JFreeChart中的跨头发跟踪 [英] CrossHair Tracing In JFreeChart

问题描述

我能够实现如下实时鼠标跟踪:

I was able to implement real-time mouse tracing as follow :

源代码如下:

http://jstock.cvs.sourceforge.net/viewvc/jstock/jstock/src/org/yccheok/jstock/charting/CrossHairUI.java?revision=1.5&view=markup

http://jstock.cvs.sourceforge.net/viewvc/jstock/jstock/src/org/yccheok/jstock/gui/ChartJDialog.java?revision=1.9&view=markup

但是，添加子图时，我无法获得正确的y屏幕坐标.

However, I unable to obtained the correct y screen coordinate, when an subplot being added.

(损坏的图像)

我怀疑我没有得到正确的屏幕数据区域.

I suspect I didn't get the correct screen data area.

当屏幕上只有一个图时，我得到一个高度为300 ++的屏幕数据区域

When there is only one plot in the screen, I get a screen data area with height 300++

当子图添加到底部时，由于新添加的子图占用的高度，我预计屏幕数据区域的高度将减小.

When a sub plot added to the bottom, I expect screen data area height will be reduced, due to the height occupied by the newly added subplot.

但是，我不知道如何为第一个绘图获得正确的屏幕数据区域.

However, I have no idea how to obtain the correct screen data area for the first plot.

final XYPlot plot = (XYPlot) cplot.getSubplots().get(0);

// Shall I get _plotArea represents screen for getSubplots().get(0)?
// How?
// I try
//
// chartPanel.getScreenDataArea(0, 0);
// chartPanel.getScreenDataArea(0, 1);
// chartPanel.getScreenDataArea(1, 0);
// chartPanel.getScreenDataArea(1, 1);
//
// All returned null

// OK. I suspect this is causing me unable to get the correct screen y coordinate
// I always get the same _plotArea, although a new sub plot had been added.
final Rectangle2D _plotArea = chartPanel.getScreenDataArea();

final RectangleEdge rangeAxisEdge = plot.getRangeAxisEdge();

final double yJava2D = rangeAxis.valueToJava2D(yValue, _plotArea, rangeAxisEdge);

推荐答案

以下是在深入研究JFreeChart源代码后获得正确矩形的代码段.

Here is the code snippet to obtained the correct rectangle after dive into JFreeChart source code.

/* Try to get correct main chart area. */
final Rectangle2D _plotArea = chartPanel.getChartRenderingInfo().getPlotInfo().getSubplotInfo(0).getDataArea();

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