float[dataSets.size()];
    for (int i = 0; i < dataSets.size(); i++) {
        float imageSize = dataSets.get(i).getCircleRadius() * 10;
        scaledBitmapOffsets[i] = imageSize / 2f;
        scaledBitmaps[i] = scaleImage((int) imageSize);
    }

    for (int i = 0; i < dataSets.size(); i++) {
        ILineDataSet dataSet = dataSets.get(i);

        if (!dataSet.isVisible() || !dataSet.isDrawCirclesEnabled() || dataSet.getEntryCount() == 0)
            continue;

        mCirclePaintInner.setColor(dataSet.getCircleHoleColor());
        Transformer trans = mChart.getTransformer(dataSet.getAxisDependency());
        mXBounds.set(mChart, dataSet);


        int boundsRangeCount = mXBounds.range + mXBounds.min;
        for (int j = mXBounds.min; j <= boundsRangeCount; j++) {
            Entry e = dataSet.getEntryForIndex(j);
            if (e == null) break;
            mCirclesBuffer[0] = e.getX();
            mCirclesBuffer[1] = e.getY() * phaseY;
            trans.pointValuesToPixel(mCirclesBuffer);
            if (!mViewPortHandler.isInBoundsRight(mCirclesBuffer[0]))
                break;
            if (!mViewPortHandler.isInBoundsLeft(mCirclesBuffer[0]) || !mViewPortHandler.isInBoundsY(mCirclesBuffer[1]))
                continue;

            if (scaledBitmaps[i] != null) {
                c.drawBitmap(scaledBitmaps[i],
                        mCirclesBuffer[0] - scaledBitmapOffsets[i],
                        mCirclesBuffer[1] - scaledBitmapOffsets[i],
                        mRenderPaint);
            }
        }
    }

}


private Bitmap scaleImage(int radius) {
    return Bitmap.createScaledBitmap(image, radius, radius, false);
}

希望这对某人有所帮助。

Answer 2

您可以简单地使用 drawable 创建条目，它将被绘制而不是图形上的圆。

new Entry(i, value, drawable)

Answer 3

我也遇到过这个问题，但有更具体的要求：

仅在图表上的特定点绘制圆圈。
可以灵活地在不同情况下使用不同的可绘制对象。

最后，我做到了：

其中每个圆圈实际上是一个常规可绘制对象，可以用其他任何东西替换。

用下一种方式解决了：

1.Create 一个以可绘制对象为参数的 Entry 子类。

/**
 * Represents an [Entry] which is able to use drawables (including different drawables for different points) instead of the circle.
 * For the points where you don't need points use a regular [Entry].
 */

class DrawableCircleEntry @JvmOverloads constructor(
        @DrawableRes val circleDrawableRes: Int,
        x: Float,
        y: Float,
        icon: Drawable? = null,
        data: Any? = null
) : Entry(x, y, icon, data)

2.Create 自定义渲染，

如果条目是 DrawableCircleEntry 类型，则绘制可绘制对象而不是圆。

如果 try 是常规条目，则不画圆圈。

internal class LineChartCustomCirclesRenderer(private val context: Context, lineChart: LineChart
  ) : LineChartRenderer(lineChart, lineChart.animator, lineChart.viewPortHandler) {

  // Contains (left, top) coordinates of the next circle which has to be drawn
  private val circleCoordinates = FloatArray(2)
  // Cached drawables
  private val drawablesCache = SparseArray<Drawable>()

  override fun drawCircles(canvas: Canvas) {
      val phaseY = mAnimator.phaseY
      circleCoordinates[0] = 0f
      circleCoordinates[1] = 0f
      val dataSets = mChart.lineData.dataSets

      dataSets.forEach { dataSet ->
          if (!dataSet.isVisible || !dataSet.isDrawCirclesEnabled || dataSet.entryCount == 0)
              return@forEach

          val transformer = mChart.getTransformer(dataSet.axisDependency)
          mXBounds[mChart] = dataSet
          val boundsRangeCount = mXBounds.range + mXBounds.min

          for (i in mXBounds.min..boundsRangeCount) {
              // don't do anything in case entry is not type of DrawableCircleEntry
              val entry = dataSet.getEntryForIndex(i) as? DrawableCircleEntry
                      ?: continue
              circleCoordinates[0] = entry.x
              circleCoordinates[1] = entry.y * phaseY

              transformer.pointValuesToPixel(circleCoordinates)

              if (!mViewPortHandler.isInBoundsRight(circleCoordinates[0])) break
              if (!mViewPortHandler.isInBoundsLeft(circleCoordinates[0]) || !mViewPortHandler.isInBoundsY(circleCoordinates[1])) continue

              // Drawable radius is taken as `dataSet.circleRadius`
              val radius = dataSet.circleRadius

              // Retrieve the drawable, center it and draw on canvas
              getDrawable(entry.circleDrawableRes)?.run {
                  setBounds((circleCoordinates[0] - radius).roundToInt(), (circleCoordinates[1] - radius).roundToInt(),
                          (circleCoordinates[0] + radius).roundToInt(), (circleCoordinates[1] + radius).roundToInt())
                  draw(canvas)
              }
          }
      }
  }


  private fun getDrawable(@DrawableRes drawableRes: Int): Drawable? {
      drawablesCache[drawableRes]?.let {
          return it
      }
      return ContextCompat.getDrawable(context, drawableRes)
              .also { drawablesCache.append(drawableRes, it) }
  }

}

3.Enable 数据集的圆圈并设置所需的半径。可绘制对象的大小将为 radius*2

 dataSet.setDrawCircles(true)
 dataSet.circleRadius = 3f

4.When构造Entries，在不需要画圆的地方创建普通Entry，需要画圆的时候创建DrawableCircleEntry。例如，

    ...
    val entry = when {
        someCondition ->  DrawableCircleEntry(R.drawable.your_awesome_drawable, floatIndex, floatValue)
        anotherCondition ->  DrawableCircleEntry(R.drawable.your_another_drawable, floatIndex, floatValue)
        else -> Entry(floatIndex, floatValue)
    }
    ...

我案例中的一个可绘制对象如下所示：

<item>
    <shape
        android:shape="ring"
        android:thickness="@dimen/chart_circle_stroke_thickness"
        android:useLevel="false">
        <solid android:color="#497EFF" />
    </shape>
</item>

但它可以是任何其他。

尽情享受吧。

在折线图上显示图像而不是圆圈

Show image instead of circle on LineChart

charts

android

linechart

mpandroidchart