1 files changed, 218 insertions, 0 deletions
diff --git a/layout/generic/MiddleCroppingBlockFrame.cpp b/layout/generic/MiddleCroppingBlockFrame.cpp
new file mode 100644
index 0000000000..4cbbb684aa
--- /dev/null
+++ b/layout/generic/MiddleCroppingBlockFrame.cpp
@@ -0,0 +1,218 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MiddleCroppingBlockFrame.h"
+#include "nsTextFrame.h"
+#include "nsLayoutUtils.h"
+#include "nsTextNode.h"
+#include "nsLineLayout.h"
+#include "gfxContext.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/intl/Segmenter.h"
+#include "mozilla/ReflowInput.h"
+#include "mozilla/ReflowOutput.h"
+
+namespace mozilla {
+
+NS_QUERYFRAME_HEAD(MiddleCroppingBlockFrame)
+  NS_QUERYFRAME_ENTRY(nsIAnonymousContentCreator)
+  NS_QUERYFRAME_ENTRY(MiddleCroppingBlockFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsBlockFrame)
+
+MiddleCroppingBlockFrame::MiddleCroppingBlockFrame(ComputedStyle* aStyle,
+                                                   nsPresContext* aPresContext,
+                                                   ClassID aClassID)
+    : nsBlockFrame(aStyle, aPresContext, aClassID) {}
+
+MiddleCroppingBlockFrame::~MiddleCroppingBlockFrame() = default;
+
+void MiddleCroppingBlockFrame::UpdateDisplayedValue(const nsAString& aValue,
+                                                    bool aIsCropped,
+                                                    bool aNotify) {
+  auto* text = mTextNode.get();
+  uint32_t oldLength = aNotify ? 0 : text->TextLength();
+  text->SetText(aValue, aNotify);
+  if (!aNotify) {
+    // We can't notify during Reflow so we need to tell the text frame about the
+    // text content change we just did.
+    if (auto* textFrame = static_cast<nsTextFrame*>(text->GetPrimaryFrame())) {
+      textFrame->NotifyNativeAnonymousTextnodeChange(oldLength);
+    }
+    if (LinesBegin() != LinesEnd()) {
+      AddStateBits(NS_BLOCK_NEEDS_BIDI_RESOLUTION);
+      LinesBegin()->MarkDirty();
+    }
+  }
+  mCropped = aIsCropped;
+}
+
+void MiddleCroppingBlockFrame::UpdateDisplayedValueToUncroppedValue(
+    bool aNotify) {
+  nsAutoString value;
+  GetUncroppedValue(value);
+  UpdateDisplayedValue(value, /* aIsCropped = */ false, aNotify);
+}
+
+nscoord MiddleCroppingBlockFrame::GetMinISize(gfxContext* aRenderingContext) {
+  nscoord result;
+  DISPLAY_MIN_INLINE_SIZE(this, result);
+
+  // Our min inline size is our pref inline size
+  result = GetPrefISize(aRenderingContext);
+  return result;
+}
+
+nscoord MiddleCroppingBlockFrame::GetPrefISize(gfxContext* aRenderingContext) {
+  nscoord result;
+  DISPLAY_PREF_INLINE_SIZE(this, result);
+
+  nsAutoString prevValue;
+  bool restoreOldValue = false;
+
+  // Make sure we measure with the uncropped value.
+  if (mCropped && mCachedPrefISize == NS_INTRINSIC_ISIZE_UNKNOWN) {
+    mTextNode->GetNodeValue(prevValue);
+    restoreOldValue = true;
+    UpdateDisplayedValueToUncroppedValue(false);
+  }
+
+  result = nsBlockFrame::GetPrefISize(aRenderingContext);
+
+  if (restoreOldValue) {
+    UpdateDisplayedValue(prevValue, /* aIsCropped = */ true, false);
+  }
+
+  return result;
+}
+
+bool MiddleCroppingBlockFrame::CropTextToWidth(gfxContext& aRenderingContext,
+                                               nscoord aWidth,
+                                               nsString& aText) const {
+  if (aText.IsEmpty()) {
+    return false;
+  }
+
+  RefPtr<nsFontMetrics> fm = nsLayoutUtils::GetFontMetricsForFrame(this, 1.0f);
+
+  // see if the text will completely fit in the width given
+  if (nsLayoutUtils::AppUnitWidthOfStringBidi(aText, this, *fm,
+                                              aRenderingContext) <= aWidth) {
+    return false;
+  }
+
+  DrawTarget* drawTarget = aRenderingContext.GetDrawTarget();
+  const nsDependentString& kEllipsis = nsContentUtils::GetLocalizedEllipsis();
+
+  // see if the width is even smaller than the ellipsis
+  fm->SetTextRunRTL(false);
+  const nscoord ellipsisWidth =
+      nsLayoutUtils::AppUnitWidthOfString(kEllipsis, *fm, drawTarget);
+  if (ellipsisWidth >= aWidth) {
+    aText = kEllipsis;
+    return true;
+  }
+
+  // determine how much of the string will fit in the max width
+  nscoord totalWidth = ellipsisWidth;
+  const Span text(aText);
+  intl::GraphemeClusterBreakIteratorUtf16 leftIter(text);
+  intl::GraphemeClusterBreakReverseIteratorUtf16 rightIter(text);
+  uint32_t leftPos = 0;
+  uint32_t rightPos = aText.Length();
+  nsAutoString leftString, rightString;
+
+  while (leftPos < rightPos) {
+    Maybe<uint32_t> pos = leftIter.Next();
+    Span chars = text.FromTo(leftPos, *pos);
+    nscoord charWidth =
+        nsLayoutUtils::AppUnitWidthOfString(chars, *fm, drawTarget);
+    if (totalWidth + charWidth > aWidth) {
+      break;
+    }
+
+    leftString.Append(chars);
+    leftPos = *pos;
+    totalWidth += charWidth;
+
+    if (leftPos >= rightPos) {
+      break;
+    }
+
+    pos = rightIter.Next();
+    chars = text.FromTo(*pos, rightPos);
+    charWidth = nsLayoutUtils::AppUnitWidthOfString(chars, *fm, drawTarget);
+    if (totalWidth + charWidth > aWidth) {
+      break;
+    }
+
+    rightString.Insert(chars, 0);
+    rightPos = *pos;
+    totalWidth += charWidth;
+  }
+
+  aText = leftString + kEllipsis + rightString;
+  return true;
+}
+
+void MiddleCroppingBlockFrame::Reflow(nsPresContext* aPresContext,
+                                      ReflowOutput& aDesiredSize,
+                                      const ReflowInput& aReflowInput,
+                                      nsReflowStatus& aStatus) {
+  // Restore the uncropped value.
+  nsAutoString value;
+  GetUncroppedValue(value);
+  bool cropped = false;
+  while (true) {
+    UpdateDisplayedValue(value, cropped, false);  // update the text node
+    AddStateBits(NS_BLOCK_NEEDS_BIDI_RESOLUTION);
+    LinesBegin()->MarkDirty();
+    nsBlockFrame::Reflow(aPresContext, aDesiredSize, aReflowInput, aStatus);
+    if (cropped) {
+      break;
+    }
+    nscoord currentICoord = aReflowInput.mLineLayout
+                                ? aReflowInput.mLineLayout->GetCurrentICoord()
+                                : 0;
+    const nscoord availSize = aReflowInput.AvailableISize() - currentICoord;
+    const nscoord sizeToFit = std::min(aReflowInput.ComputedISize(), availSize);
+    if (LinesBegin()->ISize() > sizeToFit) {
+      // The value overflows - crop it and reflow again (once).
+      if (CropTextToWidth(*aReflowInput.mRenderingContext, sizeToFit, value)) {
+        nsBlockFrame::DidReflow(aPresContext, &aReflowInput);
+        aStatus.Reset();
+        MarkSubtreeDirty();
+        AddStateBits(NS_BLOCK_NEEDS_BIDI_RESOLUTION);
+        mCachedMinISize = NS_INTRINSIC_ISIZE_UNKNOWN;
+        mCachedPrefISize = NS_INTRINSIC_ISIZE_UNKNOWN;
+        cropped = true;
+        continue;
+      }
+    }
+    break;
+  }
+}
+
+nsresult MiddleCroppingBlockFrame::CreateAnonymousContent(
+    nsTArray<ContentInfo>& aContent) {
+  auto* doc = PresContext()->Document();
+  mTextNode = new (doc->NodeInfoManager()) nsTextNode(doc->NodeInfoManager());
+  // Update the displayed text to reflect the current element's value.
+  UpdateDisplayedValueToUncroppedValue(false);
+  aContent.AppendElement(mTextNode);
+  return NS_OK;
+}
+
+void MiddleCroppingBlockFrame::AppendAnonymousContentTo(
+    nsTArray<nsIContent*>& aContent, uint32_t aFilter) {
+  aContent.AppendElement(mTextNode);
+}
+
+void MiddleCroppingBlockFrame::Destroy(DestroyContext& aContext) {
+  aContext.AddAnonymousContent(mTextNode.forget());
+  nsBlockFrame::Destroy(aContext);
+}
+
+}  // namespace mozilla