Android Bitmap The premise of not loading the picture to get the width high

Code reference:

 /** * To get thumbnails of images based on the width and height of the view (mostly ImageView) * @param path * @param viewwidth * @param viewheight * @ return */Private Bitmap Decodethumbbitmapforfile (String path, int viewwidth, int viewheight) {BITMAPFA Ctory.          Options options = new Bitmapfactory.options ();          Set to True to resolve the bitmap object, which does not account for memory Options.injustdecodebounds = true;          Bitmapfactory.decodefile (path, options);                    Set Scaling options.insamplesize = Computescale (options, Viewwidth, viewheight);                    Set to False to parse the bitmap object into memory Options.injustdecodebounds = false;      return Bitmapfactory.decodefile (path, options); /** * Calculates the bitmap scale based on the width and height of the view (mainly ImageView). The default does not scale * @param options * @param width * @param height */private int Computescale (BITMAPFACTORY.O          ptions options, int viewwidth, int viewheight) {int insamplesize = 1; if (Viewwidth = = 0 | | viewheight = = 0) {return insamplesize;          } int bitmapwidth = Options.outwidth;                    int bitmapheight = Options.outheight;              If the width or height of the bitmap is greater than the width of the view in which we set the picture, then the scaling if (Bitmapwidth > Viewwidth | | bitmapheight > Viewwidth) {              int widthscale = Math.Round ((float) bitmapwidth/(float) viewwidth);                            int heightscale = Math.Round ((float) bitmapheight/(float) viewwidth); In order to ensure that the image does not scale deformation, we take the Insamplesize = Widthscale < Heightscale with the smallest width and height ratio?          Widthscale:heightscale;      } return insamplesize;         }

Also refer to:

Bitmapfactory.options Options = new Bitmapfactory.options ();                  /**         * Most critical here, put options.injustdecodebounds = true;         * Here again DecodeFile (), return the bitmap is empty, but at this time call Options.outheight, already contains the picture of the height of         */         Options.injustdecodebounds = true;         Bitmap Bitmap = Bitmapfactory.decodefile ("/sdcard/test.jpg", options); The returned Bitmap is null         /**         *options.outheight is the height of the original picture         *         /LOG.E ("Test", "Bitmap Height = =" + Options.outheight);  

Based on these methods, you can set the picture to be reduced to the original (1/2,1/4,1/8,1/16.) before actually loading the bitmap picture.

Here is a description of insamplesize in the Android source code:

<span style= "Background-color:rgb (51, 255, 51); >public int insamplesize</span>added in API level 1If set to a value > 1, requests the decoder to subsample th E original image, returning a smaller image to save memory. The sample size is the number of pixels in either dimension this correspond to a single pixel in the decoded bitmap. For example, insamplesize = = 4 Returns an image which is the width/height of the original, and 1/16 the number of pixel S. Any value <= 1 is treated the same as 1. Note:the decoder uses a final value based on powers of 2,<span style= "Background-color:rgb (51, 255, 51);" > Any other value would be rounded down to the nearest power of 2</span>.

Android Bitmap The premise of not loading the picture to get the width high