Kyle, Thank you very much, that was what I needed to know!!
- Johannes On Sun, Aug 10, 2008 at 8:09 PM, Kyle Sluder <[EMAIL PROTECTED]> wrote: > On Fri, Aug 8, 2008 at 9:52 AM, Johannes Fahrenkrug > <[EMAIL PROTECTED]> wrote: >> I'd like to display placeholder images until the table cell gets >> displayed and then load the actual thumbnail, replacing the >> placeholder image with the real thumbnail once it has loaded. >> What would be the best way to do this? I'm thinking of something on >> the lines of a proxy object... > > Are you using the NSTableView data source API? I think that would be > easier for what you want to do. I'd create a placeholder NSImage at > first, and when I'm asked for the data for my NSImage column, if I > haven't yet finished downloading the image for that particular row, > give the NSTableView my placeholder image. Then, once the image has > finished downloading, call [myTableView > setNeedsDisplayInRect:NSIntersectionRect([myTableView > rectForColumn:indexOfImageColumn], [myTableView > rectForRow:rowOfUpdatedItem])]. > > Remember that the rows of an NSTableView don't actually exist as one > large dataset, so there isn't a one-to-one table cell to NSCell > correspondence. Instead, each NSTableColumn has its own cell, that it > uses like a rubber stamp. When a region of the table is marked as > dirty (setNeedsDisplay:/setNeedsDisplayInRect:), the table view > figures out which columns are affected, and tells them to draw > themselves. Each column then asks for the data for each table cell > that needs to be redrawn, and passes this value off to the NSCell > assigned to that column, which does the real drawing. > > So your image column has an NSImageCell. When you start scrolling, > the NSTableView figures out which logical row and column numbers have > just been revealed by your scrolling maneuver, and kicks off the above > process. Your data source is asked "alright, row 12 column 2 needs to > be painted, gimme the data", and then hands that data off to the cell > belonging to the column. The dirty little secret is that from the > table view's perspective, there aren't actually any rows at all; it > just does a bunch of math based on where the scroll point is located > to convert graphics coordinates to logical rows. Your data source is > none the wiser. > > --Kyle Sluder > -- http://blog.springenwerk.com _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
