+<!DOCTYPE html>
<html>
<head>
<title>Custom underlay callback</title>
showRoller: true,
errorBars: true,
- underlayCallback: function(canvas, area, layout) {
- var splitHeight = area.h * (layout.yscale * (2.25 - layout.minyval));
- canvas.fillStyle = 'pink';
- canvas.fillRect(area.x, area.y + area.h, area.w, -splitHeight);
+ underlayCallback: function(canvas, area, g) {
+ // Selecting a date in the middle of the graph.
+ var splitDate = new Date("2006-11-19").getTime();
+ var coords = g.toDomCoords(splitDate, 2.25);
+
+ // splitX and splitY are the coordinates on the canvas for (2006-11-19, 2.25).
+ var splitX = coords[0];
+ var splitY = coords[1];
+
+ // The drawing area doesn't start at (0, 0), it starts at (area.x, area.y).
+ // That's why we subtract them from splitX and splitY. This gives us the
+ // actual distance from the upper-left hand corder of the graph itself.
+ var leftSideWidth = splitX - area.x;
+ var rightSideWidth = area.w - leftSideWidth;
+ var topHeight = splitY - area.y;
+ var bottomHeight = area.h - topHeight;
+
+ // fillRect(x, y, width, height)
+ // Top section: y = (2.25, +Infinity)
+ // left: (x < 2006-11-19)
canvas.fillStyle = 'lightblue';
- canvas.fillRect(area.x, 0, area.w, area.y + area.h - splitHeight);
+ canvas.fillRect(area.x, area.y, leftSideWidth, topHeight);
+
+ // right: (x > 2006-11-19)
+ canvas.fillStyle = 'orange';
+ canvas.fillRect(splitX, area.y, rightSideWidth, topHeight);
+
+ // Bottom section: y = (-Infinity, 2.25)
+ canvas.fillStyle = 'pink';
+ canvas.fillRect(area.x, splitY, area.w, bottomHeight);
}
}
);
projects / dygraphs.git / blobdiff