Window with transparency

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  • Window with transparency

    Hi,

    is it possible to define a transparent background for a whole window? The window is created with "WM_CreateWindowAsChild(...)"
    If yes, how do I achieve this!

    Thanks,
    Johannes

  • Hi,

    Of course, you can set the window as transparent. Simply set the create WM_CF_HASTRANS when creating the window. While in WM_PAINT of the window avoid things like

    C Source Code

    1. GUI_SetBkColor(GUI_RED);
    2. GUI_Clear();


    This will overwrite the background and the window won't be transparent any longer.

    Here is a short sample with a transparent window (it has a white frame) which can be dragged around.

    C Source Code

    1. #include "DIALOG.h"
    3. /*********************************************************************
    4. *
    5. * Local code
    6. *
    7. **********************************************************************
    8. */
    10. /*********************************************************************
    11. *
    12. * _cbWin
    13. */
    14. static void _cbWin(WM_MESSAGE * pMsg) {
    15. GUI_RECT Rect;
    17. switch (pMsg->MsgId) {
    18. case WM_PAINT:
    19. WM_GetClientRect(&Rect);
    20. GUI_DrawRectEx(&Rect);
    21. break;
    22. default:
    23. WM_DefaultProc(pMsg);
    24. break;
    25. }
    26. }
    28. /*********************************************************************
    29. *
    30. * _cbBk
    31. */
    32. static void _cbBk(WM_MESSAGE * pMsg) {
    33. int xSize;
    34. int ySize;
    36. switch (pMsg->MsgId) {
    37. case WM_PAINT:
    38. xSize = LCD_GetXSize() - 1;
    39. ySize = LCD_GetYSize() - 1;
    40. GUI_DrawGradientV(0, 0, xSize, ySize, GUI_BLACK, GUI_GRAY);
    41. break;
    42. default:
    43. WM_DefaultProc(pMsg);
    44. break;
    45. }
    46. }
    48. /*********************************************************************
    49. *
    50. * Public code
    51. *
    52. **********************************************************************
    53. */
    54. /*********************************************************************
    55. *
    56. * MainTask
    57. */
    58. void MainTask(void) {
    59. int xSize;
    60. int ySize;
    62. GUI_Init();
    63. WM_MULTIBUF_Enable(1);
    64. WM_MOTION_Enable(1);
    65. WM_SetCallback(WM_HBKWIN, _cbBk);
    66. xSize = LCD_GetXSize();
    67. ySize = LCD_GetYSize();
    68. WM_SetSize(WM_HBKWIN, xSize, ySize);
    69. WM_CreateWindow(20, 20, 100, 100, WM_CF_SHOW | WM_CF_HASTRANS | WM_CF_MOTION_X | WM_CF_MOTION_Y, _cbWin, 0);
    70. while (1) {
    71. GUI_Delay(100);
    72. }
    73. }
    Display All


    Regards,
    Sven
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