// 擷取螢幕密度(方法1) int screenWidth = getWindowManager().getDefaultDisplay().getWidth(); // 螢幕寬(像素,如:480px) int screenHeight = getWindowManager().getDefaultDisplay().getHeight(); // 螢幕高(像素,如:800p) Log.e(TAG + " getDefaultDisplay", "screenWidth=" + screenWidth + "; screenHeight=" + screenHeight); // 擷取螢幕密度(方法2) DisplayMetrics dm = new DisplayMetrics(); dm = getResources().getDisplayMetrics(); float density = dm.density; // 螢幕密度(像素比例:0.75/1.0/1.5/2.0) int densityDPI = dm.densityDpi; // 螢幕密度(每寸像素:120/160/240/320) float xdpi = dm.xdpi; float ydpi = dm.ydpi; Log.e(TAG + " DisplayMetrics", "xdpi=" + xdpi + "; ydpi=" + ydpi); Log.e(TAG + " DisplayMetrics", "density=" + density + "; densityDPI=" + densityDPI); screenWidth = dm.widthPixels; // 螢幕寬(像素,如:480px) screenHeight = dm.heightPixels; // 螢幕高(像素,如:800px) Log.e(TAG + " DisplayMetrics(111)", "screenWidth=" + screenWidth + "; screenHeight=" + screenHeight); // 擷取螢幕密度(方法3) dm = new DisplayMetrics(); getWindowManager().getDefaultDisplay().getMetrics(dm); density = dm.density; // 螢幕密度(像素比例:0.75/1.0/1.5/2.0) densityDPI = dm.densityDpi; // 螢幕密度(每寸像素:120/160/240/320) xdpi = dm.xdpi; ydpi = dm.ydpi; Log.e(TAG + " DisplayMetrics", "xdpi=" + xdpi + "; ydpi=" + ydpi); Log.e(TAG + " DisplayMetrics", "density=" + density + "; densityDPI=" + densityDPI); int screenWidthDip = dm.widthPixels; // 螢幕寬(dip,如:320dip) int screenHeightDip = dm.heightPixels; // 螢幕寬(dip,如:533dip) Log.e(TAG + " DisplayMetrics(222)", "screenWidthDip=" + screenWidthDip + "; screenHeightDip=" + screenHeightDip); screenWidth = (int)(dm.widthPixels * density + 0.5f); // 螢幕寬(px,如:480px) screenHeight = (int)(dm.heightPixels * density + 0.5f); // 螢幕高(px,如:800px) Log.e(TAG + " DisplayMetrics(222)", "screenWidth=" + screenWidth + "; screenHeight=" + screenHeight);
測試結果如下
E/== MyScreenActivity =================================== getDefaultDisplay( 8509): screenWidth=320; screenHeight=533E/== MyScreenActivity =================================== DisplayMetrics( 8509): xdpi=156.3077; ydpi=157.51938E/== MyScreenActivity =================================== DisplayMetrics( 8509): density=1.0; densityDPI=160E/== MyScreenActivity =================================== DisplayMetrics(111)( 8509): screenWidth=320; screenHeight=533E/== MyScreenActivity =================================== DisplayMetrics( 8509): xdpi=234.46153; ydpi=236.27907E/== MyScreenActivity =================================== DisplayMetrics( 8509): density=1.5; densityDPI=240E/== MyScreenActivity =================================== DisplayMetrics(222)( 8509): screenWidthDip=320; screenHeightDip=533E/== MyScreenActivity =================================== DisplayMetrics(222)( 8509): screenWidth=480; screenHeight=800
分析結果:
在onDraw()方法中
方法1和2,得到的結果都一致,均為320*533,明顯不是測試機i9000的螢幕大小
方法3,將方法1和2得到的結果,乘以density後,完美的480*800,perfect!
註:density 大於1的情況下,需要設定targetSdkVersion在4-9之間,例如
<uses-sdk android:minSdkVersion="3" android:targetSdkVersion="10" />
但是,這就說明方法3一定是通用的嗎?
回答是否定的,因為我也在模擬器、HTC G14物理機,以及ViewSonic、Galaxy平板上測試過,方法3在density=1.5時,放大了實際螢幕值,例如:HTC G14
在HTC G14上,實際螢幕大小,直接通過dm.widthPixels、dm.heightPixels便得到了實際物理螢幕大小(540,960)
導致無法通過一種通用的方法擷取真實物理螢幕大小的原因,可能就是因為Android系統開源,不同的手機生產廠商沒有統一的製造標準,來規定手機螢幕。
仔細分析代碼,發現問題出在代碼:
getWindowManager().getDefaultDisplay().getMetrics(dm)
Initialize a DisplayMetrics object from this display's data.
dm = getResources().getDisplayMetrics()
Return the current display metrics that are in effect for this resource object. The returned object should be treated as read-only.