Android学习笔记_66_图片处理专题

浏览数：21 / 时间：2015年06月11日

　　1、图片缩放：不解析整个图片信息。

public class DemoActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ImageView iv = (ImageView) this.findViewById(R.id.iv);
//        BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
//        //按1/8的大小加载到内存 
//        bmpFactoryOptions.inSampleSize = 8;
//        Bitmap bm = BitmapFactory.decodeFile("/sdcard/img.jpg",bmpFactoryOptions);
//        iv.setImageBitmap(bm);
        
        // 
        //1. 首先得到屏幕的宽高
        Display currentDisplay = getWindowManager().getDefaultDisplay();
        int dw = currentDisplay.getWidth();
        int dh = currentDisplay.getHeight();
        // 2. 获取图片的宽度和高度 
        BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
        // 设置inJustDecodeBounds = true ,只会解析文件头信息;
        bmpFactoryOptions.inJustDecodeBounds = true;
        // 不会真正的解析这个位图 
        Bitmap bmp = BitmapFactory.decodeFile("/sdcard/img.jpg", bmpFactoryOptions);
        //得到图片的宽度和高度 
        int heightRatio = (int)Math.ceil(bmpFactoryOptions.outHeight/(float)dh);
        int widthRatio = (int)Math.ceil(bmpFactoryOptions.outWidth/(float)dw);
        Log.v("HEIGHTRATIO",""+heightRatio);
        Log.v("WIDTHRATIO",""+widthRatio);

        //真正的解析位图 
        bmpFactoryOptions.inJustDecodeBounds = false;
   
        if(heightRatio>widthRatio){
            bmpFactoryOptions.inSampleSize = heightRatio;
        }else{
            bmpFactoryOptions.inSampleSize = widthRatio;
        }
        bmp = BitmapFactory.decodeFile("/sdcard/img.jpg", bmpFactoryOptions);
        
        iv.setImageBitmap(bmp);
    }
}

　　2、ExifInterface获取或设置图片的exif信息：

public class DemoActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        try {
            ExifInterface  exif = new ExifInterface("sdcard/img.jpg");
            System.out.println( exif.getAttribute(ExifInterface.TAG_DATETIME));
            System.out.println( exif.getAttribute(ExifInterface.TAG_IMAGE_LENGTH));
            System.out.println( exif.getAttribute(ExifInterface.TAG_IMAGE_WIDTH));    
            exif.setAttribute("camera", "柯达相机");    
            System.out.println( exif.getAttribute("camera"));
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

3、从图库里面选择一个图片，然后将它设置到ImageView。

public class DemoActivity extends Activity {
    ImageView iv;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        iv = (ImageView) this.findViewById(R.id.iv);
    }
    
    public void click(View view){
        //选择图库意图，打开图库
        Intent intent = new Intent(Intent.ACTION_PICK);
        intent.setType("image/*");
        startActivityForResult(intent, 0);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if(data!=null){
            //图片的uri
            Uri uri = data.getData() ;
            iv.setImageURI(uri);
        }
        super.onActivityResult(requestCode, resultCode, data);
    }
}

　　4、创建图片（bitmap）的拷贝：

public class DemoActivity extends Activity{
    ImageView iv1;
    ImageView iv2;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        iv1= (ImageView) this.findViewById(R.id.iv1);
        iv2= (ImageView) this.findViewById(R.id.iv2);
    }
    
    public void click(View view){
        Intent intent = new Intent(Intent.ACTION_PICK);
        intent.setType("image/*");
        startActivityForResult(intent, 0);
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if(data!=null){
            //图片的uri
            Uri uri = data.getData() ;
            iv1.setImageURI(uri);
            // 获取第一个图片 的拷贝 设置到iv2的控件里面 
            try {
                //通过uri获取一个流对象。getContentResolver().openInputStream(uri)
                Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri));
                //图片缩放
                Matrix matrix = new Matrix();
//                matrix.setValues(new float[] {
//                    2, 0, 0,
//                    0, 1, 0,
//                    0, 0, 1
//                });//矩阵缩放
//                matrix.setScale(1.5f, 1.0f);//水平方向为1.5倍，垂直方向不做改变
//                matrix.setRotate(30);
                //画笔
                Paint paint = new Paint();
                paint.setAntiAlias(true);
                matrix.setRotate(15);//图片旋转
                //得到一个大小 配置跟原图一样的空白的位图 
                //Bitmap  alterbitmap  = Bitmap.createBitmap(bitmap.getWidth()*2, bitmap.getHeight(), bitmap.getConfig());
                Bitmap    alteredBitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(),
                        matrix, false);
                //画布对象
                Canvas canvas = new Canvas();
                //将图片流bitmap应用到画布上
                canvas.drawBitmap(bitmap, matrix, paint);    
                iv2.setImageBitmap(alteredBitmap);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        super.onActivityResult(requestCode, resultCode, data);
    }
}