Android中SurfaceView學習

SurfaceView和View的明顯不同在於Surface不需要通過線程來更新視圖，但在繪制之前必須使用lockCanvas方法鎖定畫布，並得 到畫布，然後繪制，完成後用unlockCanvasAndPost方法解鎖畫布。SurfaceView類的事件處理和View一樣。

首先來看一個簡單的框架。

繪制界面類：

1. package com.example.bonusball;
3. import Android.content.Context;
4. import android.graphics.Canvas;
5. import android.graphics.Color;
6. import android.graphics.Paint;
7. import android.graphics.RectF;
8. import android.util.AttributeSet;
9. import android.view.SurfaceHolder;
10. import android.view.SurfaceView;
12. public class CanvasView extends SurfaceView implements SurfaceHolder.Callback
13. {
14. private SurfaceHolder myHolder;
15. private Paint ballPaint; // Paint used to draw the cannonball
16. private int screenWidth; // width of the screen
17. private int screenHeight; // height of the screen
18. private int ballRadius;
19. private CanvasThread myThread;
20. //控制循環
21. private boolean isLoop;
23. public CanvasView(Context context) {
24. super(context);
25. // TODO Auto-generated constructor stub
26. myHolder=this.getHolder();
27. myHolder.addCallback(this);
28. ballPaint=new Paint();
29. ballPaint.setColor(Color.BLUE);
30. isLoop = true;
31. }
33. public void fireBall(float startX,float startY)
34. {
35. System.out.println("Fire");
37. }
39. @Override
40. public void surfaceChanged(SurfaceHolder holder, int format, int width,
41. int height) {
42. // TODO Auto-generated method stub
45. }
46. @Override
47. protected void onSizeChanged(int w, int h, int oldw, int oldh)
48. {
49. super.onSizeChanged(w, h, oldw, oldh);
50. screenWidth = w; // store the width
51. screenHeight = h; // store the height
52. ballRadius=w/10;
53. }
55. @Override
56. public void surfaceCreated(SurfaceHolder holder) {
57. // TODO Auto-generated method stub
58. myThread = new CanvasThread();
59. System.out.println("SurfaceCreated!");
60. myThread.start();
62. }
64. @Override
65. public void surfaceDestroyed(SurfaceHolder holder) {
66. // TODO Auto-generated method stub
67. // 停止循環
68. isLoop = false;
69. }
70. public void drawGameElements(Canvas canvas)
71. {
72. canvas.drawCircle(100, 100,ballRadius,ballPaint);
74. }
75. private class CanvasThread extends Thread
76. {
77. @Override
78. public void run()
79. {
80. while(true)
81. {
82. synchronized( myHolder )
83. {
85. Canvas canvas = myHolder.lockCanvas(null);//獲取畫布
86. drawGameElements(canvas);
87. myHolder.unlockCanvasAndPost(canvas);//解鎖畫布，提交畫好的圖像
88. //System.out.println("run");
89. }
90. }
91. }
93. }
94. }

事件處理 類：

1. package com.example.bonusball;
3. import android.os.Bundle;
4. import android.app.Activity;
5. import android.view.Menu;
6. import android.content.Context;
7. import android.graphics.Canvas;
8. import android.graphics.Color;
9. import android.graphics.Paint;
10. import android.graphics.Rect;
11. import android.view.GestureDetector;
12. import android.view.GestureDetector.SimpleOnGestureListener;
13. import android.view.MotionEvent;
14. import android.view.SurfaceHolder;
15. import android.view.SurfaceView;
16. import android.widget.Toast;
17. public class BallActivity extends Activity {
19. private GestureDetector myGestureDetector;//監聽手勢
20. private CanvasView myCanvas;
21. @Override
22. public void onCreate(Bundle savedInstanceState) {
23. super.onCreate(savedInstanceState);
24. myCanvas=new CanvasView(this);
25. setContentView(myCanvas);
26. myGestureDetector = new GestureDetector(this, new MyGestureListener());
28. }
29. @Override
30. public boolean onTouchEvent(MotionEvent event)
31. {
32. return myGestureDetector.onTouchEvent(event);
34. }
37. private class MyGestureListener extends SimpleOnGestureListener
38. {
39. public boolean onDown(MotionEvent e1) {
40. Toast.makeText(getApplicationContext(), "onDown", Toast.LENGTH_SHORT).show();
41. return true;
42. }
44. @Override
45. public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
46. {
47. System.out.println("Fling");
48. return true;
49. }
50. }
51. @Override
52. public boolean onCreateOptionsMenu(Menu menu) {
53. getMenuInflater().inflate(R.menu.activity_ball, menu);
54. return true;
56. }
57. }