# Independent Scrollbar Control

* [Definition of independent scrollbar](#definition-of-independent-scrollbar)
* [Types of Scrollbar](#types-of-scrollbar)
* [Styles of Independent Scrollbar](#styles-of-independent-scrollbar)
* [Messages of Independent Scrollbar](#messages-of-independent-scrollbar)
  * [Get Scrollbar Information](#get-scrollbar-information)
  * [Set Information of Scrollbar](#set-information-of-scrollbar)
  * [Get Current Position of Thumb](#get-current-position-of-thumb)
  * [Set The Position of Thumb](#set-the-position-of-thumb)
  * [Get Scroll Range of Scrollbar](#get-scroll-range-of-scrollbar)
  * [Set Scroll Range of Scrollbar](#set-scroll-range-of-scrollbar)
  * [Set Scroll Range of Scrollbar and Redraw Immediately](#set-scroll-range-of-scrollbar-and-redraw-immediately)
  * [Enable or Disable Arrow](#enable-or-disable-arrow)
* [Configurable Properties of Scrollbar](#configurable-properties-of-scrollbar)
* [Notification Codes of Scrollbar](#notification-codes-of-scrollbar)
  * [Trigger of Notification Message](#trigger-of-notification-message)
* [Sample Program](#sample-program)

## Definition of independent scrollbar

Arrow, shaft and thumb are the components of scrollbar control. Some scrollbars don't have arrow, and some don't have shaft and thumb, as shown in Figure 1.

![alt](https://3533682497-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F95Qe4b8fOBT2JZL5WDlF%2Fuploads%2Fgit-blob-6d10cca667ebbd87e5989b272b84285487ee382c%2Fscrollbar_specific.gif?alt=media)

**Figure 1** Scrollbar structure

Scrollbar is rectangular, it sends message to parent window when mouse clicks on it, and parent window will refresh the content of window and the position of thumb. It also sends message to parent window and do refresh when mouse clicks on arrow.

## Types of Scrollbar

There are two kinds of scrollbar:

* A part of main window or other controls, application specifies the scrollbar is horizontal or vertical by changing the style, `WS_HSCROLL` or `WS_VSCROLL`. Main window or other controls can have both of these styles.
* Independent scrollbar, class name is `CTRL_SCROLLBAR`. Application specifies the scrollbar is horizontal or vertical by selecting `SBS_HORZ` or `SBS_VERT` when it is creating scrollbar control. It can only chose one of the styles.

The first one is not the topic of this chapter, but it is closely connected independent scrollbar, so we mentioned it.

## Styles of Independent Scrollbar

Independent scrollbar has the following styles:

**Table 1** The styles of independent scrollbar

| _Style Identifier_    | _Meaning_                                                                                                                                                                   |
| --------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `SBS_HORZ`            | Create a horizontal scrollbar. The range of scrollbar is decided by the arguments (x, y, w, h) of `CreateWindowEx2` when don't specify `SBS_BOTTOMALIGN` or `SBS_TOPALIGN`. |
| `SBS_VERT`            | Create a vertical scrollbar. The range of scrollbar is decided by the arguments (x, y, w, h) of `CreateWindowEx2` when don't specify `SBS_LEFTALIGN` or `SBS_RIGHTALIGN`.   |
| `SBS_BOTTOMALIGN`     | Be used with `SBS_HORZ`. Put horizontal scrollbar on the bottom of the range which is specified by `CreateWindowEx2`.                                                       |
| `SBS_TOPALIGN`        | Be used with `SBS_HORZ`. Put horizontal scrollbar on the top of the range which is specified by `CreateWindowEx2`.                                                          |
| `SBS_LEFTALIGN`       | Be used with `SBS_VERT`. Put vertical scrollbar on the left of the range which is specified by `CreateWindowEx2`.                                                           |
| `SBS_RIGHTALIGN`      | Be used with `SBS_VERT`. Put vertical scrollbar on the right of the range which is specified by `CreateWindowEx2`.                                                          |
| `SBS_NOARROWS`        | No arrow, can't be used with `SBS_NOSHAFT`                                                                                                                                  |
| `SBS_NOSHAFT`         | No shaft, can't be used with `SBS_NOARROWS`                                                                                                                                 |
| `SBS_FIXEDBARLEN`     | Thumb of horizontal or vertical scrollbar is fixed length                                                                                                                   |
| `SBS_NOTNOTIFYPARENT` | Send message to parent window, not notification code. It sends notification code in default                                                                                 |

## Messages of Independent Scrollbar

Application can send following messages to scrollbar control:

* Get/set data information of scrollbar: `SBM_GETSCROLLINFO`, `SBM_SETSCROLLINFO`
* Get /set current position of thumb: `SBM_GETPOS`, `SBM_SETPOS`
* Get/set scroll range: `SBM_GETRANGE`, `SBM_SETRANGE`
* Get/set scroll range and redraw immediately: `SBM_SETRANGEREDRAW`
* Enable/disable arrow: `SBM_ENABLE_ARROW`

### Get Scrollbar Information

Application can get scrollbar's information (max/min value, pages of scrollbar and current position) by sending `SBM_GETSCROLLINFO` and `wParam` argument which is `SCROLLINFO` \* pointer to scrollbar. The information is stored in the memory pointed by `wParam`.

```cpp
/*
* Scroll bar information structure.
*/
typedef struct _SCROLLINFO
{
        /** Size of the structrue in bytes */
        UINT    cbSize;
        /**
        * A flag indicates which fields contain valid values,
        * can be OR'ed value of the following values:
        *      - SIF_RANGE\n
        *        Retrives or sets the range of the scroll bar.
        *      - SIF_PAGE\n
        *        Retrives or sets the page size of the scroll bar.
        *      - SIF_POS\n
        *        Retrives or sets the position of the scroll bar.
        *      - SIF_DISABLENOSCROLL\n
        *        Hides the scroll when disabled, not implemented so far.
        */
        UINT    fMask;
        /** The minimum position value of the scroll bar */
        int     nMin;
        /** The maximum position value of the scroll bar */
        int     nMax;
        /** The page size of the scroll bar */
        UINT    nPage;
        /** The position value of the scroll bar */
        int     nPos;
} SCROLLINFO, *PSCROLLINFO;
```

The field `fMask` in `SBM_GETSCROLLINFO` structure specifies the information which can be got by sending `SBM_GETSCROLLINFO` message, `fMask's` value can be:

**Table 2** The mask identifiers

\| _Information Identifier_ | _Meaning_ | | `SIF_RANGE` | Get values range of scrollbar | | `SIF_PAGE` | Get the pages of scrollbar | | `SIF_POS` | Get scrollbar's current position | | `SIF_ALL` | Get all information |

The following codes can get all information of scrollbar

```cpp
SCROLLINFO scinfo = {0};
scinfo.fMask = SIF_ALL;
SendMessage (hwnd_scrollbar, SBM_GETSCROLLINFO, (wParam)&scinfo,  0);
```

### Set Information of Scrollbar

We can send `SBM_SETSCROLLINFO` to scrollbar control to set information of scrollbar. `wParam` is a pointer of `SCROLLINFO` structure, it stores the scrollbar information which needs to be stored. `IParam` is used to determine to (`TRUE`) or not to (`FALSE`) redraw immediately.

The following sample is setting scrollbar's information and not redrawing immediately:

```cpp
SCROLLINFO scinfo = {0};
scinfo.fMask = SIF_ALL;
scinfo.nMin = 0;
scinfo.nMax = 10;
scinfo.nPage = 2;
scinfo.nPos = 0;
BOOL redraw = FALSE;
SendMessage (hwnd_scrollbar, SBM_SETCROLLINFO, (wParam)&scinfo,  redraw);
```

### Get Current Position of Thumb

We can send `SBM_GETPOS` message to scrollbar to get current position of thumb. Example is as follow:

```cpp
int pos = SendMessage (hwnd_scrollbar, SBM_GETPOS, 0, 0);
```

### Set The Position of Thumb

We can send `SBM_SETPOS` message to scrollbar to set position of thumb. Target position is stored in `wParam`. `IParam` is used to determine to (`TRUE`) or not to (`FALSE`) redraw immediately.

```cpp
int pos = 10;
SendMessage (hwnd_scrollbar, SBM_SETPOS, pos, TRUE);
```

### Get Scroll Range of Scrollbar

We can send `SBM_GETRANGE` message to get the scroll range of scrollbar. `wParam` stores min range and `IParam` stores max range.

```cpp
int min, max;
SendMessage (hwnd_scrollbar, SBM_GETRANGE, &min, &max);
```

### Set Scroll Range of Scrollbar

We can send `SBM_SETRANGE` message to set the scroll range of scrollbar. `wParam/IParam` is min/max range to set. This message will not redraw scrollbar immediately.

The following codes set the scroll range of scroll bar from 0 to 100. But you can only see the change after other message or event redraws UI.

```cpp
SendMessage (hwnd_scrollbar, SBM_SETRANGE, 0, 100);
```

### Set Scroll Range of Scrollbar and Redraw Immediately

We can send `SBM_SETRANGEREDRAW` message if we want to redraw scrollbar immediately after set the scroll range. `wParam/IParam` is min/max range to set.

The following codes set the scroll range of scroll bar from 0 to 100 and redraw immediately.

```cpp
SendMessage (hwnd_scrollbar, SBM_SETRANGEREDRAW, 0, 100);
```

### Enable or Disable Arrow

Sending `SBM_ENABLE_ARROW` message can enable or disable arrow. Disable means the scrollbar can't scroll to the direction which is specified by disabled arrow. Arrow is enabled (disabled) when `IParam` is `TRUE` (FALSE). `wParam's` value is as follow:

**Table 3** The arrow identifiers

| _Arrow Identifier_ | _Meaning_                                                                       |
| ------------------ | ------------------------------------------------------------------------------- |
| `SB_ARROW_LTUP`    | Left arrow key of horizontal scrollbar or up arrow key of vertical scrollbar    |
| `SB_ARROW_BTDN`    | Right arrow key of horizontal scrollbar or down arrow key of vertical scrollbar |
| `SB_ARROW_BOTH`    | All arrow keys                                                                  |

The following codes disable all arrows of scrollbar:

```cpp
SendMessage (hwnd_scrollbar, SBM_ENABLE_ARROW, SB_ARROW_BOTH, FALSE);
```

## Configurable Properties of Scrollbar

The following properties of scrollbar can be set by `GetWindowElementAttr`, `SetWindowElementAttr`, `GetWindowElementPixelEx` and `SetWindowElementPixelEx` functions in the following table.

**Table 4** Notification codes table

\| _Property Identifier_ | _Meaning_ | | `WE_MAINC_THREED_BODY` | Draw the colors of shaft and thumb | | `WE_FGC_THREED_BODY` | Draw the color of arrow | | `WE_FGC_DISABLED_ITEM` | Draw the color of disabled arrow | | `WE_METRICS_SCROLLBAR` | The size of scrollbar, that is, the height of horizontal scrollbar or the width of vertical scrollbar |

The following codes is an example for above properties:

```cpp
    DWORD color_3d, fgc_3d, fgc_dis;
    gal_pixel old_brush_color;

    //Get color value for each part of scrollbar
    color_3d = GetWindowElementAttr(hWnd, WE_MAINC_THREED_BODY);
    fgc_3d = GetWindowElementAttr(hWnd, WE_FGC_THREED_BODY);
    fgc_dis = GetWindowElementAttr(hWnd, WE_FGC_DISABLED_ITEM);

    //Draw shaft of scrollbar
    old_brush_color = SetBrushColor(hdc,
                           RGBA2Pixel(hdc,GetRValue(color_3d),
                               GetGValue(color_3d), GetBValue(color_3d),
                               GetAValue(color_3d)));
     FillBox(hdc, rect.left, rect.top, RECTW(rect), RECTH(rect));
     SetBrushColor(hdc, old_brush_color);

     //Draw arrow of scrollbar
     draw_3dbox(hdc, &rect, color_3d,
                        bn_status | LFRDR_3DBOX_THICKFRAME | LFRDR_3DBOX_FILLED);

     if(sb_status & SBS_DISABLED_LTUP || sb_status & SBS_DISABLED)
           draw_arrow(hWnd, hdc, &rect, fgc_dis, LFRDR_ARROW_LEFT);
      else
           draw_arrow(hWnd, hdc, &rect, fgc_3d, LFRDR_ARROW_LEFT);
```

## Notification Codes of Scrollbar

All notification codes of scrollbar are in the following table:

**Table 5** Notification codes table

| _Notification Code Identifier_ | _Meaning_                                                                                                                          |
| ------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------- |
| `SB_LINEUP`                    | Vertical scrollbar scrolls up one line                                                                                             |
| `SB_LINEDOWN`                  | Vertical scrollbar scrolls down one line                                                                                           |
| `SB_PAGEUP`                    | Vertical scrollbar scrolls up one page                                                                                             |
| `SB_PAGEDOWN`                  | Vertical scrollbar scrolls down one page                                                                                           |
| `SB_LINELEFT`                  | Horizontal scrollbar scrolls left one column                                                                                       |
| `SB_LINERIGHT`                 | Horizontal scrollbar scrolls right one column                                                                                      |
| `SB_PAGELEFT`                  | Horizontal scrollbar scrolls left one page                                                                                         |
| `SB_PAGERIGHT`                 | Horizontal scrollbar scrolls right one page                                                                                        |
| `SB_THUMBPOSITION`             | Send the position of thumb to parent window by this notification code when mouse left button presses, drags and releases thumb     |
| `SB_THUMBTRACK`                | Keep sending the position of thumb to parent window by this notification code when mouse button is pressing and dragging the thumb |
| `SB_TOP`                       | Thumb arrives at left-most (top-most) of horizontal (vertical) scrollbar, that is, get the min value of scrollbar                  |
| `SB_BOTTOM`                    | Thumb arrives at right-most (bottom) of horizontal (vertical) scrollbar, that is, get the max value of scrollbar                   |

* After scrollbar specifies `SBS_NOTNOTIFYPARENT` style, parent window of horizontal (vertical) scrollbar will receive `MSG_HSCROLL` (`MSG_VSCROLL`) message. `wParam` is notification id, `IParam` is current position of thumb, `curPos`, when id is `SB_THUMBPOSITION` or `SB_THUMBTRACK`. In other cases, `IParam` doesn't have meaning.
* When scrollbar doesn't specify `SBS_NOTNOTIFYPARENT` style, parent window of scrollbar will receive notification code. `wParam` includes control ID and notification code. When notification code is `SB_THUMBPOSITION` or `SB_THUMBTRACK`, parent window can get current position of thumb, `curPos`, by sending `SBM_GETPOS`. Of course, the control doesn't send `MSG_COMMAND` to parent window if you have invoked `SetNotificationCallback` function to set callback function of scrollbar control, it invokes given callback function directly.

### Trigger of Notification Message

Scrollbar can receive events of mouse and keyboard and trigger different notification message accroding to different situations.

* It triggers different notification message when mouse clicks different part of scrollbar. It is important to note, when dragging thumb by using mouse left button, scrollbar keeps sending `SB_THUMBTRACK` message, and it sends `SB_THUMBPOSITION` after mouse left button is released. The messages which are triggered by the part of scrollbar are as follow:

![alt](https://3533682497-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F95Qe4b8fOBT2JZL5WDlF%2Fuploads%2Fgit-blob-6a88a62eff9d16a40abfc85345ff0ddf2b0c7917%2Fscrollbar_notif.gif?alt=media)

**Figure 2** notification messages which are triggered by mouse

* The key of keyboard triggers corresponding notification message, see the following table:

**Table 6** Notification Code table

| _Key_        | _Notification Code_                                                               |
| ------------ | --------------------------------------------------------------------------------- |
| `PAGEUP`     | Horizontal scrollbar sends `SB_PAGELEFT`; Vertical scrollbar sends `SB_PAGEUP`    |
| `PAGEDOWN`   | Horizontal scrollbar sends `SB_PAGERIGHT` ；Vertical scrollbar sends `SB_PAGEDOWN` |
| `UpArrow`    | Vertical scrollbar sends `SB_LINEUP`                                              |
| `LeftArrow`  | Horizontal scrollbar sends `SB_LINELEFT`                                          |
| `DownArrow`  | Vertical scrollbar sends `SB_LINEDOWN`                                            |
| `RightArrow` | Horizontal scrollbar sends `SB_LINERIGHT`                                         |

## Sample Program

The following codes show how to create scrollbar with multiple styles. By operating mouse or keyboard, you can do many operations on scrollbar, for example, clicking, dragging and so on. To make the demo more vivid, we put a circle and a box on right of the window. The circle will become larger or smaller and the box will moved up or down, just follow scrollbar's control. Figure 3 is the screenshot, the codes are from `scrollbar_ctrl.c` in mg-samples, please see this file for full codes.

**List 1** Scrollbar sample codes

```cpp
#include <stdio.h>
#include <string.h>

#include <minigui/common.h>
#include <minigui/minigui.h>
#include <minigui/gdi.h>
#include <minigui/window.h>
#include <minigui/control.h>

#ifdef _LANG_ZHCN
#include "scrollbar_ctrl_res_cn.h"
#elif defined _LANG_ZHTW
#include "scrollbar_ctrl_res_tw.h"
#else
#include "scrollbar_ctrl_res_en.h"
#endif

/** define scrollbar data */
#define SB_MAX 20
#define SB_MIN 0
#define SB_PAGE 6

/** define circle data */
#define CC_CENTER_X    400
#define CC_CENTER_Y    100
#define CC_RADIUS_MAX   50
#define CC_RADIUS_MIN   0

/** define box data */
#define BOX_WIDTH   40
#define BOX_HEIGHT  20
#define BOX_Y_MAX   300
#define BOX_Y_MIN   200

/** x position of separator */
#define SEP   300

/** radius of circle */
int _radius;

/** y position of box */
int _box_pos_y;

/** invalidate rect */
RECT _rect_invalid;

static int ScrollbarProc(HWND hwnd, int message, WPARAM wParam, LPARAM lParam)
{
    /** IDC of SCROLLBAR control */
    static int _my_scroll_idc = 100;

    /** scrollbar handle of main window  */
    static HWND hwnd_sb_main;

    /** scrollbar handle of control */
    HWND hwnd_sb_ctrl;

    switch (message)
    {
        case MSG_CREATE:
            {
                _rect_invalid.left   = SEP;
                _rect_invalid.top    = 0;
                _rect_invalid.right  = g_rcScr.right;
                _rect_invalid.bottom = g_rcScr.bottom;

                SCROLLINFO scinfo = {0};
                scinfo.fMask = SIF_ALL;
                scinfo.nMin = SB_MIN;
                scinfo.nMax = SB_MAX;
                scinfo.nPage = SB_PAGE;
                scinfo.nPos = SB_MIN;

                calc_circle_pos (scinfo.nPos);
                calc_box_pos (scinfo.nPos);

                /** classic VSCROLL with SBS_NOTNOTIFYPARENT */

                hwnd_sb_main = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE |
                        SBS_VERT | SBS_LEFTALIGN
                        | SBS_NOTNOTIFYPARENT
                       ,
                        0,
                        ++_my_scroll_idc,
                        20, 50, 20, 150, hwnd,
                        "classic", 0,
                        0);

                SendMessage (hwnd_sb_main, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_main, MSG_SETFOCUS, 0, 0);

                /** flat VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE |
                        SBS_VERT | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        43, 50, 20, 150, hwnd,
                        "flat", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** fashion VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE |
                        SBS_VERT | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        66, 50, 20, 150, hwnd,
                        "fashion", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** tiny VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE |
                        SBS_VERT | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        92, 50, 20, 150, hwnd,
                        "tiny", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** classic NOSHAFT VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_VERT | SBS_NOSHAFT | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        120, 50, 20, 34, hwnd,
                        "classic", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** flat NOSHAFT VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_VERT | SBS_NOSHAFT | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        140, 50, 20, 34, hwnd,
                        "flat", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** fashion NOSHAFT VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_VERT | SBS_NOSHAFT | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        160, 50, 20, 34, hwnd,
                        "fashion", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** tiny NOSHAFT VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_VERT | SBS_NOSHAFT | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        184, 50, 20, 34, hwnd,
                        "tiny", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** classic NOARROW VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_VERT | SBS_NOARROW | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        210, 50, 20, 150, hwnd,
                        "classic", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** flat NOARROW VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_VERT | SBS_NOARROW | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        232, 50, 20, 150, hwnd,
                        "flat", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** fashion NOARROW VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_VERT | SBS_NOARROW | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        254, 50, 20, 150, hwnd,
                        "fashion", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** tiny NOARROW VSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_VERT | SBS_NOARROW | SBS_LEFTALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        276, 50, 20, 150, hwnd,
                        "tiny", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** classic HSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_HORZ
                        | SBS_TOPALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        20, 220, 150, 20, hwnd,
                        "classic", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** flat HSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_HORZ
                        | SBS_TOPALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        20, 240, 150, 20, hwnd,
                        "flat", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** fashion HSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_HORZ
                        | SBS_TOPALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        20, 260, 150, 20, hwnd,
                        "fashion", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);

                /** tiny HSCROLL */

                hwnd_sb_ctrl = CreateWindowEx2 (CTRL_SCROLLBAR, "",
                        WS_VISIBLE | SBS_HORZ
                        | SBS_TOPALIGN
                       ,
                        0,
                        ++_my_scroll_idc,
                        20, 280, 150, 20, hwnd,
                        "tiny", 0,
                        0);

                SendMessage (hwnd_sb_ctrl, SBM_SETSCROLLINFO, (WPARAM)&scinfo, TRUE);
                SendMessage (hwnd_sb_ctrl, MSG_SETFOCUS, 0, 0);
            }
            break;

        case MSG_COMMAND:
            {
                int code = HIWORD(wParam);
                HWND scroll = (HWND)lParam;
                int pos = 0;

                switch (code)
                {
                    case SB_LINELEFT:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);

                            SendMessage (scroll, SBM_SETPOS, --pos, TRUE);
                        }

                        break;

                    case SB_LINERIGHT:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);

                            SendMessage (scroll, SBM_SETPOS, ++pos, TRUE);
                        }
                        break;

                    case SB_PAGELEFT:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);

                            pos -= SB_PAGE;
                            SendMessage (scroll, SBM_SETPOS, pos, TRUE);
                        }
                        break;

                    case SB_PAGERIGHT:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);

                            pos += SB_PAGE;
                            SendMessage (scroll, SBM_SETPOS, pos, TRUE);
                        }
                        break;

                    case SB_LINEUP:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);

                            SendMessage (scroll, SBM_SETPOS, --pos, TRUE);
                        }

                        break;

                    case SB_LINEDOWN:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);

                            SendMessage (scroll, SBM_SETPOS, ++pos, TRUE);
                        }
                        break;

                    case SB_PAGEUP:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);

                            pos -= SB_PAGE;
                            SendMessage (scroll, SBM_SETPOS, pos, TRUE);
                        }
                        break;

                    case SB_PAGEDOWN:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);

                            pos += SB_PAGE;
                            SendMessage (scroll, SBM_SETPOS, pos, TRUE);
                        }
                        break;

                    case SB_THUMBPOSITION:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);
                        }
                        break;

                    case SB_THUMBTRACK:
                        {
                            pos = SendMessage (scroll, SBM_GETPOS, 0, 0);
                        }
                        break;

                    case SB_TOP:
                        {
                            pos = SB_MIN;
                        }
                        break;

                    case SB_BOTTOM:
                        {
                            pos = SB_MAX;
                        }
                        break;

                    default:
                        break;
                }

                draw_shape (hwnd, pos);
            }
            break;

        case MSG_HSCROLL:
            {
                int pos = 0;
                switch (wParam)
                {
                    case SB_LINELEFT:
                        {
                            pos = SendMessage (hwnd_sb_main, SBM_GETPOS, 0, 0);

                            SendMessage (hwnd_sb_main, SBM_SETPOS, --pos, TRUE);
                        }

                        break;

                    case SB_LINERIGHT:
                        {
                            pos = SendMessage (hwnd_sb_main, SBM_GETPOS, 0, 0);

                            SendMessage (hwnd_sb_main, SBM_SETPOS, ++pos, TRUE);
                        }
                        break;

                    case SB_PAGELEFT:
                        {
                            pos = SendMessage (hwnd_sb_main, SBM_GETPOS, 0, 0);

                            pos -= SB_PAGE;
                            SendMessage (hwnd_sb_main, SBM_SETPOS, pos, TRUE);
                        }
                        break;

                    case SB_PAGERIGHT:
                        {
                            pos = SendMessage (hwnd_sb_main, SBM_GETPOS, 0, 0);

                            pos += SB_PAGE;
                            SendMessage (hwnd_sb_main, SBM_SETPOS, pos, TRUE);
                        }
                        break;
                    case SB_THUMBPOSITION:
                        {
                            pos = (int)lParam;
                        }
                        break;

                    case SB_THUMBTRACK:
                        {
                            pos = (int)lParam;
                        }
                        break;

                    case SB_TOP:
                        {
                            pos = SB_MIN;
                        }
                        break;

                    case SB_BOTTOM:
                        {
                            pos = SB_MAX;
                        }
                        break;

                    default:
                        break;
                }
                draw_shape (hwnd, pos);
            }
            break;

        case MSG_VSCROLL:
            {
                int pos = 0;
                switch (wParam)
                {
                    case SB_LINEUP:
                        {
                            pos = SendMessage (hwnd_sb_main, SBM_GETPOS, 0, 0);

                            SendMessage (hwnd_sb_main, SBM_SETPOS, --pos, TRUE);

                        }

                        break;

                    case SB_LINEDOWN:
                        {
                            pos = SendMessage (hwnd_sb_main, SBM_GETPOS, 0, 0);

                            SendMessage (hwnd_sb_main, SBM_SETPOS, ++pos, TRUE);
                        }
                        break;

                    case SB_PAGEUP:
                        {
                            pos = SendMessage (hwnd_sb_main, SBM_GETPOS, 0, 0);

                            pos -= SB_PAGE;
                            SendMessage (hwnd_sb_main, SBM_SETPOS, pos, TRUE);
                        }
                        break;

                    case SB_PAGEDOWN:
                        {
                            pos = SendMessage (hwnd_sb_main, SBM_GETPOS, 0, 0);

                            pos += SB_PAGE;
                            SendMessage (hwnd_sb_main, SBM_SETPOS, pos, TRUE);
                        }
                        break;
                    case SB_THUMBPOSITION:
                        {
                            pos = (int)lParam;
                        }
                        break;

                    case SB_THUMBTRACK:
                        {
                            pos = (int)lParam;
                        }
                        break;

                    case SB_TOP:
                        {
                            pos = SB_MIN;
                        }
                        break;

                    case SB_BOTTOM:
                        {
                            pos = SB_MAX;
                        }
                        break;
                    default:
                        break;
                }
                draw_shape (hwnd, pos);
            }
            break;

        case MSG_PAINT:
            {
                HDC hdc = BeginPaint(hwnd);

                /** separator */
                MoveTo (hdc, SEP, 0);
                LineTo (hdc, SEP, g_rcScr.bottom);

                /** circle */
                Circle (hdc, CC_CENTER_X, CC_CENTER_Y, _radius);

                /** top and bottom line of box */
                MoveTo (hdc, SEP + 20, BOX_Y_MIN);
                LineTo (hdc, SEP + 20 + BOX_WIDTH + 40, BOX_Y_MIN);

                MoveTo (hdc, SEP + 20, BOX_Y_MAX);
                LineTo (hdc, SEP + 20 + BOX_WIDTH + 40, BOX_Y_MAX);

                /** box */
                SetBrushColor (hdc, PIXEL_black);
                FillBox (hdc, SEP + 40, _box_pos_y, BOX_WIDTH, BOX_HEIGHT);

                EndPaint (hwnd, hdc);
            }
            break;

        case MSG_CLOSE:
            {
                DestroyMainWindow (hwnd);
                PostQuitMessage (hwnd);
                return 0;
            }
    }

    return DefaultMainWinProc(hwnd, message, wParam, lParam);
}

int MiniGUIMain (int argc, const char* argv[])
{
    MSG Msg;
    HWND hMainWnd;
    MAINWINCREATE CreateInfo;

#ifdef _MGRM_PROCESSES
    JoinLayer(NAME_DEF_LAYER , "scrollbar" , 0 , 0);
#endif

    CreateInfo.dwStyle = WS_VISIBLE | WS_BORDER | WS_CAPTION;
    CreateInfo.dwExStyle = WS_EX_NONE;
    CreateInfo.spCaption = SCB_ST_CAP;
    CreateInfo.hMenu = 0;
    CreateInfo.hCursor = GetSystemCursor(0);
    CreateInfo.hIcon = 0;
    CreateInfo.MainWindowProc = ScrollbarProc;
    CreateInfo.lx = 0;
    CreateInfo.ty = 0;
    CreateInfo.rx = g_rcScr.right;
    CreateInfo.by = g_rcScr.bottom;
    CreateInfo.iBkColor = COLOR_lightwhite;
    CreateInfo.dwAddData = 0;
    CreateInfo.hHosting = HWND_DESKTOP;

    hMainWnd = CreateMainWindowEx (&CreateInfo, "flat", 0, 0, 0);

    if (hMainWnd == HWND_INVALID)
    {
        return -1;
    }

    ShowWindow(hMainWnd, SW_SHOWNORMAL);

    while (GetMessage(&Msg, hMainWnd)) {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }

    MainWindowThreadCleanup (hMainWnd);

    return 0;
}

#ifdef _MGRM_THREADS
#include <minigui/dti.c>
#endif
```

![alt](https://3533682497-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F95Qe4b8fOBT2JZL5WDlF%2Fuploads%2Fgit-blob-b1b09a3ce89a9ede2563ad95467206339d20ee62%2Fscrollbar_sample.png?alt=media)

**Figure 3** Scrollbar control

***

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