Android圖形與圖像處理-采用雙緩沖實現畫圖板

Android圖形與圖像處理-采用雙緩沖實現畫圖板

創建項目：HandDraw

運行項目效果：

DrawView.java

1. package wwj.handdraw;
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.util.AttributeSet;
11. import android.view.MotionEvent;
12. import android.view.View;
14. public class DrawView extends View{
15. float preX;
16. float preY;
17. private Path path;
18. public Paint paint = null;
19. final int VIEW_WIDTH = 320;
20. final int VIEW_HEIGHT = 480;
21. //定義一個內存中的圖片，該圖片將作為緩沖區
22. Bitmap cacheBitmap = null;
23. //定義cacheBitmap上的Canvas對象
24. Canvas cacheCanvas = null;
25. public DrawView(Context context, AttributeSet attrs) {
26. super(context, attrs);
27. //創建一個與該View相同大小的緩沖區
28. cacheBitmap = Bitmap.createBitmap(VIEW_WIDTH, VIEW_HEIGHT, Config.ARGB_8888);
29. cacheCanvas = new Canvas();
30. path = new Path();
31. //設置cacheCanvas將會繪制到內存中cacheBitmap上
32. cacheCanvas.setBitmap(cacheBitmap);
33. //設置畫筆的顏色
34. paint = new Paint(Paint.DITHER_FLAG);
35. paint.setColor(Color.RED);
36. //設置畫筆風格
37. paint.setStyle(Paint.Style.STROKE);
38. paint.setStrokeWidth(1);
39. //反鋸齒
40. paint.setAntiAlias(true);
41. paint.setDither(true);
42. }
43. @Override
44. public boolean onTouchEvent(MotionEvent event) {
45. // TODO Auto-generated method stub
46. //獲取拖動事件的發生位置
47. float x = event.getX();
48. float y = event.getY();
49. switch(event.getAction()){
50. case MotionEvent.ACTION_DOWN:
51. path.moveTo(x, y);
52. preX = x;
53. preY = y;
54. break;
55. case MotionEvent.ACTION_MOVE:
56. path.quadTo(preX, preY, x, y);
57. preX = x;
58. preY = y;
59. break;
60. case MotionEvent.ACTION_UP:
61. cacheCanvas.drawPath(path, paint);
62. path.reset();
63. break;
64. }
65. invalidate();
66. //返回true表明處理方法已經處理該事件
67. return true;
68. }
69. @Override
70. protected void onDraw(Canvas canvas) {
71. // TODO Auto-generated method stub
72. Paint bmpPaint = new Paint();
73. //將cacheBitmap繪制到該View組件
74. canvas.drawBitmap(cacheBitmap, 0, 0, bmpPaint);
75. //沿著Path繪制
76. canvas.drawPath(path, bmpPaint);
77. }
79. }

menu文件：my_menu.xml

1. <?xml version="1.0" encoding="utf-8"?>
2. <menu xmlns:android="http://schemas.android.com/apk/res/android">
3. <item android:title="@string/color">
4. <menu>
5. <!-- 定義一組單選菜單項 -->
6. <group android:checkableBehavior="single">
7. <!-- 定義多個菜單項 -->
8. <item
9. android:id="@+id/red" android:title="@string/color_red"/>
10. <item
11. android:id="@+id/green" android:title="@string/color_green"/>
12. <item
13. android:id="@+id/blue" android:title="@string/color_blue"/>
14. </group>
15. </menu>
16. </item>
17. <item android:title="@string/width">
18. <menu>
19. <!-- 定義一組菜單項 -->
20. <group>
21. <!-- 定義3個菜單項 -->
22. <item
23. android:id="@+id/width_1" android:title="@string/width_1"/>
24. <item
25. android:id="@+id/width_3" android:title="@string/width_3"/>
26. <item
27. android:id="@+id/width_5" android:title="@string/width_5"/>
28. </group>
29. </menu>
30. </item>
31. <item
32. android:id="@+id/blur" android:title="@string/blur"/>
33. <item
34. android:id="@+id/emboss" android:title="@string/emboss"/>
35. </menu>

HandDraw.java

1. package wwj.handdraw;
3. import android.os.Bundle;
4. import android.app.Activity;
5. import android.graphics.BlurMaskFilter;
6. import android.graphics.Color;
7. import android.graphics.BlurMaskFilter.Blur;
8. import android.graphics.EmbossMaskFilter;
9. import android.view.Menu;
10. import android.view.MenuInflater;
11. import android.view.MenuItem;
12. import android.support.v4.app.NavUtils;
14. public class HandDraw extends Activity {
16. EmbossMaskFilter emboss;
17. BlurMaskFilter blur;
18. @Override
19. public void onCreate(Bundle savedInstanceState) {
20. super.onCreate(savedInstanceState);
21. setContentView(R.layout.main);
22. emboss = new EmbossMaskFilter(new float[]{1.5f, 1.5f, 1.5f}, 0.6f, 6, 4.2f);
23. blur = new BlurMaskFilter(8, Blur.NORMAL);
24. }
26. @Override
27. public boolean onCreateOptionsMenu(Menu menu) {
28. MenuInflater inflator = new MenuInflater(this);
29. //狀態R.menu.context對應的菜單，並添加到menu中
30. inflator.inflate(R.menu.my_menu, menu);
31. return super.onCreateOptionsMenu(menu);
32. }
34. @Override
35. public boolean onOptionsItemSelected(MenuItem item) {
36. // TODO Auto-generated method stub
37. DrawView dv = (DrawView)findViewById(R.id.draw);
38. //判斷單擊的是哪個菜單項，並有針對性地做出響應
39. switch(item.getItemId()){
40. case R.id.red:
41. dv.paint.setColor(Color.RED);
42. item.setChecked(true);
43. break;
44. case R.id.green:
45. dv.paint.setColor(Color.GREEN);
46. item.setChecked(true);
47. break;
48. case R.id.blue:
49. dv.paint.setColor(Color.BLUE);
50. item.setChecked(true);
51. break;
52. case R.id.width_1:
53. dv.paint.setStrokeWidth(1);
54. break;
55. case R.id.width_3:
56. dv.paint.setStrokeWidth(3);
57. break;
58. case R.id.width_5:
59. dv.paint.setStrokeWidth(5);
60. break;
61. case R.id.blur:
62. dv.paint.setMaskFilter(blur);
63. break;
64. case R.id.emboss:
65. dv.paint.setMaskFilter(emboss);
66. break;
67. }
68. return true;
69. }
70. }

布局文件：main.xml

1. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
2. xmlns:tools="http://schemas.android.com/tools"
3. android:id="@+id/LinearLayout1"
4. android:layout_width="match_parent"
5. android:layout_height="match_parent"
6. android:orientation="vertical" >
7. <wwj.handdraw.DrawView
8. android:id="@+id/draw"
9. android:layout_width="wrap_content"
10. android:layout_height="wrap_content"
11. android:width="320px"
12. android:height="480px"
13. />
14. </LinearLayout>

1. <resources>
3. <string name="app_name">手繪</string>
4. <string name="hello_world">Hello world!</string>
5. <string name="menu_settings">Settings</string>
6. <string name="title_activity_hand_draw">HandDraw</string>
7. <string name="width_1">1像素</string>
8. <string name="width_3">3像素</string>
9. <string name="width_5">5像素</string>
10. <string name="color_red">紅色</string>
11. <string name="color_green">綠色</string>
12. <string name="color_blue">藍色</string>
13. <string name="color">畫筆顏色</string>
14. <string name="width">畫筆寬度</string>
15. <string name="blur">模糊效果</string>
16. <string name="emboss">浮雕效果</string>
17. </resources>