View处理常用方法封装

处理View常用的一些方法：Drawable和Bitmap互相转换，Bitmap改变大小，dp、px互相转换，sp、px互相转换，根据Id查找Drawable，获取屏幕大小等方法。

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.PixelFormat;
import android.graphics.Point;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.support.v4.content.ContextCompat;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.WindowManager;

/**
 * 剪裁视图的工具类
 * Created by ChenSS on 2016/9/19.
 */
public class ViewHelper {
    /***
     * 画布重绘的方式改变Bitmap的大小
     */
    public static Bitmap zoomImage(Bitmap bgimage, double newWidth,
                                   double newHeight) {
        // 获取这个图片的宽和高
        float width = bgimage.getWidth();
        float height = bgimage.getHeight();
        // 创建操作图片用的matrix对象
        Matrix matrix = new Matrix();
        // 计算宽高缩放率
        float scaleWidth = ((float) newWidth) / width;
        float scaleHeight = ((float) newHeight) / height;
        // 缩放图片动作
        matrix.postScale(scaleWidth, scaleHeight);
        Bitmap bitmap = Bitmap.createBitmap(bgimage, 0, 0, (int) width,
                (int) height, matrix, true);
        bgimage.recycle();
        return bitmap;
    }

    /**
     * Drawable转Bitamp方法
     */
    public Bitmap drawableToBitmap(Drawable drawable) {
        if (drawable instanceof BitmapDrawable) {
            BitmapDrawable bd = (BitmapDrawable) drawable;
            return bd.getBitmap();
        }
        int w = drawable.getIntrinsicWidth();
        int h = drawable.getIntrinsicHeight();
        Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ?
                Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565;
        Bitmap bitmap = Bitmap.createBitmap(w, h, config);
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, w, h);
        drawable.draw(canvas);
        return bitmap;
    }

    /**
     * 寻找并裁剪图片(正方形)
     */
    public static Drawable findImgAsSquare(Context context, int id, int sidedp) {
        Drawable drawable = ContextCompat.getDrawable(context, id);
        int px = ViewHelper.dip2px(context, sidedp);
        drawable.setBounds(0, 0, px, px);
        return drawable;
    }

    /**
     * 寻找Drawable
     */
    public static Drawable findDrawableById(Context context, int id) {
        return ContextCompat.getDrawable(context, id);
    }

    /**
     * 将px值转换为dip或dp值，保证尺寸大小不变
     */
    public static int px2dip(Context context, float pxValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (pxValue / scale + 0.5f);
    }

    /**
     * 将dip或dp值转换为px值，保证尺寸大小不变
     */
    public static int dip2px(Context context, float dipValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dipValue * scale + 0.5f);
    }

    /**
     * 将px值转换为sp值，保证文字大小不变
     */
    public static int px2sp(Context context, float pxValue) {
        final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
        return (int) (pxValue / fontScale + 0.5f);
    }

    /**
     * 将sp值转换为px值，保证文字大小不变
     */
    public static int sp2px(Context context, float spValue) {
        final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
        return (int) (spValue * fontScale + 0.5f);
    }

    /**
     * 以Point对象返回屏幕大小(可使用Context代替Activity)
     */
    public static Point getScreenSize(Activity activity) {
        Display display = activity.getWindowManager().getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);
        return size;
    }

    /**
     * 以Point对象返回屏幕大小
     */
    public static Point getScreenHW(Context context) {
        Point point = new Point();
        WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics dm = new DisplayMetrics();
        manager.getDefaultDisplay().getMetrics(dm);
        point.x = dm.widthPixels;
        point.y = dm.heightPixels;
        return point;
    }

    /**
     * 获取屏幕的宽度
     */
    public static int getScreenW(Context context) {
        return getScreenHW(context).x;
    }

    /**
     * 获取屏幕的高度
     */
    public static int getScreenH(Context context) {
        return getScreenHW(context).y;
    }
}