[text shaping] Overflowing glyph gets clipped

https://bugs.webkit.org/show_bug.cgi?id=299818

Reviewed by Antti Koivisto.

m_paintRect does not include ink overflow (e.g glyph overflow) so let's only clip
the content in inline direction (regular text paint does not clip at all).

Test: fast/text/clipped-glyph-across-inline-boxes.html

* LayoutTests/fast/text/clipped-glyph-across-inline-boxes-expected.html: Added.
* LayoutTests/fast/text/clipped-glyph-across-inline-boxes.html: Added.
* Source/WebCore/rendering/TextBoxPainter.cpp:
(WebCore::TextBoxPainter::paintForegroundForShapeRange):

Canonical link: https://commits.webkit.org/300823@main

Author: alanbaradlay

LayoutTests/fast/text/clipped-glyph-across-inline-boxes-expected.html

@@ -0,0 +1,10 @@
+<meta charset=utf-8>
+<style>
+div {
+  font-size: 50px;
+  font-family: Monospace;
+}
+</style>
+PASS if these glyphs don't get clipped.
+<div>ممم</div>
+<div>ممم</div>

LayoutTests/fast/text/clipped-glyph-across-inline-boxes.html

@@ -0,0 +1,11 @@
+<meta charset=utf-8>
+<meta name="fuzzy" content="maxDifference=0-2; totalPixels=0-3" />
+<style>
+div {
+  font-size: 50px;
+  font-family: Monospace;
+}
+</style>
+PASS if these glyphs don't get clipped.
+<div><span>م</span><span>مم</span></div>
+<div>ممم</div>

Source/WebCore/rendering/TextBoxPainter.cpp

@@ -663,9 +663,20 @@ bool TextBoxPainter::paintForegroundForShapeRange(TextPainter& textPainter)
 
     auto& context = m_paintInfo.context();
 
+    auto clipRect = [&] {
+        // We could also just use ink overflow here but since non-range painting
+        // sets up no clipping, we should not do that either here.
+        auto rect = FloatRect::infiniteRect();
+        rect.setX(m_paintRect.x());
+        // Note that this is RTL direction.
+        auto& textContent = m_textBox.box().text();
+        if (!textContent.isAtShapingBoundaryStart())
+            rect.setWidth(m_paintRect.width());
+        // FIXME: Setup a semi-inifite rect for the (visually) first box where x is -inifite with fixed maxX.
+        return rect;
+    };
     context.save();
-    context.clip(m_paintRect);
-
+    context.clip(clipRect());
     auto shapedContent = ShapedContent { };
     buildTextForShaping(shapedContent, m_textBox);