diff options
Diffstat (limited to 'devdoc')
| -rw-r--r-- | devdoc/dw-size-request-pos.doc | 85 |
1 files changed, 62 insertions, 23 deletions
diff --git a/devdoc/dw-size-request-pos.doc b/devdoc/dw-size-request-pos.doc index dc497d00..32cc3089 100644 --- a/devdoc/dw-size-request-pos.doc +++ b/devdoc/dw-size-request-pos.doc @@ -6,6 +6,10 @@ dw-widget-sizes, \ref dw-grows, and **Size requisitions depending on positions** (this document). </div> +<div style="border: 2px solid #ff4040; margin: 1em 0; + padding: 0.5em 1em; background-color: #fff0f0"><b>Info:</b> + May not be up to date, needs a review.</div> + Motivation ========== @@ -23,32 +27,57 @@ General Idea A widget size may depend on the position relative to an anchestor widget. If a widget wants to get the size of a child widget, it should -1. call the new method dw::core::Widget::sizeRequestReference, - which returns NULL, when the child's size does not depend on the - position, or a widget relative to which the child's position must - be calculated; -2. call dw::core::Widget::sizeRequest with the position relative to - this widget. +1. call the new methods dw::core::Widget::numSizeRequestReferences and + dw::core::Widget::sizeRequestReference, which return all widgets + relative to which the child's position must be calculated; +2. call dw::core::Widget::sizeRequest with the positions relative to + these widgets. -The position passed to dw::core::Widget::sizeRequest must be the -position at which this child will be allocated. +All positions passed to dw::core::Widget::sizeRequest must costitute +the position at which this child will be allocated. There are situations where the parent widget is unable to determine -this position before the size is known. An example: a textblock widget -cannot determine the position of an inline widget (like an image, or -an inline block) before the line is finished; on the other hand, -finishing the line depends on knowing the sizes of the inline widgets. - -This may result in a conflict, when the size of an inline widgets -depends on the position. Fortunately, this is not the case in dillo: -the only widget whose size depends on the position is dw::Textblock -(the size will depend on the position within its floats container); but -an inline blocks constitute its own floats container, so that there is -no dependance on a position within another widget. - -Generally, this case should be handled by providing a fallback -strategy. (TODO: How does this look like? The widget is forced to -calculate its size independant of the position?) +these positions before the size is known. An example: a textblock +widget cannot determine the positions of an inline widget (like an +image, or an inline block) before the line is finished; on the other +hand, finishing the line depends on knowing the sizes of the inline +widgets. + +This may result in a conflict, when the size of an inline widget +depends on positions. Generally, the only widget whose size depends on +positions is dw::Textblock (the size will depend on the positions +within its oof container, see \ref dw-out-of-flow), so this conflict +occurs with inline blocks. + +This conflict is handled in different ways: + +1. Fortunately, this case is irrelevat for floats: an inline blocks + constitute its own floats container, so that there is no dependance + on a position within another widget. + +2. For positioned elements, this case is relevant, since an inline + block is in most cases not a container for positioned element. In + this case, a generator will call the methods + dw::oof::OutOfFlowMgr::tellIncompletePosition1 and + dw::oof::OutOfFlowMgr::tellIncompletePosition2, instead of + dw::oof::OutOfFlowMgr::tellPosition and + dw::oof::OutOfFlowMgr::tellPosition2, respectively. (Since this + case is irrelevant for floats, + dw::oof::OOFFloatsMgr::tellIncompletePosition1 and + dw::oof::OOFFloatsMgr::tellIncompletePosition2 are not implemented but + simply abort.) + +(This is not (yet) considered for borders: borders are only relevant +for floats, but conflicts do not occur for floats.) + + +Extremes +-------- +Extremes may depend on the position in an analogue way, see: + +- dw::core::Widget::numGetExtremesReferences, +- dw::core::Widget::getExtremesReference, and +- dw::core::Widget::getExtremes. Resizing -------- @@ -102,4 +131,14 @@ Plan 6. Implement step 3 for positioned elements (affects only dw::oof:OOFPositionedMgr). *INCOMPLETE.* + +Issues +====== + +- Since the signature of dw::core::Widget::sizeRequestImpl changes + quite often during the development of *size requisitions depending + on positions*, a simpler option dw::core::Widget::sizeRequestSimpl + has been added. May be removed again, after the design is stable. + + */ |