Bug 937268 - Should implement getBBox() for tspan r=longsonr

We implements getBBox for tspan. The implementation also has consistent
behavior as getBoundingClientRect.

Differential Revision: https://phabricator.services.mozilla.com/D27428

--HG--
extra : moz-landing-system : lando

dom/svg/SVGTransformableElement.cpp

@@ -15,6 +15,7 @@
 #include "mozilla/dom/SVGSVGElement.h"
 #include "nsContentUtils.h"
 #include "nsIFrame.h"
+#include "SVGTextFrame.h"
 #include "SVGContentUtils.h"
 #include "nsSVGDisplayableFrame.h"
 #include "nsSVGUtils.h"
@@ -164,9 +165,41 @@ already_AddRefed<SVGIRect> SVGTransformableElement::GetBBox(
     return nullptr;
   }
   nsSVGDisplayableFrame* svgframe = do_QueryFrame(frame);
+
   if (!svgframe) {
-    rv.Throw(NS_ERROR_NOT_IMPLEMENTED);  // XXX: outer svg
-    return nullptr;
+    if (!nsSVGUtils::IsInSVGTextSubtree(frame)) {
+      rv.Throw(NS_ERROR_NOT_IMPLEMENTED);  // XXX: outer svg
+      return nullptr;
+    }
+
+    // For <tspan>, <textPath>, the frame is an nsInlineFrame or
+    // nsBlockFrame, |svgframe| will be a nullptr.
+    // We implement their getBBox directly here instead of in
+    // nsSVGUtils::GetBBox, because nsSVGUtils::GetBBox is more
+    // or less used for other purpose elsewhere. e.g. gradient
+    // code assumes GetBBox of <tspan> returns the bbox of the
+    // outer <text>.
+    // TODO: cleanup this sort of usecase of nsSVGUtils::GetBBox,
+    // then move this code nsSVGUtils::GetBBox.
+    SVGTextFrame* text =
+        static_cast<SVGTextFrame*>(nsLayoutUtils::GetClosestFrameOfType(
+            frame->GetParent(), LayoutFrameType::SVGText));
+
+    if (text->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY)) {
+      rv.Throw(NS_ERROR_FAILURE);
+      return nullptr;
+    }
+
+    gfxRect rec = text->TransformFrameRectFromTextChild(
+        frame->GetRectRelativeToSelf(), frame);
+
+    // Should also add the |x|, |y| of the SVGTextFrame itself, since
+    // the result obtained by TransformFrameRectFromTextChild doesn't
+    // include them.
+    rec.x += float(text->GetPosition().x) / AppUnitsPerCSSPixel();
+    rec.y += float(text->GetPosition().y) / AppUnitsPerCSSPixel();
+
+    return NS_NewSVGRect(this, ToRect(rec));
   }
 
   if (!NS_SVGNewGetBBoxEnabled()) {

dom/svg/test/bbox-helper.svg

@@ -4,12 +4,13 @@
     <foreignObject id="fO" x="10" y="10" width="100" height="100"/>
     <image id="i" x="10" y="10" width="100" height="100"/>
   </g>
-  <text id="b" x="20" y="20">b</text>
+  <text id="b" x="100" y="100">abcdef</text>
   <text id="a" x="20" y="30">a</text>
   <text id="y" x="20" y="40">y</text>
-  <text id="tspan">
-    <tspan x="20" y="20">b</tspan>
+  <text id="tspantext1">
+    <tspan id="tspan1" x="100" y="100">abcdef</tspan>
   </text>
+  <text id="tspantext2" x="100" y="100">ABCEDF<tspan id="tspan2">ABCEDF</tspan></text>
   <text id="text" x="20" y="60">text</text>
   <!-- &#8206; is the same as the HTML &lrm; -->
   <text id="lrmText" x="20" y="60">&#8206;text</text>

dom/svg/test/test_bbox.xhtml

@@ -46,17 +46,33 @@ function run() {
     isFuzzy(bbox1.width, bbox2.width, 0.0002, id1 + ".getBBox().width");
     is(bbox1.height, bbox2.height, id1 + ".getBBox().height");
   }
+  function compareBBoxFuzzy(id1, id2, err) {
+    var bbox1 = getBBox(id1);
+    var bbox2 = getBBox(id2);
+    isfuzzy(bbox1.x, bbox2.x, err, id1 + ".getBBox().x");
+    isfuzzy(bbox1.y, bbox2.y, err, id1 + ".getBBox().y");
+    isfuzzy(bbox1.width, bbox2.width, err, id1 + ".getBBox().width");
+    isfuzzy(bbox1.height, bbox2.height, err, id1 + ".getBBox().height");
+  }
   function compareBBoxHeight(id1, id2) {
     var bbox1 = getBBox(id1);
     var bbox2 = getBBox(id2);
     is(bbox1.height, bbox2.height, id1 + ".getBBox().height");
   }
+  function compareBBoxWidthWithScaleFuzzy(id1, id2, scaleOfId2, err) {
+    var bbox1 = getBBox(id1);
+    var bbox2 = getBBox(id2);
+    isfuzzy(bbox1.width, bbox2.width * scaleOfId2, err, id1 + ".getBBox().width");
+  }
 
   checkBBox("fO", 10, 10, 100, 100, 0.0);
   checkBBox("i", 10, 10, 100, 100, 0.0);
   compareBBoxHeight("a", "b");
   compareBBoxHeight("a", "y");
-  compareBBox("b", "tspan");
+  compareBBox("b", "tspantext1");
+  compareBBoxFuzzy("tspantext1", "tspan1", 5);
+  compareBBoxHeight("tspantext2", "tspan2");
+  compareBBoxWidthWithScaleFuzzy("tspantext2", "tspan2", 2, 5);
   compareBBoxHeight("text", "lrmText");
   checkBBox("v", 95, 45, 10, 155, 0.001);
   checkBBox("h", 195, 45, 105, 55, 0.001);