获取点在AndroidPlot中的正确位置

Posted 2021-04-28

我正在尝试获取我的androidPlot中值的像素位置，但无法使其正常工作。想法是将光标按特定术语放置在绘图上显示的确切点上。你们中有人遇到过类似的问题吗？

关于杰斯珀

答案

我不知道是否有更好的内置解决方案，但这是一种手动方法。下面的代码将光标置于用户触摸屏幕的X坐标和绘图的第一个数据序列的相应Y坐标。

//NOTE about XYPlotZoomPan: when an OnTouchListener is set, zooming is disabled. Subclass to avoid it.
mPlot.setOnTouchListener(new View.OnTouchListener(){
    @Override
    public boolean onTouch(View v, MotionEvent me) {
        float touchX = me.getX();
        float touchY = me.getY();
        XYGraphWidget widget = mPlot.getGraphWidget();
        RectF gridRect = widget.getGridRect();
        if(gridRect.contains(touchX, touchY)){ //Check the touch event is in the grid
            XYSeries xyData = mPlot.getSeriesSet().iterator().next();
            long targetValX = Math.round(widget.getXVal(touchX));
            Log.d(TAG, "Touched at " + touchX + ", " + touchY + ". Target val X: " + targetValX);
            Long targetValY = null; 
            Long prevValX = null;
            if(mPlot.getSeriesSet().size() > 1){
                Log.w(TAG, "More than one series in plot. Using only the first one");
            }
            for(int i = 0; i < xyData.size(); ++i){
                long currValX = xyData.getX(i).longValue();
                long currValY = xyData.getY(i).longValue();
                //Calculate the range value of the closest domain value (assumes xyData is sorted in ascending X order)
                if(currValX >= targetValX){
                    long currDiff = currValX - targetValX; 
                    if(prevValX != null && (targetValX - prevValX) < currDiff){
                        targetValY = xyData.getY(i-1).longValue();
                    }else{
                        targetValY = currValY;
                    }
                    break;
                }
                prevValX = currValX;
            }
            if(targetValY != null){
                long maxValY = mPlot.getCalculatedMaxY().longValue();
                long minValY = mPlot.getCalculatedMinY().longValue();
                float pixelPosY = gridRect.top + ValPixConverter.valToPix(
                        (double)targetValY, (double)minValY, (double)maxValY, (float)gridRect.height(), true);
                widget.setRangeCursorPosition(pixelPosY);
                widget.setDomainCursorPosition(touchX);
                Log.d(TAG, String.format("Domain cursor set at Y %.2f, val %.2f = %d, min-maxValY (%d, %d)",
                        pixelPosY,
                        widget.getRangeCursorVal(), targetValY,
                        minValY, maxValY));
            }else{
                Log.w(TAG, "Couldn't find the closest range to the selected domain coordinate");
            }
            mPlot.invalidate();
        }else{
            Log.d(TAG, "Touched outside the plot grid");
        }

        return false;
    }
});

另一答案

我找到了解决方案。我的目的是找到给定像素的值（例如，通过点击绘图，我想要代表值）。因此，经过一番搜索，我发现了助手类ValPixConverter。它提供了一些适合我需求的方法。不幸的是，没有方法的文档，但是我找到了解决方法：

    private float pixelToValueY(float y) {
    //Parameters: 1=input y-value, 2=minmal y-value that is shown,  3=maximal y-value that is shown, 4=Hight of the view, 5=flip
    return (float) ValPixConverter.pixToVal(y, minXY.y, maxXY.y, mySimpleXYPlot.getHeight(), false);
    }

    private float pixelToValueX(float x) {
    //Parameters: 1=input y-value, 2=minmal y-value that is shown,  3=maximal y-value that is shown, 4=Hight of the view, 5=flip
    return (float) ValPixConverter.pixToVal(x, minXY.x, maxXY.x, mySimpleXYPlot.getWidth(), false);
    }

您需要另一种方式。方法valToPix（）将执行此操作。然后，它与上面的代码非常相似。

另一答案

更新的解决方案

[我试图遵循rbarriuso的方法，但是我发现它已经过时并且过于复杂。

使用rbarriuso答案作为指导，我想到了以下内容：

private void placeMarkerOnGraph(XYPlot plot, XYSeries plotSeries, XValueMarker xMarker, YValueMarker yMarker, float touchX, float touchY) {
    if(plot.getRegistry().getSeriesList().contains(plotSeries)) {
        if (plot.getGraph().getGridRect().contains(touchX, touchY)) {
            int targetValX = plot.screenToSeriesX(touchX).intValue();
            int targetValY = plot.screenToSeriesY(touchY).intValue();
            int threshold = (int)(plot.getBounds().getHeight().intValue() * 0.1f); //How close to a trace does the user have to click to move the markers?

            if (plotSeries.getY(targetValX).intValue() - targetValY < threshold) {
                Log.w(TAG, "Touched within threshold to trace line");
                xMarker.setValue(targetValX);
                yMarker.setValue(plotSeries.getY(targetValX).intValue());
            }
        } else {
            Log.w(TAG, "Touched outside graph");
        }
    } else {
        Log.w(TAG, "Plot does not contain series provided");
    }
}

如何运作

步骤1.检查您是否确实触摸了图形内部

步骤2.从触摸线转换为屏幕图形坐标

步骤3.取X值（已转换为图形坐标）并找到其Y值

步骤4.如果您触摸得足够近，则移动标记/光标

其他提示

• 我在我的示例中使用标记而不是光标，因为绘图可以有多少个标记没有限制，但是您只能有一个光标。

• 此功能仅更改标记的位置，您必须选择格式化并首先将标记添加到绘图中。

• XYSeries现在使用数字，因此请使用必要的值，例如：如果您的系列从0.0f到1.0f，请使用.floatValue()

• 除非您使用plot.redraw()

• 阈值是要考虑缩放的绘图总高度的百分比

更高级的解决方案

第一种解决方案对于不是很陡的图形来说可以正常工作，但是否则它的准确性就不高，因为它没有考虑不在用户触摸图形下方的数据点。

下面，我添加了一个更强大的解决方案，该解决方案依赖于for循环，但更加准确。其工作原理与第一个解决方案非常相似。

private void placeMarkerOnGraph(XYPlot plot, XYSeries plotSeries, XValueMarker xMarker, YValueMarker yMarker, float touchX, float touchY) {
    if(plot.getRegistry().getSeriesList().contains(plotSeries)) {
        if (plot.getGraph().getGridRect().contains(touchX, touchY)) {
            int targetValX = plot.screenToSeriesX(touchX).intValue();
            int targetValY = plot.screenToSeriesY(touchY).intValue();
            int threshold = (int)(plot.getBounds().getWidth().intValue() * 0.1f); //How close to a trace does the user have to click to move the markers?
            Integer closestValue = null;
            Integer xPos = null;
            Integer yPos = null;

            for(int i = targetValX - threshold; i < targetValX + threshold; i++){
                //If the user touches near either end of the graph we need to make sure we don't go out of the arrays bounds
                if(i > 0 && i < graphSize) {
                    int closeness = Math.abs(Math.abs(plotSeries.getY(i).intValue() - targetValY) + Math.abs(i - targetValX));
                    Log.d(TAG,"Distance to nearest trace: " + closeness);
                    if ((closestValue != null && closeness < closestValue) || (closestValue == null && closeness < threshold)) {
                        closestValue = closeness;
                        xPos = i;
                        yPos = plotSeries.getY(i).intValue();
                    }
                }
            }

            if (xPos != null) {
                Log.d(TAG, "Touched within threshold");
                xMarker.setValue(xPos);
                yMarker.setValue(yPos);
            } else {
                Log.d(TAG, "Touched outside threshold");
            }
        } else {
            Log.w(TAG, "Touched outside graph");
        }
    } else {
        Log.w(TAG, "Plot does not contain series provided");
    }
}