Semitransparent listbox overwrites the selected line with the text from the previous line

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    • Semitransparent listbox overwrites the selected line with the text from the previous line

      I'm trying to make a semitransparent listbox using this code

      static void _cbTool2(WM_MESSAGE* pMsg) {
      char acBuffer[32];
      int Sel;
      int NCode, Id;
      static LISTBOX_Handle hListbox, hText;
      static GUI_MEMDEV_Handle hMem;
      int i;
      // USER START (Optionally insert additional variables)
      // USER END
      switch (pMsg->MsgId) {
      case WM_CREATE:

      GUI_SetAlpha(50);
      hListbox = LISTBOX_CreateEx(60, 60, 210, 137, hTool2, WM_CF_SHOW, 0, ID_LISTBOX_0, _acContent);
      //WM_ClrHasTrans(hListbox);
      WM_SetHasTrans(hListbox);
      WIDGET_SetFocusable(hListbox, 1);
      LISTBOX_SetFont(hListbox, &GUI_Font8x18);
      LISTBOX_SetBkColor(hListbox, LISTBOX_CI_SELFOCUS, GUI_DARKGRAY);
      LISTBOX_SetBkColor(hListbox, LISTBOX_CI_UNSEL, GUI_LIGHTGRAY);
      LISTBOX_SetTextColor(hListbox, LISTBOX_CI_UNSEL, GUI_BLACK);
      LISTBOX_SetItemSpacing(hListbox, 4);
      LISTBOX_SetSel(hListbox, 1);
      LISTBOX_SetAutoScrollV(hListbox, 1);
      hText = TEXT_CreateEx(120, 40, 80, 20, pMsg->hWin, WM_CF_SHOW, TEXT_CF_HCENTER, ID_TEXT_2, "Main Menu");
      TEXT_SetFont(hText, &GUI_Font8x18);
      TEXT_SetTextColor(hText, GUI_BLACK);

      break;
      case WM_PAINT:
      //GUI_SetBkColor(GUI_BLACK);

      GUI_Clear();
      break;

      WM_HWIN CreateChild2(void);
      WM_HWIN CreateChild2(void) {

      hTool2 = WM_CreateWindowAsChild(43, 35, 240, 180, hParent, WM_CF_HASTRANS, _cbTool2, 0);

      return hTool2;
      }

      Every thins seems fine until i move down then the widget overwrites the selected line with the text from the previous line and become darker

    • Hi,

      You have to call GUI_SetAlpha() during the drawing process of the LISTBOX. It is also important that you reset the alpha value to fully opaque after the semi-transparent drawings are finished, because otherwise the set alpha value will be used globally.

      Try to set the following callback to your LISTBOX widget:

      C Source Code

      1. static void _cbListbox(WM_MESSAGE * pMsg) {
      2. switch (pMsg->MsgId) {
      3. case WM_PAINT:
      4. GUI_SetAlpha(50);
      5. LISTBOX_Callback(pMsg);
      6. GUI_SetAlpha(0xFF);
      7. break;
      8. default:
      9. LISTBOX_Callback(pMsg);
      10. }
      11. }
      Display All

      It draws the widget using the standard callback but with a modified alpha value.

      Best regards,
      Florian
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