How do I use DrawText DT_CALCRECT properly?

问题

I am generating a report that has a caption in the footer. I use DrawText to find out the caption's dimensions. The problem is the text is always clipped, but when I have a carriage return at the end of the text, all the text appears perfectly.

lClientRect := Rect(0, 0, 4770, 59);
lFlags := DT_CALCRECT or DT_EXPANDTABS or Alignments[Alignment]
       or WordWraps[WordWrap] or DT_NOPREFIX or DT_TOP or DT_EXTERNALLEADING;

DrawText(lCanvas.Handle, PChar(lsCaption), Length(lsCaption), lClientRect, lFlags);

I examined the rect after the call to DrawText, and it is (0, 0, 4366, 59), but when I have a carriage return, it is (0, 0, 4366, 118).

I don't have any clue on what is happening. Any help will be appreciated.

回答1:

The carriage return adds a second line of text to the string, thus doubling the height of the calculated rectangle. (Windows is flexible about whether a line-feed or carriage-return character starts a new line.)

As for why the text is clipped (on the bottom edge, I assume), it might be that you're calculating the size using a different font than you have when you draw the text.

来源：https://stackoverflow.com/questions/16343147/how-do-i-use-drawtext-dt-calcrect-properly