Re: Rendering performance on custom text view on Gdk::Drawable

["ivar ." <ivarbug gmail com>]

As I tested TextView with Pixbufs, I noticed it's nearly as slow as my
example while flipping whole pages of lines on fast scrolling. On slow
scrolling, it looks like it's actually drawing only new lines, that
become visible while scrolling. Maybe it's Pango then, that can render
whole paragraphs of text really quickly.

On Tue, Jun 12, 2012 at 1:02 AM, ivar . <ivarbug gmail com> wrote:
> Cool, I'll see what I can do with the TextView.
>
> But still, it would be interesting to get my own rendering sorted aswell.
>
> I'm not good at reading pure C code, but It seems to me that, GTK+'s
> TextView is using Pango, which sounds pretty heavy, and is normally
> redrawing all the lines on scrolling(could be wrong on that one. a
> very brief skim). So I must be doing something very wrong.
>
> On Tue, Jun 12, 2012 at 12:26 AM, Giuseppe Penone <giuspen gmail com> wrote:
>> Hi,
>> It seems to me to understand that you are drawing a pixbuf per byte in a
>> drawing area.
>> In my opinion you should use a Gtk::TextBuffer / Gtk::TextView.
>> In a textbuffer you can place characters, pixbufs, widgets... anything.
>> Cheers,
>> Giuseppe.
>>
>>
>> On Mon, Jun 11, 2012 at 10:59 PM, ivar kängsepp <ivarbug gmail com> wrote:
>>>
>>> Hi.
>>>
>>> windows, gtkmm 2.24, mingw
>>>
>>> I'm trying to write a hex-editor-like thingie using Gtkmm and
>>> Gdk::Drawable and I'm having troubles getting any reasonable
>>> performance out of it. I'm desperate for help.
>>>
>>> Right now my code looks something like this: So far I've ended up
>>> using prerendered characters for text.
>>>
>>> void HexView::on_vScrl_value_changed() {
>>>    drawingArea.queue_draw();
>>> }
>>>
>>> bool HexView::DrawingArea::on_expose_event(GdkEventExpose* event) {
>>>    /* */
>>>    Glib::RefPtr<Gdk::Window> window = get_window();
>>>    if(window && data && numBytes) {
>>>        /* */
>>>        unsigned int scrlY = hexView->vScrl.get_value();
>>>        /* */
>>>
>>>        for(/*loop visible bytes*/) {
>>>            /* */
>>>            window->draw_pixbuf(char_pixbuf, 0, 0, x, y, 20, 20,
>>> Gdk::RGB_DITHER_NONE, 0, 0);
>>>        }
>>>    }
>>>    return true;
>>> }
>>>
>>> Gtk::TexView widget renders huge amounts of text perfectly and
>>> scrolling is nice and fast on a 1600x1200 window. My code gives me 2
>>> updates/second. Using Cairo with Cairo::ToyFontFace and
>>> Cairo::Context::show_text was twice as slow.
>>>
>>> Thanks for reading.
>>> _______________________________________________
>>> gtkmm-list mailing list
>>> gtkmm-list gnome org
>>> https://mail.gnome.org/mailman/listinfo/gtkmm-list
>>
>>
>>
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