Closed Bug 720 Opened 27 years ago Closed 26 years ago

Font size rounding bug

Categories

(MozillaClassic Graveyard :: FontLib, defect, P1)

x86
Windows NT
defect

Tracking

(Not tracked)

VERIFIED FIXED

People

(Reporter: harishd, Assigned: harishd)

Details

Peter Linss wrote: In working to make NGLayout's font handling match that of Nav's, I've uncovered a rounding error in the Win libfont code: modules/libfont/producers/win/src/winfp.cpp: line 875 // for passing to Windows, convert pointsize to pixel size and negative. if( pointSize > 0 ) pixelSize = (int) - pointSize * pPrmFont->YPixelPerInch / 72.0; pointSize is the input size (a double), the rounding error is introduced in the conversion to pixel size. The problem is a classic lack of parentheses, the int conversion is happening before the divide by 72.0. To do what was meant, the line should read: pixelSize = (int) - ((pointSize * pPrmFont->YPixelPerInch) / 72.0); However, this is also wrong. The proper (ie: Windows) way is to round to the rearest integer, not the smallest. According to the Windows docs the code should read: pixelSize = - MulDiv((int)pointSize, pPrmFont->YPixelPerInch, 72); That would give the correct rounding. This bug results in Nav being unable to render certain font sizes, ie: 8 point text comes out significantly smaller (more like 7 point). For more information about the way it looks checkout the above URL.
dp, since this may require a code review to verify the fix, who would be the appropriate engineer to look at the code.
assigning Fenella as QA Assigned to
tell me if this is a regression from 4.05...
This isn't a regression. We are still evaluating whether we need to fix it ASAP. Data is pretty convoluted betn. 3.0,4.0,IE4.0,IE5.0 and word. We should revisit this for 4.5
Putting on b2 radar. Changing from P0 to P1.
This is not a regression nor a crash, nor data loss, nor an escalation, therefore this bug doesn't meet the 4.5 criteria (http://webgroup/novabugs.html). Marking TFV 5.0.
Setting all current Open/Normal to M4.
Component: html display → FontLib
Status: NEW → RESOLVED
Closed: 26 years ago
Resolution: --- → FIXED
QA Contact: 3849
Old bug. beppe, couldyou assign QA to Verify this one please.
asking dp who is the best person to review this within fontlib.
I talked with Harish about how we could verify this bug and there really isn't any way that we can do this visually. This would really need to be done through assessing what the code pushes out. Maybe Peter Linss has a suggestion on how to verify this.
I talked with Harish about how we could verify this bug and there really isn't any way that we can do this visually. This would really need to be done through assessing what the code pushes out. Maybe Peter Linss has a suggestion on how to verify this.
Status: RESOLVED → VERIFIED
per Peters assessment, marking this as verified
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