PHPlot Sample - Annotated Candlesticks Plot
This sample shows a candlestick plot with an extra annotation label. The label is drawn on the right side Y axis and shows the closing price of the stock on the final day. A call-back is used to place the label.
The label position is calculated as follows. Take the final closing price, $y_final. This is the world coordinate Y value. Convert this to a Y device coordinate (pixel value) $yd. For X, use the plot_area array which is passed to the callback by PHPlot. This array contains the plot area coordinates as (x1, y1, x2, y2). The value we want is x2, the X device coordinate of the right side of the plot area. Using these values ($x2, $yd) as the base point, we can position the label just right of the right side Y axis, at the Y position corresponding to the closing price on the plot.
(2015-07-30)
Reference: Discussion forum thread
The Plot:
The Code:
~~~~
:::php
GetDeviceXY(0, $y_final);
// Allocate colors for label text, box background and border:
$color_fg = imagecolorresolve($img, 255, 0, 0); // Red
$color_bg = imagecolorresolve($img, 0xff, 0xff, 0xcc); // Light yellow
$color_border = imagecolorresolve($img, 0, 0, 0); // Black
// Get the text size, and draw an outlined box behind the text:
list($text_width, $text_height) = $plot->SizeText('', 0, $y_final);
$x1 = $plot_area[2] + 2;
$y1 = $yd - $text_height / 2;
$x2 = $x1 + $text_width + 4;
$y2 = $yd + $text_height / 2 + 2;
imagefilledrectangle($img, $x1, $y1, $x2, $y2, $color_bg);
imagerectangle($img, $x1, $y1, $x2, $y2, $color_border);
// Finally, draw the label:
$plot->DrawText('', 0, $x1 + 2, $yd, $color_fg, $y_final, 'left', 'center');
}
$plot = new PHPlot(600, 400);
$plot->SetTitle('Demo Candlestick Plot with Annotation');
$plot->SetDataType('text-data');
$plot->SetDataValues($data);
$plot->SetPlotType('candlesticks');
// Disable the Y axis 'zero magnet' : let it fit to the data.
$plot->TuneYAutoRange(0);
// Don't draw X ticks - with data labels they have no meaning.
$plot->SetXTickPos('none');
// Place the Y axis on the right:
$plot->SetYTickPos('plotright');
$plot->SetYTickLabelPos('plotright');
// And make the right margin wider, for the extra label
$plot->SetMarginsPixels(NULL, 50);
// Register a callback for drawing the extra label:
$plot->SetCallback('draw_all', 'post_draw', array($plot, $data));
// Draw the graph:
$plot->DrawGraph();
~~~~~
?>
