18 Jul
2014
18 Jul
'14
10:34 a.m.
Hi,
Sometimes we have to show large text files and Pharo takes some time to get
their contents and display them. In a Glamour browser, for example, the
user would click and then wait for a few seconds before he'll get the
desired results. In such cases, it will be useful to show the user a
certain text in the text presentation, and once the contents of the file
are available, the presentation updates itself with it (something on the
lines of Cursor>>showWhile:)
Conceptually, with Glamour this can be achieved in two ways: triggering two
transmissions for the text display pane and updating the text presentation
when file contents are available.
Triggering transmission (or placing values manually in entity/selection
ports) means that if the pane contains multiple presentations, each one
will get affected the "delayed" behaviour even when there is none.
Updating the text presentation is better suited. Something like:
| tab textDisplayBlock|
tab := GLMTabulator new.
tab title: 'Playing with huge text files'.
tab column: #list span: 0.5; column:[:c | c row: #code; row: #details].
textDisplayBlock := [ :each | 'Loading file ...' ].
tab transmit to:#list; andShow: [:a |
a list display: #yourself].
tab transmit to:#code; from:#list; andShow: [:a |
a rubricText
display: textDisplayBlock.
a roassal2 painting: [ :view :entity | view add: (((RTBox new color: Color
red) + RTLabel) elementOn: entity) ]
].
tab transmit to:#details; from:#list; andShow: [:a |
a rubricText
display: #yourself.
].
tab openOn: RubLipsumBasicExample selectors.
"I just displayed text presentation, you can provide me the alternate block"
textDisplayBlock:= [:each | (RubLipsumBasicExample sourceCodeAt: each)].
tab update.
But this has to be done with Announcements not to introduce a specific
delay each time and outside browser interpretation loop so that the pane is
visible during the file reading operation. I haven't found so far how to
change the display behaviour of a presentation from an announcement raised
by an object outside the browser/presentation like:
on: FileContentsAvailable do: [block := textDisplayBlock:= [:each |
(RubLipsumBasicExample sourceCodeAt: each)]. browser update]
So my questions: am I trying achieve something glamour does not support
(yet)? Can we add a generic showWhile: mechanism for Glamour textual
presentations without too much effort? Or there is a simple way to achieve
it that I don't see?
tx,
usman