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Investigation: inconclusive further research (context_save/restore)

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Indeed I had missed to connect the new "free standing" StyleContext to
some Gdk::Screen, typically the default screen (connected to the current
top level window). But seemingly this was not really necessary, since,
somehow magically, the style context must have connected itself to some
screen, otherwise it wouldn't be able to access the CSS cascade.

Anyhow, fixing this omission does not resolve our problem.
Nor does any combination of re-connecting, invalidating etc.

I poked around in the GTK (C) code a lot, but could not spot any obvious
missing initialisation step. To much magic around here. Without massive
debugging into GTK internals, I don't see any way to further this
investigation. And, moreover there is a viable workaround
(namely to set and remove the classes explicitly, which works as intended)

I posted a question on Stackoverflow and for now
I'll file this topic as "inconclusive"
https://stackoverflow.com/q/57342478
This commit is contained in:
Fischlurch 2019-08-03 23:26:37 +02:00
parent ec3c49f612
commit 7bf7c51375
4 changed files with 65 additions and 7 deletions
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13
research/gtk-style-experiment.cpp
View file

@ -44,6 +44,7 @@
#include "lib/error.hpp"
#include "lib/util.hpp"
#include <gtk/gtk.h> ////////////////////TODO WIP
#include <string>
using util::cStr;
@ -218,6 +219,7 @@ namespace research {
Gtk::WidgetPath path = srcWidget.get_path();
PStyleContext style = Gtk::StyleContext::create();
style->set_screen(Gdk::Screen::get_default());
style->set_path(path);
// style->add_class(slopeClassName(2));
return style;
@ -317,8 +319,14 @@ namespace research {
{
int marT = style_->get_margin().get_top();
auto path = style_->get_path();
if (xBorderSiz > 1) {
style_->context_save();
// style_->invalidate();
// style_->context_save();
// style_->set_screen(Gdk::Screen::get_default());
// style_->set_path(path);
// style_->invalidate();
style_->add_class(slopeClassName(xBorderSiz));
}
@ -335,7 +343,8 @@ namespace research {
);
if (xBorderSiz > 1) {
style_->context_restore();
// style_->context_restore();
style_->remove_class(slopeClassName(xBorderSiz));
}
}
//////////////////TEST drawing via Gtk::StyleContext

4
src/stage/timeline/body-canvas-widget.cpp
View file

@ -219,7 +219,7 @@ namespace timeline {
void
close (uint n) override
{
// style_->context_save();
// style_->context_save(); // <<<---does not work. Asked on SO: https://stackoverflow.com/q/57342478
style_->add_class (slopeClassName(n));
style_->invalidate();
int slopeWidth = style_->get_border().get_bottom();
@ -235,8 +235,8 @@ namespace timeline {
,visible_.b
,visible_.e
);
// style_->context_restore(); // <<<---does not work...
style_->remove_class (slopeClassName(n));
// style_->context_restore();
line_ += slopeWidth;
}

1
src/stage/workspace/ui-style.cpp
View file

@ -139,6 +139,7 @@ namespace workspace {
for (int i=0; i<pos; ++i) // reset any state flags accidentally set (resulting in pseudo classes like ":backdrop")
gtk_widget_path_iter_set_state(path.gobj(), i, GTK_STATE_FLAG_NORMAL);
PStyleContext style = Gtk::StyleContext::create(); // create a new style context and configure it according to the path defined thus far
style->set_screen(Gdk::Screen::get_default());
style->set_path (path);
styleAdviceTrackBody_.setAdvice (style); // publish as Advice "style(trackBody)"
INFO (stage, "Body-CSS: path=%s", util::cStr (path.to_string())); ////////////////////////TICKET #1201 : this yields "paned:dir-ltr.horizontal box:dir-ltr.vertical TrackScope.timeline"

54
wiki/thinkPad.ichthyo.mm
View file

@ -23026,10 +23026,58 @@
<icon BUILTIN="idea"/>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1564841527588" ID="ID_1377435126" MODIFIED="1564841582490" TEXT="TODO: Untersuchung context_save() auf einem kopierten / frei konstruierten StyleContext">
<icon BUILTIN="flag-yellow"/>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1564841527588" ID="ID_1377435126" MODIFIED="1564868164039" TEXT="Untersuchung context_save() auf einem kopierten / frei konstruierten StyleContext">
<icon BUILTIN="pencil"/>
<node CREATED="1564868166273" ID="ID_945377761" MODIFIED="1564868267923" TEXT="kann das problematische Verhalten reproduzieren">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
Wenn man einen neuen Gtk::StyleContext erzeugt,
</p>
<p>
und (wie in der Doku beschrieben) den path und den screen manuell setzt,
</p>
<p>
dann f&#252;hrt ein context_save() dazu, da&#223; pl&#246;tzlich die CSS-Werte auf Defaults zur&#252;ckspringen
</p>
</body>
</html>
</richcontent>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1564841584180" ID="ID_1444331441" MODIFIED="1564841601195" TEXT="TODO: Untersuchung wie box-shadow gerendert wird">
<node CREATED="1564868280687" ID="ID_593595518" MODIFIED="1564871156101" TEXT="es hilft nichts, wenn man den Screen (nochmal) setzt">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
und ja, den Screen sollte man generell setzten.<br />Steht auch so in der Doku.
</p>
<p>
</p>
<p>
Allerdings hat es bisher auch ohne das bei mir funktioniert.
</p>
</body>
</html>
</richcontent>
<icon BUILTIN="broken-line"/>
</node>
<node CREATED="1564868338325" ID="ID_1826179725" MODIFIED="1564871159899" TEXT="es hilft nichts, wenn man den Pfad erneut setzt">
<icon BUILTIN="broken-line"/>
</node>
<node CREATED="1564868348236" ID="ID_1509661918" MODIFIED="1564871163619" TEXT="es hilft nichts, wenn man den Context invalidiert">
<icon BUILTIN="broken-line"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1564871053125" HGAP="30" ID="ID_1611854805" LINK="https://stackoverflow.com/q/57342478/444796" MODIFIED="1564871092888" TEXT="habe auf Stackoverflow gefragt" VSHIFT="16">
<icon BUILTIN="hourglass"/>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1564841584180" ID="ID_1444331441" MODIFIED="1564866024773" TEXT="TODO: Untersuchung wie box-shadow gerendert wird">
<icon BUILTIN="flag-yellow"/>
</node>
</node>