Bounty $60: rework of GTK2 ExtTextOut to use new API

[AlexTP]

I want to suggest such small bounty.
It should affect speed of text rendering in my text editor CudaText.
If it will not affect the speed, it will be problematic patch, which I dislike and cannot give the bounty.

Current ExtTextOut in GTK2 calls this core function
(file lcl/interfaces/gtk2/gtk2devicecontext.inc)

Code: Pascal  [Select][+][-]

1. procedure TGtkDeviceContext.DrawTextWithColors(AText: PChar; ALength: LongInt;
2.   X, Y: Integer; FGColor, BGColor: PGdkColor);
3. var
4.   WidgetCont: PPangoContext;
5.   NewMatrix: TPangoMatrix;
6.   OldMatrix: PPangoMatrix;
7.   renderer: PGdkPangoRenderer;
8.   Direction : TPangoDirection;
9.   AFont: PGdiObject;
10.  
11.   procedure SetColors(AFGColor, ABGColor: PGdkColor); inline;
12.   begin
13.     gdk_pango_renderer_set_override_color(renderer, PANGO_RENDER_PART_FOREGROUND, AFGColor);
14.     gdk_pango_renderer_set_override_color(renderer, PANGO_RENDER_PART_UNDERLINE, AFGColor);
15.     gdk_pango_renderer_set_override_color(renderer, PANGO_RENDER_PART_STRIKETHROUGH, AFGColor);
16.     gdk_pango_renderer_set_override_color(renderer, PANGO_RENDER_PART_BACKGROUND, ABGColor);
17.   end;
18.  
19. begin
20.   AFont := GetFont;
21.   SetLayoutText(AFont^.GDIFontObject, AText, ALength);
22.  
23.   WidgetCont := pango_layout_get_context(AFont^.GDIFontObject);
24.   Direction := pango_find_base_dir(AText, ALength);
25.   pango_context_set_base_dir(WidgetCont, Direction);
26.  
27.   if AFont^.LogFont.lfEscapement <> 0 then
28.   begin
29.     if Widget <> nil then
30.       renderer := gdk_pango_renderer_get_default(gtk_widget_get_screen(Widget))
31.     else
32.       renderer := gdk_pango_renderer_get_default(gdk_screen_get_default);
33.     RemovePixbuf;
34.     gdk_pango_renderer_set_drawable(renderer, drawable);
35.     gdk_pango_renderer_set_gc(renderer, GC);
36.     SetColors(FGColor, BGColor);
37.  
38.     OldMatrix := pango_context_get_matrix(WidgetCont);
39.     NewMatrix.xx := 1.0;
40.     NewMatrix.xy := 0.0;
41.     NewMatrix.yx := 0.0;
42.     NewMatrix.yy := 1.0;
43.     NewMatrix.x0 := 0.0;
44.     NewMatrix.y0 := 0.0;
45.     pango_matrix_translate(@NewMatrix, X, Y);
46.     pango_matrix_rotate(@NewMatrix, AFont^.LogFont.lfEscapement / 10);
47.  
48.     pango_context_set_matrix(WidgetCont, @NewMatrix);
49.     pango_layout_context_changed(AFont^.GDIFontObject);
50.     pango_renderer_draw_layout(PPangoRenderer(renderer), AFont^.GDIFontObject, X, Y);
51.  
52.     //now reset
53.     pango_context_set_matrix(WidgetCont, OldMatrix);
54.     pango_layout_context_changed(AFont^.GDIFontObject);
55.    
56.     SetColors(nil, nil);
57.     gdk_pango_renderer_set_drawable(renderer, nil);
58.     gdk_pango_renderer_set_gc(renderer, nil);
59.   end
60.   else
61.     gdk_draw_layout_with_colors(drawable, GC, X, Y, AFont^.GDIFontObject, FGColor, BGColor);
62. end;
63.  

I looked at the GTK2 docs about these gdk_xxxxx APIs and docs say that they are deprecated! We must use some newer API from GTK2.
I don't have URL at hands, so please look at docs by yourself. If you won't find this text, I will help to find it.