[android]自定義組件及其內組件大小的正確設置

一、自定義組件大小的設置 不管你怎麼設置，自定義組件似乎總是match_parent。我們需要覆蓋onMeasure方法，並在其內正確設置組件大小。 [java]   @Override   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {       //注意：為盡可能簡潔本文只討論EXACTLY和AT_MOST模式       int mode = MeasureSpec.getMode(widthMeasureSpec);       if(mode == MeasureSpec.AT_MOST || mode == MeasureSpec.EXACTLY) {           this.widthMeasureSpec = widthMeasureSpec;           this.heightMeasureSpec = heightMeasureSpec;           int width = MeasureSpec.getSize(widthMeasureSpec);           int height = MeasureSpec.getSize(heightMeasureSpec);           setMeasuredDimension(width, height);       } else if(mode == MeasureSpec.UNSPECIFIED) {           Log.d("WOGU", "mode=UNSPECIFIED");           super.onMeasure(widthMeasureSpec, heightMeasureSpec);       }   }   二、自定義組件內的組件的大小設置 除了覆蓋onMeasure還需覆蓋onLayout，在其內設置子元素的大小。 [java]   public class MyViewGroup extends ViewGroup {       protected int widthMeasureSpec, heightMeasureSpec;          @Override       protected void onLayout(boolean changed, int left, int top, int right, int bottom) {           if(changed) {               View view = getChildAt(0);               //measure將觸發View的onMeasure。               //widthMeasureSpec包括尺寸和模式               //int width = MeasureSpec.getSize(widthMeasureSpec);               //int height = MeasureSpec.getSize(heightMeasureSpec);               //int mode = MeasureSpec.getMode(widthMeasureSpec);               //mode的可能值MeasureSpec.AT_MOST,MeasureSpec.EXACTLY,MeasureSpec.UNSPECIFIED               //這裡只是簡單的在onMeasure中記錄widthMeasureSpec和heightMeasureSpec               //其實MeasureSpec提供了根據sizet和模式合成widthMeasureSpec,heightMeasureSpec的方法               //int widthMeasureSpec = MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.EXACTLY);               //int heightMeasureSpec = MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.EXACTLY);               view.measure(widthMeasureSpec, heightMeasureSpec);               view.layout(0, 0, getWidth(), getHeight());           }       }          @Override       protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {           this.widthMeasureSpec = widthMeasureSpec;           this.heightMeasureSpec = heightMeasureSpec;           ...       }   }