Android繪圖開發教程 - 手寫板

效果圖：

View代碼：activity裡設置顯示該view即可

1. package com.tszy.view;
3. import Android.content.Context;
4. import android.graphics.Bitmap;
5. import android.graphics.Bitmap.Config;
6. import android.graphics.Canvas;
7. import android.graphics.Color;
8. import android.graphics.Paint;
9. import android.graphics.Path;
10. import android.view.MotionEvent;
11. import android.view.View;
13. /**
14. * 雙緩沖區繪圖demo 手寫板
15. *
16. * @author JianbinZhu
17. *
18. */
19. public class View7 extends View {
20. private Paint paint;
21. private Canvas cacheCanvas;
22. private Bitmap cachebBitmap;
23. private Path path;
25. public View7(Context context) {
26. super(context);
27. // TODO Auto-generated constructor stub
28. paint = new Paint();
29. paint.setAntiAlias(true);
30. paint.setStrokeWidth(3);
31. paint.setStyle(Paint.Style.STROKE);
32. paint.setColor(Color.CYAN);
34. path = new Path();
35. cachebBitmap = Bitmap.createBitmap(480, 320, Config.ARGB_8888);
36. cacheCanvas = new Canvas(cachebBitmap);
37. }
39. @Override
40. protected void onDraw(Canvas canvas) {
41. canvas.drawColor(Color.BLACK);
43. //繪制上一次的，否則不連貫
44. canvas.drawBitmap(cachebBitmap, 0, 0, null);
45. canvas.drawPath(path, paint);
46. }
48. private float cur_x, cur_y;
49. private boolean isMoving;
50. @Override
51. public boolean onTouchEvent(MotionEvent event) {
52. // TODO Auto-generated method stub
53. float x = event.getX();
54. float y = event.getY();
56. switch (event.getAction()) {
57. case MotionEvent.ACTION_DOWN : {
58. cur_x = x;
59. cur_y = y;
60. path.moveTo(cur_x, cur_y);
61. isMoving = true;
62. break;
63. }
65. case MotionEvent.ACTION_MOVE : {
66. // 二次曲線方式繪制
67. path.quadTo(cur_x, cur_y, x, y);
68. // 下面這個方法貌似跟上面一樣
69. // path.lineTo(x, y);
70. cur_x = x;
71. cur_y = y;
72. break;
73. }
75. case MotionEvent.ACTION_UP : {
76. // 鼠標彈起保存最後狀態
77. cacheCanvas.drawPath(path, paint);
78. path.reset();
79. isMoving = false;
80. break;
81. }
82. }
84. // 刷新界面
85. invalidate();
87. return true;
88. }
89. }