FastTable question

Hi,

Sorry late response but yesterday I was not around.


> On 20 Oct 2015, at 18:42, stepharo <[hidden email]> wrote:
>
> for the mooc videos I must use larger fonts.
> So I ended up hacking and changing the hardcoded number in default
>
> defaultRowHeight
>    ^ 24
>
> rowHeight
>    "This is the row height your rows will have. Cells answered in dataSource will be forced to have
>     this height number... We force it instead allowing lists to have any height because the logic to
>     calculate rows becomes complicated. Possible, but complicated :)"
>
>    ^ rowHeight ifNil: [ self class defaultRowHeight ]
>
>
> Esteban two questions:
>
> - when I read the code of FTmorph I was thinking that a lot of it has not much to do with UI but looks like a model :).

this is not a question :)
in the case of rowHeight, it determines how the row looks (and not what it shows) then is UI (IMO)… anyway I’m aware this is not 100% MVC but knowing the height of rows is very important to calculate in a fast way how many rows fit and get the rows from datasource (an operation that happens a lot so is convenient to have it as fast as possible (at least in a “fast table”).
this do not supports variable height but that can be achieved by extending the table without compromising the performance of the parent(just very few use-cases need a variable height table).

>
> - if I were about to manage the height of a row based on its actual contents where should I put it.

as described, you need to extend the functionality, this is not supported in current version (reason already explained).
For me, to support this you need to extend:

- rowHeight should be rowHeightFor: index
- visibleRows and around need to take first visible row height, then iterate one by one asking for the each row size.
- datasource needs to be extended with “rowHeight: index”

> FTTableContainerMorph is containing what is visible but I wonder why it was asking this to the FastTable and to the elements displayed?

explained above: speed needs.

>
> Why the ContainerMorph does not ask the FTTableRowMorph for its height and it could be computed based on the font.
> I still did not get where the strings built.

I didn’t thought about, that’s why is not calculating font size :)
Also… I cannot know your table will contain text… that’s a task for the datasource, then (to answer appropriate row height)… but it needs to be fast! :)

Esteban

>
>
> may be here
>
> updateExposedRows
>
>    ...
>
>    | cell |
>            cell := (self owner dataSource
>                cellColumn: (columns at: columnIndex)
>                row: rowIndex).
>            cell width: (columnWidths at: columnIndex).
>
> We should add more comments to methods.
>
>
> Stef
>
>
>
> drawOn: canvas
>    | x y cellWidth cellHeight rowsToDisplay rowSubviews highligtedRowIndexes primarySelectionIndex |
>
>    self bounds ifNil: [ ^ self ]. "Nothing to show yet"
>    self owner ifNil: [ ^ self ].
>
>    x := self left + self class rowLeftMargin.
>    y := self top.
>    cellWidth := self width - self class rowLeftMargin.
>    cellHeight := self owner rowHeight.
>                    ^^^^^^^^^^^^^^^^^^^^^^^
>
>    highligtedRowIndexes :=
>        self owner selectedRowIndexes,
>        self owner highlightedRowIndexes.
>    primarySelectionIndex := self owner selectedRowIndex.
>
>    "For some superweird reason, calling #calculateExposedRows here instead in #changed (where
>     it should be called) is 10x faster. Since the whole purpose of this component is speed, for
>     now I'm calling it here and adding the #setNeedRecalculateRows mechanism.
>     History, please forgive me."
>    self updateAllRows.
>
>    rowsToDisplay := self exposedRows.
>    rowSubviews := OrderedCollection new: rowsToDisplay size + 1.
>    headerRow ifNotNil: [
>        headerRow bounds: (x@y extent: cellWidth@cellHeight).
>        y := y + cellHeight + self owner intercellSpacing.
>        rowSubviews add: headerRow ].
>
>    rowsToDisplay keysAndValuesDo: [ :rowIndex :row | | visibleHeight |
>        visibleHeight := cellHeight min: (self bottom - y).
>        row bounds: (x@y extent: cellWidth@visibleHeight).
>        y := y + visibleHeight + self owner intercellSpacing.
>        rowSubviews add: ((highligtedRowIndexes includes: rowIndex)
>            ifTrue: [
>                "IMPORTANT: I need to set owner to nil because otherwise it will trigger an
>                 invalidation of the owner when adding morph to selectionMorph, causing an
>                 infinite loop"
>                self
>                    toSelectionRow: (row privateOwner: nil)
>                    primary: primarySelectionIndex = rowIndex ]
>            ifFalse: [ row ]) ].
>
>    submorphs := rowSubviews asArray.
>    super drawOn: canvas.
>    needsRefreshExposedRows := false
>