android 获取图片像素密度,android 获取屏幕的密度和像素 点

经过测试发现屏幕的像素点 如果

density =1 那么 1dp = 1px

density =2 那么 1dp = 2px

density =3 那么 1dp = 3px

在字体设置的时候用dp比用px好，因为这样可以防止在不同的分辨率上显示的字体大小不同

textView_bacMsg = (TextView) findViewById(R.id.textView_bacMsg);

bacImg = (ImageView) findViewById(R.id.bacImg);

drawable = new MyProgressDrawable(this);

// 获取屏幕密度(方法2)

DisplayMetrics dm = new DisplayMetrics();

dm = getResources().getDisplayMetrics();

float density  = dm.density;        // 屏幕密度(像素比例：0.75/1.0/1.5/2.0)

int densityDPI = dm.densityDpi;     // 屏幕密度(每寸像素：120/160/240/320)

float xdpi = dm.xdpi;

float ydpi = dm.ydpi;

int screenWidth  = dm.widthPixels;      // 屏幕宽(像素，如：480px)

int  screenHeight = dm.heightPixels;     // 屏幕高(像素，如：800px)

RelativeLayout.LayoutParams  layoutParams =new  RelativeLayout.LayoutParams(-2, -2);

layoutParams.width = screenWidth-200;

layoutParams.height = screenWidth-200;

layoutParams.topMargin = (int) ((screenHeight - 240*density - ( screenWidth-200))/2);

layoutParams.leftMargin = (int) ((screenWidth- ( screenWidth-200))/2);

bacImg.setLayoutParams(layoutParams);

bacImg.setBackgroundDrawable(drawable);

drawable.start();

RelativeLayout.LayoutParams  layoutParams_text =(LayoutParams) textView_bacMsg.getLayoutParams();

layoutParams_text.topMargin =(int) ((screenHeight - 240*density - (layoutParams_text.height))/2);

Log.e("中间的字体宽度", layoutParams_text.width+"");

layoutParams_text.leftMargin = (int) ((screenWidth - (20*4*density))/2);

textView_bacMsg.setLayoutParams(layoutParams_text);