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Calculate maximum height of a character built from parts when measuring. b=403559, r+sr+a=roc

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karlt+@karlt.net 2008-01-02 20:21:36 -08:00
parent 2e38d99c6a
commit e8c2e3f296
1 changed files with 61 additions and 37 deletions
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98
layout/mathml/base/src/nsMathMLChar.cpp
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@ -1098,23 +1098,32 @@ ComputeSizeFromParts(nsPresContext* aPresContext,
PRUint32 aHint)
{
enum {first, middle, last, glue};
float flex[] = {0.901f, 0.901f, 0.901f};
// refine the flexibility depending on whether some parts can be left out
if (aGlyphs[glue] == aGlyphs[middle]) flex[middle] = 0.0f;
if (aGlyphs[glue] == aGlyphs[first]) flex[first] = 0.0f;
if (aGlyphs[glue] == aGlyphs[last]) flex[last] = 0.0f;
// get the minimum allowable size
nscoord computedSize = nscoord(flex[first] * aSizes[first] +
flex[middle] * aSizes[middle] +
flex[last] * aSizes[last]);
if (computedSize <= aTargetSize) {
// if we can afford more room, the default is to fill-up the target area
return aTargetSize;
// Add the parts that cannot be left out.
nscoord sum = 0;
for (PRInt32 i = first; i <= last; i++) {
if (aGlyphs[i] != aGlyphs[glue]) {
sum += aSizes[i];
}
}
// settle with the size, and let Paint() do the rest
return computedSize;
// Get the minimum allowable size using some flex.
const float flex = 0.901f;
nscoord minSize = NSToCoordRound(flex * sum);
if (minSize > aTargetSize)
return minSize; // settle with the minimum size
// Pick a maximum size using a maximum number of glue glyphs that we are
// prepared to draw for one character.
const PRInt32 maxGlyphs = 1000;
// This also takes into account the fact that, if the glue has no size,
// then the character can't be lengthened.
nscoord maxSize = sum + maxGlyphs * aSizes[glue];
if (maxSize < aTargetSize)
return maxSize; // settle with the maximum size
// Fill-up the target area
return aTargetSize;
}
// Insert aFallbackFamilies before the first generic family in or at the end
@ -1350,8 +1359,13 @@ nsMathMLChar::TryParts(nsPresContext* aPresContext,
// empty slots are filled with the glue if it is not null
if (!ch.Exists()) ch = glue;
nsBoundingMetrics bm;
// if (!ch.Exists()) glue is null, leave bounding metrics at 0
if (ch.Exists()) {
chdata[i] = ch;
if (!ch.Exists()) {
// Null glue indicates that a rule will be drawn, which can stretch to
// fill any space. Leave bounding metrics at 0.
sizedata[i] = aTargetSize;
}
else {
SetFontFamily(aRenderingContext, font, aGlyphTable, ch, aFamily);
nsresult rv = aRenderingContext.GetBoundingMetrics(&ch.code, 1, bm);
if (NS_FAILED(rv)) {
@ -1363,11 +1377,10 @@ nsMathMLChar::TryParts(nsPresContext* aPresContext,
// TODO: For the generic Unicode table, ideally we should check that the
// glyphs are actually found and that they each come from the same
// font.
bmdata[i] = bm;
sizedata[i] = isVertical ? bm.ascent + bm.descent
: bm.rightBearing - bm.leftBearing;
}
chdata[i] = ch;
bmdata[i] = bm;
sizedata[i] = isVertical ? bm.ascent + bm.descent
: bm.rightBearing - bm.leftBearing;
}
// Build by parts if we have successfully computed the
@ -2198,18 +2211,25 @@ nsMathMLChar::PaintVertically(nsPresContext* aPresContext,
last++;
}
}
else { // glue is present
else if (bmdata[3].ascent + bmdata[3].descent > 0) {
// glue is present
nscoord overlap;
nsCOMPtr<nsIFontMetrics> fm;
aRenderingContext.GetFontMetrics(*getter_AddRefs(fm));
nsMathMLFrame::GetRuleThickness(fm, overlap);
overlap = 2 * PR_MAX(overlap, onePixel);
// Ensure the stride for the glue is not reduced to less than onePixel
while (overlap > 0 && bmdata[3].ascent + bmdata[3].descent <= 2*overlap + onePixel)
overlap -= onePixel;
if (overlap > 0) {
// to protect against gaps, pretend the glue is smaller than
// it says to allow a small overlap when adjoining it
// To protect against gaps, pretend the glue is smaller than
// it says to allow a small overlap when adjoining it.
// XXXkt Does the overlap need to be this large: removing from both
// ascent and descent means the overlap between glue glyphs is 4 *
// max(ruleThickness, onePixel), while the overlap between glue and
// other glyphs is 2 * max(ruleThickness, onePixel).
// See also bug 349907.
bmdata[3].ascent -= overlap;
bmdata[3].descent -= overlap;
}
@ -2235,11 +2255,6 @@ nsMathMLChar::PaintVertically(nsPresContext* aPresContext,
bm = bmdata[3]; // glue
stride += bm.ascent;
}
// defensive code against odd things such as a smallish TextZoom...
NS_ASSERTION(1000 != count, "something is probably wrong somewhere");
if (stride < onePixel || 1000 == count) {
return NS_ERROR_UNEXPECTED;
}
dy += stride;
aRenderingContext.DrawString(&glue.code, 1, dx, dy);
}
@ -2252,6 +2267,12 @@ nsMathMLChar::PaintVertically(nsPresContext* aPresContext,
#endif
}
}
#ifdef DEBUG
else { // no glue
NS_ASSERTION(end[0] >= start[1] && end[1] >= start[2],
"gap between parts with no glue");
}
#endif
return NS_OK;
}
@ -2287,7 +2308,7 @@ nsMathMLChar::PaintHorizontally(nsPresContext* aPresContext,
// empty slots are filled with the glue if it is not null
if (!ch.Exists()) ch = glue;
nsBoundingMetrics bm;
// if (!ch.Exists()) glue is null, leave bounding metrics at 0
// if (!ch.Exists()) glue is null, leave bounding metrics at 0.
if (ch.Exists()) {
SetFontFamily(aRenderingContext, aFont, aGlyphTable, ch, mFamily);
rv = aRenderingContext.GetBoundingMetrics(&ch.code, 1, bm);
@ -2393,12 +2414,14 @@ nsMathMLChar::PaintHorizontally(nsPresContext* aPresContext,
last++;
}
}
else { // glue is present
else if (bmdata[3].rightBearing - bmdata[3].leftBearing > 0) {
// glue is present
nscoord overlap;
nsCOMPtr<nsIFontMetrics> fm;
aRenderingContext.GetFontMetrics(*getter_AddRefs(fm));
nsMathMLFrame::GetRuleThickness(fm, overlap);
overlap = 2 * PR_MAX(overlap, onePixel);
// Ensure the stride for the glue is not reduced to less than onePixel
while (overlap > 0 && bmdata[3].rightBearing - bmdata[3].leftBearing <= 2*overlap + onePixel)
overlap -= onePixel;
@ -2430,11 +2453,6 @@ nsMathMLChar::PaintHorizontally(nsPresContext* aPresContext,
bm = bmdata[3]; // glue
stride -= bm.leftBearing;
}
// defensive code against odd things such as a smallish TextZoom...
NS_ASSERTION(1000 != count, "something is probably wrong somewhere");
if (stride < onePixel || 1000 == count) {
return NS_ERROR_UNEXPECTED;
}
dx += stride;
aRenderingContext.DrawString(&glue.code, 1, dx, dy);
}
@ -2447,5 +2465,11 @@ nsMathMLChar::PaintHorizontally(nsPresContext* aPresContext,
#endif
}
}
#ifdef DEBUG
else { // no glue
NS_ASSERTION(end[0] >= start[1] && end[1] >= start[2],
"gap between parts with no glue");
}
#endif
return NS_OK;
}