Help with function calls to change window size, set current zoom/scale value, and data offset.

[8bit-glitch]

I have been experimenting with IMPLOT and it's been great so far. I am running into a few issues that I cannot figure out based on the code and was hoping someone could point me in the right direction.

For the following questions assume I have 1000 data points in the x axis and 256 in the y axis

1- I want to specify the size of the plot "Window". In my case I want it to be smaller than my data. For example: even though my data is 1000 points, I want my window to only be 100 pixels wide and 32 pixels high. So at any given time the plot window would be displaying a subset of 100 points of my full 1000.

2-How do control what range of data is being viewed in the plot window above? In my case I have 1000 data points but the window would only be 100 pixels wide. How do I call the plot command to display the data at a certain range or offset. For Example: Display values 200-300 ?

3- How can I specify the zoom/scale value for a plot via a function call? For example: say I want to make some imgui buttons that can be clicked to zoom in/out on the y axis? Is there a function I can call to set the zoom/scale of an axis?

Any help is appreciated.

Thanks.

[8bit-glitch]

Just a follow up as I was able to figure out part 2, but I am still trying to figure out how to specify the pixel height and width of the window and how to zoom.

For those who see this post in the future, the answer to part 2

I was able to setup the plot window of 100 x 10 with the 0,0 coordinates locked by using:

float xmin_view=0;
float xmax_view=100;
float ymin_view=0;
float ymax_view=10;
ImPlot::SetupAxis(ImAxis_Y1,0,(ImPlotAxisFlags_LockMin));//lock 0 for axis
ImPlot::SetupAxis(ImAxis_X1,0,(ImPlotAxisFlags_LockMin));//lock 0 for axis
ImPlot::SetupAxesLimits(xmin_view, xmax_view, ymin_view,ymax_view, ImGuiCond_Always);

This view can be moved over the data by adding an offset to the min and max values.

I was able to do this using an int value that I update via a imgui slider with:
float xmin_view=0+xslider;
float xmax_view=100+xslider;

Hopefully someone can help with the command that is needed to do zoom manually and how to force the pixel size for the window. I am sure it's a similar sort of function call, but I have not been able to figure it out yet.

I just need to know now how to specify something that will scale

[brmarkus]

Currently I'm not into the source code- but maybe you can trace-down to the place which is handling mouse-events (mouse-wheel event to zoom-in and zoom-out) (and maybe keyboard event like +/-, page-up/page-down from the keyboard-num-block or similar).

[8bit-glitch]

I'll take a look and see if I can find that portion of the code. Thanks for the suggestion brmarkus. Once I figure out how to scale/zoom manually I should be good.

As for Part 1 of my question I figured it out:

For anyone looking at this in the future, I was able to figure out how to fix the size of the plot. It's done via the BeginPlot call. The second argument that is of ImVec2 type is where you specify the X and Y pixel height for the plot.

ie. to set it to 200 pixels by 200 pixels this is what I did:

BeginPlot("DevC",ImVec2(200,200),( ImPlotFlags_NoTitle | ImPlotFlags_NoLegend | ImPlotFlags_NoMenus | ImPlotFlags_NoBoxSelect | ImPlotFlags_NoMouseText|ImPlotFlags_NoFrame )))

[8bit-glitch]

Ok I think I found a way to do what I want. Basically you fix the window size using the BeginPlot as mentioned in my previous post. Then you set the Axis limits which scales it to the size of the window you set in the BeginPlot phase. The setting of the Axis limits automatically scales to the size of the window you specify with the BeginPlot call. Growing/Shrinking the axis limits will zoom out/zoom in on the plot. I tried doing this with a imgui slider and it worked.

Hopefully this will help others in the future.