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     <LinearLayout13         android:layout_width="match_parent"14         android:layout_height="wrap_content" >15 16         <Button17             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         <Button24             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         <Button31             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         <Button38             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     <ImageView46         android:id="@+id/imageView"47         android:layout_width="wrap_content"48         android:layout_height="wrap_content"49         android:src="@drawable/qq" />50 51 </LinearLayout>

View Code

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 }

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