Android屏幕适配框架（二）

由于上一篇框架需要控件重新渲染一次，对于大型项目性能方面运行不够快，针对该问题进行优化

核心思想：自定义组件，在组件的onMeasure中就改变控件的长宽等属性

实现方法：自定义百分比组件，使用该组件自动适配该组件下所有子view，以下例子以针对Linearlayout为基础

在attrs.xml中加入如下属性

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="percentlayout">
        <attr name="width_percent" format="float"></attr>
        <attr name="height_percent" format="float"></attr>
    </declare-styleable>
</resources>

自定义LayoutParams

public static class PercentLinearLayoutParams extends LinearLayoutCompat.LayoutParams implements IGetPercent {
        private float widthPercent;
        private float heightPercent;

        public PercentLinearLayoutParams(Context c, AttributeSet attrs) {
            super(c, attrs);
            TypedArray typedArray = c.obtainStyledAttributes(attrs, R.styleable.percentlayout);
            widthPercent = typedArray.getFloat(R.styleable.percentlayout_width_percent, 0);
            heightPercent = typedArray.getFloat(R.styleable.percentlayout_height_percent, 0);
        }

        public float getWidthPercent() {
            return widthPercent;
        }

        public void setWidthPercent(float widthPercent) {
            this.widthPercent = widthPercent;
        }

        public float getHeightPercent() {
            return heightPercent;
        }

        public void setHeightPercent(float heightPercent) {
            this.heightPercent = heightPercent;
        }
    }

自定义IGetPercent接口利于封装，代码如下：

public interface IGetPercent {
    float getHeightPercent();

    float getWidthPercent();
}

自定义组件继承LinearLayoutCompat

public class PercentLinearLayout extends LinearLayoutCompat

给childView使用自己定义的LayoutParams，只需要改写generateLayoutParams方法

/**
     * 生成自己定义的LayoutParams
     *
     * @param attrs
     * @return
     */
    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
         return new PercentLinearLayout.PercentLinearLayoutParams(context, attrs);
    }

核心代码：改写onMeasure方法，遍历childView并改变他们的LayoutParams中的属性

/**
     * 子控件逻辑处理操作
     *
     * @param widthMeasureSpec
     * @param heightMeasureSpec
     */
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        //获取当前组件的长宽
        int width = View.MeasureSpec.getSize(widthMeasureSpec);
        int height = View.MeasureSpec.getSize(heightMeasureSpec);

        //遍历子view
        for (int i = 0; i < viewGroup.getChildCount(); i++) {
            View view = viewGroup.getChildAt(i);

            ViewGroup.LayoutParams layoutParams = view.getLayoutParams();
            if (layoutParams instanceof IGetPercent) {
                //获取百分比
                float widthPercent = ((IGetPercent) layoutParams).getWidthPercent();
                float heightPercent = ((IGetPercent) layoutParams).getHeightPercent();

                //适配不同屏幕
                ViewsParseUtil.catchChildView(view);
                //设置子view的长宽,优先使用自定义的百分比，会将上一行代码中对长宽的设置覆盖
                if (widthPercent > 0) {
                    layoutParams.width = (int) (width * widthPercent);
                }
                if (heightPercent > 0) {
                    layoutParams.height = (int) (height * heightPercent);
                }
            }
        }
    }

xml中使用自定义的组件，并在子控件中使用自定义属性就能实现百分比布局

<?xml version="1.0" encoding="utf-8"?>
<com.aruba.screenlibrary.layout.PercentLinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="100px"
        android:layout_marginLeft="30px"
        android:background="@android:color/darker_gray"
        android:text="Hello World!"
        app:height_percent="0.5"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:width_percent="0.5" />

</com.aruba.screenlibrary.layout.PercentLinearLayout>

结论：在测量方法onMeasure中就完成对控件的适配，不需要重新渲染，提高了性能

项目地址： https://gitee.com/aruba/ScreenAdapter.git