| | 1 | |
| | 2 | = contain-intrinsic-size = |
| | 3 | |
| | 4 | Per [1], |
| | 5 | > These properties allow elements with size containment to specify an explicit intrinsic inner size, causing the box to size as if its in-flow content totals to a width and height matching the specified explicit intrinsic inner size (rather than sizing as if it were empty). |
| | 6 | |
| | 7 | The implementation is roughly split into two parts: |
| | 8 | * Get the size from the contain-intrinsic-* properties as an explicit intrinsic inner size. |
| | 9 | * Make the sizecontainment box sizing as if its content is the explicit intrinsic inner size. |
| | 10 | |
| | 11 | == The explicit intrinsic inner size == |
| | 12 | The part has landed in [2]. |
| | 13 | * Added `explicitIntrinsicInnerLogicalWidth/Height()` to RenderBox.h, it gets the value of `contain-intrinsic-*` from RenderStyle. |
| | 14 | * To handle the logicalWidth, in `computeIntrinsicLogicalWidths`, the intrinsic size of sizeContainment was zero, now it is explicitIntrinsicInnerLogicalWidth() if existing. We need to handle every `computeIntrinsicLogicalWidths()` in the code. |
| | 15 | * To handle the logicalWidth, in `updateLogicalHeight()`, sizeContainment was treated as if there is no content, now it added explicitIntrinsicInnerLogicalHeight() if existing. |
| | 16 | == The size from the contain-intrinsic-* properties == |
| | 17 | === Value `none` and value `length` === |
| | 18 | These two values are simple, for `none`, there is nothing to do, for `length`, we need to set the value to RenderStyle. |
| | 19 | === Value `auto length` === |
| | 20 | The explicit intrinsic inner size is its last remembered size if any, if no, then it is the value of `length`. |
| | 21 | ==== The last remembered size ==== |
| | 22 | Per [3], the last remembered size is the size when the element is not size-contained. The value is determined when ResizeObserver events are determined and delivered. |
| | 23 | * The last remembered size is related to Element, we add `RefPtr<ResizeObserverSize> m_lastRememberedSize` to `ElementRareData`. See the implementation in [4]. |
| | 24 | * Create a ResizeObserver to handle the last remembered size. See the implementation in [5]. |
| | 25 | - To create a specific ResizeObserver, we need to create a callback to handle the last remembered size, it is `CallbackForContainIntrinsicSize`, which removes or saves LastRememberedSize to the target. |
| | 26 | - Document will create and own `m_resizeObserverForContainIntrinsicSize` if there is an element with `contain-intrinsic-size: auto length`. |
| | 27 | - In `RenderTreeUpdater::updateElementRenderer`, it will observe the element if it is with `contain-intrinsic-size: auto length`, if not unobserve it. |
| | 28 | - When `deliverResizeObservations`, the LastRememberedSize will be saved. |
| | 29 | |
| | 30 | |
| | 31 | [1] https://w3c.github.io/csswg-drafts/css-sizing-4/#intrinsic-size-override\\ |
| | 32 | [2] https://github.com/WebKit/WebKit/pull/1799\\ |
| | 33 | [3] https://w3c.github.io/csswg-drafts/css-sizing-4/#last-remembered\\ |
| | 34 | [4] https://github.com/WebKit/WebKit/pull/7375\\ |
| | 35 | [5] https://github.com/WebKit/WebKit/pull/7829\\ |
