Android 關於GridView 以及圖片處理一些知識

Android 關於GridView控件的處理

本人一直以為做一般的Android應用開發，其中創意也就是有好的Idea是至關重要的，其次是要有解決一般問題的想法，如如何實現一個應用兼容多種屏幕分辨率的問題（即使android對於圖片的處理，默認情況先是自適應的，即等比例或縮放圖片），如何自己實現網絡圖片的分段下載，如何實現不同Activity之間的數據傳遞問題，當Listview中數據量過大時，如何實現數據的分批下載等問題。結果上周去參加了一個面試，嗚嗚---，讓當場編寫一個GridView實現手機SDcard內置圖片的Thumb nail以及圖片的修剪也翻轉問題。以前都是現用現查文檔或者幫助的，以至於當時傻眼了，控件都不知道怎麼用，哎，離開了網絡感覺什麼都干不了啊，今天下午有些閒暇就整理了一個應用，實現其功能。先看下源代碼實現了對圖片的Thumbnails功能：

1. package com.daisy.android.components;
3. import java.io.File;
4. import java.util.ArrayList;
5. import java.util.HashMap;
6. import java.util.List;
7. import java.util.Map;
9. import android.app.Activity;
10. import android.content.Context;
11. import android.content.Intent;
12. import android.graphics.Bitmap;
13. import android.graphics.BitmapFactory;
14. import android.net.Uri;
15. import android.os.Bundle;
16. import android.util.Log;
17. import android.view.View;
18. import android.widget.AdapterView;
19. import android.widget.GridView;
20. import android.widget.ImageView;
21. import android.widget.ListAdapter;
22. import android.widget.SimpleAdapter;
23. import android.widget.AdapterView.OnItemClickListener;
25. public class GridViewActivity extends Activity {
26. public static String TAG = "Grid_view";
27. private GridView gridView;
28. private ArrayList<HashMap<String, String>> list;
30. /** Called when the activity is first created. */
31. @Override
32. public void onCreate(Bundle savedInstanceState) {
33. super.onCreate(savedInstanceState);
34. setContentView(R.layout.main);
35. findView();
36. }
38. private void findView() {
39. gridView = (GridView) findViewById(R.id.gridview);
40. list = new ArrayList();
41. filepath("/sdcard");
42. // test the contents in the list
43. for (int i = 0; i < list.size(); i++) {
44. Log.i(TAG, list.get(i).get("path") + "-----");
45. }
46. String[] from = { "path" };
47. int[] to = { R.id.imageView };
48. ListAdapter adapter = new GridAdapter(this, list, R.layout.item, from,
49. to);
50. gridView.setAdapter(adapter);
51. gridView.setOnItemClickListener(listener);
52. }
54. OnItemClickListener listener = new OnItemClickListener() {
56. @Override
57. public void onItemClick(AdapterView<?> parent, View view, int position,
58. long id) {
59. // TODO Auto-generated method stub
60. String imagePath = list.get(position).get("path");
61. Intent intent = new Intent(GridViewActivity.this, ImageViewer.class);
62. intent.putExtra("path", imagePath);
63. startActivity(intent);
64. }
65. };
67. public void filepath(String str) {
68. Log.i(TAG, str + "---path---");
69. File file = new File(str);
70. if (file.isDirectory()) {
71. String[] filePath = file.list();
72. for (String path : filePath) {
73. file = new File(str + "/" + path);
74. if (file.isDirectory() && !path.equals("DCIM")) {
75. filepath(str + "/" + path);
76. } else if (path.endsWith(".jpg")) {
77. HashMap hash = new HashMap();
78. hash.put("path", str + "/" + path);
79. list.add(hash);
80. }
81. }
82. }
83. }
85. class GridAdapter extends SimpleAdapter {
87. public GridAdapter(Context context,
88. List<? extends Map<String, ?>> data, int resource,
89. String[] from, int[] to) {
90. super(context, data, resource, from, to);
91. // TODO Auto-generated constructor stub
92. }
94. // set the imageView using the path of image
95. public void setViewImage(ImageView v, String value) {
96. try {
97. Bitmap bitmap = BitmapFactory.decodeFile(value);
98. Bitmap newBit = Bitmap
99. .createScaledBitmap(bitmap, 100, 80, true);
100. v.setImageBitmap(newBit);
101. } catch (NumberFormatException nfe) {
102. v.setImageURI(Uri.parse(value));
103. }
104. }
105. }
107. }