Drawable与 Bitmap 转换总结

摘要：进行缩放然后比对进行缩放调用中转换成创建操作图片用的对象计算缩放比例设置缩放比例建立新的，其内容是对原的缩放后的图至此，本篇已结束，如有不对的地方，欢迎您的建议与指正。同时期待您的关注，感谢您的阅读，谢谢

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Drawable 使用方法详解请看上篇文章.
Drawable 使用方法详解

本篇文章主要介绍 Android 开发中的部分知识点，通过阅读本篇文章，您将收获以下内容:

从资源中获取Bitmap
Bitmap ----> byte[]
byte[] ----> Bitmap
Bitmap 缩放方法
Drawable ----> Bitmap
圆角图片
获取带倒影的图片
bitmap ----> Drawable
drawable缩放 ，先转 bitmap 后缩放

    // 1.从资源中获取Bitmap
    public void UseBitmap(Context context, ImageView imageView, int drawableId) {

        Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(),
                drawableId);
        imageView.setImageBitmap(bitmap);

    }

    // 2.Bitmap ---> byte[]
    public byte[] BitmapToBytes(Bitmap bitmap) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
        return baos.toByteArray();
    }

    // 3.byte[] ---->bitmap
    public Bitmap BytesToBitmap(byte[] b) {
        if (b.length != 0) {
            return BitmapFactory.decodeByteArray(b, 0, b.length);
        } else {
            return null;
        }
    }

    // 4.Bitmap 缩放方法
    public static Bitmap ZoomBitmap(Bitmap bitmap, int width, int heigh) {
        int w = bitmap.getWidth();
        int h = bitmap.getHeight();
        Matrix matrix = new Matrix();
        float scalewidth = (float) width / w;
        float scaleheigh = (float) heigh / h;
        matrix.postScale(scalewidth, scaleheigh);
        Bitmap newBmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
        return newBmp;

    }

    // 5. Drawable----> Bitmap
    public static Bitmap DrawableToBitmap(Drawable drawable) {

        // 获取 drawable 长宽
        int width = drawable.getIntrinsicWidth();
        int heigh = drawable.getIntrinsicHeight();

        drawable.setBounds(0, 0, width, heigh);

        // 获取drawable的颜色格式
        Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                : Bitmap.Config.RGB_565;
        // 创建bitmap
        Bitmap bitmap = Bitmap.createBitmap(width, heigh, config);
        // 创建bitmap画布
        Canvas canvas = new Canvas(bitmap);
        // 将drawable 内容画到画布中
        drawable.draw(canvas);
        return bitmap;
    }

-实现效果如下：

实现代码如下：

    // 6.圆角图片
    public static Bitmap SetRoundCornerBitmap(Bitmap bitmap, float roundPx) {
        int width = bitmap.getWidth();
        int heigh = bitmap.getHeight();
        // 创建输出bitmap对象
        Bitmap outmap = Bitmap.createBitmap(width, heigh,
                Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(outmap);
        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, width, heigh);
        final RectF rectf = new RectF(rect);
        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectf, roundPx, roundPx, paint);
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);

        return outmap;
    }

实现效果如下：

实现代码如下：

    // 7.获取带倒影的图片
    public static Bitmap CreateReflectionImageWithOrigin(Bitmap bitmap) {

        final int reflectionGap = 4;
        int w = bitmap.getWidth();
        int h = bitmap.getHeight();
        Matrix matrix = new Matrix();
        matrix.preScale(1, -1);

        Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, h / 2, w,
                h / 2, matrix, false);

        Bitmap bitmapWithReflection = Bitmap.createBitmap(w, (h + h / 2),
                Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmapWithReflection);
        canvas.drawBitmap(bitmap, 0, 0, null);
        Paint deafalutPaint = new Paint();
        canvas.drawRect(0, h, w, h + reflectionGap, deafalutPaint);

        canvas.drawBitmap(reflectionImage, 0, h + reflectionGap, null);

        Paint paint = new Paint();
        LinearGradient shader = new LinearGradient(0, bitmap.getHeight(), 0,
                bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff,
                0x00ffffff, Shader.TileMode.CLAMP);
        paint.setShader(shader);
        // Set the Transfer mode to be porter duff and destination in
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
        // Draw a rectangle using the paint with our linear gradient
        canvas.drawRect(0, h, w, bitmapWithReflection.getHeight()
                + reflectionGap, paint);
        return bitmapWithReflection;
    }

    // 8. bitmap ---Drawable
    public static Drawable BitmapToDrawable(Bitmap bitmap, Context context) {
        BitmapDrawable drawbale = new BitmapDrawable(context.getResources(),
                bitmap);
        return drawbale;
    }

drawable缩放 ，先转 bitmap，调用 5中的方法 后缩放。

    // 9. drawable进行缩放 ---> bitmap 然后比对bitmap进行缩放
    public static Drawable ZoomDrawable(Drawable drawable, int w, int h) {
        int width = drawable.getIntrinsicWidth();
        int height = drawable.getIntrinsicHeight();
        // 调用5 中 drawable转换成bitmap
        Bitmap oldbmp = DrawableToBitmap(drawable);

        // 创建操作图片用的Matrix对象
        Matrix matrix = new Matrix();
        // 计算缩放比例
        float sx = ((float) w / width);
        float sy = ((float) h / height);
        // 设置缩放比例
        matrix.postScale(sx, sy);
        // 建立新的bitmap，其内容是对原bitmap的缩放后的图
        Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height,
                matrix, true);
        return new BitmapDrawable(newbmp);
    }

至此，本篇已结束，如有不对的地方，欢迎您的建议与指正。同时期待您的关注，感谢您的阅读，谢谢！