图形与动画在Android中的实现

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

public class MyView extends
View{

    Bitmap myBitmap;

    Paint paint;

    public
MyView(Context context, AttributeSet attrs) {

        super(context, attrs);

        this.initBitmap();

    }

    public
void initBitmap(){

        paint = new
Paint();

        myBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.img);

    }

    @Override

    protected
void onDraw(Canvas canvas) {

        super.onDraw(canvas);

        paint.setAntiAlias(true);

        paint.setColor(Color.WHITE);

        paint.setTextSize(15);

        canvas.drawBitmap(myBitmap, 10,  10, paint);

        //Saves the current matrix and clip onto a private stack.

        //Subsequent calls to translate,scale,rotate,skew,concat or clipRect,clipPath

        //will all operate as usual, but when the balancing call to restore() is made,

        //those calls will be forgotten, and the settings that existed before the save() will be reinstated(恢复).

        //Returns:

        //The value to pass to restoreToCount() to balance this save()

        int
i = canvas.save(); 

        System.out.println("current count -- > "
+ i);

        Matrix m1 = new
Matrix();

        m1.setTranslate(500, 10);

        Matrix m2 = new
Matrix();

        m2.setRotate(15);

        Matrix m3 = new
Matrix();

        m3.setConcat(m1, m2);

        m1.setScale(0.8f, 0.8f);

        m2.setConcat(m3, m1);

        canvas.drawBitmap(myBitmap, m2, paint);

        //This call balances a previous call to save(), and is used to

        //remove all modifications to the matrix/clip state since the last save call.

        //It is an error to call restore() more times than save() was called.

        canvas.restore();

        int
j = canvas.save();

        System.out.println("current count -- > "
+ j);

        paint.setAlpha(180);

        m1.setTranslate(200, 100);

        m2.setScale(1.3f, 1.3f);

        m2.setConcat(m1, m2);

        canvas.drawBitmap(myBitmap, m3, paint);

        //Restores the paint to its default settings.

        paint.reset();

        canvas.restore();

        paint.setTextSize(40);

        paint.setColor(Color.BLUE);

        canvas.drawText("图片的宽度:"
+ myBitmap.getWidth(), 150, 220, paint);

        canvas.drawText("图片的高度:"
+ myBitmap.getHeight(), 150, 300, paint);

        paint.reset();

    }

}