android 自定义控件 onMeasure

android 自定义控件SurfaceView

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int originalWidth = MeasureSpec.getSize(widthMeasureSpec);//800
int calculatedHeight = originalWidth * aspectHeight / aspectWidth;//1095
super.onMeasure(
MeasureSpec.makeMeasureSpec(originalWidth, MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(calculatedHeight, MeasureSpec.EXACTLY));
}

    对onMeasure方法表示不理解，
    上述代码中的originalWidth，calculatedHeight，是指控件本身还是真个屏幕？通过debug，发现打印出来的值都对不上啊？



     <view
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    class="com.sensetime.facesign.util.DefinedSurfaceView"
    android:id="@+id/surfaceView"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true" />



    package com.sensetime.facesign.util;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.SurfaceView;

import com.sensetime.facesign.R;

/**

• Created by SenseTime on 2015/1/10.
  */
  public class DefinedSurfaceView extends SurfaceView {

  private int aspectWidth = 480;
  private int aspectHeight = 640;
  private Context mContext;

  public DefinedSurfaceView(Context context) {
  super(context);
  mContext = context;
  }

  public DefinedSurfaceView(Context context, AttributeSet attrs) {
  super(context, attrs);
  mContext = context;
  setCustomAttributes(attrs);
  }

  public DefinedSurfaceView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  mContext = context;
  setCustomAttributes(attrs);
  }

  private void setCustomAttributes(AttributeSet attrs) {
  TypedArray a = mContext.obtainStyledAttributes(attrs,
  R.styleable.definedlayout);
  aspectWidth = a.getDimensionPixelSize(
  R.styleable.definedlayout_target_width, 480);//aspectWidth == 480 //??
  aspectHeight = a.getDimensionPixelSize(
  R.styleable.definedlayout_target_height, 640);//aspectHeight == 640 //??

  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  int originalWidth = MeasureSpec.getSize(widthMeasureSpec);//800
  int calculatedHeight = originalWidth * aspectHeight / aspectWidth;//1095
  super.onMeasure(
  MeasureSpec.makeMeasureSpec(originalWidth, MeasureSpec.EXACTLY),
  MeasureSpec.makeMeasureSpec(calculatedHeight, MeasureSpec.EXACTLY));
  }
  }

 如果是SurfaceView，则不能根据 onMeasure获取高宽
需要用
SurfaceHolder.Callback的surfaceCreated才能获取实际的高度和宽度
public void surfaceCreated(SurfaceHolder holder) {
  // TODO Auto-generated method stub
Log.d("TEST","Width="+ this.getWidth()+"|Height="+this.getHeight());

 }

 view可以用onMeasure