Bug 1308113 - Account for letter- and word-spacing when resolving tab-size <number>. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D117331
2021-06-10 09:19:23 +00:00
parent 92b71b2c6b
commit fd9023b910
5 changed files with 40 additions and 29 deletions
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -3419,15 +3419,17 @@ void nsTextFrame::PropertyProvider::GetSpacing(Range aRange,

 static bool CanAddSpacingAfter(const gfxTextRun* aTextRun, uint32_t aOffset,
                               bool aNewlineIsSignificant) {
-  if (aOffset + 1 >= aTextRun->GetLength()) return true;
-  return aTextRun->IsClusterStart(aOffset + 1) &&
-         aTextRun->IsLigatureGroupStart(aOffset + 1) &&
-         !aTextRun->CharIsFormattingControl(aOffset) &&
-         !(aNewlineIsSignificant && aTextRun->CharIsNewline(aOffset));
+  if (aOffset + 1 >= aTextRun->GetLength()) {
+    return true;
+  }
+  const auto* g = aTextRun->GetCharacterGlyphs();
+  return g[aOffset + 1].IsClusterStart() &&
+         g[aOffset + 1].IsLigatureGroupStart() &&
+         !g[aOffset].CharIsFormattingControl() && !g[aOffset].CharIsTab() &&
+         !(aNewlineIsSignificant && g[aOffset].CharIsNewline());
 }

-static gfxFloat ComputeTabWidthAppUnits(const nsIFrame* aFrame,
-                                        gfxTextRun* aTextRun) {
+static gfxFloat ComputeTabWidthAppUnits(const nsIFrame* aFrame) {
  const auto& tabSize = aFrame->StyleText()->mMozTabSize;
  if (tabSize.IsLength()) {
    nscoord w = tabSize.length._0.ToAppUnits();
@@ -3439,13 +3441,17 @@ static gfxFloat ComputeTabWidthAppUnits(const nsIFrame* aFrame,
  gfxFloat spaces = tabSize.number._0;
  MOZ_ASSERT(spaces >= 0);

-  // Round the space width when converting to appunits the same way
-  // textruns do.
-  gfxFloat spaceWidthAppUnits = NS_round(
-      GetFirstFontMetrics(aTextRun->GetFontGroup(), aTextRun->IsVertical())
-          .spaceWidth *
-      aTextRun->GetAppUnitsPerDevUnit());
-  return spaces * spaceWidthAppUnits;
+  const nsIFrame* cb = aFrame->GetContainingBlock(0, aFrame->StyleDisplay());
+  const auto* styleText = cb->StyleText();
+
+  // Round the space width when converting to appunits the same way textruns do.
+  RefPtr<nsFontMetrics> fm = nsLayoutUtils::GetFontMetricsForFrame(cb, 1.0f);
+  bool vertical = cb->GetWritingMode().IsCentralBaseline();
+  nscoord spaceWidth = nscoord(NS_round(
+      GetFirstFontMetrics(fm->GetThebesFontGroup(), vertical).spaceWidth *
+      cb->PresContext()->AppUnitsPerDevPixel()));
+  return spaces * (spaceWidth + styleText->mLetterSpacing.ToAppUnits() +
+                   styleText->mWordSpacing.Resolve(spaceWidth));
 }

 void nsTextFrame::PropertyProvider::GetSpacingInternal(Range aRange,
@@ -3498,7 +3504,7 @@ void nsTextFrame::PropertyProvider::GetSpacingInternal(Range aRange,

  // Now add tab spacing, if there is any
  if (!aIgnoreTabs) {
-    gfxFloat tabWidth = ComputeTabWidthAppUnits(mFrame, mTextRun);
+    gfxFloat tabWidth = ComputeTabWidthAppUnits(mFrame);
    if (tabWidth > 0) {
      CalcTabWidths(aRange, tabWidth);
      if (mTabWidths) {
@@ -8476,7 +8482,7 @@ void nsTextFrame::AddInlineMinISizeForFlow(gfxContext* aRenderingContext,
      provider.GetSpacing(Range(i, i + 1), &spacing);
      aData->mCurrentLine += nscoord(spacing.mBefore);
      if (tabWidth < 0) {
-        tabWidth = ComputeTabWidthAppUnits(this, textRun);
+        tabWidth = ComputeTabWidthAppUnits(this);
      }
      gfxFloat afterTab = AdvanceToNextTab(aData->mCurrentLine, tabWidth,
                                           provider.MinTabAdvance());
@@ -8646,7 +8652,7 @@ void nsTextFrame::AddInlinePrefISizeForFlow(
      provider.GetSpacing(Range(i, i + 1), &spacing);
      aData->mCurrentLine += nscoord(spacing.mBefore);
      if (tabWidth < 0) {
-        tabWidth = ComputeTabWidthAppUnits(this, textRun);
+        tabWidth = ComputeTabWidthAppUnits(this);
      }
      gfxFloat afterTab = AdvanceToNextTab(aData->mCurrentLine, tabWidth,
                                           provider.MinTabAdvance());
--- a/layout/reftests/bugs/411059-1-ref.html
+++ b/layout/reftests/bugs/411059-1-ref.html
@@ -3,7 +3,8 @@
 <head>
 <style>
 p { float:left; white-space:pre; border:1px solid black; clear:both; }
-.space { padding:0 2px; }
+.letterspace { letter-spacing:4px; }
+.space { padding:0 4px 0 0; }
 table { clear:both; }
 </style>
 </head>
@@ -20,12 +21,12 @@ table { clear:both; }
 </div>

 <p>
-        <span class="space">a</span>
+<span class="letterspace">        </span><span class="space">a</span>
 </p>

 <div style="width:0">
-  <p class="letterspace">
-        <span class="space">a</span>
+  <p>
+<span class="letterspace">        </span><span class="space">a</span>
  </p>
 </div>

--- a/layout/reftests/bugs/411059-1.html
+++ b/layout/reftests/bugs/411059-1.html
@@ -3,7 +3,7 @@
 <head>
 <style>
 p { float:left; white-space:pre; border:1px solid black; clear:both; }
-.letterspace { letter-spacing:2px; }
+.letterspace { letter-spacing:4px; }
 table { clear:both; }
 </style>
 </head>
@@ -19,8 +19,9 @@ table { clear:both; }
  </p>
 </div>

-<!-- there should be 1px of letter-spacing after the tab, 1px before the 'a' and 2px after
-     the a -->
+<!-- there should be no letter-spacing after the tab, because letter-spacing is
+     already incorporated into the calculation of the tab position, but there
+     will be 4px after the a -->
 <p class="letterspace">
 	a
 </p>
--- a/layout/reftests/text/word-spacing-01-ref.html
+++ b/layout/reftests/text/word-spacing-01-ref.html
@@ -2,10 +2,13 @@
 <html>
 <head>
 <style>
-span { display:inline-block; width:10em; }
+span { display:inline-block; width:10ch; }
+/* first tab-position will be at 2 * (space-width + word-spacing), i.e. 22ch,
+   so to advance there after the 3-ch word "tab" we need 19ch of added space */
+span.tab { width: 19ch; }
 </style>
 </head>
-<body style="width: 433px; height: 590px;">
+<body style="font-family: monospace; width: 433px; height: 590px;">

 <table border="1">
 <tr><td>space <span></span>.</td>
@@ -23,7 +26,7 @@ span { display:inline-block; width:10em; }
 <tr><td>ideographic-space&#x3000;.</td>
 <tr><td>newline
 .</td>
-<tr><td>tab&#9;.</td>
+<tr><td>tab<span class=tab></span>.</td>
 <tr><td>form-feed&#12;.</td>
 </table>

@@ -42,7 +45,7 @@ span { display:inline-block; width:10em; }
 <tr><td>ideographic-space&#x3000;.</td>
 <tr><td>newline
 .</td>
-<tr><td>tab&#9;.</td>
+<tr><td>tab<span class=tab></span>.</td>
 <tr><td>form-feed&#12;.</td>
 </table>

--- a/layout/reftests/text/word-spacing-01.html
+++ b/layout/reftests/text/word-spacing-01.html
@@ -1,6 +1,6 @@
 <!DOCTYPE HTML>
 <html>
-<body style="word-spacing:10em; width: 433px; height: 590px;">
+<body style="font-family: monospace; word-spacing:10ch; -moz-tab-size: 2; width: 433px; height: 590px;">

 <table border="1">
 <tr><td>space .</td>