Android 图片的处理方法 更新中

// 压缩图片大小
    public static Bitmap compressImage(Bitmap image) {

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        image.compress(Bitmap.CompressFormat.JPEG, 100, baos);// 将压缩的图片存到baos中
        // >100kb go on compress
        int option = 100;
        while (baos.toByteArray().length / 1024 > 100) {
            baos.reset();
            image.compress(Bitmap.CompressFormat.JPEG, option, baos);
            option -= 10;
        }

        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());// 把压缩后的数据baos存放到ByteArrayInputStream中
        Bitmap bitmap = BitmapFactory.decodeStream(bais, null, null);// 把ByteArrayInputStream数据生成图片

        return bitmap;
    }
    
    
    /**  
     * 将彩色图转换为灰度图  
     * @param img 位图  
     * @return  返回转换好的位图  
     */    
    public Bitmap convertGreyImg(Bitmap img) {    
        int width = img.getWidth();         //获取位图的宽    
        int height = img.getHeight();       //获取位图的高    
            
        int []pixels = new int[width * height]; //通过位图的大小创建像素点数组    
            
        img.getPixels(pixels, 0, width, 0, 0, width, height);    
        int alpha = 0xFF << 24;     
        for(int i = 0; i < height; i++)  {    
            for(int j = 0; j < width; j++) {    
                int grey = pixels[width * i + j];    
                    
                int red = ((grey  & 0x00FF0000 ) >> 16);    
                int green = ((grey & 0x0000FF00) >> 8);    
                int blue = (grey & 0x000000FF);    
                    
                grey = (int)((float) red * 0.3 + (float)green * 0.59 + (float)blue * 0.11);    
                grey = alpha | (grey << 16) | (grey << 8) | grey;    
                pixels[width * i + j] = grey;    
            }    
        }    
        Bitmap result = Bitmap.createBitmap(width, height, Config.RGB_565);    
        result.setPixels(pixels, 0, width, 0, 0, width, height);    
        return result;    
    }    

 

public static Bitmap decodeFile (String pathName)

Added in API level 1

Decode a file path into a bitmap. If the specified file name is null, or cannot be decoded into a bitmap, the function returns null.

Parameters

pathName	complete path name for the file to be decoded.

Returns

• the resulting decoded bitmap, or null if it could not be decoded.  

/** 
    * 放大缩小图片 
    */  
    public static Bitmap zoomBitmap(Bitmap bitmap, int w, int h) {  
       int width = bitmap.getWidth();  
       int height = bitmap.getHeight();  
       Matrix matrix = new Matrix();  
       float scaleWidht = ((float) w / width);  
       float scaleHeight = ((float) h / height);  
       matrix.postScale(scaleWidht, scaleHeight);  
       Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);  
       return newbmp;  
    }