android特殊用法_uri erasecolor-优快云博客

本文介绍了Android开发中的一些特殊用法，包括让图片透明、直接发送邮件、控制屏幕变亮、过滤文本、ScrollView滚动停止事件、特定程序关联打开、创建圆角图片、通知图标加数字提示、背景渐变、数据存储、应用实例等。涵盖了从图片处理到系统控制、从UI设计到应用开发的多个方面。

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一些android特殊用法

1.让一个图片透明：

                   Bitmap buffer = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_4444);buffer.eraseColor(Color.TRANSPARENT);

2.直接发送邮件：

                 Intent intent = new Intent(Intent.ACTION_SENDTO,  Uri .fromParts("mailto", "", null));    
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);     
context.startActivity(intent);

3.程序控制屏幕变亮：

             WindowManager.LayoutParams lp = getWindow().getAttributes();     
lp.screenBrightness = 100 / 100.0f;     
getWindow().setAttributes(lp);

4.过滤特定文本

                Filter filter = myAdapter.getFilter();     
filter.filter(mySearchText);

5.scrollView scroll停止事件

               setOnScrollListener(new OnScrollListener(){        
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {         
// TODO Auto-generated method stub    }        
public void onScrollStateChanged(AbsListView view, int scrollState) {          
// TODO Auto-generated method stub          
if(scrollState == 0) Log.i("a", "scrolling stopped...");    }  });}

6. 对于特定的程序发起一个关联供打开

               Bitmap bmp = getImageBitmap(jpg);     
String path = getFilesDir().getAbsolutePath() + "/test.png";     
File file = new File(path);     
FileOutputStream fos = new FileOutputStream(file);     
bmp.compress( CompressFormat.PNG, 100, fos );     
  fos.close();     
      
   Intent intent = new Intent();     
   intent.setAction(android .content.Intent.ACTION_VIEW);     
   intent.setDataAndType(Uri .fromFile(new File(path)), "image/png");     
   startActivity(intent);

对于图片上边的不适用索引格式会出错。

                  Intent intent = new Intent();      
intent.setAction(android .content.Intent.ACTION_VIEW);      
File file = new File("/sdcard/test.mp4");      
intent.setDataAndType(Uri .fromFile(file), "video/*");      
startActivity(intent);     
   
Intent intent = new Intent();      
intent.setAction(android .content.Intent.ACTION_VIEW);      
File file = new File("/sdcard/test.mp3");      
intent.setDataAndType(Uri .fromFile(file), "audio/*");      
startActivity(intent);

7.设置文本外观

                  setTextAppearance(context, android .R.style.TextAppearance_Medium);     
android :textAppearance="?android :attr/textAppearanceMedium"

8.设置单独的发起模式：

                <activity            
  android :name=".ArtistActivity"            
  android :label="Artist"            
  android :launchMode="singleTop">        
  </activity>     
   
Intent i = new Intent();            
   i.putExtra(EXTRA_KEY_ARTIST, id);           
    i.setClass(this, ArtistActivity.class);            
    i.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);           
     startActivity(i);

9.创建一个圆角图片
这个的主要原理其实就是利用遮罩，先创建一个圆角方框然后将图片放在下面：

                Bitmap myCoolBitmap = ... ;    
      int w = myCoolBitmap.getWidth(), h = myCoolBitmap.getHeight();    
      Bitmap rounder = Bitmap.createBitmap(w,h,Bitmap.Config.ARGB_8888);    
      Canvas canvas = new Canvas(rounder);       
      Paint xferPaint = new Paint(Paint.ANTI_ALIAS_FLAG);    
      xferPaint.setColor(Color.RED);    
      canvas.drawRoundRect(new RectF(0,0,w,h), 20.0f, 20.0f, xferPaint);        
      xferPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));   
//然后呢实现    
canvas.drawBitmap(myCoolBitmap, 0,0, null);    
canvas.drawBitmap(rounder, 0, 0, xferPaint);

10.在notification 上的icon上加上数字给人提示有多少个未读

                Notification notification = new Notification (icon, tickerText, when);    
notification .number = 4;

11背景渐变：
首先建立文件drawable/shape.xml

                 <?xml version="1.0" encoding="utf-8"?>    
<shape xmlns:android ="http://schemas.android .com/apk/res/android " android :shape="rectangle">   
    <gradient android :startColor="#FFFFFFFF" android :endColor="#FFFF0000"    
            android :angle="270"/>    
</shape>

在该文件中设置渐变的开始颜色(startColor)、结束颜色(endColor)和角度(angle)

接着创建一个主题values/style.xml

                 <?xml version="1.0" encoding="utf-8"?>    
<resources>    
<style name="NewTheme" parent="android :Theme">    
<item name="android :background">@drawable/shape</item>    
</style>    
</resources>

然后在AndroidManifest.xml文件中的application或activity中引入该主题,如:

              <activity android :name=".ShapeDemo" android :theme="@style/NewTheme">

该方法同样适用于控件 http://17f8.cn/trackback.php?tbID=259&extra=9d45e9

12. 储存数据当你在一个实例中保存静态数据，此示例关闭后下一个实例想引用静态数据就会为null，这里呢必须重写applition

          public class MyApplication extends Application{       
   private String thing = null;       
   public String getThing(){           
     return thing;       
     }       
     public void setThing( String thing ){          
      this.thing = thing;    }    
      }    
      public class MyActivity extends Activity {       
      private MyApplication app;       
      public void onCreate(Bundle savedInstanceState) {           
      super.onCreate(savedInstanceState);           
      app = ((MyApplication)getApplication());           
      String thing = app.getThing();       
      }    
      }