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fl_measure() doc clarifications for common use errors.

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git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@9233 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
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Greg Ercolano 2012-02-04 17:24:47 +00:00
parent 4e40f1b339
commit 78e2cdf50b
1 changed files with 16 additions and 0 deletions
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16
src/fl_draw.cxx
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@ -383,9 +383,25 @@ void fl_draw(
Measure how wide and tall the string will be when printed by the
fl_draw() function with \p align parameter. If the incoming \p w
is non-zero it will wrap to that width.
The 'current font' is used to do the width/height calculations,
so unless its value is known at the time fl_measure() is called,
it is advised to first set the current font with fl_font().
\b Note: In the general use case, it's a common error to forget to set
\p w to 0 before calling fl_measure() when wrap behavior isn't needed.
\param[in] str nul-terminated string
\param[out] w,h width and height of string in current font
\param[in] draw_symbols non-zero to enable @@symbol handling [default=1]
\code
// Example: Common use case for fl_measure()
const char *s = "This is a test";
int wi=0, hi=0; // initialize to zero before calling fl_measure()
fl_font(FL_HELVETICA, 14); // set current font face/size to be used for measuring
fl_measure(s, wi, hi); // returns pixel width/height of string in current font
\endcode
*/
void fl_measure(const char* str, int& w, int& h, int draw_symbols) {
if (!str || !*str) {w = 0; h = 0; return;}