I think what Robert is saying is that the term "factor" usually refers to something that is multiplicative (you multiply by a factor of 0.5 for example), while something that you add/subtract is called something like an "offset".
On Mon, Jan 17, 2011 at 2:40 PM, Kees Kling <[email protected]> wrote: > Hi Robert, > > perhaps it is not the usual way to imic zooming, but when you reduce the > destination width and height the image becomes smaller and that is what I do > with substracting a factor. At startup the factor is always 0, so that > cannot cause the problem. I think that the prob lem lies more in the fact > that at the moment I want to display the image it is still not fully loaded > and I suspect that using the call "mage = > Gdk::Pixbuf::create_from_file("path and dir of picture); " a thread is > started to load te file. Not a problem, but I need to know when the thread > has finnished > > Thanks > > Kees > > > > Robert Pearce wrote: > > Hi Kees, > > On Mon, 17 Jan 2011 10:26:34 +0100 you wrote: > > > after the loading I display it with a queue_redraw and in the > expose_event handler it is displayed with > > image->scale_simple(image->get_width() - scaleFactor, > image->get_height() - scaleFactor, > > > Why on earth are you SUBTRACTING something called "factor"? > > > > Normally this goes well, but sometimes I get the error and crash of the > app The errmsg is : > GdkPixbuf-CRITICAL **: gdk_pixbuf_scale_simple: assertion `dest_width > > 0' failed. > > What is causing this error and how to avoid it?? > > > What's causing it is that you're passing a negative (or zero) width, > probably due to the way you're subtracting your scaleFactor. Without > seeing the rest of the code we can't possibly know what you're putting > in that variable, but if the name is anything like honest it's not > something you'd want to subtract. > > However, I wouldn't like to imply any certainty that the error is > related in any way to a "crash". > _______________________________________________ > gtkmm-list mailing > [email protected]http://mail.gnome.org/mailman/listinfo/gtkmm-list > > > > _______________________________________________ > gtkmm-list mailing list > [email protected] > http://mail.gnome.org/mailman/listinfo/gtkmm-list > >
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