I would like to have a gradient feature: - create gradients with multiple color-steps at specified positions - be able to load and save them At the moment I need to create svg and do afterworks in inkscape. And I have to do that after each iteration in labplot. offtopic: why Prefix-Texts for data-values are not rendered as text in SVG?
(In reply to H.H. from comment #0) > I would like to have a gradient feature: > > - create gradients with multiple color-steps at specified positions > - be able to load and save them I have already some code for colormaps handling. This can also be used to define gradients. For 2.9 we have already enough new features. For 2.10 I can finalize this feature. > At the moment I need to create svg and do afterworks in inkscape. And I have > to do that after each iteration in labplot. In which areas of LabPlot do you need need? For the plot background? > offtopic: why Prefix-Texts for data-values are not rendered as text in SVG? I fixed this now. The fix will be part of 2.8.2 and of 2.9.
Thanks. Yes, for the plot background. But also very helpful would be under a math-function: - you define percentual gradient offsets for each color - then the gradient is plottet below a curve - the y-value defines the length of the gradient and the offsets are adapted for each y-value You understand what I mean? For example I have a biological norm-value-curve (y) in dependency of age (x), and like to indicate good and bad with green, yellow and red along the curve. I fear, that would be nearly impossible to implement in svg-export? But perhaps at least as raster-graphics?
(In reply to H.H. from comment #2) > Thanks. Yes, for the plot background. > > But also very helpful would be under a math-function: > - you define percentual gradient offsets for each color > - then the gradient is plottet below a curve > - the y-value defines the length of the gradient and the offsets are adapted > for each y-value > > You understand what I mean? For example I have a biological norm-value-curve > (y) in dependency of age (x), and like to indicate good and bad with green, > yellow and red along the curve. Yes. This would be something similar what is being discussed here https://stackoverflow.com/a/31699594 for matlab. Here the color is set based on a third value but in principle it can also be similarly set based on the y-value. > I fear, that would be nearly impossible to implement in svg-export? But > perhaps at least as raster-graphics? At the moment we're drawing the curve as one single "graphics path" which is constructed out of many lines - the lines connecting the evaluated data points. If we want to allow multiple colors for the curve line based on the use specified color palette (or "gradient"), we'll need to draw the interpolating lines having separately colors separately. In the SVG export you'll get then multiple line objects. I think this feature is kind of trivial and we had already this request in the past. We should implement it in near feature.
I now implemented something like that for jfreechart: For my own gradient-renderer I give an array of gradient-colors and and array of "Function2D" Objects, which deliver the stop points for each color in dependency of a function of x (one function for each gradient-stop-point). Then I draw a polygon for each sampled-function point, filled with that gradient. To look good, there have to be enough sample points, and antialias needs to be off for the polygons (else there are little background-gaps between the polygons, not solved this problem for svg output unfortunately).