标签：android旋转
本文主要介绍Android ViewGroup/View的绘制流程，及常用的自定义ViewGroup的方法。在此基础上介绍动态控制View的位置的三种方法，并给出最佳的一种方法。
简单的说一个View从无到有需要三个步骤，onMeasure、onLayout、onDraw,即测量大小、放置位置、绘制三个步骤。而ViewGroup的onMeasure、onLayout流程里，又会遍历每个孩子，并最终调到孩子的measure()、layout()函数里。与View不同的是，ViewGroup没有onDraw流程，但有dispatchDraw()流程，该函数最终又调用drawChild()绘制每个孩子，调每个孩子View的onDraw流程。
在onMeasure流程里是为了获得控件的高和宽，这块有个getWidth()和getMeasuredWidth()的概念，前者指宽度，后者是测量宽度。一般来说，一个自定义VIewGroup(如继承自RelativeLayout)一般要进两次onMeasure，一次onLayout，一次drawChild()。虽然onMeasure流程是测量大小，且进了两次。但直到最后一次出去的时候调用getWidth()得到的仍然是0.getWidth()的数值一直到onSizeChanged()的时候才能够得到正确的，此后进到onLayout里当然也能正常得到。
下面是我截的一段代码：
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub
Log.i(TAG, "onMeasure enter...");
Log.i(TAG, "width = " + getWidth() + " height = " + getHeight());
Log.i(TAG, "MeasuredWidth = " + getMeasuredWidth() + " MeasuredHeight = " + getMeasuredHeight());
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
Log.i(TAG, "00000000000 width = " + getWidth() + " height = " + getHeight());
Log.i(TAG, "00000000000 MeasuredWidth = " + getMeasuredWidth() + " MeasuredHeight = " + getMeasuredHeight());
Log.i(TAG, "onMeasure exit...");
}Line 355: 01-03 10:15:40.526 I/YanZi (10793): onMeasure enter...
Line 357: 01-03 10:15:40.526 I/YanZi (10793): width = 0 height = 0
Line 359: 01-03 10:15:40.527 I/YanZi (10793): MeasuredWidth = 0 MeasuredHeight = 0
Line 361: 01-03 10:15:40.531 I/YanZi (10793): 00000000000 width = 0 height = 0
Line 363: 01-03 10:15:40.532 I/YanZi (10793): 00000000000 MeasuredWidth = 1080 MeasuredHeight = 1701
Line 365: 01-03 10:15:40.532 I/YanZi (10793): onMeasure exit...
Line 367: 01-03 10:15:40.532 I/YanZi (10793): onMeasure enter...
Line 369: 01-03 10:15:40.533 I/YanZi (10793): width = 0 height = 0
Line 371: 01-03 10:15:40.533 I/YanZi (10793): MeasuredWidth = 1080 MeasuredHeight = 1701
Line 373: 01-03 10:15:40.536 I/YanZi (10793): 00000000000 width = 0 height = 0
Line 375: 01-03 10:15:40.536 I/YanZi (10793): 00000000000 MeasuredWidth = 1080 MeasuredHeight = 1701
Line 377: 01-03 10:15:40.537 I/YanZi (10793): onMeasure exit...
Line 379: 01-03 10:15:40.537 I/YanZi (10793): onSizeChanged enter...
Line 381: 01-03 10:15:40.538 I/YanZi (10793): width = 1080 height = 1701
Line 383: 01-03 10:15:40.538 I/YanZi (10793): onSizeChanged exit...
Line 385: 01-03 10:15:40.538 I/YanZi (10793): onLayout enter...
Line 387: 01-03 10:15:40.539 I/YanZi (10793): width = 1080 height = 1701
Line 389: 01-03 10:15:40.540 I/YanZi (10793): onLayout exit...至于为啥要进两次onMeasure，翻遍了网络么有找到合理的解释。有人说是大小发生变化时要进两次，如Linearlayout里设置了weight属性，则第一次测量时得到一个大小，第二次测量时把weight加上得到最终的大小。可是我用Linearlayout把里面所有的母和子的view大小都写死，onMeasure还是进了两次。RelativeLayout就不用说了也是进的两次。国外文档也有解释说，当子view不能够填满父控件时，要第二次进到onMeasure里。经我测试，貌似也是扯淡。我全都match_parent还是进了两次。
当然在onMeasure里可以直接setMeasuredDimension(measuredWidth, measuredHeight)设置控件宽和高，这样不管xml里咋写的，最终以此句设置的width和height进行放置、显示。关于View/ViewGroup绘制原理本文就介绍到这，更详细请参考：链接1 链接2 链接3 链接4 都大同小异，可以看看。
方法一：
c_nanshi_guide.xml布局文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<FrameLayout
android:id="@+id/guide_nan_layout"
android:layout_width="200dp"
android:layout_height="150dp"
android:background="@drawable/nan1" >
<TextView
android:id="@+id/guide_nan_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|center_horizontal"
android:gravity="center"
android:text="南公怀瑾."
android:textColor="@android:color/white"
android:textSize="20sp" />
</FrameLayout>
</RelativeLayout>可以看到布局里并没出现任何自定义信息。NanShiGuide.java
package org.yanzi.ui;
import org.yanzi.util.DisplayUtil;
import android.R.color;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Point;
import android.graphics.drawable.Drawable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.RelativeLayout;
import android.widget.TextView;
import com.example.test1.R;
public class NanShiGuide extends BaseGuideView {
private static final String TAG = "YanZi";
int LAYOUT_ID = R.layout.c_nanshi_guide;
View guideNanLayout;
TextView guideNanText;
private Drawable mDrawable;
private Context mContext = null;
public NanShiGuide(Context context, GuideViewCallback callback) {
super(context, callback);
// TODO Auto-generated constructor stub
mContext = context;
initView();
mDrawable = context.getResources().getDrawable(R.drawable.ong);
}
@Override
protected void initView() {
// TODO Auto-generated method stub
Log.i(TAG, "NanShiGuide initView enter...");
View v = LayoutInflater.from(mContext).inflate(LAYOUT_ID, this, true);
guideNanLayout = v.findViewById(R.id.guide_nan_layout);
guideNanText = (TextView) v.findViewById(R.id.guide_nan_text);
}
@Override
protected void onFinishInflate() {
// TODO Auto-generated method stub
Log.i(TAG, "onFinishInflate enter...");
super.onFinishInflate();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// TODO Auto-generated method stub
Log.i(TAG, "onLayout enter...");
Log.i(TAG, "width = " + getWidth() + " height = " + getHeight());
int transX = 0;
int transY = 0;
if(mOrientation == 0){
guideNanLayout.setRotation(0);
transX += 0;
transY += 0;
}else if(mOrientation == 270){
guideNanLayout.setRotation(90);
transX += -DisplayUtil.dip2px(mContext, 25) + DisplayUtil.dip2px(mContext, 210);
transY += DisplayUtil.dip2px(mContext, 25);
}else if(mOrientation == 180){
guideNanLayout.setRotation(180);
transX += DisplayUtil.dip2px(mContext, 160);
transY += b - DisplayUtil.dip2px(mContext, 150);
}else if(mOrientation == 90){
guideNanLayout.setRotation(270);
transX += -DisplayUtil.dip2px(mContext, 25);
transY += b - DisplayUtil.dip2px(mContext, 200 - 25);
}
guideNanLayout.setTranslationX(transX);
guideNanLayout.setTranslationY(transY);
// this.setTranslationX(transX);
// this.setTranslationY(transY);
RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) guideNanLayout.getLayoutParams();
params.leftMargin = 100;
params.topMargin = 100;
guideNanLayout.setLayoutParams(params);
super.onLayout(changed, l, t, r, b);
Log.i(TAG, "onLayout exit...");
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub
Log.i(TAG, "onMeasure enter...");
Log.i(TAG, "width = " + getWidth() + " height = " + getHeight());
Log.i(TAG, "MeasuredWidth = " + getMeasuredWidth() + " MeasuredHeight = " + getMeasuredHeight());
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
Log.i(TAG, "00000000000 width = " + getWidth() + " height = " + getHeight());
Log.i(TAG, "00000000000 MeasuredWidth = " + getMeasuredWidth() + " MeasuredHeight = " + getMeasuredHeight());
Log.i(TAG, "onMeasure exit...");
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
// TODO Auto-generated method stub
Log.i(TAG, "onSizeChanged enter...");
Log.i(TAG, "width = " + getWidth() + " height = " + getHeight());
super.onSizeChanged(w, h, oldw, oldh);
Log.i(TAG, "onSizeChanged exit...");
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
Log.i(TAG, "onDraw enter...");
super.onDraw(canvas);
}
@Override
protected void dispatchDraw(Canvas canvas) {
// TODO Auto-generated method stub
Log.i(TAG, "dispatchDraw enter...");
super.dispatchDraw(canvas);
}
@Override
protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
// TODO Auto-generated method stub
Log.i(TAG, "drawChild enter...");
int w = getWidth();
int h = getHeight();
Point centerPoint = new Point(w / 2, h / 2);
canvas.save();
mDrawable.setBounds(centerPoint.x - 150, centerPoint.y - 150, centerPoint.x + 150, centerPoint.y + 150);
mDrawable.draw(canvas);
canvas.restore();
return super.drawChild(canvas, child, drawingTime);
}
}
package org.yanzi.ui;
import org.yanzi.util.OrientationUtil;
import android.content.Context;
import android.graphics.Canvas;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.RelativeLayout;
import android.widget.TextView;
public abstract class BaseGuideView extends RelativeLayout implements Rotatable, View.OnClickListener {
protected int mOrientation = 0;
protected Context mContext;
private GuideViewCallback mGuideViewCallback;
public interface GuideViewCallback{
public void onGuideViewClick();
}
public BaseGuideView(Context context, GuideViewCallback callback) {
super(context);
// TODO Auto-generated constructor stub
mContext = context;
mGuideViewCallback = callback;
setOnClickListener(this);
mOrientation = OrientationUtil.getOrientation();
}
@Override
public void setOrientation(int orientation, boolean animation) {
// TODO Auto-generated method stub
mOrientation = orientation;
requestLayout();
}
protected abstract void initView();
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
// TODO Auto-generated method stub
return true; //super.onInterceptTouchEvent(ev)
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
mGuideViewCallback.onGuideViewClick();
}
}
if(baseGuideView == null){
baseGuideView = new NanShiGuide(getApplicationContext(), new GuideViewCallback() {
@Override
public void onGuideViewClick() {
// TODO Auto-generated method stub
hideGuideView();
}
});
guideLayout.addView(baseGuideView);
}方法二：不通过LayoutInflater来映射,而是直接使用类名映射
请参考我的前文：http://blog.csdn.net/yanzi1225627/article/details/30763555 的HeadControlPanel.java的封装方法。这种方法不适合做动态添加，因为它不能new，只能通过在母布局里include来添加。正因为它是从布局里加载的，因此会调用onFinishInflate()流程，当执行到此时表示布局已经加载进来了，里面的孩子view可以实例化了。 但第一种方法是不会调用onFinishInflate的，所以必须用LayoutInflator。 再者，使用第二种方法也就意味着自定义view的构造函数只能是：
public NanShiGuide(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
}
无法再多传递其他重要变量。
综合两种方法的优缺点，我个人强烈建议使用第一种方式来自定义ViewGroup，但google的部分原生应用里使用的是第二种方法。本文代码使用第一种方式。另外，这两种加载机制不同，所以在对view动态改变位置时也会不同。
方法一：设置LayoutParams，通过params设置四个margin来改变
方法二：通过setX()、setY()这两个函数直接设置坐标位置。
方法三：通过setTranslationX、setTranslationY来设置相对偏移量，当然是在onLayout流程里。
这三种方法里个人最推荐的是第三种，除此外方法1在有些场合下也会用到，方法2比较坑爹一般不用。下面是方法3的示例，先来看一副图片：
自然状态下，图片靠左上顶点摆放：
下图为旋转了90°后，我在代码里guideNanLayout.setRotation()进行旋转后的。guideNanLayout就是那个图片的布局。
记View的宽度为W，高度为H。如上图所示，在旋转90°后，图片在x轴和y轴上分别塌缩了Abs(W - H) / 2的像素。为此，我们可以首先把这个“塌缩”给补回来，让旋转90°后的view还是以左上顶点为基准点，之后用如下代码进行平移。
guideNanLayout.setTranslationX(transX);
guideNanLayout.setTranslationY(transY);
最终的onLayout函数如下：
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// TODO Auto-generated method stub
Log.i(TAG, "onLayout enter...");
Log.i(TAG, "width = " + getWidth() + " height = " + getHeight());
int transX = 0;
int transY = 0;
if(mOrientation == 0){
guideNanLayout.setRotation(0);
transX += 0;
transY += 0;
}else if(mOrientation == 270){
guideNanLayout.setRotation(90);
transX += -DisplayUtil.dip2px(mContext, 25) + DisplayUtil.dip2px(mContext, 210);
transY += DisplayUtil.dip2px(mContext, 25);
}else if(mOrientation == 180){
guideNanLayout.setRotation(180);
transX += DisplayUtil.dip2px(mContext, 160);
transY += b - DisplayUtil.dip2px(mContext, 150);
}else if(mOrientation == 90){
guideNanLayout.setRotation(270);
transX += -DisplayUtil.dip2px(mContext, 25);
transY += b - DisplayUtil.dip2px(mContext, 200 - 25);
}
guideNanLayout.setTranslationX(transX);
guideNanLayout.setTranslationY(transY);
// this.setTranslationX(transX);
// this.setTranslationY(transY);
// RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) guideNanLayout.getLayoutParams();
// params.leftMargin = 100;
// params.topMargin = 100;
// guideNanLayout.setLayoutParams(params);
super.onLayout(changed, l, t, r, b);
Log.i(TAG, "onLayout exit...");
}最终旋转屏幕时效果图如下：
注意这块我并没用android自有的让布局旋转的那种机制，那个效果不好，转换太慢。因为onLayout里设置偏移量是在onDraw前，所以此方法方向变换时不会有残留。即便一开始就90°拿手机，不会出现那种先是正常显示再转过去的现象。每次方向变时就设置下角度，然后调用requestLayout():
@Override
public void setOrientation(int orientation, boolean animation) {
// TODO Auto-generated method stub
mOrientation = orientation;
requestLayout();
}
可以参考这里，当调用requestLayout时会让View重新measure、layout。
为什么不用setX()这种方法呢？查看其api解释：
/**
* Sets the visual x position of this view, in pixels. This is equivalent to setting the
* {@link #setTranslationX(float) translationX} property to be the difference between
* the x value passed in and the current {@link #getLeft() left} property.
*
* @param x The visual x position of this view, in pixels.
*/
public void setX(float x) {
setTranslationX(x - mLeft);
}// guideNanLayout.setTranslationX(transX);
// guideNanLayout.setTranslationY(transY);
换成：
guideNanLayout.setX(transX);
guideNanLayout.setY(transY);
得到的结果是一模一样的，这是因为这里的mLeft等于0的原因。
再来看方法1，通过设置LayoutParams来动态改变位置，这有时好用，但有时完全没有效果。因为要改变LayoutParams首先view要加载进来，才能get得到。2，这种设params的方法一旦rotate后本身的margins就变了，很难计算旋转后的margins。
而且更严重的是，在本例中在onLayout里通过
// RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) guideNanLayout.getLayoutParams();
// params.leftMargin = 100;
// params.topMargin = 100;
// guideNanLayout.setLayoutParams(params);
是看不到一点效果的，这是个十分诡异的事情。但将其放在initView或onMeasure里则是ok的。根据这个现象我认为，在onlayout的时候再对子view设置margins已经晚了，不起作用了，要设margins也必须在onlayout进来之前就设好。
另外有个问题，在onlayout里默认的setX这些都是this.setX（）对应的是母布局的设置，如果对里面的孩子设置前面必须加上孩子的名字。还有，在super.onLayout(changed, l, t, r, b);之前设置好setTranslationX就好了，并不需要再super.onLayout(changed, l, t, r, b);对这里的五个参数进行改变。
其实看setLayoutParams(params)的流程可以知道：
public void setLayoutParams(ViewGroup.LayoutParams params) {
if (params == null) {
throw new NullPointerException("Layout parameters cannot be null");
}
mLayoutParams = params;
resolveLayoutParams();
if (mParent instanceof ViewGroup) {
((ViewGroup) mParent).onSetLayoutParams(this, params);
}
requestLayout();
}至此旋转搞好了，接下来是如何获得角度：
mOrientationEvent= new OrientationEventListener(this) {
@Override
public void onOrientationChanged(int orientation) {
// TODO Auto-generated method stub
if(orientation == OrientationEventListener.ORIENTATION_UNKNOWN){
return;
}
mOrientation = RoundUtil.roundOrientation(orientation, mOrientation);
int orientationCompensation = (mOrientation + RoundUtil
.getDisplayRotation(MainActivity.this)) % 360;
if(mOrientationCompensation != orientationCompensation){
mOrientationCompensation = orientationCompensation;
Log.i("YanZi", "mOrientationCompensation = " + mOrientationCompensation);
OrientationUtil.setOrientation(mOrientationCompensation == -1 ? 0 :
mOrientationCompensation);
setOrientation(OrientationUtil.getOrientation(), false);
}
} @Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
mOrientationEvent.enable();
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
mOrientationEvent.disable();
}用到的RoundUtil：package org.yanzi.util;
import android.app.Activity;
import android.view.OrientationEventListener;
import android.view.Surface;
public class RoundUtil {
public static final int ORIENTATION_HYSTERESIS = 5;
public static int roundOrientation(int orientation, int orientationHistory) {
boolean changeOrientation = false;
if (orientationHistory == OrientationEventListener.ORIENTATION_UNKNOWN) {
changeOrientation = true;
} else {
int dist = Math.abs(orientation - orientationHistory);
dist = Math.min( dist, 360 - dist );
changeOrientation = ( dist >= 45 + ORIENTATION_HYSTERESIS );
}
if (changeOrientation) {
return ((orientation + 45) / 90 * 90) % 360;
}
return orientationHistory;
}
public static int getDisplayRotation(Activity activity) {
int rotation = activity.getWindowManager().getDefaultDisplay()
.getRotation();
switch (rotation) {
case Surface.ROTATION_0: return 0;
case Surface.ROTATION_90: return 90;
case Surface.ROTATION_180: return 180;
case Surface.ROTATION_270: return 270;
}
return 0;
}
}
最后，一个view通过rotate()无论怎么转都是以自身的中心点进行旋转的，只要母布局么有旋转，坐标系原点就是屏幕左上角，且x、y轴不交换。
源码下载：http://download.csdn.net/detail/yanzi1225627/7681731
--------------------本文系原创，转载请注明作者yanzi1225627
让Android控件随着屏幕旋转自由转移至任何地方(附demo)
标签：android旋转
原文地址：http://blog.csdn.net/yanzi1225627/article/details/38147205
