Translating between screen and graph co-ordinates

[Daniel van Enckevort]

Hi Dave, although we have ValueAxis.translateJava2DtoValue and ValueAxis.translateValueToJava2D, we have no way of going from screen co-ordinates to Java2D co-ordinates.

This is beacause there is no way to access the ChartPanel.scaleX and ChartPanel.scaleY fields.

ChartPanel frequently converts between screen and Java2D co-ordinates, maybe you could refactor this into two public methods on ChartPanel?


// BTW, I have no idea whether the choice of Point and Point2D below is
// right.
// Maybe everything should be Point2D (even though screen coords are
// always integer)?

public Point translateJava2DToScreen(Point2D java2DPoint){
Insets insets = getInsets();
int x = (int) (java2DPoint.getX() * scaleX + insets.left);
int y = (int) (java2DPoint.getY() * scaleY + insets.top);
return new Point(x,y);
}

public Point2D translateScreenToJava2D(Point2D screenPoint){
Insets insets = getInsets();
double x = (screenPoint.getX()-insets.left)/scaleX;
double y = (screenPoint.getY()-insets.top)/scaleY;
return new Point.Double(x,y);
}

Thanks
Dan

[Dave Gilbert]

Hi Dan,

Thanks for the suggestion, I will make the change now. I will start with Point for the screen coordinates and Point2D for the Java2D coordinates, and wait for any other feedback if someone thinks it should be different.

Regards,

DG.