【知识点】Bitmap的常用方法

总结几个开发过程中Bitmap经常使用到几个方法

 

public class BitmapUtil {
	
	/**
     * 从SDCard上读取图片
     * @param pathName
     * @return
     */
    public static Bitmap getBitmapFromSDCard(String pathName) {
        return BitmapFactory.decodeFile(pathName);
    }
 
    /**
     * 缩放图片
     * @param bitmap
     * @param width
     * @param height
     * @return
     */
    public static Bitmap zoomBitmap(Bitmap bitmap, int width, int height) {
        int w = bitmap.getWidth();
        int h = bitmap.getHeight();
        Matrix matrix = new Matrix();
        matrix.postScale((float) width / w, (float) height / h);
        return Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
    }
 
    /**
     * 将Drawable转化为Bitmap
     * @param drawable
     * @return
     */
    public static Bitmap drawableToBitmap(Drawable drawable) {
        int width = drawable.getIntrinsicWidth();
        int height = drawable.getIntrinsicHeight();
        Bitmap bitmap = Bitmap.createBitmap(width, height, drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565);
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, width, height);
        drawable.draw(canvas);
        return bitmap;
    }
 
    /**
     * 获得圆角图片
     * @param bitmap
     * @param roundPx
     * @return
     */
    public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) {
        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
        final RectF rectF = new RectF(rect);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);
        return output;
    }
 
    /**
     * 获得带倒影的图片
     * @param bitmap
     * @return
     */
    public static Bitmap getReflectionImageWithOrigin(Bitmap bitmap) {
        final int reflectionGap = 4;
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
 
        Matrix matrix = new Matrix();
        matrix.preScale(1, -1);
        Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, height/2, width, height/2, matrix, false);
        Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height/2), Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmapWithReflection);
        canvas.drawBitmap(bitmap, 0, 0, null);
        Paint defaultPaint = new Paint();
        canvas.drawRect(0, height, width, height + reflectionGap, defaultPaint);
        canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
 
        Paint paint = new Paint();
        LinearGradient shader = new LinearGradient(0, bitmap.getHeight(), 0, bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.CLAMP);
        paint.setShader(shader);
        paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
        canvas.drawRect(0, height, width, bitmapWithReflection.getHeight() + reflectionGap, paint);
        return bitmapWithReflection;
    }
}