Custom Drawn Interface

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Introduction

LCL-CustomDrawn-Android has the following features:

  • Backends for X11, Android and Windows and a partially working one for Cocoa, more can be added in the future
  • 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
  • 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
  • Utilizes the Lazarus Custom Drawn Controls for implementing the LCL standard controls
  • Utilizes as it's painting engine the lcl parts: TLazIntfImage, TRawImage, lazcanvas and lazregions

FAQ

LCL-CustomDrawn versus a native interfaces for Android/iPhone

Anyone who says that a native LCL-Android interface is nearly feasable clearly has never used the Android API. I, Felipe Monteiro de Carvalho, actually started LCL-Android and it lived for a time in Lazarus 0.9.31 until I deleted it in favor of LCL-CustomDrawn-Android. The Android API does not match the LCL at all and it is not fit for a native LCL interface. It doesn't even properly support setting the X, Y, width, height position of components, controls do not match what the LCL offers, the API is in Java, etc. LCL-CustomDrawn fixes all those issues by implementing everything in a powerful Pascal framework and interfacing with Java via JNI. It has automatic layout adjustment for the DPI, it makes changes to adapt the form as much as possible to the Android way of being, with the form ocupying the entire display width and the height being scrollable if larger then the display. It automatically adjusts the form when the display orientation changes on a rotation, it supports GPS, accelerometer, SMS sending, etc, etc. In general, it is the full power of the LCL with a lot more of unique features on your Android device.

And in general, I, Felipe Monteiro de Carvalho, started the LCL-CustomDrawn interface because several things convinced me that it is the future of Lazarus. Each native interface takes aproximately 5 years of a lot of work to get ready for production use in large projects. That's a huge, immense amount of work, and platforms die all the time. So by the time you finished, it will soon be obsolete and when it gets obsolete, all your work is flushed down the toiled. After seing Microsoft drop Windows CE without any reason after years and years that I worked on LCL-WinCE, see Apple drop Carbon, see Nokia drop both Symbian and Meego, I am convinced that the big corporations that make the calls are unreliable and will drop their platforms in an eye blink when a big shot director has a new favorite toy framework. So there is no point in wasting 5 years to write an interface which will die. In LCL-CustomDrawn nothing is wasted, because 99% of the code is common amount all backends, 99% of bugs fixed in LCL-CustomDrawn are fixed forever and it only goes forward, gets better, faster and more reliable. No effort is wasted anymore and I can very easily debug smartphone applications in my desktop, get a 100% reliable LCL across platforms and at the same time have power features like the ones developed for our Android support: layout auto-adjustment, GPS support, accelerometer support, etc.

Comparison of LCL-CustomDrawn and LCL-fpGUI

Due to continuous FUD being spread by Felipe, this section has been removed. Felipe, you are welcome to use your personal Blog page to slander other projects.

Diagram of the Custom Drawn Interface

customdrawn diagram.png

Legend:

  • Blue - New elements implemented as part of the LCL-CustomDrawn project
  • Yellow - Pre-existing LCL elements
  • Gray - System APIs

The LCL-CustomDrawn Backends

LCL-CustomDrawn needs backends to implement the most basic parts of the widgetset. Each backend should implement the following minimal parts:

  • TWidgetSet.Run, ProcessMessages, etc
  • TForm
  • TWinControl with all events
  • TTrayIcon

LCL-CustomDrawn-Android

This backend is working. See this page Custom Drawn Interface/Android

And also Android Programming

LCL-CustomDrawn-X11

This backend is working. See Custom Drawn Interface/X11

LCL-CustomDrawn-Cocoa

This backend is working.

LCL-CustomDrawn-Windows

This backend is working.

LCL-CustomDrawn-iPhone

This is planned, but not yet started.

Canvas

TCanvas will be fully non-native in this widgetset and based on 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.

Font rendering

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.

Message and Common Dialogs

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.

Windowed visual controls

All Windowed visual controls (TButton, TPageControl, etc) will be based in the Lazarus Custom Drawn Controls

Conditional defines accepted by LCL-CustomDrawn

One easy way to set a conditional define for the LCL-CustomDrawn is to define it in the file lcl/interfaces/customdrawn/customdrawndefines.inc

Here are defines which affect the functionality offered by this interface:

  • 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.

And here debug information defines:

  • VerboseCDPaintProfiler - Adds profiling information to indicate how fast the paint event is processed
  • VerboseCDWinAPI - Extended verbose information for LCLIntf calls, except those which are covered by one of these defines instead:
    • VerboseCDText - Verbose info for text winapi calls
    • VerboseCDDrawing - Verbose info for Canvas and drawing operations
    • VerboseCDBitmap - Verbose info for Bitmap and rawimage creation and handling
  • VerboseCDForms - Extended verbose information for TWSCustomForm methods and about the non-native form from customdrawnproc (when utilized)
  • VerboseCDEvents - Extended verbose information for native events (for example mouse click, key input, etc). This excludes the paint event
  • VerboseCDPaintEvent - Debug info for the paint event
  • VerboseCDApplication - Verbose info for App routines from the Widgetset object
  • VerboseCDMessages - Verbose info for messages from the operating system (Paint, keyboard, mouse)

Screenshots

Lazclock customdrawn.png

See Also