Widgets depending on each other

StefanSalewski · June 1, 2019, 9:21am

Fixing the issue from

StefanSalewski/gintro/blob/master/examples/drawingarea.nim

# Plain demo for zooming, panning, scrolling with GTK DrawingArea
# (c) S. Salewski, 21-DEC-2010 (initial Ruby version)
# Nim version April 2019
# License MIT

# This version of the demo program uses a separate proc paint()
# which allocates a custom surface for buffered drawing.
# That may be not really necessary, for simple drawings doing all
# the drawing in the "draw" call back is easier and faster. But for
# more complicated drawing operations, for example when using a
# background grid, which is a bit larger than the window size and
# is reused when scrolling, a custom surface may be useful.
# And finally that custom surface and custom cairo context is an
# important test for the language bindings.

import gintro/[gtk, gdk, glib, gobject, gio, cairo]

const
  ZoomFactorMouseWheel = 1.1
  ZoomFactorSelectMax = 10 # ignore zooming in tiny selection

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may be not that easy as expected.

It is clear that calling setValue() on Scrollbar-Adjustment from within configure-callback of drawing-area may not be a good idea, as the scrollbars are currently resizing and not accept new value. But on the other hand, I can not just use a own configure-callback for the scrollbars, as setvalue() may then be executed too early. SetValue() for scrollbars receives new size of drawingArea, so it has to be executed after drawingArea is resizes. So all that is not that easy, and such interactions are generally not covered by tutorials or the Krause book.

Maybe I have to emit a custom signal for this interaction?

system · June 15, 2019, 9:21am

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