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Issue 2850893003:
Add container_block_offset,top_offset to NGFloatingObject. (Closed)
| Index: third_party/WebKit/Source/core/layout/ng/ng_floating_object.h |
| diff --git a/third_party/WebKit/Source/core/layout/ng/ng_floating_object.h b/third_party/WebKit/Source/core/layout/ng/ng_floating_object.h |
| index 619f9cf4c670d2e556b25b3dbf66708ee0bdb714..4c49a5be69e2a6aa5e5e2a988332c1bc37c5dfd7 100644 |
| --- a/third_party/WebKit/Source/core/layout/ng/ng_floating_object.h |
| +++ b/third_party/WebKit/Source/core/layout/ng/ng_floating_object.h |
| @@ -40,7 +40,7 @@ struct CORE_EXPORT NGFloatingObject : public RefCounted<NGFloatingObject> { |
| // NGLayoutOpportunityIterator to position this floating object. |
| NGLogicalSize available_size; |
| - // To correctly position a float we need 2 offsets: |
| + // To correctly **position** a float we need 2 offsets: |
| // - origin_offset which represents the layout point for this float. |
| // - from_offset which represents the point from where we need to calculate |
| // the relative logical offset for this float. |
| @@ -51,6 +51,31 @@ struct CORE_EXPORT NGFloatingObject : public RefCounted<NGFloatingObject> { |
| NGLogicalOffset origin_offset; |
| NGLogicalOffset from_offset; |
| + // To correctly **paint** a float we need to know the BFC offset of the |
| + // container to which we are attaching this float. It's used to calculate |
| + // {@code left_offset}, {@code top_offset}. |
| + // In most situations {@code (left|top)_offset} equals to float's logical |
| + // offset except the cases where a float needs to be re-attached to a non-zero |
| + // height parent. |
| + // |
| + // Example: |
| + // <body> |
| + // <p style="height: 60px">Example</p> |
| + // <div id="zero-height-div"><float></div> |
| + // |
| + // Here the float's logical offset is 0 relative to its #zero-height-div |
| + // parent. Because of the "zero height" div this float is re-attached to the |
| + // 1st non-empty parent => body. To paint this float correctly we provide the |
| + // modified {@code (top|left)_offset} which is relative to the float's new |
| + // parent. |
| + // I.e. for our example {@code top_offset} == #zero-height-div's BFC offset |
| + // - body's BFC offset + float's logical offset |
| + // |
| + // For code safety reasons {@code container_block_offset} is Optional here |
| + // because the block's offset can be only determined before the actual float's |
| + // placement event. |
| + WTF::Optional<LayoutUnit> container_block_offset; |
| + |
| // Calculated logical offset. It's never {@code nullopt} for a positioned |
| // float. |
| WTF::Optional<NGLogicalOffset> logical_offset; |
| @@ -68,6 +93,7 @@ struct CORE_EXPORT NGFloatingObject : public RefCounted<NGFloatingObject> { |
| // {@code left_offset} is calculated when we know to which parent this float |
| // would be attached. |
|
ikilpatrick
2017/05/01 17:48:32
does this comment block need to be updated?
|
| LayoutUnit left_offset; |
| + LayoutUnit top_offset; |
| bool IsLeft() const { return exclusion_type == NGExclusion::kFloatLeft; } |
