摘要：進行縮放然后比對進行縮放調用中轉換成創建操作圖片用的對象計算縮放比例設置縮放比例建立新的，其內容是對原的縮放后的圖至此，本篇已結束，如有不對的地方，歡迎您的建議與指正。同時期待您的關注，感謝您的閱讀，謝謝

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Drawable 使用方法詳解請看上篇文章.
Drawable 使用方法詳解

本篇文章主要介紹 Android 開發中的部分知識點，通過閱讀本篇文章，您將收獲以下內容:

從資源中獲取Bitmap
Bitmap ----> byte[]
byte[] ----> Bitmap
Bitmap 縮放方法
Drawable ----> Bitmap
圓角圖片
獲取帶倒影的圖片
bitmap ----> Drawable
drawable縮放 ，先轉 bitmap 后縮放

    // 1.從資源中獲取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 縮放方法
    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) {

        // 獲取 drawable 長寬
        int width = drawable.getIntrinsicWidth();
        int heigh = drawable.getIntrinsicHeight();

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

        // 獲取drawable的顏色格式
        Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                : Bitmap.Config.RGB_565;
        // 創建bitmap
        Bitmap bitmap = Bitmap.createBitmap(width, heigh, config);
        // 創建bitmap畫布
        Canvas canvas = new Canvas(bitmap);
        // 將drawable 內容畫到畫布中
        drawable.draw(canvas);
        return bitmap;
    }

-實現效果如下：

實現代碼如下：

    // 6.圓角圖片
    public static Bitmap SetRoundCornerBitmap(Bitmap bitmap, float roundPx) {
        int width = bitmap.getWidth();
        int heigh = bitmap.getHeight();
        // 創建輸出bitmap對象
        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;
    }

實現效果如下：

實現代碼如下：

    // 7.獲取帶倒影的圖片
    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縮放 ，先轉 bitmap，調用 5中的方法 后縮放。

    // 9. drawable進行縮放 ---> bitmap 然后比對bitmap進行縮放
    public static Drawable ZoomDrawable(Drawable drawable, int w, int h) {
        int width = drawable.getIntrinsicWidth();
        int height = drawable.getIntrinsicHeight();
        // 調用5 中 drawable轉換成bitmap
        Bitmap oldbmp = DrawableToBitmap(drawable);

        // 創建操作圖片用的Matrix對象
        Matrix matrix = new Matrix();
        // 計算縮放比例
        float sx = ((float) w / width);
        float sy = ((float) h / height);
        // 設置縮放比例
        matrix.postScale(sx, sy);
        // 建立新的bitmap，其內容是對原bitmap的縮放后的圖
        Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height,
                matrix, true);
        return new BitmapDrawable(newbmp);
    }

至此，本篇已結束，如有不對的地方，歡迎您的建議與指正。同時期待您的關注，感謝您的閱讀，謝謝！