I am using flot charts to display ecg signals. The requirement is that the chart background should look exactly like the ecg graph paper.
All the inner grey lines should be lined at precise points to draw perfect squares on the ecg sheet. However, there are some lines which are not spaced evenly (they are closer to each other), making the ecg graph background incorrect.
Here is what my code does :
MARKINGS : I have written a function to generate markings on x and y axis. Markings are the dark pink lines on the graph. These markings will be generated on x and y axis after 4 grey lines (which make up the smaller grey squares inside the bigger dark pink boxes). These seem to be drawn correctly.
TICKS: I have overridden Flot charts native tick generator by writing two functions which generate ticks on x and y axis . On x axis, each 40 ms represents one tick (one grey line) and on y axis 0.1 millivolt represents one grey line. Even though the functions generate correct arrays with correct values for ticks, the tick spacing on flot chart is not even. Some tick lines are more closely spaced which is incorrect.
Not all ticks are drawn incorrectly.However, the ones that have irregular spacing are significant in number and are visible on more careful inspection of the graph. For a start, the 4 th column and row of the graph has unevenly spaced tick lines. (On browser outside of jsfiddle, this becomes 3rd row and 3rd column ). These uneven ticks repeat randomly throughout the graph.
My code is as shown below. It has also been uploaded at Flot for ECG
I have also attached picture of the generated ECG Graph on my browser with irregularities marked with green boxes.
Has anyone gone through similar problem with flot charts while drawing tick lines? Am I using ticks incorrectly? Appreciate your help on this.