Bug 1412179 - Implement non-empty legends for wr r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D4963 --HG-- extra : moz-landing-system : lando
trman · Sep 12, 2018 · 7f98514 · 7f98514
1 parent 8f3f22d
commit 7f98514
Showing 1 changed file with 26 additions and 11 deletions.
diff --git a/layout/forms/nsFieldSetFrame.cpp b/layout/forms/nsFieldSetFrame.cpp
@@ -164,27 +164,42 @@ nsDisplayFieldSetBorder::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder
   auto frame = static_cast<nsFieldSetFrame*>(mFrame);
   auto offset = ToReferenceFrame();
   nsRect rect;
+  bool pushedClip = false;
 
   if (nsIFrame* legend = frame->GetLegend()) {
     rect = frame->VisualBorderRectRelativeToSelf() + offset;
-
-    // Legends require a "negative" clip around the text, which WR doesn't support yet.
     nsRect legendRect = legend->GetNormalRect() + offset;
+
     if (!legendRect.IsEmpty()) {
-      return false;
+      auto appUnitsPerDevPixel = frame->PresContext()->AppUnitsPerDevPixel();
+      auto layoutRect = wr::ToLayoutRect(LayoutDeviceRect::FromAppUnits(rect, appUnitsPerDevPixel));
+
+      wr::ComplexClipRegion region;
+      region.rect = wr::ToLayoutRect(LayoutDeviceRect::FromAppUnits(legendRect, appUnitsPerDevPixel));
+      region.mode = wr::ClipMode::ClipOut;
+      nsTArray<mozilla::wr::ComplexClipRegion> array{region};
+
+      wr::WrClipId clip = aBuilder.DefineClip(Nothing(), layoutRect, &array, nullptr);
+      aBuilder.PushClip(clip);
+      pushedClip = true;
     }
+
   } else {
     rect = nsRect(offset, frame->GetRect().Size());
   }
 
-  return nsCSSRendering::CreateWebRenderCommandsForBorder(this,
-                                                          mFrame,
-                                                          rect,
-                                                          aBuilder,
-                                                          aResources,
-                                                          aSc,
-                                                          aManager,
-                                                          aDisplayListBuilder);
+  bool result = nsCSSRendering::CreateWebRenderCommandsForBorder(this,
+                                                                 mFrame,
+                                                                 rect,
+                                                                 aBuilder,
+                                                                 aResources,
+                                                                 aSc,
+                                                                 aManager,
+                                                                 aDisplayListBuilder);
+  if (pushedClip) {
+    aBuilder.PopClip();
+  }
+  return result;
 };
 
 void