From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED.3d73Ybk3C5U4I2t8lv+lAQ.user.gioia.aioe.org!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: GtkAda Scrollbars Date: Mon, 30 Dec 2019 11:58:37 +0100 Organization: Aioe.org NNTP Server Message-ID: References: <5e01bff5$0$18422$e4fe514c@news.kpn.nl> NNTP-Posting-Host: 3d73Ybk3C5U4I2t8lv+lAQ.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 Content-Language: en-US X-Notice: Filtered by postfilter v. 0.9.2 Xref: reader01.eternal-september.org comp.lang.ada:57772 Date: 2019-12-30T11:58:37+01:00 List-Id: On 2019-12-30 11:09, L Dries wrote: > Op 25-12-2019 om 17:49 schreef Dmitry A. Kazakov: >> On 2019-12-24 08:36, L Dries wrote: >> >>> I am trying to create a program using a "drawingarea". In some cases >>> the drawing is to large for the window so I want to use scrollbars >>> but I can get these correct. >> >> Gtk_Drawing_Area must process the event "draw" in order to redraw >> itself according to the allocation area and the current cairo context. >> Moving sliders of the scrolled window would ultimately send "draw" >> down to its drawing area child. >> >> For an example of using Gtk_Drawing_Area for drawing various shapes >> see AICWL: >> >>     http://www.dmitry-kazakov.de/ada/aicwl.htm >> >> The base type for all instruments is Gtk_Layered_Record derived from >> Gtk_Drawing_Area_Record. >> >> Merry Christmas! >> > I cannot find any reference in this answer to the problem I have because > for instance the scrollbars cannot move if even shown. That is likely because it has the size less than the client area of the scroll window. The parent widget queries its children for the desirable size. See Get_Request_Mode Get_Preferred_Height Get_Preferred_Height_For_Width etc You might wish to override them for your widget derived from drawing area because the default behavior is that the parent tells the child what the size must be. There are variations from any size, minimal size up to fixed size. Finally, at the end of the size negotiation process you get the signal "size_allocate" which tells the widget about its final size (until first resize). There you can allocate memory, prepare other size-dependent stuff etc. See the Height-for-width Geometry Management section in https://developer.gnome.org/gtk3/stable/GtkWidget.htm for detailed information how the widget size is maintained. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de