[chronojump] Cairo: added methods for knowing real point of a coordinate

[Xavier de Blas <xaviblas src gnome org>]

commit beea05435559b713c15d28e8249bb031817614f7
Author: Xavier de Blas <xaviblas gmail com>
Date:   Fri Jan 10 20:12:25 2020 +0100

    Cairo: added methods for knowing real point of a coordinate

 src/gui/cairo/xy.cs | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)
---
diff --git a/src/gui/cairo/xy.cs b/src/gui/cairo/xy.cs
index 7135bef1..baabea95 100644
--- a/src/gui/cairo/xy.cs
+++ b/src/gui/cairo/xy.cs
@@ -245,7 +245,13 @@ public abstract class CairoXY
                        printText(xgraph, graphHeight - Convert.ToInt32(bottomMargin/2), 0, textHeight, 
Util.TrimDecimals(p.X, 2), g, true);
                        printText(Convert.ToInt32(leftMargin/2), ygraph, 0, textHeight, 
Util.TrimDecimals(p.Y, 2), g, true);
                        */
+
+                       LogB.Information(string.Format("xgraph: {0} corresponds to x real point: {1}", xgraph,
+                                               calculateRealX(xgraph, graphWidth, absoluteMaxX, minX, 
totalMargins, totalMargins)));
+                       LogB.Information(string.Format("ygraph: {0} corresponds to y real point: {1}", ygraph,
+                                               calculateRealY(ygraph, graphHeight, absoluteMaxY, minY, 
totalMargins, totalMargins)));
                }
+               getMinMaxXDrawable(graphWidth, absoluteMaxX, minX, totalMargins, totalMargins);
        }
 
        protected void plotPredictedMaxPoint()
@@ -384,16 +390,33 @@ public abstract class CairoXY
                return step;
        }
 
-       protected double calculatePaintX(double currentValue, int ancho, double maxValue, double minValue, 
int rightMargin, int leftMargin)
+       protected double calculatePaintX (double realX, int ancho, double maxValue, double minValue, int 
rightMargin, int leftMargin)
+       {
+                return leftMargin + (realX - minValue) * (ancho - rightMargin - leftMargin) / (maxValue - 
minValue);
+        }
+       protected double calculatePaintY (double realY, int alto, double maxValue, double minValue, int 
topMargin, int bottomMargin)
        {
-                return leftMargin + (currentValue - minValue) * (ancho - rightMargin - leftMargin) / 
(maxValue - minValue);
+                return alto - bottomMargin - ((realY - minValue) * (alto - topMargin - bottomMargin) / 
(maxValue - minValue));
         }
 
-       protected double calculatePaintY(double currentValue, int alto, double maxValue, double minValue, int 
topMargin, int bottomMargin)
+       //get the real point of a graph point
+       private double calculateRealX (double graphX, int ancho, double maxValue, double minValue, int 
rightMargin, int leftMargin)
+       {
+                return minValue + ( (graphX - leftMargin) * (maxValue - minValue) / (ancho - rightMargin - 
leftMargin) );
+        }
+       private double calculateRealY (double graphY, int alto, double maxValue, double minValue, int 
topMargin, int bottomMargin)
        {
-                return alto - bottomMargin - ((currentValue - minValue) * (alto - topMargin - bottomMargin) 
/ (maxValue - minValue));
+                return minValue + (- graphY + alto - bottomMargin) * (maxValue - minValue) / (alto - 
topMargin - bottomMargin);
         }
 
+       private void getMinMaxXDrawable(int ancho, double maxValue, double minValue, int rightMargin, int 
leftMargin)
+       {
+               LogB.Information(string.Format("Real points fitting on graph margins:  {0} , {1}",
+                                       calculateRealX(outerMargins, graphWidth, absoluteMaxX, minX, 
totalMargins, totalMargins),
+                                       calculateRealX(graphWidth - outerMargins, graphWidth, absoluteMaxX, 
minX, totalMargins, totalMargins)
+                                       ));
+       }
+
        protected Cairo.Color colorFromRGB(int red, int green, int blue)
        {
                return new Cairo.Color(red/256.0, green/256.0, blue/256.0);