Changeset 126438 in webkit

Timestamp:

Aug 23, 2012 9:24:15 AM (12 years ago)

Author:

commit-queue@webkit.org

Message:

Text Autosizing: Multiply large fonts less, as they are already more legible.
​https://bugs.webkit.org/show_bug.cgi?id=94227

Patch by John Mellor <​johnme@chromium.org> on 2012-08-23
Reviewed by Kenneth Rohde Christiansen.

Source/WebCore:

Rather than uniformly multiplying font sizes by the multiplier (derived
from the width of the block), we should multiply fonts that are already
large less, since they are already more legible hence there is less need
for them to grow.

However it is still important to maintain differentiation between text
that the author specified to be of different sizes.

This algorithm multiplies text by the multiplier up until a predefined
"pleasant" font size; beyond that the computedSize goes up with
specifiedSize but at a gradient of less than 1 in order to gradually
fade out the size increase; finally for very large specifiedSizes the
computedSize will be the same as the specifiedSize.

For further details, including a graph, please see the bug report.

Test: fast/text-autosizing/various-font-sizes.html

• rendering/TextAutosizer.cpp:

(WebCore::TextAutosizer::computeAutosizedFontSize):

Implements the custom multiplication. See comment for details.

• rendering/style/RenderStyle.cpp:

(WebCore::RenderStyle::lineHeight):

Use computeAutosizedFontSize instead of directly multiplying.

(WebCore::RenderStyle::setFontSize):

Use computeAutosizedFontSize instead of directly multiplying.

LayoutTests:

Added test demonstrating how various font sizes are affected.

• fast/text-autosizing/various-font-sizes-expected.html: Added.
• fast/text-autosizing/various-font-sizes.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/fast/text-autosizing/various-font-sizes-expected.html (added)
• LayoutTests/fast/text-autosizing/various-font-sizes.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/TextAutosizer.cpp (modified) (1 diff)
• Source/WebCore/rendering/TextAutosizer.h (modified) (1 diff)
• Source/WebCore/rendering/style/RenderStyle.cpp (modified) (3 diffs)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2012-08-23  John Mellor  <johnme@chromium.org>
+
+        Text Autosizing: Multiply large fonts less, as they are already more legible.
+        https://bugs.webkit.org/show_bug.cgi?id=94227
+
+        Reviewed by Kenneth Rohde Christiansen.
+
+        Added test demonstrating how various font sizes are affected.
+
+        * fast/text-autosizing/various-font-sizes-expected.html: Added.
+        * fast/text-autosizing/various-font-sizes.html: Added.
+
 2012-08-23  Zan Dobersek  <zandobersek@gmail.com>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2012-08-23  John Mellor  <johnme@chromium.org>
+
+        Text Autosizing: Multiply large fonts less, as they are already more legible.
+        https://bugs.webkit.org/show_bug.cgi?id=94227
+
+        Reviewed by Kenneth Rohde Christiansen.
+
+        Rather than uniformly multiplying font sizes by the multiplier (derived
+        from the width of the block), we should multiply fonts that are already
+        large less, since they are already more legible hence there is less need
+        for them to grow.
+
+        However it is still important to maintain differentiation between text
+        that the author specified to be of different sizes.
+
+        This algorithm multiplies text by the multiplier up until a predefined
+        "pleasant" font size; beyond that the computedSize goes up with
+        specifiedSize but at a gradient of less than 1 in order to gradually
+        fade out the size increase; finally for very large specifiedSizes the
+        computedSize will be the same as the specifiedSize.
+
+        For further details, including a graph, please see the bug report.
+
+        Test: fast/text-autosizing/various-font-sizes.html
+
+        * rendering/TextAutosizer.cpp:
+        (WebCore::TextAutosizer::computeAutosizedFontSize):
+
+            Implements the custom multiplication. See comment for details.
+
+        * rendering/style/RenderStyle.cpp:
+        (WebCore::RenderStyle::lineHeight):
+
+            Use computeAutosizedFontSize instead of directly multiplying.
+
+        (WebCore::RenderStyle::setFontSize):
+
+            Use computeAutosizedFontSize instead of directly multiplying.
+
 2012-08-23  Emil A Eklund  <eae@chromium.org>
 

trunk/Source/WebCore/rendering/TextAutosizer.cpp

@@ -108 +108 @@
 }
 
+float TextAutosizer::computeAutosizedFontSize(float specifiedSize, float multiplier)
+{
+    // Somewhat arbitrary "pleasant" font size.
+    const float pleasantSize = 16;
+
+    // Multiply fonts that the page author has specified to be larger than
+    // pleasantSize by less and less, until huge fonts are not increased at all.
+    // For specifiedSize between 0 and pleasantSize we directly apply the
+    // multiplier; hence for specifiedSize == pleasantSize, computedSize will be
+    // multiplier * pleasantSize. For greater specifiedSizes we want to
+    // gradually fade out the multiplier, so for every 1px increase in
+    // specifiedSize beyond pleasantSize we will only increase computedSize
+    // by gradientAfterPleasantSize px until we meet the
+    // computedSize = specifiedSize line, after which we stay on that line (so
+    // then every 1px increase in specifiedSize increases computedSize by 1px).
+    const float gradientAfterPleasantSize = 0.5;
+
+    float computedSize;
+    if (specifiedSize <= pleasantSize)
+        computedSize = multiplier * specifiedSize;
+    else {
+        computedSize = multiplier * pleasantSize + gradientAfterPleasantSize * (specifiedSize - pleasantSize);
+        if (computedSize < specifiedSize)
+            computedSize = specifiedSize;
+    }
+    return computedSize;
+}
+
 bool TextAutosizer::isNotAnAutosizingContainer(const RenderObject* renderer)
 {

trunk/Source/WebCore/rendering/TextAutosizer.h

@@ -52 +52 @@
     bool processSubtree(RenderObject* layoutRoot);
 
+    static float computeAutosizedFontSize(float specifiedSize, float multiplier);
+
 private:
     explicit TextAutosizer(Document*);

trunk/Source/WebCore/rendering/style/RenderStyle.cpp

@@ -43 +43 @@
 #include <wtf/StdLibExtras.h>
 #include <algorithm>
+
+#if ENABLE(TEXT_AUTOSIZING)
+#include "TextAutosizer.h"
+#endif
 
 using namespace std;
@@ -1224 +1228 @@
     float multiplier = textAutosizingMultiplier();
     if (multiplier > 1 && lh.isFixed())
-        return Length(lh.value() * multiplier, Fixed);
+        return Length(TextAutosizer::computeAutosizedFontSize(lh.value(), multiplier), Fixed);
 #endif
     return lh;
@@ -1263 +1267 @@
     float multiplier = textAutosizingMultiplier();
     if (multiplier > 1) {
-        // FIXME: Large font sizes needn't be multiplied as much since they are already more legible.
-        desc.setComputedSize(size * multiplier);
+        desc.setComputedSize(TextAutosizer::computeAutosizedFontSize(size, multiplier));
     }
 #endif