android背景滚动+Matrix实现图片拉伸（实现近大远小效果）

01package com.sarnath.activity;

02 

03import java.util.Timer;

04import java.util.TimerTask;

05 

06import android.app.Activity;

07import android.content.Context;

08import android.graphics.Bitmap;

09import android.graphics.BitmapFactory;

10import android.graphics.Canvas;

11import android.graphics.Matrix;

12import android.os.Bundle;

13import android.os.Handler;

14import android.os.Message;

15import android.view.Display;

16import android.view.View;

17 

18public class GbdemoActivity extends Activity {

19    public void onCreate(Bundle savedInstanceState) {

20        super.onCreate(savedInstanceState);

21 

22        setContentView(new MyView(this));

23         

24    }

25 

26    class MyView extends View {

27         

28        // 得到容器分辨率 高，宽

29        Display display = getWindowManager().getDefaultDisplay();

30         

31        // 记录背景图片实际的高度

32        final int BACK_HEIGHT = 960;

33        // 背景图片

34        private Bitmap back;

35        private Bitmap plane;

36        private Bitmap map_01;

37        // 背景图片的开始位置  320 480

38        final int WIDTH = display.getWidth();

39        final int HEIGHT = display.getHeight();

40        private int startY = BACK_HEIGHT - HEIGHT;

41 

42        public MyView(Context context) {

43            super(context);

44            // 获取背景图片

45            back = BitmapFactory.decodeResource(context.getResources(),

46                    R.drawable.map_02);

47            plane = BitmapFactory.decodeResource(context.getResources(),

48                    R.drawable.plan_1);

49            final Handler handler = new Handler() {

50 

51                public void handleMessage(Message msg) {

52                    if (msg.what == 0x123) {

53                        // 重新开始移动

54                        if (startY <= 0) {

55                            startY = BACK_HEIGHT - HEIGHT;

56                        } else {

57                            startY -= 10;

58                        }

59                    }

60                    //该函数的作用是使整个窗口客户区无效。窗口的客户区无效意味着需要重绘

61                    invalidate();

62                }

63            };

64            new Timer().schedule(new TimerTask(){

65 

66                @Override

67                public void run() {

68                    handler.sendEmptyMessage(0x123);

69                }

70                 

71                 

72            }, 0,100);

73        }

74         

75     

76        @Override

77        protected void onDraw(Canvas canvas) {

78            // 根据原始位图和Matrix创建新图片

79            Bitmap bitmap2 = Bitmap.createBitmap(back, 0, startY, WIDTH,HEIGHT);

80            //设置拉伸的比例  实现 等腰梯形

81            float[] src=new float[] { 0, 0, WIDTH,    0, WIDTH, HEIGHT, 0, HEIGHT };

82            float[] dst=new float[] { 100, 0, 200, 0, 500, 450, -150, 450 };

83            //获取Matrix对象 实现 图片拉伸

84            Matrix mMatrix=new Matrix();

85            mMatrix.setPolyToPoly(src, 0, dst, 0, src.length >> 1);

86            // 绘制新位图

87            canvas.drawBitmap(bitmap2, mMatrix, null);

88             

89            //绘制小飞机

90            canvas.drawBitmap(plane, 160, 380 ,null);

91        }

92    }

93}