替换linearLayout权重机制
and*_*per 18 android android-layout android-linearlayout android-layout-weight android-percent-library
背景:
- 由于性能原因,Google建议避免使用嵌套加权linearLayouts.
- 使用嵌套加权linearLayout很难读,写和维护.
- 对于放置可用大小百分比的视图,仍然没有其他好的选择.只有解决方案才是权重并使用OpenGL.甚至没有类似WPF/Silverlight上显示的"viewBox"来自动缩放内容.
这就是为什么我决定创建我自己的布局,你要告诉每个孩子他们的重量(和周围的重量)与它的大小相比应该是什么.
看来我已经成功了,但出于某种原因,我认为有一些我无法追查的错误.
其中一个错误就是textView,即使我为它提供了大量空间,它也会将文本放在顶部而不是放在中心.另一方面,imageViews工作得很好.另一个错误是,如果我在自定义布局中使用布局(例如frameLayout),则其中的视图将不会显示(但布局本身将会显示).
请帮我弄清楚它为什么会发生.
如何使用:而不是线性布局的下一个用法(我故意使用长XML,以显示我的解决方案如何缩短事物):
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:orientation="vertical">
<View android:layout_width="wrap_content" android:layout_height="0px"
android:layout_weight="1" />
<LinearLayout android:layout_width="match_parent"
android:layout_height="0px" android:layout_weight="1"
android:orientation="horizontal">
<View android:layout_width="0px" android:layout_height="wrap_content"
android:layout_weight="1" />
<TextView android:layout_width="0px" android:layout_weight="1"
android:layout_height="match_parent" android:text="@string/hello_world"
android:background="#ffff0000" android:gravity="center"
android:textSize="20dp" android:textColor="#ff000000" />
<View android:layout_width="0px" android:layout_height="wrap_content"
android:layout_weight="1" />
</LinearLayout>
<View android:layout_width="wrap_content" android:layout_height="0px"
android:layout_weight="1" />
</LinearLayout>
我所做的只是(x是将视图本身放在权重列表中的位置):
<com.example.weightedlayouttest.WeightedLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res/com.example.weightedlayouttest"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" tools:context=".MainActivity">
<TextView android:layout_width="0px" android:layout_height="0px"
app:horizontalWeights="1,1x,1" app:verticalWeights="1,1x,1"
android:text="@string/hello_world" android:background="#ffff0000"
android:gravity="center" android:textSize="20dp" android:textColor="#ff000000" />
</com.example.weightedlayouttest.WeightedLayout>
我的特殊布局代码是:
public class WeightedLayout extends ViewGroup
{
@Override
protected WeightedLayout.LayoutParams generateDefaultLayoutParams()
{
return new WeightedLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT);
}
@Override
public WeightedLayout.LayoutParams generateLayoutParams(final AttributeSet attrs)
{
return new WeightedLayout.LayoutParams(getContext(),attrs);
}
@Override
protected ViewGroup.LayoutParams generateLayoutParams(final android.view.ViewGroup.LayoutParams p)
{
return new WeightedLayout.LayoutParams(p.width,p.height);
}
@Override
protected boolean checkLayoutParams(final android.view.ViewGroup.LayoutParams p)
{
final boolean isCorrectInstance=p instanceof WeightedLayout.LayoutParams;
return isCorrectInstance;
}
public WeightedLayout(final Context context)
{
super(context);
}
public WeightedLayout(final Context context,final AttributeSet attrs)
{
super(context,attrs);
}
public WeightedLayout(final Context context,final AttributeSet attrs,final int defStyle)
{
super(context,attrs,defStyle);
}
@Override
protected void onLayout(final boolean changed,final int l,final int t,final int r,final int b)
{
for(int i=0;i<this.getChildCount();++i)
{
final View v=getChildAt(i);
final WeightedLayout.LayoutParams layoutParams=(WeightedLayout.LayoutParams)v.getLayoutParams();
//
final int availableWidth=r-l;
final int totalHorizontalWeights=layoutParams.getLeftHorizontalWeight()+layoutParams.getViewHorizontalWeight()+layoutParams.getRightHorizontalWeight();
final int left=l+layoutParams.getLeftHorizontalWeight()*availableWidth/totalHorizontalWeights;
final int right=r-layoutParams.getRightHorizontalWeight()*availableWidth/totalHorizontalWeights;
//
final int availableHeight=b-t;
final int totalVerticalWeights=layoutParams.getTopVerticalWeight()+layoutParams.getViewVerticalWeight()+layoutParams.getBottomVerticalWeight();
final int top=t+layoutParams.getTopVerticalWeight()*availableHeight/totalVerticalWeights;
final int bottom=b-layoutParams.getBottomVerticalWeight()*availableHeight/totalVerticalWeights;
//
v.layout(left+getPaddingLeft(),top+getPaddingTop(),right+getPaddingRight(),bottom+getPaddingBottom());
}
}
// ///////////////
// LayoutParams //
// ///////////////
public static class LayoutParams extends ViewGroup.LayoutParams
{
int _leftHorizontalWeight =0,_rightHorizontalWeight=0,_viewHorizontalWeight=0;
int _topVerticalWeight =0,_bottomVerticalWeight=0,_viewVerticalWeight=0;
public LayoutParams(final Context context,final AttributeSet attrs)
{
super(context,attrs);
final TypedArray arr=context.obtainStyledAttributes(attrs,R.styleable.WeightedLayout_LayoutParams);
{
final String horizontalWeights=arr.getString(R.styleable.WeightedLayout_LayoutParams_horizontalWeights);
//
// handle horizontal weight:
//
final String[] words=horizontalWeights.split(",");
boolean foundViewHorizontalWeight=false;
int weight;
for(final String word : words)
{
final int viewWeightIndex=word.lastIndexOf('x');
if(viewWeightIndex>=0)
{
if(foundViewHorizontalWeight)
throw new IllegalArgumentException("found more than one weights for the current view");
weight=Integer.parseInt(word.substring(0,viewWeightIndex));
setViewHorizontalWeight(weight);
foundViewHorizontalWeight=true;
}
else
{
weight=Integer.parseInt(word);
if(weight<0)
throw new IllegalArgumentException("found negative weight:"+weight);
if(foundViewHorizontalWeight)
_rightHorizontalWeight+=weight;
else _leftHorizontalWeight+=weight;
}
}
if(!foundViewHorizontalWeight)
throw new IllegalArgumentException("couldn't find any weight for the current view. mark it with 'x' next to the weight value");
}
//
// handle vertical weight:
//
{
final String verticalWeights=arr.getString(R.styleable.WeightedLayout_LayoutParams_verticalWeights);
final String[] words=verticalWeights.split(",");
boolean foundViewVerticalWeight=false;
int weight;
for(final String word : words)
{
final int viewWeightIndex=word.lastIndexOf('x');
if(viewWeightIndex>=0)
{
if(foundViewVerticalWeight)
throw new IllegalArgumentException("found more than one weights for the current view");
weight=Integer.parseInt(word.substring(0,viewWeightIndex));
setViewVerticalWeight(weight);
foundViewVerticalWeight=true;
}
else
{
weight=Integer.parseInt(word);
if(weight<0)
throw new IllegalArgumentException("found negative weight:"+weight);
if(foundViewVerticalWeight)
_bottomVerticalWeight+=weight;
else _topVerticalWeight+=weight;
}
}
if(!foundViewVerticalWeight)
throw new IllegalArgumentException("couldn't find any weight for the current view. mark it with 'x' next to the weight value");
}
//
arr.recycle();
}
public LayoutParams(final int width,final int height)
{
super(width,height);
}
public LayoutParams(final ViewGroup.LayoutParams source)
{
super(source);
}
public int getLeftHorizontalWeight()
{
return _leftHorizontalWeight;
}
public void setLeftHorizontalWeight(final int leftHorizontalWeight)
{
_leftHorizontalWeight=leftHorizontalWeight;
}
public int getRightHorizontalWeight()
{
return _rightHorizontalWeight;
}
public void setRightHorizontalWeight(final int rightHorizontalWeight)
{
if(rightHorizontalWeight<0)
throw new IllegalArgumentException("negative weight :"+rightHorizontalWeight);
_rightHorizontalWeight=rightHorizontalWeight;
}
public int getViewHorizontalWeight()
{
return _viewHorizontalWeight;
}
public void setViewHorizontalWeight(final int viewHorizontalWeight)
{
if(viewHorizontalWeight<0)
throw new IllegalArgumentException("negative weight:"+viewHorizontalWeight);
_viewHorizontalWeight=viewHorizontalWeight;
}
public int getTopVerticalWeight()
{
return _topVerticalWeight;
}
public void setTopVerticalWeight(final int topVerticalWeight)
{
if(topVerticalWeight<0)
throw new IllegalArgumentException("negative weight :"+topVerticalWeight);
_topVerticalWeight=topVerticalWeight;
}
public int getBottomVerticalWeight()
{
return _bottomVerticalWeight;
}
public void setBottomVerticalWeight(final int bottomVerticalWeight)
{
if(bottomVerticalWeight<0)
throw new IllegalArgumentException("negative weight :"+bottomVerticalWeight);
_bottomVerticalWeight=bottomVerticalWeight;
}
public int getViewVerticalWeight()
{
return _viewVerticalWeight;
}
public void setViewVerticalWeight(final int viewVerticalWeight)
{
if(viewVerticalWeight<0)
throw new IllegalArgumentException("negative weight :"+viewVerticalWeight);
_viewVerticalWeight=viewVerticalWeight;
}
}
}
我接受了您的挑战,并尝试根据我的评论创建您描述的布局.你是对的.实现起来非常困难.除此之外,我喜欢拍摄苍蝇.所以我跳上船,想出了这个解决方案.
扩展现有的布局类,而不是从头开始创建自己的布局类.我使用RelativeLayout开始,但所有人都可以使用相同的方法.这使您能够在不想操作的子视图上使用该布局的默认行为.
我在布局中添加了四个属性,分别是top,left,width和height.我的目的是通过允许诸如"10%","100px","100dp"等的值来模仿HTML.此时,接受的唯一值是表示父项%的整数."20"=布局的20%.
为了获得更好的性能,我允许super.onLayout()执行所有迭代,并仅在最后一次传递时使用自定义属性操作视图.由于这些视图将独立于兄弟姐妹进行定位和缩放,因此我们可以在其他所有内容确定后移动它们.
这是atts.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="HtmlStyleLayout">
<attr name="top" format="integer"/>
<attr name="left" format="integer"/>
<attr name="height" format="integer"/>
<attr name="width" format="integer"/>
</declare-styleable>
</resources>
这是我的布局类.
package com.example.helpso;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;
public class HtmlStyleLayout extends RelativeLayout{
private int pass =0;
@Override
protected HtmlStyleLayout.LayoutParams generateDefaultLayoutParams()
{
return new HtmlStyleLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT,RelativeLayout.LayoutParams.WRAP_CONTENT);
}
@Override
public HtmlStyleLayout.LayoutParams generateLayoutParams(final AttributeSet attrs)
{
return new HtmlStyleLayout.LayoutParams(getContext(),attrs);
}
@Override
protected RelativeLayout.LayoutParams generateLayoutParams(final android.view.ViewGroup.LayoutParams p)
{
return new HtmlStyleLayout.LayoutParams(p.width,p.height);
}
@Override
protected boolean checkLayoutParams(final android.view.ViewGroup.LayoutParams p)
{
final boolean isCorrectInstance=p instanceof HtmlStyleLayout.LayoutParams;
return isCorrectInstance;
}
public HtmlStyleLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public void setScaleType(View v){
try{
((ImageView) v).setScaleType (ImageView.ScaleType.FIT_XY);
}catch (Exception e){
// The view is not an ImageView
}
}
@Override
protected void onLayout(final boolean changed,final int l,final int t,final int r,final int b)
{
super.onLayout(changed, l, t, r, b); //Let the parent layout do it's thing
pass++; // After the last pass of
final int childCount = this.getChildCount(); // the parent layout
if(true){ // we do our thing
for(int i=0;i<childCount;++i)
{
final View v=getChildAt(i);
final HtmlStyleLayout.LayoutParams params = (HtmlStyleLayout.LayoutParams)v.getLayoutParams();
int newTop = v.getTop(); // set the default value
int newLeft = v.getLeft(); // of these to the value
int newBottom = v.getBottom(); // set by super.onLayout()
int newRight= v.getRight();
boolean viewChanged = false;
if(params.getTop() >= 0){
newTop = ( (int) ((b-t) * (params.getTop() * .01)) );
viewChanged = true;
}
if(params.getLeft() >= 0){
newLeft = ( (int) ((r-l) * (params.getLeft() * .01)) );
viewChanged = true;
}
if(params.getHeight() > 0){
newBottom = ( (int) ((int) newTop + ((b-t) * (params.getHeight() * .01))) );
setScaleType(v); // set the scale type to fitxy
viewChanged = true;
}else{
newBottom = (newTop + (v.getBottom() - v.getTop()));
Log.i("heightElse","v.getBottom()=" +
Integer.toString(v.getBottom())
+ " v.getTop=" +
Integer.toString(v.getTop()));
}
if(params.getWidth() > 0){
newRight = ( (int) ((int) newLeft + ((r-l) * (params.getWidth() * .01))) );
setScaleType(v);
viewChanged = true;
}else{
newRight = (newLeft + (v.getRight() - v.getLeft()));
}
// only call layout() if we changed something
if(viewChanged)
Log.i("SizeLocation",
Integer.toString(i) + ": "
+ Integer.toString(newLeft) + ", "
+ Integer.toString(newTop) + ", "
+ Integer.toString(newRight) + ", "
+ Integer.toString(newBottom));
v.layout(newLeft, newTop, newRight, newBottom);
}
pass = 0; // reset the parent pass counter
}
}
public class LayoutParams extends RelativeLayout.LayoutParams
{
private int top, left, width, height;
public LayoutParams(final Context context, final AttributeSet atts) {
super(context, atts);
TypedArray a = context.obtainStyledAttributes(atts, R.styleable.HtmlStyleLayout);
top = a.getInt(R.styleable.HtmlStyleLayout_top , -1);
left = a.getInt(R.styleable.HtmlStyleLayout_left, -1);
width = a.getInt(R.styleable.HtmlStyleLayout_width, -1);
height = a.getInt(R.styleable.HtmlStyleLayout_height, -1);
a.recycle();
}
public LayoutParams(int w, int h) {
super(w,h);
Log.d("lp","2");
}
public LayoutParams(ViewGroup.LayoutParams source) {
super(source);
Log.d("lp","3");
}
public LayoutParams(ViewGroup.MarginLayoutParams source) {
super(source);
Log.d("lp","4");
}
public int getTop(){
return top;
}
public int getLeft(){
return left;
}
public int getWidth(){
return width;
}
public int getHeight(){
return height;
}
}
}
这是一个示例活动xml
<com.example.helpso.HtmlStyleLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:html="http://schemas.android.com/apk/res/com.example.helpso"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:scaleType="fitXY"
android:src="@drawable/bg" />
<ImageView
android:id="@+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/overlay"
html:height="10"
html:left="13"
html:top="18"
html:width="23" />
</com.example.helpso.HtmlStyleLayout>
这是我用于测试的图像.
如果您没有为特定属性设置值,则将使用默认值.因此,如果您设置宽度而不是高度,则图像将按宽度缩放,而wrap_content则为高度.
我找到了bug的来源.问题是我使用布局的子计数作为指示它将对onLayout进行多少次调用的指示器.这在旧版本的android中似乎不适用.我注意到2.1 onLayout只被调用一次.所以我改变了
if(pass == childCount){
至
if(true){
它开始按预期工作.
我仍然认为仅在超级完成后才调整布局是有益的.只需要找到一种更好的方法来了解它是什么时候.
编辑
我没有意识到你的意图是用逐像素精度拼凑图像.我通过使用双浮点精度变量而不是整数来实现您正在寻找的精度.但是,在允许图像缩放的同时,您将无法实现此目的.当放大图像时,在现有像素之间以某个间隔添加像素.新像素的颜色是周围像素的一些加权平均值.当您彼此独立地缩放图像时,它们不会共享任何信息.结果是在接缝处总会有一些神器.再加上舍入的结果,因为你不能有一个部分像素,你将始终具有+/- 1像素容差.
要验证这一点,您可以在高级照片编辑软件中尝试相同的任务.我使用PhotoShop.使用与我的apk中相同的图像,我将它们放在单独的文件中.我将它们垂直放大168%,水平放大127%.然后我将它们放在一起放在一个文件中并尝试对齐它们.结果与我在apk中看到的完全相同.
为了演示布局的准确性,我在apk中添加了第二个活动.在此活动中,我没有缩放背景图像.其他一切都完全一样.结果是无缝的.
我还添加了一个按钮来显示/隐藏叠加图像,还有一个用于在活动之间切换.
我在google驱动器上更新了apk和压缩项目文件夹.您可以通过上面的链接获取它们.
现在有一个比我制作的自定义布局更好的解决方案：
示例代码：
<android.support.percent.PercentRelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<ImageView
app:layout_widthPercent="50%"
app:layout_heightPercent="50%"
app:layout_marginTopPercent="25%"
app:layout_marginLeftPercent="25%"/>
</android.support.percent.PercentFrameLayout/>
或者：
<android.support.percent.PercentFrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<ImageView
app:layout_widthPercent="50%"
app:layout_heightPercent="50%"
app:layout_marginTopPercent="25%"
app:layout_marginLeftPercent="25%"/>
</android.support.percent.PercentFrameLayout/>
我想知道它是否可以解决我在这里展示的问题。
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