我想在我的AndroidPlot中获取值的像素位置，但我无法让它工作。我们的想法是将光标放在图中所示的确切点上，具体用语。你们有没有遇到/解决类似的问题？
此致 的Jesper
答案 0 :(得分：3)
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 以下代码将光标放在用户触摸屏幕的X坐标和绘图的第一个数据系列的相应Y坐标上。
//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;
}
});
答案 1 :(得分：2)
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）。 所以，经过一番搜索，我发现了辅助级ValPixConverter。 它提供了一些符合我需求的方法。不幸的是没有这些方法的文档，但我找到了一个解决方案：
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);
}
你只需要另一种方式。方法valToPix（）将执行此操作。它与上面的代码非常相似。
答案 2 :(得分：0)
我试图遵循rbarriuso的方法，但是我发现它已经过时且过于复杂。
使用rbarriuso答案作为指导，我提出了以下建议：
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");
}
}
第1步。检查您是否真正触摸了图形内部
步骤2。从触摸线转换为屏幕图形坐标
第3步。获取X值（已转换为图形坐标）并找到其Y值
第4步。如果触摸得足够近，则移动标记/光标
在我的示例中，我使用标记而不是游标，因为对一个绘图可以有多少个标记没有限制，但是只能有一个游标。
该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()
阈值是要考虑缩放比例的地块总高度的百分比
第一种解决方案对于不太陡峭的图形也可以正常工作，但否则精度不高，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");
}
}