Android - View流程
Android -- View流程
在自定义view中打log，view的显示共有三种，visible、invisible和gone，分别看一下log：
gone
onVisibilityChanged construct 2 parameters onFinishInflate onVisibilityChanged onVisibilityChanged onRtlPropertiesChanged onRtlPropertiesChanged onAttachedToWindow onWindowVisibilityChanged onWindowFocusChanged
invisible
onVisibilityChanged construct 2 parameters . onFinishInflate onVisibilityChanged onVisibilityChanged onRtlPropertiesChanged onRtlPropertiesChanged onAttachedToWindow onWindowVisibilityChanged onMeasure , width : 1080 ; height: 1557 onMeasure , width : 144 ; height: 1500 onSizeChanged onLayout --> l: 0 ; r : 144 ; t: 57 ; b: 201 : changed :true onMeasure , width : 1080 ; height: 1557 onMeasure , width : 144 ; height: 1500 onLayout --> l: 0 ; r : 144 ; t: 57 ; b: 201 : changed :false onWindowFocusChanged
visible
construct 2 parameters . onFinishInflate onVisibilityChanged onVisibilityChanged onRtlPropertiesChanged onRtlPropertiesChanged onAttachedToWindow onWindowVisibilityChanged onMeasure , width : 1080 ; height: 1557 onMeasure , width : 144 ; height: 1500 onSizeChanged onLayout --> l: 0 ; r : 144 ; t: 57 ; b: 201 : changed :true onMeasure , width : 1080 ; height: 1557 onMeasure , width : 144 ; height: 1500 onLayout --> l: 0 ; r : 144 ; t: 57 ; b: 201 : changed :false onDraw onWindowFocusChanged
1、从中看到view默认为可见的，不是默认值时先调用 onVisibilityChanged ，但是此时该view的任何位置信息都不知道。
2、可见性改变后才是调用带有两个参数的构造函数
3、从xml 文件中 inflate 完成
4、将view 加到 window 中(View 是gone 的，那么View创建生命周期也就结束)
5、测量view的长宽(onMeasure)
6、定位View在父View中的位置(onLayout)--->(View 是invisible ，View 创建生命周期结束)
7、onDraw(只有可见的View 才在window 中绘制)
setContentView(new View(this))
construct 1 parameter onVisibilityChanged onVisibilityChanged onRtlPropertiesChanged onRtlPropertiesChanged onAttachedToWindow onWindowVisibilityChanged onMeasure , width : 1080 ; height: 1557 onSizeChanged onLayout --> l: 0 ; r : 1080 ; t: 0 ; b: 1557 : changed :true onMeasure , width : 1080 ; height: 1557 onLayout --> l: 0 ; r : 1080 ; t: 0 ; b: 1557 : changed :false onDraw onWindowFocusChanged
默认情况下view的长和宽默认和父view的长和宽一致。
销毁
onWindowFocusChanged
onWindowVisibilityChanged
onDetachedFromWindow
总结
View 的关键生命周期为
构造View --> onFinishInflate --> onAttachedToWindow --> onMeasure --> onSizeChanged --> onLayout --> onDraw --> onDetackedFromWindow
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- 1楼我爱物联网
- 屏幕上拖动view(通过修改view的layout)， private float mDownX, mDownY, x, y; private int dx, dy, il, ir, it, ib; @Override public boolean onTouchEvent(MotionEvent event) { x = event.getX(); y = event.getY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: mDownX = event.getX(); mDownY = event.getY(); il = getLeft(); ir = getRight(); it = getTop(); ib = getBottom(); break; case MotionEvent.ACTION_MOVE: case MotionEvent.ACTION_UP: dx += Math.round(x - mDownX); dy += Math.round(y - mDownY); layout(il + dx, it + dy, ir + dx, ib + dy); break;