Libharu pdf创作：如何知道印刷文字的大小

Michaël Azevedo 发表于 Dev

米歇尔·阿兹维多（MichaëlAzevedo）

我目前正在使用libharu库，以便在C ++程序中呈现一些pdf。

我不知道是否可能知道用特定字体绘制特定文本所需的大小。

该HPDF_Page_TextRect绘制方法会返回一个HPDF_PAGE_INSUFFICIENT_SPACE消息，如果文本不能在所提供的矩形放进去，但我想知道是否有计算，其中文本将适合一个特定的字体最小尺寸的一种方式。

在临时，谢谢。

米歇尔·阿兹维多（MichaëlAzevedo）

我发现了一种解决方法，其中包括在缩小页面宽度的同时将页面外部绘制文本，直到绘制失败。它一点也不枯燥，但是可以。

HPDF_STATUS drawString_2(HPDF_Page pdfPage, CString texte, COLORREF textColor, HPDF_Font font, HPDF_REAL fontSize, HPDF_REAL left, HPDF_REAL right, HPDF_REAL top, 
                         HPDF_REAL bottom, HPDF_TextAlignment alignment, HPDF_REAL textRise = 0, HPDF_TextRenderingMode renderingMode = HPDF_FILL);


HPDF_REAL calculateMaxWidthForTextInRect2(HPDF_Page pdfPage, CString texte, HPDF_REAL left, HPDF_REAL right, HPDF_REAL top, HPDF_REAL bottom, HPDF_Font font, HPDF_REAL fontSize);


HPDF_STATUS drawString_2(HPDF_Page pdfPage, CString texte, COLORREF textColor, HPDF_Font font, HPDF_REAL fontSize, HPDF_REAL left, HPDF_REAL right, HPDF_REAL top, 
                         HPDF_REAL bottom, HPDF_TextAlignment alignment, HPDF_REAL textRise, HPDF_TextRenderingMode renderingMode)
{
#ifdef DEBUG
        assert(font != NULL);
#else
        if (font == NULL)
            return 1;
#endif
    HPDF_Page_SetFontAndSize(pdfPage, font, fontSize);
    HPDF_Page_SetTextRise(pdfPage, textRise);
    HPDF_Page_SetTextRenderingMode(pdfPage, renderingMode);
    HPDF_Page_SetRGBFill(pdfPage, GetRValue(textColor) / 255.f, GetGValue(textColor) / 255.f, GetBValue(textColor) / 255.f);
    HPDF_Page_BeginText(pdfPage);
    HPDF_STATUS returnValue = HPDF_Page_TextRect(pdfPage, left, top, right, bottom, (LPCSTR)texte, alignment, NULL);
    HPDF_Page_EndText(pdfPage);

    return returnValue;
}

HPDF_REAL calculateMaxWidthForTextInRect2(HPDF_Page pdfPage, CString texte, HPDF_REAL left, HPDF_REAL right, HPDF_REAL top, HPDF_REAL bottom, HPDF_Font font, HPDF_REAL fontSize)
{
    // Let's draw outside the page size, so the text, even invisible, will not be selectionnable and copyable
    HPDF_REAL leftTmp           = -(right - left);
    HPDF_REAL rightTmp          = 0;
    HPDF_REAL topTmp            = -(bottom - top);
    HPDF_REAL bottomTmp         = 0;

    HPDF_Page_SetTextRenderingMode(pdfPage, HPDF_INVISIBLE);

    // Let's reduce horizontally the rect until the drawing fails
    while (drawString_2(pdfPage, texte, RGB(0, 0, 0), font, fontSize, leftTmp, rightTmp, topTmp, bottomTmp, HPDF_TALIGN_CENTER, 0, HPDF_INVISIBLE) == HPDF_OK)
    {
        leftTmp ++;
        rightTmp --;
    }   

    // If no drawing has be performed, the text cannot be rendered in the provided rect
    if (rightTmp == 0)
        return -1;

    // Let's decrement the shifting in order to get the latest correct value
    leftTmp --;
    rightTmp ++;

    return (rightTmp - leftTmp);
}