path: root/alf/alfcombobox.cpp

#include "alfpriv.h"

// Win32s doesn't like using the original message numbers for custom messages
#define ALF_CB_INSERTSTRING     (ALF_WM__BASE + 200)
#define ALF_CB_ADDSTRING        (ALF_WM__BASE + 201)
#define ALF_CB_GETCURSEL        (ALF_WM__BASE + 202)
#define ALF_CB_SETCURSEL        (ALF_WM__BASE + 203)
#define ALF_CB_GETLBTEXTLEN     (ALF_WM__BASE + 204)
#define ALF_CB_GETLBTEXT        (ALF_WM__BASE + 205)
#define ALF_CB_DELETESTRING     (ALF_WM__BASE + 206)
#define ALF_CB_GETSTYLE         (ALF_WM__BASE + 207)
#define ALF_CB_FINDSTRINGEXACT  (ALF_WM__BASE + 208)

TCHAR *_alf_comboClass = NULL;

typedef struct {
    DWORD  comboStyle;
} ALFComboCreateParams;

typedef struct {
    HWND hwndChild;
    int  dpi;
} ALFComboPriv;

static ALFComboPriv *
ALF_Combo_InitializePriv(HWND hwnd, ALFComboCreateParams *params)
{
    ALFComboPriv *priv = ALF_New(ALFComboPriv, 1);
    priv->dpi = 96;

    DWORD comboStyle = params->comboStyle | CBS_OWNERDRAWFIXED | CBS_HASSTRINGS;

    priv->hwndChild = CreateWindowEx(0,
                                     TEXT("COMBOBOX"),
                                     TEXT(""),
                                     WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_TABSTOP | comboStyle,
                                     0, 0, 100, 200 /* FIXME needed for commctl32 v5, what is the best value here? */,
                                     hwnd,
                                     (HMENU) GetWindowLongPtrW(hwnd, GWLP_ID),
                                     ALF_HINSTANCE,
                                     NULL);

    return priv;
}

static void
ALF_Combo_FreePriv(ALFComboPriv *priv)
{
    ALF_Free(priv);
}

static int
ALF__ComboItemHeight(HWND hwnd)
{
    int height = 0;
    HDC hDc = GetDC(hwnd);
    HFONT font = (HFONT)SendMessage(hwnd, WM_GETFONT, 0, 0);
    HFONT oldfont = SelectFont(hDc, font);

    TEXTMETRIC tm;
    ZeroMemory(&tm, sizeof(tm));

    if (GetTextMetrics(hDc, &tm)) {
        height = tm.tmHeight;
    }

    SelectFont(hDc, oldfont);

    if (!ALF_Compat_IsMinWindowsVersion(4, 0)) {
            // baseline alignment for NT3.x/Win32s
            // ideally, this would only be applied for the ODS_COMOBOXEDIT state,
            // but that state is not sent pre-Win95.
            height += 2;
        }

    ReleaseDC(hwnd, hDc);
    return height;
}

static LRESULT CALLBACK
ALF__ComboWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    ALFComboPriv *priv = (ALFComboPriv *)GetWindowLongPtr(hwnd, 0);

    if (uMsg == WM_CREATE) {
        ALFComboCreateParams *params = (ALFComboCreateParams*)((CREATESTRUCT*)lParam)->lpCreateParams;

        priv = ALF_Combo_InitializePriv(hwnd, params);
        SetWindowLongPtr(hwnd, 0, (LONG_PTR)priv);
    }

    if (uMsg == WM_DESTROY) {
        ALF_Combo_FreePriv(priv);
        priv = NULL;
        SetWindowLongPtr(hwnd, 0, 0);
    }

    if (uMsg == WM_ENABLE && priv) {
        EnableWindow(priv->hwndChild, (BOOL)wParam);
        return 0;
    }
    if (uMsg == WM_SETTEXT && priv) {
        SetWindowText(priv->hwndChild, (TCHAR*)lParam);
        ALF_InvalidateLayout(GetParent(hwnd));
    }
    if (uMsg == WM_GETTEXTLENGTH && priv) {
        return (LRESULT)GetWindowTextLength(priv->hwndChild);
    }
    if (uMsg == WM_GETTEXT && priv) {
        return GetWindowText(priv->hwndChild, (TCHAR*)lParam, (int)wParam);
    }
    if (uMsg == WM_SETFONT && priv) {
        SendMessage(priv->hwndChild, WM_SETFONT, wParam, lParam);
        SendMessage(priv->hwndChild, CB_SETITEMHEIGHT, (WPARAM)0, (LPARAM)ALF__ComboItemHeight(hwnd));

        ALF_InvalidateLayout(GetParent(hwnd));

        return 0;
    }
    if (uMsg == WM_GETFONT && priv) {
        return SendMessage(priv->hwndChild, WM_GETFONT, wParam, lParam);
    }
    if (uMsg == ALF_CB_GETSTYLE && priv) {
        return GetWindowLong(priv->hwndChild, GWL_STYLE);
    }
    if ((uMsg == ALF_CB_FINDSTRINGEXACT || uMsg == CB_FINDSTRINGEXACT) && priv) {
        return SendMessage(priv->hwndChild, CB_FINDSTRINGEXACT, wParam, lParam);
    }
    if ((uMsg == ALF_CB_ADDSTRING || uMsg == CB_ADDSTRING) && priv) {
        return SendMessage(priv->hwndChild, CB_ADDSTRING, wParam, lParam);
    }
    if ((uMsg == ALF_CB_INSERTSTRING || uMsg == CB_INSERTSTRING) && priv) {
        return SendMessage(priv->hwndChild, CB_INSERTSTRING, wParam, lParam);
    }
    if ((uMsg == ALF_CB_DELETESTRING || uMsg == CB_DELETESTRING) && priv) {
        return SendMessage(priv->hwndChild, CB_DELETESTRING, wParam, lParam);
    }
    if ((uMsg == ALF_CB_GETCURSEL || uMsg == CB_GETCURSEL) && priv) {
        return SendMessage(priv->hwndChild, CB_GETCURSEL, wParam, lParam);
    }
    if ((uMsg == ALF_CB_SETCURSEL || uMsg == CB_SETCURSEL) && priv) {
        LRESULT curSel = SendMessage(priv->hwndChild, CB_GETCURSEL, 0, 0);
        if ((WPARAM)curSel != wParam) {
            LRESULT newSel = SendMessage(priv->hwndChild, CB_SETCURSEL, wParam, 0);
            SendMessage(hwnd, WM_COMMAND, MAKEWPARAM(GetWindowLong(priv->hwndChild, GWL_ID), CBN_SELCHANGE), (LPARAM)priv->hwndChild);
            return newSel;
        }
    }
    if ((uMsg == ALF_CB_GETLBTEXTLEN || uMsg == CB_GETLBTEXTLEN) && priv) {
        return SendMessage(priv->hwndChild, CB_GETLBTEXTLEN, wParam, lParam);
    }
    if ((uMsg == ALF_CB_GETLBTEXT || uMsg == CB_GETLBTEXT) && priv) {
        return SendMessage(priv->hwndChild, CB_GETLBTEXT, wParam, lParam);
    }

    if (uMsg == WM_COMMAND && priv && (HWND)lParam == priv->hwndChild) {
        // XXX: for whatever reason, Win95 (and only win95 - doesn't happen on NT)
        // sends a wrong ID value in WPARAM. We fix it by replacing it with our own id.
        return SendMessage(GetParent(hwnd), WM_COMMAND, MAKEWPARAM(GetWindowLong(hwnd, GWL_ID), HIWORD(wParam)), (LPARAM)hwnd);
    }

    if (uMsg == ALF_WM_QUERYSIZE) {
        HDC hDc = GetDC(hwnd);
        HFONT font = (HFONT)SendMessage(hwnd, WM_GETFONT, 0, 0);

        if (font) {
            HFONT oldfont = SelectFont(hDc, font);

            TEXTMETRIC tm;
            ZeroMemory(&tm, sizeof(tm));

            if (GetTextMetrics(hDc, &tm)) {
                SIZE *ps = (SIZE*)lParam;
                int cx = ALF_CentipointsToPixels(12000, priv->dpi);
                int cy = ps->cy = tm.tmHeight + 2*ALF_Compat_GetSystemMetricsForDpi(
                            SM_CYEDGE, (UINT)priv->dpi)
                        + 4 /* padding internal to the edit control */;

                if (ps->cx < cx)
                    ps->cx = cx;

                if (ps->cy < cy)
                    ps->cy = cy;
            }

            SelectFont(hDc, oldfont);
        }

        ReleaseDC(hwnd, hDc);
        return 0;
    }

    if (uMsg == WM_MEASUREITEM) {
        PMEASUREITEMSTRUCT lpmis = (LPMEASUREITEMSTRUCT) lParam;

        lpmis->itemHeight = (UINT)ALF__ComboItemHeight(hwnd);

        return TRUE;
    }

    if (uMsg == WM_DRAWITEM) {
        LPDRAWITEMSTRUCT lpdis = (LPDRAWITEMSTRUCT) lParam;

        if (lpdis->itemID != (UINT)-1) { // Empty item
            DWORD clrForeground = SetTextColor(lpdis->hDC,
                GetSysColor(lpdis->itemState & (ODS_SELECTED | ODS_FOCUS) ?
                COLOR_HIGHLIGHTTEXT : COLOR_WINDOWTEXT));

            DWORD clrBackground = SetBkColor(lpdis->hDC,
                GetSysColor(lpdis->itemState & (ODS_SELECTED | ODS_FOCUS) ?
                COLOR_HIGHLIGHT : COLOR_WINDOW));

            LONG y = lpdis->rcItem.top;
            LONG x = lpdis->rcItem.left;

            if (!ALF_Compat_IsMinWindowsVersion(4, 0)) {
                // baseline alignment for NT3.x/Win32s
                // ideally, this would only be applied for the ODS_COMOBOXEDIT state,
                // but that state is not sent pre-Win95.
                y += 1;
            }

            // add left padding like an edit control
            TEXTMETRIC tm;
            ZeroMemory(&tm, sizeof(tm));
            if (GetTextMetrics(lpdis->hDC, &tm)) {
                if (tm.tmPitchAndFamily & (TMPF_VECTOR | TMPF_TRUETYPE))
                    x += ALF_GetAveCharWidth(lpdis->hDC) / 2;
            }

            // Get and display the text for the list item.
            int len = (int)SendMessage(lpdis->hwndItem, CB_GETLBTEXTLEN, (WPARAM)lpdis->itemID, 0);
            if (len != CB_ERR) {
                TCHAR *buf = (TCHAR*)LocalAlloc(LPTR, (SIZE_T)(len+1) * sizeof(TCHAR));

                SendMessage(lpdis->hwndItem, CB_GETLBTEXT,
                    lpdis->itemID, (LPARAM)buf);

                ExtTextOut(lpdis->hDC, x, y,
                    ETO_CLIPPED | ETO_OPAQUE, &lpdis->rcItem,
                    buf, (UINT)lstrlen(buf), NULL);

                LocalFree(buf);
            }

            // Restore the previous colors.
            SetTextColor(lpdis->hDC, clrForeground);
            SetBkColor(lpdis->hDC, clrBackground);
        }

        // If the item has the focus, draw the focus rectangle.
        if ((lpdis->itemState & ODS_FOCUS) && !(lpdis->itemState & ODS_NOFOCUSRECT))
            DrawFocusRect(lpdis->hDC, &lpdis->rcItem);

        return TRUE;
    }

    if (uMsg == WM_WINDOWPOSCHANGED && priv) {
        WINDOWPOS *pos = (WINDOWPOS *)lParam;
        if (!(pos->flags & SWP_NOSIZE)) {
            // XXX: When resizing the combo box, it will improperly draw a selection.
            // this appears to be a well-known bug that is still not fixed, even in Win10.
            // workaround based on https://stackoverflow.com/questions/49603893/how-to-deal-with-invalidly-painted-combobox-control-in-win32-winapi
            LRESULT sel = SendMessage(priv->hwndChild, CB_GETEDITSEL, 0, 0);
            SendMessage(priv->hwndChild, CB_SETEDITSEL, 0, -1);
            // SWP_NOCOPYBITS because NT 3.51 doesn't properly repaint the drop-down button
            SetWindowPos(priv->hwndChild, NULL, 0, 0, pos->cx, 200, SWP_NOZORDER|SWP_NOACTIVATE|SWP_NOCOPYBITS);
            SendMessage(priv->hwndChild, CB_SETEDITSEL, 0, (LPARAM)sel);

            int heightOffset = 0;
            if (ALF_Compat_IsMinWindowsVersion(4, 0)) {
                heightOffset = - 2*ALF_Compat_GetSystemMetricsForDpi(
                            SM_CYEDGE, (UINT)priv->dpi)
                            - 2;
            }

            SendMessage(priv->hwndChild, CB_SETITEMHEIGHT, (WPARAM)-1, pos->cy + heightOffset);
            SendMessage(priv->hwndChild, CB_SETITEMHEIGHT, (WPARAM)0, (LPARAM)ALF__ComboItemHeight(hwnd));
        }
    }

    if (uMsg == ALF_WM_DPICHANGE && priv) {
        priv->dpi = (int)lParam;
        ALF_InvalidateLayout(GetParent(hwnd));
        return TRUE;
    }

    if (!ALF_Compat_IsMinWindowsVersion(4, 0)) {
        // HACK to draw the space between edit control and button as COLOR_BTNFACE
        if (uMsg == WM_CTLCOLORLISTBOX && priv && !(GetWindowLong(priv->hwndChild, GWL_STYLE) & 1)) {
            return (LRESULT)GetSysColorBrush(COLOR_BTNFACE);
        }
    }

    if (ALF_ShouldMessageBubble(hwnd, uMsg, wParam, lParam)) {
        return SendMessage(GetParent(hwnd), uMsg, wParam, lParam);
    }

    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}


void
ALF_RegisterComboClass(void)
{
    WNDCLASS cls;
    ZeroMemory(&cls, sizeof(cls));

    TCHAR  classNameBuf[256];
    ALF_BuildUniqueName(classNameBuf, TEXT("ALFComboBox."), (ULONG_PTR)&_alf_comboClass);

    cls.hInstance = ALF_HINSTANCE;
    cls.hCursor = LoadCursor(NULL, (LPTSTR)IDC_ARROW);
    cls.hbrBackground = (HBRUSH)(COLOR_BTNFACE+1);
    cls.lpszClassName = classNameBuf;
    cls.cbWndExtra = sizeof(void*);
    cls.lpfnWndProc = ALF__ComboWindowProc;

    ATOM classatom = RegisterClass(&cls);
    if (!classatom)
        MessageBox(NULL, TEXT("FATAL: Could not register Combo class"), NULL, MB_OK);

    _alf_comboClass = MAKEINTATOM(classatom);
}

static HWND
ALF_InternalAddComboBox(HWND win, WORD id, int x, int y, DWORD style, const TCHAR *defaultText)
{
    ALFComboCreateParams cp;
    cp.comboStyle = style;

    HWND hwndCombo = CreateWindowEx(WS_EX_CONTROLPARENT,
                                    _alf_comboClass,
                                    TEXT(""),
                                    WS_CHILD | WS_VISIBLE | WS_CLIPCHILDREN,
                                    0, 0, 0, 0,
                                    win,
                                    (HMENU)(ULONG_PTR)id,
                                    ALF_HINSTANCE,
                                    &cp);

    if (defaultText)
        SetWindowText(hwndCombo, defaultText);

    ALF_AddWidget(win, x, y, hwndCombo, 0, 0, ALF_LAYOUT_SIZE_QUERY | ALF_LAYOUT_INHERITFONT | ALF_LAYOUT_SENDDPICHANGE);

    return hwndCombo;
}

HWND
ALF_AddEditableComboBox(HWND win, WORD id, int x, int y, const TCHAR *defaultText)
{
    return ALF_InternalAddComboBox(win, id, x, y, CBS_DROPDOWN, defaultText);
}

HWND
ALF_AddSelectionOnlyComboBox(HWND win, WORD id, int x, int y)
{
    return ALF_InternalAddComboBox(win, id, x, y, CBS_DROPDOWNLIST, NULL);
}

int /* index */
ALF_ComboBoxAddString(HWND combo, const TCHAR *text)
{
    return (int)SendMessage(combo, ALF_CB_ADDSTRING, 0, (LPARAM)text);
}

TCHAR *
ALF_ComboBoxCurrentText(HWND combo)
{
    LRESULT style = SendMessage(combo, ALF_CB_GETSTYLE, 0, 0);
    if (style & CBS_DROPDOWNLIST) {
        int i = ALF_ComboBoxCurrentIndex(combo);
        if (i >= 0) {
            return ALF_ComboBoxStringForIndex(combo, i);
        }
    }

    return ALF_Text(combo);
}

void
ALF_ComboBoxSetText(HWND combo, const TCHAR *text)
{
    LRESULT index = SendMessage(combo, ALF_CB_FINDSTRINGEXACT, (WPARAM)-1, (LPARAM)text);
    if (index >= 0) {
        SendMessage(combo, ALF_CB_SETCURSEL, (WPARAM)index, 0);
    } else {
        SetWindowText(combo, text);
    }
}

int
ALF_ComboBoxCurrentIndex(HWND combo)
{
    return (int)SendMessage(combo, ALF_CB_GETCURSEL, 0, 0);
}

void
ALF_ComboBoxSetCurrentIndex(HWND combo, int index)
{
    SendMessage(combo, ALF_CB_SETCURSEL, (WPARAM)index, 0);
}

TCHAR * // free with ALF_Free
ALF_ComboBoxStringForIndex(HWND combo, int index)
{
    int len = (int)SendMessage(combo, ALF_CB_GETLBTEXTLEN, (WPARAM)index, 0);
    if (len > 0) {
        TCHAR* buf = ALF_New(TCHAR, (SIZE_T)len + 1);
        if (SendMessage(combo, ALF_CB_GETLBTEXT, (WPARAM)index, (LPARAM)buf)) {
            return buf;
        } else {
            ALF_Free(buf);
        }
    }

    return NULL;
}

void
ALF_ComboBoxInsertString(HWND combo, int index, const TCHAR *text)
{
    SendMessage(combo, ALF_CB_INSERTSTRING, (WPARAM)index, (LPARAM)text);
}

void
ALF_ComboBoxRemoveString(HWND combo, int index)
{
    SendMessage(combo, ALF_CB_DELETESTRING, (WPARAM)index, 0);
}