图片的放大缩小

布局文件

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:orientation="vertical"
 6     android:paddingBottom="@dimen/activity_vertical_margin"
 7     android:paddingLeft="@dimen/activity_horizontal_margin"
 8     android:paddingRight="@dimen/activity_horizontal_margin"
 9     android:paddingTop="@dimen/activity_vertical_margin"
10     tools:context=".MainActivity" >
11
12     <LinearLayout
13         android:layout_width="match_parent"
14         android:layout_height="wrap_content" >
15
16         <Button
17             android:layout_width="0dp"
18             android:layout_height="wrap_content"
19             android:layout_weight="1"
20             android:onClick="zoomIn"
21             android:text="放大" />
22
23         <Button
24             android:layout_width="0dp"
25             android:layout_height="wrap_content"
26             android:layout_weight="1"
27             android:onClick="zoomOut"
28             android:text="缩小" />
29
30         <Button
31             android:layout_width="0dp"
32             android:layout_height="wrap_content"
33             android:layout_weight="1"
34             android:onClick="rotate"
35             android:text="旋转" />
36
37         <Button
38             android:layout_width="0dp"
39             android:layout_height="wrap_content"
40             android:layout_weight="1"
41             android:onClick="inverse"
42             android:text="镜像" />
43     </LinearLayout>
44
45     <ImageView
46         android:id="@+id/imageView"
47         android:layout_width="wrap_content"
48         android:layout_height="wrap_content"
49         android:src="@drawable/qq" />
50
51 </LinearLayout>

代码

 1 public class MainActivity extends Activity {
 2
 3     private ImageView imageView;
 4     private Bitmap bitmap;
 5
 6     @Override
 7     protected void onCreate(Bundle savedInstanceState) {
 8         super.onCreate(savedInstanceState);
 9         setContentView(R.layout.activity_main);
10         imageView = (ImageView) findViewById(R.id.imageView);
11         bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.qq);
12     }
13
14     public void zoomIn(View v) {
15         Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth() * 2, bitmap.getHeight() * 2, bitmap.getConfig());    // 创建新的Bitmap, 指定大小
16         Canvas canvas = new Canvas(newBitmap);        // 创建画布
17         Matrix matrix = new Matrix();                // 创建模型
18         matrix.postScale(2, 2);                        // 设置缩放比例, x轴和y轴都是2倍大小
19         canvas.drawBitmap(bitmap, matrix, null);    // 参照matrix模型, 在画布上按照bitmap画
20
21         imageView.setImageBitmap(newBitmap);        // 把新图片设置到ImageView中
22         bitmap = newBitmap;                            // 记住新图片, 下次从这个图片操作
23     }
24
25     public void zoomOut(View v) {
26         Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth() / 2, bitmap.getHeight() / 2, bitmap.getConfig());
27         Canvas canvas = new Canvas(newBitmap);
28         Matrix matrix = new Matrix();
29         matrix.postScale(0.5f, 0.5f);
30         canvas.drawBitmap(bitmap, matrix, null);
31
32         imageView.setImageBitmap(newBitmap);
33         bitmap = newBitmap;
34     }
35
36     public void rotate(View v) {
37         Bitmap newBitmap = Bitmap.createBitmap(bitmap.getHeight(), bitmap.getWidth(), bitmap.getConfig());
38         Canvas canvas = new Canvas(newBitmap);
39         Matrix matrix = new Matrix();
40         matrix.postRotate(90, bitmap.getWidth() / 2, bitmap.getHeight() / 2);
41         canvas.drawBitmap(bitmap, matrix, null);
42
43         imageView.setImageBitmap(newBitmap);
44         bitmap = newBitmap;
45     }
46
47     public void inverse(View v) {
48         Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight() , bitmap.getConfig());
49         Canvas canvas = new Canvas(newBitmap);
50         Matrix matrix = new Matrix();
51         matrix.postScale(-1, 1);                        // -1 代表x轴做镜像(镜像之后图片会移动到左边)
52         matrix.postTranslate(bitmap.getWidth(), 0);        // 向右移动
53         canvas.drawBitmap(bitmap, matrix, null);
54
55         imageView.setImageBitmap(newBitmap);
56         bitmap = newBitmap;
57     }
58
59 }