加载大图片到内存，进行缩放

最新推荐文章于 2021-05-29 02:17:31 发布

原创最新推荐文章于 2021-05-29 02:17:31 发布 · 428 阅读

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#图片 #内存 #imageview

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本文详细解析了Android应用中如何高效地加载和优化图片资源，通过使用BitmapFactory进行图片尺寸预判和inSampleSize参数设置，实现图片在不同屏幕分辨率设备上的适配与快速加载，同时优化内存使用，提升用户体验。

    public class MainActivity extends Activity {

    private ImageView iv;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        iv = (ImageView) findViewById(R.id.iv);

        BitmapFactory.Options opts = new BitmapFactory.Options();
        opts.inJustDecodeBounds = true ;
        BitmapFactory.decodeFile("/mnt/sdcard/a.jpg", opts);

        int bmWidth = opts.outWidth;
        int bmHeight = opts.outHeight;

        WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();
        int screenWidth = display.getWidth();
        int screenHeight = display.getHeight();

        int scale = 1 ;
        int dx = bmWidth/screenWidth;
        int dy = bmHeight/screenHeight;

        if(dx>dy&&dy>0){
            scale = dx;
        }
        if(dy>dx&&dx>0){
            scale = dy;
        }

        opts.inJustDecodeBounds = false;
        opts.inSampleSize = scale;

        Bitmap bm = BitmapFactory.decodeFile("/mnt/sdcard/a.jpg", opts);
        iv.setImageBitmap(bm);
    }



}