Unwanted redrawing of FRAMEWIN

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    • Unwanted redrawing of FRAMEWIN

      Hi all,

      I am using a 176x220px display on a Cortex-M without buffering, so I need to avoid unnecessary redrawings etc. to minimize flickering.
      My application uses several Dialogs but only one is shown at a time. To switch between the dialogs, I implemented a swipe detection that is, the user swipes left or right to go through the dialogs.
      After swiping, I hide the current window and show the desired window like this

      C Source Code

      1. WM_HideWindow(hDlgInputSelect);
      2. WM_ShowWindow(hDlgPreset);
      3. WM_SetFocus(hDlgPreset);


      So far, that works. However, there is one annoying issue:
      After the new dialog is displayed, the first touch to any area triggers a redraw and I don't know how to prevent this.
      I recorded the messages sent to the window directly after it is activated via swiping, see below.
      Of course, it's no C code, but it's nicely displayed using the quoting.
      The comments translate the msg IDs to WM_ message codes.

      C Source Code

      1. // user message to update the contents
      2. PresetDlg: MsgId: 1026, src: 0, dst: 3, code: 3
      3. // NOTIFY_PARENT -> GOT_FOCUS
      4. PresetDlg: MsgId: 38, src: 12, dst: 3, code: 8
      5. // CHILD_HAS_FOCUS
      6. PresetDlg: MsgId: 32, src: 0, dst: 3, code: 268450896
      7. // PRE_PAINT
      8. PresetDlg: MsgId: 46, src: 0, dst: 3, code: 0
      9. // PAINT
      10. PresetDlg: MsgId: 15, src: 0, dst: 4, code: 268450700
      11. // POST_PAINT
      12. PresetDlg: MsgId: 47, src: 0, dst: 3, code: 0
      14. Now, the window is displayed properly and has focus.
      15. At this point, when I touch the display, a redraw is triggered as follows:
      16. // PID_STATE_CHANGED
      17. PresetDlg: MsgId: 17, src: 0, dst: 3, code: 268450768
      18. // TOUCH
      19. PresetDlg: MsgId: 12, src: 0, dst: 3, code: 268450732
      20. // TOUCH
      21. PresetDlg: MsgId: 12, src: 0, dst: 3, code: 268450732
      22. // TOUCH
      23. PresetDlg: MsgId: 12, src: 0, dst: 3, code: 268450732
      24. // PRE_PAINT
      25. PresetDlg: MsgId: 46, src: 0, dst: 3, code: 0
      26. // PAINT
      27. PresetDlg: MsgId: 15, src: 0, dst: 4, code: 268450700
      28. // POST_PAINT
      29. PresetDlg: MsgId: 47, src: 0, dst: 3, code: 0
      31. After this one redraw, no further redraws are done (except when desired by actions caused by touching a button).
      32. // TOUCH
      33. PresetDlg: MsgId: 12, src: 0, dst: 3, code: 268450732
      34. // PID_STATE_CHANGED
      35. PresetDlg: MsgId: 17, src: 0, dst: 3, code: 268450768
      36. // TOUCH
      37. PresetDlg: MsgId: 12, src: 0, dst: 3, code: 268450732
      38. ...
      39. PresetDlg: MsgId: 17, src: 0, dst: 3, code: 268450768
      41. PresetDlg: MsgId: 12, src: 0, dst: 3, code: 268450732
      43. PresetDlg: MsgId: 12, src: 0, dst: 3, code: 268450732
      45. PresetDlg: MsgId: 12, src: 0, dst: 3, code: 268450732
      47. PresetDlg: MsgId: 18, src: 0, dst: 3, code: 268450732
      Display All


      Any idea what causes this redrawing and how to remove it?

      Best regards,

      Rainer