Custom Drawn Interface: what changed

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Title: Custom Drawn Interface

New		Line
1	+	> Warning: THIS INFORMATION IS EXTREMELY DATED AND NEEDS UPDATING as of 2015
2	+
3	+	## Introduction
4	+
5	+	LCL-CustomDrawn-Android has the following features:
6	+
7	+	- Backends for X11, Android and Windows and a partially working one for Cocoa, more can be added in the future
8	+	- Painting is done completely inside Lazarus without any interference from the native libraries except for text drawing. This assures a complete perfection of the executed drawings in all platforms and a uniform level of supported features
9	+	- Only 1 native window is utilized for each form, in the Android backend at the moment this is 1 native window for the entire application
10	+	- Utilizes the Lazarus Custom Drawn Controls for implementing the LCL standard controls
11	+	- Utilizes as it's painting engine the lcl parts: TLazIntfImage, TRawImage, lazcanvas and lazregions
12	+
13	+	## FAQ
14	+
15	+	### Diagram of the Custom Drawn Interface
16	+
17	+	<figure>
18	+	<img src="customdrawn_diagram.png" title="customdrawn_diagram.png" />
19	+	<figcaption>customdrawn_diagram.png</figcaption>
20	+	</figure>
21	+
22	+	Legend:
23	+
24	+	- Blue - New elements implemented as part of the LCL-CustomDrawn project
25	+	- Yellow - Pre-existing LCL elements
26	+	- Gray - System APIs
27	+
28	+	## The LCL-CustomDrawn Backends
29	+
30	+	LCL-CustomDrawn needs backends to implement the most basic parts of the widgetset. Each backend should implement the following minimal parts:
31	+
32	+	- TWidgetSet.Run, ProcessMessages, etc
33	+	- TForm
34	+	- TWinControl with all events
35	+	- TTrayIcon
36	+
37	+	### LCL-CustomDrawn-Android
38	+
39	+	This backend is working. See this page [[Custom Drawn Interface/Android]]
40	+
41	+	And also [[Android Programming]]
42	+
43	+	### LCL-CustomDrawn-X11
44	+
45	+	This backend is working. See [[Custom Drawn Interface/X11]]
46	+
47	+	### LCL-CustomDrawn-Cocoa
48	+
49	+	This backend is working.
50	+
51	+	### LCL-CustomDrawn-Windows
52	+
53	+	This backend is working.
54	+
55	+	### LCL-CustomDrawn-iPhone
56	+
57	+	This is planned, but not yet started.
58	+
59	+	## Canvas
60	+
61	+	TCanvas will be fully non-native in this widgetset and based on [[Developing with Graphics\|LazCanvas]]. All drawings to visual controls and on the OnPaint event of controls of the form are naturally double-buffered because the entire drawing of the form is first performed on an off-screen buffer and then copied in 1 operation to the form native canvas. In reality there is only 1 TLazCanvas for the entire form, but sub-controls will think they are on a separate canvas because the property BaseWindowOrg sets an internal start position of the canvas and also because all drawings will be clipped to reflect the size and shape of the sub-control.
62	+
63	+	### Getting the TLazCanvas object inside TCanvas
64	+
65	+	This works only in the LCL-CustomDrawn interface:
66	+
67	+	``` pascal
68	+	uses lazcanvas, lclintf;
69	+
70	+	var
71	+	MyLazCanvas: TLazCanvas:
72	+	begin
73	+	if nctLazCanvas in LCLIntf.GetAvailableNativeCanvasTypes(MyCanvas.Handle) then
74	+	begin
75	+	MyLazCanvas := TLazCanvas(LCLIntf.GetNativeCanvas(MyCanvas.Handle, nctLazCanvas));
76	+	// do something here with TLazCanvas
77	+	end;
78	+	```
79	+
80	+	### Drawing optimization roadmap
81	+
82	+	#### Optimizations already done
83	+
84	+	- Give 1 bitmap to each control and buffer the control images and only redraw them if invalidated. This greatly helps in large forms when invalidating only 1 control.
85	+	- Don't draw controls which are completely covered by other ones. Commits:
86	+	- <http://svn.freepascal.org/cgi-bin/viewvc.cgi?view=rev&root=lazarus&revision=36437>
87	+	- <http://svn.freepascal.org/cgi-bin/viewvc.cgi?view=rev&root=lazarus&revision=36455>
88	+	- Change the control bitmaps to use the native format (with ifdefs for ARGB32 for alpha blending support). This was implemented together with the next optimization:
89	+	- Optimize the case of drawing a bitmap to a canvas, when the pixel formats match and the clip rect is inexistent or rectangular. The magnifier full painting went from 630ms to 477ms for me.
90	+	- <http://svn.freepascal.org/cgi-bin/viewvc.cgi?view=rev&root=lazarus&revision=36576>
91	+	- <http://svn.freepascal.org/cgi-bin/viewvc.cgi?view=rev&root=lazarus&revision=36578>
92	+	- Optimize rectangle area filling if the clip rect is inexistent or rectangular. Decreased the drawing of a fullscreen form in X11 with 4 buttons from 95ms to 33ms for me
93	+	- <http://svn.freepascal.org/cgi-bin/viewvc.cgi?view=rev&root=lazarus&revision=36580>
94	+
95	+	#### Optimizations to be done
96	+
97	+	- Buffer the native bitmap of the form instead of generating it on each operation
98	+	- Reuse the buffered native bitmap contents if they don't change
99	+	- Support invalidating only a rectangle instead of the entire control
100	+
101	+	## Font rendering
102	+
103	+	When the define CD_UseNativeText is activated, LCL-CustomDrawn will use the native text rendering of the platform as provided by the backend. If it isn't activated, then it will use [[LazFreeType]] to render the text. The define is automatically activated for some backends if convenient when using them.
104	+
105	+	## Message and Common Dialogs
106	+
107	+	Message and Common Dialogs might be native if this is considered very convenient for the backend. If not, they will be non-native. At the moment the Android backend has native message boxes.
108	+
109	+	## Windowed visual controls
110	+
111	+	All Windowed visual controls (TButton, TPageControl, etc) will be based in the [[Lazarus Custom Drawn Controls]]
112	+
113	+	## Conditional defines accepted by LCL-CustomDrawn
114	+
115	+	One easy way to set a conditional define for the LCL-CustomDrawn is to define it in the file lcl/interfaces/customdrawn/customdrawndefines.inc
116	+
117	+	Here are defines which affect the functionality offered by this interface:
118	+
119	+	- CD_UseNativeText - Activates using native text instead of PasFreeType. This define will be automatically set if convenient for a particular backend, don't set it manually unless you know what you are doing.
120	+
121	+	And here debug information defines:
122	+
123	+	- VerboseCDPaintProfiler - Adds profiling information to indicate how fast the paint event is processed
124	+	- VerboseCDWinAPI - Extended verbose information for LCLIntf calls, except those which are covered by one of these defines instead:
125	+	- VerboseCDText - Verbose info for text winapi calls
126	+	- VerboseCDDrawing - Verbose info for Canvas and drawing operations
127	+	- VerboseCDBitmap - Verbose info for Bitmap and rawimage creation and handling
128	+	- VerboseCDForms - Extended verbose information for TWSCustomForm methods and about the non-native form from customdrawnproc (when utilized)
129	+	- VerboseCDEvents - Extended verbose information for native events (for example mouse click, key input, etc). This excludes the paint event
130	+	- VerboseCDPaintEvent - Debug info for the paint event
131	+	- VerboseCDApplication - Verbose info for App routines from the Widgetset object
132	+	- VerboseCDMessages - Verbose info for messages from the operating system (Paint, keyboard, mouse)
133	+
134	+	## Screenshots
135	+
136	+	<figure>
137	+	<img src="Lazclock_customdrawn.png" title="Lazclock_customdrawn.png" />
138	+	<figcaption>Lazclock_customdrawn.png</figcaption>
139	+	</figure>
140	+
141	+	![](/wiki-images/4/4c/Lcl_android_30_mar.png) ![](/wiki-images/d/df/Vpr-android.png)
142	+
143	+	## See Also
144	+
145	+	- [[Lazarus Custom Drawn Controls]]
146	+
147	+	---
148	+	From the Free Pascal wiki, page "Custom Drawn Interface", as it stood on 2020-02-08 after a change by Trev, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).
149	+	Category: Custom Drawn

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