Android 手写百分比布局

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百分比布局:通过设定百分比参数,自动适应手机屏幕,有时候还是比较实用的!
思路:
1:Android 自定义xmlns,百分比布局有2个自定义参数所有要自定义 ximls
2:自定义百分比布局继承相对布局,重写LayoutParams 内部类(这里增加 2个百分比参数)
3:重写 onMeasure( )方法,在onMeasure 里获取容器的宽高,然后获得所有子控件,判断子空间的 LayoutParams 是否为百分比布局的 LayoutParams,相同则读取子控件的长宽百分比参数,然后计算出实际的长宽参数!

实现:
1: 自定义xmlns,首先在 res下创建 attr.xml文件声明一个styleable

<resources>    <declare-styleable name="percentLayout">        <attr name="layout_widthPercent" format = "float"> </attr>         <attr name="layout_heightPercent" format = "float"> </attr>    </declare-styleable></resources>

在布局文件中添加自定义属性:
eclipse 这样写

http://schemas.android.com/apk/res/你的自定义View所在的包路径.

stuido 使用统一默认的

xmlns:app="http://schemas.android.com/apk/res-auto"

然后在需要使用的子控件添加百分比属性

<Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="nice"         app:layout_widthPercent="0.6"        app:layout_heightPercent="0.8"        android:background="#00ff00"        />

整个自定义 xmlns 就完成了,接下来实现自定义控件

public class PercentLayout extends RelativeLayout{    public PercentLayout(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        // TODO Auto-generated constructor stub    }    public PercentLayout(Context context, AttributeSet attrs) {        super(context, attrs);        // TODO Auto-generated constructor stub    }    public PercentLayout(Context context) {        super(context);        // TODO Auto-generated constructor stub    }    /***     * 测量容器的宽高     */    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        // 获取容器的宽高        int width = MeasureSpec.getSize(widthMeasureSpec);        int height = MeasureSpec.getSize(heightMeasureSpec);        //测量子控件的宽高，然后进行改变        int childCount = getChildCount();        for (int i = 0; i < childCount; i++) {            View child = getChildAt(i);            float widthPercent = 0;            float heightPercent = 0;            //获得子控件的布局参数            ViewGroup.LayoutParams params = child.getLayoutParams();            //判断是否为百分比布局            if(params instanceof LayoutParams){                widthPercent = ((LayoutParams) params).getWidthPercent();                heightPercent = ((LayoutParams) params).getHeightPerccent();            }            if(widthPercent!=0){                params.width = (int) (width*widthPercent);                params.height = (int) (height*heightPercent);            }        }        super.onMeasure(widthMeasureSpec, heightMeasureSpec);    }    /***     * 排列摆放子控件     */    @Override    protected void onLayout(boolean changed, int l, int t, int r, int b) {        super.onLayout(changed, l, t, r, b);    }    @Override    public LayoutParams generateLayoutParams(AttributeSet attrs) {        return new LayoutParams(getContext(), attrs);    }    //布局参数内部类,xml解析会自动关联对应的布局参数    class LayoutParams extends RelativeLayout.LayoutParams{        private float widthPercent;        private float heightPerccent;        public float getWidthPercent() {            return widthPercent;        }        public void setWidthPercent(float widthPercent) {            this.widthPercent = widthPercent;        }        public float getHeightPerccent() {            return heightPerccent;        }        public void setHeightPerccent(float heightPerccent) {            this.heightPerccent = heightPerccent;        }        public LayoutParams(Context arg0, AttributeSet arg1) {            super(arg0, arg1);            TypedArray array = arg0.obtainStyledAttributes(arg1, R.styleable.percentLayout);            widthPercent = array.getFloat(R.styleable.percentLayout_layout_widthPercent, widthPercent);            heightPerccent = array.getFloat(R.styleable.percentLayout_layout_heightPercent, heightPerccent);            array.recycle();        }        public LayoutParams(int arg0, int arg1) {            super(arg0, arg1);        }        public LayoutParams(ViewGroup.LayoutParams arg0) {            super(arg0);        }        public LayoutParams(MarginLayoutParams arg0) {            super(arg0);        }    }}

这个自定义控件代码,下面是整个页面布局

<go.lqb.com.nettest.dn_sindy_layout.PercentLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:layout_width="400dp"    android:layout_height="600dp"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    >    <Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="nice"         app:layout_widthPercent="0.6"        app:layout_heightPercent="0.8"        android:background="#00ff00"        /></go.lqb.com.nettest.dn_sindy_layout.PercentLayout>

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