[escher] TableViewDataSource: implement default cumulatedWidthFromIndex,

cumulatedWidthFromIndex, indexFromCumulatedWidth,
indexFromCumulatedHeight

escher/src/table_view_data_source.cpp

@@ -2,3 +2,37 @@
 
 void TableViewDataSource::willDisplayCellAtLocation(HighlightCell * cell, int i, int j) {
 }
+
+KDCoordinate TableViewDataSource::cumulatedWidthFromIndex(int i) {
+  int result = 0;
+  for (int k = 0; k < i; k++) {
+    result += columnWidth(k);
+  }
+  return result;
+}
+
+KDCoordinate TableViewDataSource::cumulatedHeightFromIndex(int j) {
+  int result = 0;
+  for (int k = 0; k < j; k++) {
+    result += rowHeight(k);
+  }
+  return result;
+}
+
+int TableViewDataSource::indexFromCumulatedWidth(KDCoordinate offsetX) {
+  int result = 0;
+  int i = 0;
+  while (result < offsetX && i < numberOfColumns()) {
+    result += columnWidth(i++);
+  }
+  return (result < offsetX || offsetX == 0) ? i : i - 1;
+}
+
+int TableViewDataSource::indexFromCumulatedHeight(KDCoordinate offsetY) {
+  int result = 0;
+  int j = 0;
+  while (result < offsetY && j < numberOfRows()) {
+    result += rowHeight(j++);
+  }
+  return (result < offsetY || offsetY == 0) ? j : j - 1;
+}