Android 屏幕适配-自定义View适配

承接Android 屏幕适配

说明:本文仅为简单思路,没有实现项目适用的轮子

通过自定义View做屏幕适配的主要思路是:

以一个特定宽度尺寸的设备为参考，在View的加载过程，根据当前
设备的实际像素换算出目标像素，再作用在控件上。

核心思路为在自定义一个ViewGroup,重写onMeasure()方法,在onMeasure()方法中遍历子View,以特定宽高尺寸参考,计算出目标像素,作用在子View上,看下主要代码和备注:

 @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            float scaleX = Utils.getInstance(getContext()).getHorizontalScale();//获取横向百分比
            float scaleY = Utils.getInstance(getContext()).getVerticalScale();//获取纵向百分比
            int count = getChildCount();
            for (int i = 0; i < count; i++) {
                View child = getChildAt(i);//获取子View
                LayoutParams params = (LayoutParams) child.getLayoutParams();
                //重新设置子View的布局属性,再进行View的测量
                params.width = (int) (params.width * scaleX);//计算目标宽度
                params.height = (int) (params.height * scaleY);//计算目标高度
                //计算四周间距值
                params.leftMargin = (int)(params.leftMargin * scaleX);
                params.rightMargin = (int)(params.rightMargin * scaleX);
                params.topMargin = (int)(params.topMargin * scaleY);
                params.bottomMargin = (int)(params.bottomMargin * scaleY);
            }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

贴下完整代码:

public class ScreenAdapterLayout extends RelativeLayout {

    private boolean flag;

    public ScreenAdapterLayout(Context context) {
        super(context);
    }

    public ScreenAdapterLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public ScreenAdapterLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        if (!flag){
            float scaleX = Utils.getInstance(getContext()).getHorizontalScale();
            float scaleY = Utils.getInstance(getContext()).getVerticalScale();

            int count = getChildCount();
            for (int i = 0; i < count; i++) {
                View child = getChildAt(i);
                LayoutParams params = (LayoutParams) child.getLayoutParams();
                params.width = (int) (params.width * scaleX);
                params.height = (int) (params.height * scaleY);
                params.leftMargin = (int)(params.leftMargin * scaleX);
                params.rightMargin = (int)(params.rightMargin * scaleX);
                params.topMargin = (int)(params.topMargin * scaleY);
                params.bottomMargin = (int)(params.bottomMargin * scaleY);
            }
            flag = true;
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
}

其中用到的Utils类主要用于,定义设计稿参考宽高,获取屏幕显示宽高,判断横竖屏状态,以及获取状态栏高度,代码如下:

public class Utils {

    private static Utils utils;

    //这里是设计稿参考宽高
    private static final float STANDARD_WIDTH = 1080;
    private static final float STANDARD_HEIGHT = 1920;

    //这里是屏幕显示宽高
    private int mDisplayWidth;
    private int mDisplayHeight;

    private Utils(Context context){
        //获取屏幕的宽高
        if(mDisplayWidth == 0 || mDisplayHeight == 0){
            WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
            if (manager != null){
                DisplayMetrics displayMetrics = new DisplayMetrics();
                manager.getDefaultDisplay().getMetrics(displayMetrics);
                if (displayMetrics.widthPixels > displayMetrics.heightPixels){
                    //横屏
                    mDisplayWidth = displayMetrics.heightPixels;
                    mDisplayHeight = displayMetrics.widthPixels;
                }else{
                    mDisplayWidth = displayMetrics.widthPixels;
                    mDisplayHeight = displayMetrics.heightPixels - getStatusBarHeight(context);
                }
            }
        }

    }

    public int getStatusBarHeight(Context context){
        int resID = context.getResources().getIdentifier("status_bar_height", "dimen", "android");
        if (resID > 0){
            return context.getResources().getDimensionPixelSize(resID);
        }
        return 0;
    }

    public static Utils getInstance(Context context){
        if (utils == null){
            utils = new Utils(context.getApplicationContext());
        }
        return utils;
    }

    //获取水平方向的缩放比例
    public float getHorizontalScale(){
        return mDisplayWidth / STANDARD_WIDTH;
    }

    //获取垂直方向的缩放比例
    public float getVerticalScale(){
        return mDisplayHeight / STANDARD_HEIGHT;
    }

}