RichTextbox控件如何根据自身宽、高，以及用户设定的字体、字号和行距，计算1屏有几行？1行有几列？

CLEAR
CLEAR ALL

PUBLIC cDefPath
cDefPath = ADDBS(JUSTPATH(SYS(16)))
SET DEFAULT TO (cDefPath)

**    int GetRichEditCharsW(HWND hRichEdit, LPCWSTR text, char* cFontName, int nFontSize)
DECLARE integer GetRichEditCharsW IN TextMetric long,string@,string@,integer

**    int SetRichEditLineHeight(HWND hRichEdit, int nPixels)
DECLARE integer SetRichEditLineHeight IN TextMetric long,integer

**    int GetRichEditLineCount(HWND hRichEdit, char* pFontName, int nFontSize)
DECLARE integer GetRichEditLineCount IN TextMetric long,string@,integer

of = CREATEOBJECT("form1")
of.show(1)
CLEAR ALL
RETURN

DEFINE CLASS form1 as Form
    width       = 420
    height      = 420
    AllowOutput = .f.
    AutoCenter  = .t.
    ADD OBJECT edit as OleControl WITH left=10,top=10,width=400,height=400,;
        OleClass="RICHTEXT.RichtextCtrl.1"
   
    PROCEDURE init
        #if 1
            this.edit.font.name = "宋体"   
        #else
            this.edit.font.name = "微软雅黑"
        #endif
        this.edit.font.size = 12
        
        ** 行高 = 字高 + 行间距
        nLineHeight = FONTMETRIC(1,this.edit.font.name, MTON(this.edit.font.size)) + 5
        SetRichEditLineHeight(this.edit.hWnd, nLineHeight)    && 设置行高
        
        ** 获取总行数

        nLineCount = GetRichEditLineCount(this.edit.hWnd, this.edit.font.name, MTON(this.edit.font.size))

        this.Caption = "    FontName: "+this.edit.font.name;
                     + "    FontSize: "+TRANSFORM(MTON(this.edit.font.size));
                     + "    LineCount: "+TRANSFORM(nLineCount)

        ** 显示一页字（测试只显示一页）
        cText = REPLICATE("AaBbCcDdEeFfGgHhIiJjKk字字字字1234567890",100)
        cStr = ""    && 一页字串
        nCount = 0   && 行计数
        DO WHILE !EMPTY(cText) AND nCount < nLineCount
            ** 获取一行字串
            nChars = GetRichEditCharsW(this.edit.hWnd, STRCONV(cText,5), this.edit.font.name, MTON(this.edit.font.size))
            IF nChars < LENC(cText)    && 如果不是最后一行
                nChars = nChars - 1    && 减一个字，忽略边际不完整的字
            ENDIF
            cStr  = cStr + LEFTC(cText,nChars) + 0h0D0A && 添加一行
            cText = SUBSTRC(cText, nChars+1)            && 下一行开始
            nCount = nCount + 1                         && 行计数
        ENDDO
        
        ** 显示输出
        this.edit.text = ""                                    && test方法会清除字体设置信息
        SetRichEditLineHeight(this.edit.hWnd, nLineHeight)     && 重新设置字体信息
        this.edit.SelText  = cStr
        this.edit.selstart = 0
    ENDPROC
ENDDEFINE

/*
    库文件 gdi32.lib
*/
#define DLLIMPORT_C extern "C" __declspec(dllexport)
#include <windows.h>
#include <richedit.h>

//获取 Rich Edit 字体信息并创建字体对象句柄
HFONT GetRichEditFontHandle(HWND hRichEdit, char* pFontName, int nFontSize)
{
    HDC hdc = CreateDCW(L"DISPLAY", NULL, NULL, NULL);

    CHARFORMAT cf;
    ZeroMemory(&cf, sizeof(CHARFORMAT));
    cf.cbSize = sizeof(CHARFORMAT);

    // 获取当前选择文本的字符格式
    SendMessage(hRichEdit, EM_GETCHARFORMAT, SCF_SELECTION, (LPARAM)&cf);

    // 从CHARFORMAT创建字体对象
    HFONT hFont = CreateFont(
        -MulDiv(nFontSize, GetDeviceCaps(hdc,LOGPIXELSY), 72),   //转换单位
        0, 0, 0,
        (cf.dwEffects & CFE_BOLD) ? FW_BOLD : FW_NORMAL,
        (cf.dwEffects & CFE_ITALIC) ? TRUE : FALSE,
        (cf.dwEffects & CFE_UNDERLINE) ? TRUE : FALSE,
        (cf.dwEffects & CFE_STRIKEOUT) ? TRUE : FALSE,
        DEFAULT_CHARSET,
        OUT_DEFAULT_PRECIS,
        CLIP_DEFAULT_PRECIS,
        DEFAULT_QUALITY,
        DEFAULT_PITCH | FF_DONTCARE,
        pFontName
    );

    DeleteDC(hdc);
    return hFont;
}

//获取 Rich Edit 在客户区一行字串的字数
DLLIMPORT_C int GetRichEditCharsW(HWND hRichEdit, LPCWSTR text, char* pFontName, int nFontSize)
{
    //获取控件尺寸和边距
    RECT rect;
    GetClientRect(hRichEdit, &rect);
    int editWidth = rect.right - rect.left;

    DWORD margins = SendMessage(hRichEdit, EM_GETMARGINS, 0, 0);
    editWidth -= (LOWORD(margins) + HIWORD(margins));

    HDC hdc = GetDC(hRichEdit);

    //获取当前字体
    HFONT hFont    = GetRichEditFontHandle(hRichEdit, pFontName, nFontSize);
    HFONT hOldFont = (HFONT)SelectObject(hdc, hFont);

    int len    = lstrlenW(text);
    int nChars = 0;
    SIZE sz;

    //计算一行的字数
    for (int i = 1; i <= len; i++) {
        if (!GetTextExtentPoint32W(hdc, text, i, &sz)) break;
        if (sz.cx > editWidth) break;
        nChars = i;
    }

    SelectObject(hdc, hOldFont);
    ReleaseDC(hRichEdit, hdc);
    return nChars;
}

//设置 Rich Edit 行高
DLLIMPORT_C int SetRichEditLineHeight(HWND hRichEdit, int nPixels)
{
    //获取当前设备DPI
    HDC hdc = CreateDCW(L"DISPLAY", NULL, NULL, NULL);
    int dpi = GetDeviceCaps(hdc, LOGPIXELSY);
    DeleteDC(hdc);
   
    //设置行高
    PARAFORMAT2 pf;
    ZeroMemory(&pf, sizeof(PARAFORMAT2));
    pf.cbSize           = sizeof(PARAFORMAT2);
    pf.dwMask           = PFM_LINESPACING;
    pf.bLineSpacingRule = 4;                                        //精确行高
    pf.dyLineSpacing    = (nPixels * 20 * 72) / dpi;                //像素转换为缇
    return SendMessage(hRichEdit, EM_SETPARAFORMAT, 0, (LPARAM)&pf);
}

//获取 Rich Edit 客户区的行数
DLLIMPORT_C int GetRichEditLineCount(HWND hRichEdit, char* pFontName, int nFontSize)
{
    HDC hdc = GetDC(hRichEdit);

    // 强制重新获取当前字体
    HFONT hFont    = GetRichEditFontHandle(hRichEdit, pFontName, nFontSize);
    HFONT hOldFont = (HFONT)SelectObject(hdc, hFont);

    //获取当前设备DPI
    HDC hdc2 = CreateDCW(L"DISPLAY", NULL, NULL, NULL);
    int dpi  = GetDeviceCaps(hdc2, LOGPIXELSY);

    // 获取行高
    PARAFORMAT2 pf;
    ZeroMemory(&pf, sizeof(PARAFORMAT2));
    pf.cbSize = sizeof(PARAFORMAT2);
    pf.dwMask = PFM_LINESPACING;
    SendMessage(hRichEdit, EM_GETPARAFORMAT, 0, (LPARAM)&pf);
    int lineHeight = 0;
    if (pf.dyLineSpacing > 0)
    {
        lineHeight = (pf.dyLineSpacing * dpi) / (20 * 72); // 转换为像素值
    }

    DeleteDC(hdc2);
    SelectObject(hdc, hOldFont);
    ReleaseDC(hRichEdit, hdc);
   
    // 计算客户区行数
    RECT rc;
    GetClientRect(hRichEdit, &rc);
    return rc.bottom / lineHeight;
}

BOOL WINAPI DllMain(HINSTANCE hinstDLL,DWORD fdwReason,LPVOID lpvReserved)
{
    return TRUE;
}