Bug 1615142 - Fix triple-click selection on pre-formatted text. r=mats

We need to check for terminal new-lines on ourselves before looking at our next
sibling frame.

Differential Revision: https://phabricator.services.mozilla.com/D62766

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

layout/generic/nsFrame.cpp

@@ -183,8 +183,8 @@ struct nsBoxLayoutMetrics {
 };
 
 struct nsContentAndOffset {
-  nsIContent* mContent;
-  int32_t mOffset;
+  nsIContent* mContent = nullptr;
+  int32_t mOffset = 0;
 };
 
 // Some Misc #defines
@@ -8461,21 +8461,39 @@ nsIFrame::CaretPosition nsIFrame::GetExtremeCaretPosition(bool aStart) {
   return result;
 }
 
+// If this is a preformatted text frame, see if it ends with a newline
+static nsContentAndOffset FindLineBreakInText(nsIFrame* aFrame,
+                                              nsDirection aDirection) {
+  nsContentAndOffset result;
+
+  if (aFrame->IsGeneratedContentFrame() ||
+      !aFrame->HasSignificantTerminalNewline()) {
+    return result;
+  }
+
+  int32_t startOffset, endOffset;
+  aFrame->GetOffsets(startOffset, endOffset);
+  result.mContent = aFrame->GetContent();
+  result.mOffset = endOffset - (aDirection == eDirPrevious ? 0 : 1);
+  return result;
+}
+
 // Find the first (or last) descendant of the given frame
 // which is either a block-level frame or a BRFrame, or some other kind of break
 // which stops the line.
 static nsContentAndOffset FindLineBreakingFrame(nsIFrame* aFrame,
                                                 nsDirection aDirection) {
   nsContentAndOffset result;
-  result.mContent = nullptr;
-  result.mOffset = 0;
 
-  if (aFrame->IsGeneratedContentFrame()) return result;
+  if (aFrame->IsGeneratedContentFrame()) {
+    return result;
+  }
 
   // Treat form controls as inline leaves
   // XXX we really need a way to determine whether a frame is inline-level
-  nsIFormControlFrame* fcf = do_QueryFrame(aFrame);
-  if (fcf) return result;
+  if (nsIFormControlFrame* fcf = do_QueryFrame(aFrame)) {
+    return result;
+  }
 
   // Check the frame itself
   // Fall through block-in-inline split frames because their mContent is
@@ -8497,12 +8515,8 @@ static nsContentAndOffset FindLineBreakingFrame(nsIFrame* aFrame,
     return result;
   }
 
-  // If this is a preformatted text frame, see if it ends with a newline
-  if (aFrame->HasSignificantTerminalNewline()) {
-    int32_t startOffset, endOffset;
-    aFrame->GetOffsets(startOffset, endOffset);
-    result.mContent = aFrame->GetContent();
-    result.mOffset = endOffset - (aDirection == eDirPrevious ? 0 : 1);
+  result = FindLineBreakInText(aFrame, aDirection);
+  if (result.mContent) {
     return result;
   }
 
@@ -8570,6 +8584,10 @@ nsresult nsIFrame::PeekOffsetParagraph(nsPeekOffsetStruct* aPos) {
         reachedBlockAncestor = true;
         break;
       }
+
+      // Try to find our own line-break before looking at our siblings.
+      blockFrameOrBR = FindLineBreakInText(frame, eDirNext);
+
       nsIFrame* sibling = frame->GetNextSibling();
       while (sibling && !blockFrameOrBR.mContent) {
         blockFrameOrBR = FindLineBreakingFrame(sibling, eDirNext);

layout/generic/test/test_selection_tripleclick.html

@@ -10,31 +10,52 @@
 
 <p id="b">Here's <span>some</span> <code><span>code</span><br><span>broken</span></code> with <span>text</span> with <code><span>code</span><br><span>broken</span></code> in <span>it and such</span> and so on</p>
 
+<pre id="c">Here's some text and
+some <span>more</span> code <span>with</span> pre-formatted
+whitespace <span>that</span> should be selected
+line <span>by</span> line</pre>
+
 <script>
   SimpleTest.waitForExplicitFinish();
+
+  function testTripleClick(elem, expectation) {
+    window.getSelection().removeAllRanges();
+    synthesizeMouse(elem, 5, 5, { clickCount: 3 });
+    is(window.getSelection().toString(), expectation);
+  }
+
   SimpleTest.waitForFocus(function () {
-    for (let child of document.querySelectorAll("#a span, #a code")) {
-      synthesizeMouse(child, 5, 5, { clickCount: 3 });
-      is(window.getSelection().toString(), "Some code with text with code in it");
-      window.getSelection().removeAllRanges();
+    for (let child of document.querySelectorAll("#a span, #a code"))
+      testTripleClick(child, "Some code with text with code in it");
+
+    {
+      let spans = document.querySelectorAll("#b span");
+      let expectations = [
+        "Here's some code", // First span, at the beginning of the text.
+        "Here's some code", // Top span in the inline-block, before break.
+        "broken with text with code", // Bottom span in inline-block, after break
+        "broken with text with code", // Center of the text.
+        "broken with text with code", // Top span in the second inline-block, before break.
+        "broken in it and such and so on", // Bottom span in the second inline-block, after break.
+        "broken in it and such and so on", // Last span, at the end of the text.
+      ];
+      is(spans.length, expectations.length);
+      for (let i = 0; i < expectations.length; ++i)
+        testTripleClick(spans[i], expectations[i]);
     }
 
-    let spans = document.querySelectorAll("#b span");
-    let expectations = [
-      "Here's some code", // First span, at the beginning of the text.
-      "Here's some code", // Top span in the inline-block, before break.
-      "broken with text with code", // Bottom span in inline-block, after break
-      "broken with text with code", // Center of the text.
-      "broken with text with code", // Top span in the second inline-block, before break.
-      "broken in it and such and so on", // Bottom span in the second inline-block, after break.
-      "broken in it and such and so on", // Last span, at the end of the text.
-
-    ];
-    is(spans.length, expectations.length);
-    for (let i = 0; i < expectations.length; ++i) {
-      synthesizeMouse(spans[i], 5, 5, { clickCount: 3 });
-      is(window.getSelection().toString(), expectations[i]);
-      window.getSelection().removeAllRanges();
+    {
+      testTripleClick(document.getElementById("c"), "Here's some text and");
+      let spans = document.querySelectorAll("#c span");
+      let expectations = [
+        "some more code with pre-formatted",
+        "some more code with pre-formatted",
+        "whitespace that should be selected",
+        "line by line",
+      ];
+      is(spans.length, expectations.length);
+      for (let i = 0; i < expectations.length; ++i)
+        testTripleClick(spans[i], expectations[i]);
     }
 
     SimpleTest.finish();