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Chapter 5: MVC Architecture

Chapter 5: MVC Architecture. We will …. Learn MVC software architecture Describe MVC-based solution for ball shooting Examine Expendability of MVC solutions Develop software library support for MVC framework: UWBGL. In a nutshell …. So far … Programming model: event driven

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Chapter 5: MVC Architecture

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  1. Chapter 5: MVC Architecture Chapter 5

  2. We will … • Learn MVC software architecture • Describe MVC-based solution for ball shooting • Examine Expendability of MVC solutions • Develop software library support for MVC framework: UWBGL Chapter 5

  3. In a nutshell … • So far … • Programming model: event driven • GUI API: elements and event registrations • Graphics API: GHC initialization and drawing with RC • This chapter: • MVC Architecture: consolidate all of the above! Chapter 5

  4. The MVC Architecture Chapter 5

  5. Model-View-Controller • Model • Application state • The persistent variables • View • Draws the application state • Graphics API support • Controller • Accepts input from user to change the model • GUI API support Chapter 5

  6. Model of Ball shooting program Chapter 5

  7. Model: • Application State: • All persistent variables • Support: • State Inquiries • State Changes • Timer event support (Simulation update) • State Visualization Chapter 5

  8. View of Ball shooting program Chapter 5

  9. Controller of Ball shooting program Chapter 5

  10. Expanding Ball shooting program Chapter 5

  11. Implement 2 views … Chapter 5

  12. Notes on MVC … • Simplicity: • Model: usually most complex • MVC: allow design of Model to be independent from user interaction and from drawing • Portability: • E.g., Change of controller ports Model to a different GUI platform • Expendability: • As we have seen: adding new view/controller pairs is straightforward Chapter 5

  13. MVC: component interactions • User change application state: • Via controllers • Application changes its own state • Via timer events • All controllers and views must present consistent state • GUI element must be correct: e.g., slider bar reflecting the falling hero ball position • Drawing must be update to date • Classic MVC architecture • Elaborate protocol to ensure all states are consistent … Chapter 5

  14. MVC with real-time simulation … • Real-time simulation • Every 25 milliseconds: timer fires! • Application state likely to change • MUST redraw all views!! • During Timer event … ALWAYS • Poll/update all controllers • Update Application state • Update all views • Simple update protocol Chapter 5

  15. 2-View ball shooting component interaction Chapter 5

  16. View/Controller Abstraction Chapter 5

  17. GUI Support: • Normal GUI support • Main application window • GUI elements: buttons, slider bars, etc. • Graphics Drawing: • UIWindow class: • To display GHC frame buffer • “drawing area” that can receive mouse events • Capable of placing itself into application window Chapter 5

  18. WindowHandler class • A View/Controller pair abstraction • Reference to View (GraphicsSystem class) • The Rendering Context (RC) • In D3D case: DIRECT3DDEVICE(9) • In OGL case: HGLRC • Reference to Controller • The GUI drawing area • UWBMFC_UIWindow class • Activates View and draw to UI drawing area • RC draw to UIWindow • Receives mouse events from UIWindow • Application can poll the mouse events Chapter 5

  19. Tutorial 5.1: UWBGL libraries • The same square drawing program • MFC_Lib1 • MFC_UIWindow • UWBGL_Lib1 • WindowHandler • GraphcsSystem Chapter 5

  20. UWB_MFC_LIB1 • Our GUI wrapper • Wrap over GUI API to “simplify” programming with GUI • Library files (9 files): • uwbgl_MFCDefines.h: • MFC compilation parameter • We will not change this • uwbgl_MFC_Lib1.h: • Include file for developers (us) • Being included in the Stdafx.h of the project • uwbgl_MFCUtility.h/.cpp • ReplaceDialogControl implementation • uwbgl_MFCSliderCtrlWithEcho1.h/.cpp • Slider bard with echo • uwbgl_MFCUIWindow1.h/.cpp • UI drawing area designed to be referenced by WindowHandler • Accepts Graphics drawing results • Able to forward mouse events (to our application) • Will _use_ this library (calling functions) • Will not change this library (will not modify any of the functions) Chapter 5

  21. MFC_Lib1 Classes: Chapter 5

  22. UWBGL_D3D_Lib1 • First attempt at • wrapping over Graphics API • Facilitate support for implementing MVC • Library files: (14 files) in three folders • Common Files • Graphics API independent programming code • D3D Files • Direct3D specific support • Header Files • Header files for programmer (our programs) • math3d++ • Math support (from public domain) • not developed at UWB, mainly, we will only use this library. Chapter 5

  23. UWBGL_D3D_Lib1: files Chapter 5

  24. UWBGL_Lib1: WindowHandler + GraphicsSystem Chapter 5

  25. UWBGL_Lib1: Geometry and Math Chapter 5

  26. UWBGL_Lib1: Common files • (uwbgl_)Common.h: • Defines Constants (PI) • Macros • E.g., degree-to-radian conversion • Compilation parameters • We will not change this file Chapter 5

  27. UWBGL_Lib1: WindowHandler • IWindowHandler: • In Common/WindowHandler folder • View/Controller pair abstraction Chapter 5

  28. Lib1: WindowHandler1.h/cpp • In Common/WindowHandler folder • API independent implementation of IWindowHandler abstraction • Designed to be subclass by Graphics API specific classes • E.g.,: D3DWindowHandler or • E.g.,: OGLWindowHandler Chapter 5

  29. Lib1: Header Files Folder • 2 .h files • D3DDefines.h • All compilation parameters • (uwbgl_)D3D_Lib1.h: this is the “.h” file meant to be included by programmers • Being included in the Stdafx.h of the project Chapter 5

  30. Lib1: D3D Files Folder • 8 files • D3DCircleGeom/D3DRectangGeom (h/cpp) • In D3D/D3D_Geoms folder • Circle and rectangle drawing • D3DGraphicsSystem.h/.cpp • In D3D/D3D_GraphicsSystem folder • D3DWindowHandler.h/.cpp • D3D/D3D_WindowHandler folder • Supports: • BeginDraw() • EndDrawAndShow Chapter 5

  31. WindowHandler Hierarchy: • IWindowHandler • Pure abstract • WindowHandler • Reference to UIWindow • D3D_WindowHandler • D3D RC reference • Application handler • E.g. DrawOnlyHandler • Must define UIWindow • Refer to next slider … Chapter 5

  32. Recall … View/Controller pair … Chapter 5

  33. Tutorial 5.1: Project • The CModel class: • Contains application state and support • Rectangle and circle + Manipulation functions • Knows how to draw itself Chapter 5

  34. DrawOnlyHandler class • Concrete WindowHandler class • Only handles output drawing … Chapter 5

  35. DrawOnlyHandler::DrawGraphics() Chapter 5

  36. Tutorial 5.1: GUI Main Window • CTutorialDlg : subclass from CDialog Chapter 5

  37. TutorialDlg::OnInitDlg() • Recall, this is GUI, SystemInitialization! • Must create Graphics API GHC • Create/initialize GUI elements. Etc. … Chapter 5

  38. CTutorial::OnTimer() Chapter 5

  39. Tutorial 5.1: Summary • Model: is the CModel class. Very simple. • Controllers: Two controllers: • CTutorialDlg (application container window) • CCircleRadiusControls • View/Controller Pair: One • DrawOnlyHandler: works via UIWindow • Collaborations: • CTutorialDlg contains all other components • Components are not aware of each other • CTutorialDlg polls/updates component states and triggers all redraws • Because components are not aware of each other, we can insert/delete components from CTutorialDlg. • Inconsistent state: • May occur in between OnTimer events! • However, the inconsistency will only last 25 mSec! • Redraw/Paint • Performed at the end of 25 mSec! • Notice: we do not service the onPaint event! • Our redraw occurs at fixed intervals of once every 25 mSec. Chapter 5

  40. Tutorial 5.2: Mouse Events • Left mouse click/drag to define circle • The Model: Chapter 5

  41. Tut 5.2: The Controller • Design: • Implementation (declaration) Chapter 5

  42. Tut 5.2: Controller implementation Chapter 5

  43. Inconsistent State • Mouse events – serviced immediately! • Via call backs • Until next redraw • Internal circle radius is different from what is drawn on the screen • Inconsistency lasts at most 25 mSec • Typical user cannot see the inconsistency Chapter 5

  44. UWBGL_Lib2 • WindowHandler::HardwareToDevice() • Origin from upper left to lower left • UWB_EchoToStatusArea(echoString) • Output echoString to IDC_STATUS element … we must • define a static textbox and • name it IDC_STATUS at GUI building time • If element not defined, echoString is not shown • At initialization, sets UWB_hEchoWindow • UWB_hEchoWindow defined in • Lib2:Common Files/Utilities/uwbgl_Utility1.cpp Chapter 5

  45. Tut 5.3: Real-time simulation • ball … drops continuously Chapter 5

  46. Tut 5.3: The Model Chapter 5

  47. Tut 5.3: The simulation … Chapter 5

  48. Tut 5.3: OnTimer service … • During OnTimer (once every 25 mSec) • Simply call • UpdateSimulation() • And • Redraws everything (DrawGraphics()). Chapter 5

  49. Tut 5.4: Two views • Multiple View/Controller pairs • Requires: • 2 Rendering Contexts (RC) or • RC connecting to separate GHC buffers • GraphicsSystem class improvements Chapter 5

  50. Drawing to multiple buffers • OGL: • Each RC connects to unique buffer • Need multiple RC (HGLRC) • D3D: • RC (DIRECT3DDEVICE) capable of driving multiple buffers • SwapChain Chapter 5

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