I've been trying to understand how to draw something in a window. I have a STM32F746G-Disco board and started with the STemWin Hello World example. Currently I have used the GUIBuilder to create a Window and inside that window are some images. Which creates this:



Along with the associated callback function _cbDialog to initiate and "set" the images, which displays correctly.

I have also implemented touch and would like for some actions to happen when they are pressed, so I have added



in my switch case statement for the callback _cbDialog, similar to how a button works. This works for manipulating the images that already exists in the window (redrawing them, set to top, etc).

I now would like to draw a line, or display text. This is where it gets fuzzy for me. Looking at the manual and searches on the forum, it seems I should add the WM_PAINT case to the callback and call a draw function in there. So I try


but it does not get displayed.

I have looked at: Drawing over widgets , Paint text on top of all existing dialog windows , and Cannot execute line drawing functions in any other window other than the Desktop Window. . I have read through the manual and have not been able to find my answer.

When debugging, I see that it is getting to the WM_NOTIFICATION_CLICKED and WM_PAINT, so they are being reached.

Is there any examples that show how to properly implement this?

Thank you,
amorgan

From my testing and reading through of the manual I have found that there is one primary window and then any other window created after that summarized (by me) here:

Possible Windows:
1. Background / Desktop Window (WM_HBKWIN)

• a. This is where any text or 2D graphics draw functions will be normally drawn
• b. The z-position of this window cannot be changed

2. Any Window / Widget created

• a. All Windows have a z-position that is stacked in the order of creation
• b. All Windows can have children, which also are given a z-position stacked in the order of creation
• c. The z-position can be manipulated by WM_* functions, such as WM_BringToTop()
• d. The GUIBuilder uses a Dialog Box for a Window that has Widget(s) as children

Therefore what that means is that any draw functions that want to be used with a Widget / Window, needs to be called inside the case WM_PAINT of a widgets callback function (Note 1), which will be clipped by the window's / widget's defined area, otherwise it will get drawn on the Background / Desktop Window and has a change to be drawn over top of.

Can you verify if these assumption / findings are correct?

It then seems to be possible to create a transparent Window that has been brought to the front in order to draw on the most top layer, but I will need to verify this.

Note1: Refer to STemwin528, page 435 17.8 example for assigning a callback function