Android中Widget的不同visibility属性值调用

View的绘制流程

  绘制流程主要关乎这三个方法：onMesure()、onLayout()、onDraw()，分别是测量、布局、绘制。

定义一个View类，重写三个方法

public class MyDiyView extends View {

    public MyDiyView(Context context) {
        super(context);
    }

    public MyDiyView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public MyDiyView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public MyDiyView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        Log.d("MyDiyViewTest:==>","onMeasure()");
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        Log.d("MyDiyViewTest:==>","onLayout()");
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Log.d("MyDiyViewTest:==>","onDraw()");
    }

}

结论：

android:visibility="visible"   //可见

D/MyDiyViewTest:==>: onMeasure()
D/MyDiyViewTest:==>: onLayout()
D/MyDiyViewTest:==>: onDraw()

android:visibility="invisible"   //占位不可见

D/MyDiyViewTest:==>: onMeasure()
D/MyDiyViewTest:==>: onLayout()

android:visibility="gone"  //不占位不可见

三个方法都不调用