因為很多代碼前面五次進階已經設計，在此不贅述。單列出核心代碼。
第一部分：xml文件
一個按鈕選擇圖片，一個按鈕保存圖片
代碼如下：
1. <?xml version="1.0" encoding="utf-8"?>
2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
3. android:layout_width="fill_parent"
4. android:layout_height="fill_parent"
5. android:orientation="vertical" >
6.
7. <Button
8. android:id="@+id/pickImageBtn"
9. android:layout_width="wrap_content"
10. android:layout_height="wrap_content"
11. android:text="pickImage" />
12.
13. <ImageView
14. android:id="@+id/pickedImage"
15. android:layout_width="wrap_content"
16. android:layout_height="wrap_content"
17. android:src="@drawable/ic_launcher" />
18.
19. <Button
20. android:id="@+id/saveBtn"
21. android:layout_width="wrap_content"
22. android:layout_height="wrap_content"
23. android:text="Save" />
24.
25. </LinearLayout>
第二部分：初始化
代碼如下：
1. public void onCreate(Bundle savedInstanceState) {
2. super.onCreate(savedInstanceState);
3. setContentView(R.layout.main);
4.
5. Button pickImageBtn = (Button) findViewById(R.id.pickImageBtn);
6. Button saveBtn = (Button) findViewById(R.id.saveBtn);
7. mImageView = (ImageView) findViewById(R.id.pickedImage);
8.
9.
10. pickImageBtn.setOnClickListener(this);
11. saveBtn.setOnClickListener(this);
12.
13.
14. }
第三部分：選擇圖片，監聽Touch
代碼如下：
1. public void onClick(View v) {
2. // TODO Auto-generated method stub
3. Log.d("bitmap", "has onClick");
4. switch (v.getId()) {
5. case R.id.pickImageBtn:
6. Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
7. startActivityForResult(intent, REQUEST_CODE);
8. break;
1. @Override
2. protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
3. // TODO Auto-generated method stub
4. super.onActivityResult(requestCode, resultCode, intent);
5. Log.d("bitmap", "requestCode is :" + requestCode);
6. if (resultCode == RESULT_OK) {
7. Log.d("bitmap", "has result ok");
8. Uri uri = intent.getData();
9.
10. int dw = getWindowManager().getDefaultDisplay().getWidth();
11. int dh = getWindowManager().getDefaultDisplay().getHeight();
12.
13. try {
14. BitmapFactory.Options opts = new BitmapFactory.Options();
15. opts.inJustDecodeBounds = true;//如果設置為true，本身不會返回
16. Bitmap chooseBitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, opts);
17. int bw = opts.outWidth;//此時，chooseBitmap的值為null，但opts仍然獲得其config
18. int bh = opts.outHeight;
19.
20. int widthRatio = (int) Math.ceil(bw / (float) dw);
21. int heightRatio = (int) Math.ceil(bh / (float) dh);
22.
23. if (widthRatio > 1 || heightRatio >1) {
24. if (widthRatio > heightRatio) {
25. opts.inSampleSize = widthRatio;//設置比例
26. } else {
27. opts.inSampleSize = heightRatio;
28. }
29. }
30. opts.inJustDecodeBounds = false;
31. chooseBitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, opts);
32. Log.d("bitmap", "chooseBitmap is :" + chooseBitmap);
33.
34. alteredBitmap = Bitmap.createBitmap(chooseBitmap.getWidth(), chooseBitmap.getHeight(), chooseBitmap.getConfig());
35. canvas = new Canvas(alteredBitmap);//畫佈
36. paint = new Paint();
37. paint.setColor(Color.WHITE);
38. paint.setStyle(Style.STROKE);
39. Matrix matrix = new Matrix();
40. canvas.drawBitmap(chooseBitmap, matrix , paint);
41.
42. mImageView.setImageBitmap(alteredBitmap);
43. mImageView.setOnTouchListener(this);//設置監聽
44.
45. } catch (FileNotFoundException e) {
46. // TODO Auto-generated catch block
47. e.printStackTrace();
48. }
49.
50.
51.
52. }
53.
54. }
第四部分：在圖片上觸摸移動，實時繪制。
代碼如下：
1. public boolean onTouch(View v, MotionEvent event) {
2. // TODO Auto-generated method stub
3. Log.d("touch_draw", "ontouch()");
4.
5. switch (event.getAction()) {
6. case MotionEvent.ACTION_UP:
7. // upX = event.getX();
8. // upY = event.getY();//畫直線的相關代碼，可自己測試。同理，畫圓橢圓都可在相關方法裡設置
9. // canvas.drawLine(downX, downY, upX, upY, paint);
10. // mImageView.invalidate();
11. // break;
12. case MotionEvent.ACTION_DOWN:
13. downX = event.getX();
14. downY = event.getY();
15. break;
16. case MotionEvent.ACTION_MOVE:
17. upX = event.getX();
18. upY = event.getY();
19. canvas.drawLine(downX, downY, upX, upY, paint);
20. mImageView.invalidate();
21. downX = upX;
22. downY = upY;
23. break;
24. case MotionEvent.ACTION_CANCEL:
25. break;
26.
27. }
28.
29. return true;
30. }
第五部分：保存圖片
代碼如下：
1. public void onClick(View v) {
2. // TODO Auto-generated method stub
3. Log.d("bitmap", "has onClick");
4. switch (v.getId()) {
5. case R.id.pickImageBtn:
6. Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
7. startActivityForResult(intent, REQUEST_CODE);
8. break;
9. case R.id.saveBtn://保存已經塗鴉過的圖片
10.
11.
12. /*
13. * PNG :非常適合藝術線條和圖形：始終保持所有數據
14. * JPEG:非常適合帶漸變的全彩圖像，例如照片。是“有損的”編解碼器，可設置質量
15. */
16.
17.
18. if (null != alteredBitmap) {
19. Uri imageFileUri = getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, new ContentValues());//創建一個新的uri
20.
21. try {
22. OutputStream imageFileOS = getContentResolver().openOutputStream(imageFileUri);//輸出流
23.
24. alteredBitmap.compress(CompressFormat.JPEG, 90, imageFileOS);//生成圖片
25.
26. Toast.makeText(this, "has saved", Toast.LENGTH_SHORT).show();
27.
28. } catch (FileNotFoundException e) {
29. // TODO Auto-generated catch block
30. e.printStackTrace();
31. }
32. }
33. break;
34. }
35. }
摘自 小新專欄