答案1
您需要(a)增加行距(您的设置有零前导) 并将\par
指令放在最后的花括号之前而不是之后}
。
以下屏幕截图显示了 0pt、5pt 和 10pt 行距之间的差异。(水平线只是为了指示标题材料的垂直范围。)只有您才能决定您的文档的“正确”行距量。
顺便问一下,为什么要强制使用OT1
字体编码?我衷心建议使用该T1
编码。
\documentclass{article}
\begin{document}
\centering
% OP's code (zero leading)
\hrule
{\fontsize{25}{25}\usefont{T1}{phv}{bc}{n}\selectfont\par
This is a very long title and I want to increase the spacing between the two lines}\par
\hrule
% 5pt leading
\bigskip
\hrule
{\fontsize{25}{30}\usefont{T1}{phv}{bc}{n}\selectfont\par
This is a very long title and I want to increase the spacing between the two lines\par}
\hrule
% 10pt leading
\bigskip
\hrule
{\fontsize{25}{35}\usefont{T1}{phv}{bc}{n}\selectfont\par
This is a very long title and I want to increase the spacing between the two lines\par}
\hrule
\end{document}