ECE 462 Object-Oriented Programming using C++ and Java. Flickering and Double Buffering

Transcription

1 ECE 462 Object-Oriented Programming g using C++ and Java Flickering and Double Buffering Yung-Hsiang Lu yunglu@purdue.edu d YHL Double Buffering 1

2 Flickering YHL Double Buffering 2

3 No Flickering YHL Double Buffering 3

4 Flickering Goal: continuously iterate through the three images Approach: draw background first then draw an image Problem: occasionally, only the background is shown on the screen without any of the three images Result: the character sometimes disappears YHL Double Buffering 4

5 Interleaving of Drawing and Display public void draw(graphics g) { // draw background g.drawimage(bgimage, 0, 0, null); } sent to screen // draw image g.drawimage(anim.getimage(), 0, 0, null); YHL Double Buffering 5

6 Possible Solutions erase and draw difference find the differences between each pair of images is not trivial. Interleaving is still a problem. make draw atomic (i.e. cannot interleave) When the screen refreshes and drawing is incomplete, the screen will appear black. YHL Double Buffering 6

7 Double Buffering + Page Flipping double buffering buffer 1: working buffer for drawing, incomplete, invisible to user buffer 2: completed, shown on screen switching between the two buffers for frame updates page flipping the pixels are not copied instead, a pointer switching between the two buffers flipping between monitor refresh buffer 1 buffer 2 screen YHL Double Buffering 7

8 YHL Double Buffering 8

9 YHL Double Buffering 9

10 window.createbufferstrategy(2); BufferStrategy strategy = window.getbufferstrategy(); Graphics g = strategy.getdrawgraphics(); draw(g); g.dispose(); strategy.show(); YHL Double Buffering 10

11 Screen Manager with BufferStrategy YHL Double Buffering 11

12 Automatic Document Generation using Javadoc YHL Double Buffering 12

13 YHL Double Buffering 13

14 YHL Double Buffering 14

15 YHL Double Buffering 15

16 YHL Double Buffering 16

17 YHL Double Buffering 17

18 YHL Double Buffering 18

19 YHL Double Buffering 19

20 YHL Double Buffering 20

21 YHL Double Buffering 21

22 YHL Double Buffering 22

23 YHL Double Buffering 23

24 YHL Double Buffering 24

25 YHL Double Buffering 25

26 YHL Double Buffering 26

27 Images may be stored in volatile memory for performance reasons. YHL Double Buffering 27

28 AnimationTest2 Using ScreenManager YHL Double Buffering 28

29 Using ScreenManager POSSIBLE_ MODES: an array of different DisplayMode create ScreenManager findfirstcompatiblemode(possible_modes) setfullscreen(displaymode) animationloop getgraphics draw dispose update YHL Double Buffering 29

30 YHL Double Buffering 30

31 YHL Double Buffering 31

32 YHL Double Buffering 32

33 YHL Double Buffering 33

34 ECE 462 Object-Oriented Programming g using C++ and Java Moving Image: Sprite Yung-Hsiang Lu yunglu@purdue.edu d YHL Sprite 1

35 YHL Sprite 2

36 YHL Sprite 3

37 Sprite YHL Sprite 4

38 YHL Sprite 5

39 YHL Sprite 6

40 YHL Sprite 7

41 YHL Sprite 8

42 SpriteTest1 YHL Sprite 9

43 YHL Sprite 10

44 YHL Sprite 11

45 YHL Sprite 12

46 YHL Sprite 13

47 YHL Sprite 14

48 ECE 462 Object-Oriented Programming g using C++ and Java Unified Modeling Language Yung-Hsiang Lu yunglu@purdue.edu d YHL UML 1

49 Unified Modeling Language UML why to model? abstraction, ignore details, or multiple levels of details identify participating objects communicate with people use tools to generate code, check correctness... why UML? language independent platform independent international standard expressive (state, sequence, time, interface...) tool rich (UML code, code UML... ) YHL UML 2

50 YHL UML 3

51 YHL UML 4

52 UML Example in Netbeans YHL UML 5

53 YHL UML 6

54 YHL UML 7

55 YHL UML 8

56 YHL UML 9

57 What Does a Model Say? relationships among objects which objects participate in an activity actions and interfaces transitions of attributes sequence of actions specialization, composition, ownership quantities In addition, one critical value of a model is to help a developer think before doing. YHL UML 10

58 Modeling a Bank objects: people: customers, tellers, bank managers, loan evaluators, ATM maintainers... data: accounts properties: branch offices, ATM machines, furniture... actions: deposit, withdraw, apply for loans, approve or reject applications, collect money from ATM... relationships among objects customer can deposit, withdraw cash, or talk to teller customer cannot talk to ATM maintainer ATM maintainer cannot approve or reject loan applications ATM can accept deposit; desk cannot... YHL UML 11

59 YHL UML 12

60 YHL UML 13

61 Model States and Transitions Many objects' behaviors depend on the values (i.e. state) of the objects' attributes. age vote account balance withdraw available credit purchase Objects' behaviors often follow strict orders based on the transitions of the attributes. vending machine must accept payment before returning changes customer must open an account before withdrawing money a user must enter the password before checking a bank customer must insert the ATM card and enter PIN before deposit YHL UML 14

62 YHL UML 15

63 Sequence of Actions State diagrams do not express the objects involved. For example, the previous diagram does not specify the necessity of a customer and an ATM machine. In fact, three objects are involved customer ATM account (and the balance) YHL UML 16

64 YHL UML 17

65 Class Diagram YHL UML 18

66 YHL UML 19

67 Quantity YHL UML 20

68 YHL UML 21

69 Start a UML Project in Netbeans YHL UML 22

70 YHL UML 23

71 YHL UML 24

72 YHL UML 25

73 YHL UML 26