ANDROID笔记:ImageView的简单使用

 1 package com.example.classtest;

 2 

 3 import android.app.Activity;

 4 import android.graphics.Bitmap;

 5 import android.graphics.BitmapFactory;

 6 import android.graphics.Matrix;

 7 import android.os.Bundle;

 8 import android.view.View;

 9 import android.view.View.OnClickListener;

10 import android.widget.Button;

11 import android.widget.ImageView;

12 import android.widget.ZoomButton;

13 

14 public class ImageViewActivity extends Activity implements OnClickListener {

15     // 透明度取值:0-255

16     int alpha = 255;

17     ImageView imageView = null;

18     float towidth = 1;

19     float toheight = 1;

20     Bitmap bitmapsrc = null;

21     int bwidth;

22     int bheight;

23 

24     @Override

25     protected void onCreate(Bundle savedInstanceState) {

26         super.onCreate(savedInstanceState);

27         setContentView(R.layout.imageview);

28         // 缩放按钮

29         ZoomButton button3 = (ZoomButton) findViewById(R.id.btn3);

30         ZoomButton button4 = (ZoomButton) findViewById(R.id.btn4);

31         button3.setOnClickListener(this);

32         button4.setOnClickListener(this);

33         // 设置透明度的按钮

34         Button button1 = (Button) findViewById(R.id.btn1);

35         Button button2 = (Button) findViewById(R.id.btn2);

36         button1.setOnClickListener(this);

37         button2.setOnClickListener(this);

38         imageView = (ImageView) findViewById(R.id.image);

39         // 得到需要缩放的图片资源

40         bitmapsrc = BitmapFactory.decodeResource(getResources(),

41                 R.drawable.ic_launcher);

42         bwidth = bitmapsrc.getWidth();

43         bheight = bitmapsrc.getHeight();

44 

45     }

46 

47     @Override

48     public void onClick(View v) {

49         Matrix matrix = new Matrix();

50         Bitmap bitmap = null;

51         switch (v.getId()) {

52         case R.id.btn3:

53             // 放大图片

54             towidth = (float) (towidth * 1.25);

55             toheight = (float) (toheight * 1.25);

56             // 矩阵计算

57             matrix.postScale(towidth, toheight);

58             bitmap = Bitmap.createBitmap(bitmapsrc, 0, 0, bwidth, bheight,

59                     matrix, true);

60             imageView.setImageBitmap(bitmap);

61             break;

62         case R.id.btn4:

63             towidth = (float) (towidth * 0.75);

64             toheight = (float) (toheight * 0.75);

65 

66             matrix.postScale(towidth, toheight);

67             bitmap = Bitmap.createBitmap(bitmapsrc, 0, 0, bwidth, bheight,

68                     matrix, true);

69             imageView.setImageBitmap(bitmap);

70             break;

71         case R.id.btn1:

72             alpha += 40;

73             if (alpha > 255) {

74                 alpha = 255;

75             }

76             // 设置图片透明度

77             imageView.setAlpha(alpha);

78             break;

79         case R.id.btn2:

80             alpha -= 40;

81             if (alpha < 0) {

82                 alpha = 0;

83             }

84             imageView.setAlpha(alpha);

85             break;

86 

87         }

88 

89     }

90 }

 1 <?xml version="1.0" encoding="utf-8"?>

 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

 3     android:layout_width="match_parent"

 4     android:layout_height="match_parent"

 5     android:orientation="vertical" >

 6 

 7     <!-- 横向滚动条 -->

 8 

 9     <HorizontalScrollView

10         android:layout_width="320px"

11         android:layout_height="wrap_content" >

12 

13         <!-- 纵向滚动条 -->

14 

15         <ScrollView

16             android:layout_width="wrap_content"

17             android:layout_height="200px" >

18 

19             <ImageView

20                 android:id="@+id/image"

21                 android:layout_width="wrap_content"

22                 android:layout_height="350dp"

23                 android:scaleType="centerInside"

24                 android:src="@drawable/ic_launcher" />

25         </ScrollView>

26     </HorizontalScrollView>

27 

28     <LinearLayout

29         android:layout_width="fill_parent"

30         android:layout_height="wrap_content"

31         android:orientation="horizontal" >

32 

33         <Button

34             android:id="@+id/btn1"

35             android:layout_width="wrap_content"

36             android:layout_height="wrap_content"

37             android:text="增加透明度" />

38 

39         <Button

40             android:id="@+id/btn2"

41             android:layout_width="wrap_content"

42             android:layout_height="wrap_content"

43             android:text="减小透明度" />

44 

45     </LinearLayout>

46 

47     <LinearLayout

48         android:layout_width="wrap_content"

49         android:layout_height="wrap_content"

50         android:orientation="horizontal" >

51 

52         <!-- 缩放按钮 -->

53 

54         <ZoomButton

55             android:id="@+id/btn3"

56             android:layout_width="wrap_content"

57             android:layout_height="wrap_content"

58             android:src="@android:drawable/btn_plus" />

59 

60         <ZoomButton

61             android:id="@+id/btn4"

62             android:layout_width="wrap_content"

63             android:layout_height="wrap_content"

64             android:src="@android:drawable/btn_minus" />

65     </LinearLayout>

66 

67 </LinearLayout>

 

重点：

　　图片的透明度：imageView.setAlpha(alpha);（alpha 0-255）

　　图片的缩放:    matrix.postScale(towidth, toheight);
            　　　　 bitmap = Bitmap.createBitmap(bitmapsrc, 0, 0, bwidth, bheight, matrix, true);

　　　　　　　　　imageView.setImageBitmap(bitmap);