Android中Bitmap和Drawable

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Android中Bitmap和Drawable (轉自：http://dyh7077063.iteye.com/blog/970672)一、相關概念

1、Drawable就是一個可畫的對象，其可能是一張位元影像（BitmapDrawable），也可能是一個圖形（ShapeDrawable），還有可能是一個圖層（LayerDrawable），我們根據畫圖的需求，建立相應的可畫對象 

2、Canvas畫布，繪圖的目的地區，用於繪圖 

3、Bitmap位元影像，用於圖的處理 

4、Matrix矩陣 

二、Bitmap1、從資源中擷取Bitmap

　　

1 Resources res = getResources();   2 Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.icon);   

 

 

2、Bitmap → byte[]

1 public byte[] Bitmap2Bytes(Bitmap bm) {   2     ByteArrayOutputStream baos = new ByteArrayOutputStream();   3     bm.compress(Bitmap.CompressFormat.PNG, 100, baos);   4     return baos.toByteArray();   5  6 }   

 

 

 3、byte[] → Bitmap

1 public Bitmap Bytes2Bimap(byte[] b) {  2 if (b.length != 0) {  3 return BitmapFactory.decodeByteArray(b, 0, b.length);  4 else {  5 return null;  6     }  7 }  

 

4、Bitmap縮放

 1 public static Bitmap zoomBitmap(Bitmap bitmap, int width, int height) {   2 int w = bitmap.getWidth();   3 int h = bitmap.getHeight();   4 new Matrix();   5 float scaleWidth = ((float) width / w);   6 float scaleHeight = ((float) height / h);   7     matrix.postScale(scaleWidth, scaleHeight);   8 0, 0, w, h, matrix, true);   9 return newbmp;  10 }  

 

  5、將Drawable轉化為Bitmap

 1 public static Bitmap drawableToBitmap(Drawable drawable) {   2 // 取 drawable 的長寬   3 int w = drawable.getIntrinsicWidth();   4 int h = drawable.getIntrinsicHeight();   5    6 // 取 drawable 的顏色格式   7         Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888   8                 : Bitmap.Config.RGB_565;   9 // 建立對應 bitmap  10         Bitmap bitmap = Bitmap.createBitmap(w, h, config);  11 // 建立對應 bitmap 的畫布  12 new Canvas(bitmap);  13 0, 0, w, h);  14 // 把 drawable 內容畫到畫布中  15         drawable.draw(canvas);  16 return bitmap;  17     }  

 

6、獲得圓角圖片 

 1 public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) {   2 int w = bitmap.getWidth();   3 int h = bitmap.getHeight();   4     Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);   5 new Canvas(output);   6 final int color = 0xff424242;   7 final Paint paint = new Paint();   8 final Rect rect = new Rect(0, 0, w, h);   9 final RectF rectF = new RectF(rect);  10 true);  11 0, 0, 0, 0);  12     paint.setColor(color);  13     canvas.drawRoundRect(rectF, roundPx, roundPx, paint);  14 new PorterDuffXfermode(Mode.SRC_IN));  15     canvas.drawBitmap(bitmap, rect, rect, paint);  16   17 return output;  18 }  

 

 7、獲得帶倒影的圖片

 1 public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap) {   2 final int reflectionGap = 4;   3 int w = bitmap.getWidth();   4 int h = bitmap.getHeight();   5    6 new Matrix();   7 1, -1);   8    9 0, h / 2, w,  10 2, matrix, false);  11   12 2),  13             Config.ARGB_8888);  14   15 new Canvas(bitmapWithReflection);  16 0, 0, null);  17 new Paint();  18 0, h, w, h + reflectionGap, deafalutPaint);  19   20 0, h + reflectionGap, null);  21   22 new Paint();  23 new LinearGradient(0, bitmap.getHeight(), 0,  24 0x70ffffff,  25 0x00ffffff, TileMode.CLAMP);  26     paint.setShader(shader);  27 // Set the Transfer mode to be porter duff and destination in  28 new PorterDuffXfermode(Mode.DST_IN));  29 // Draw a rectangle using the paint with our linear gradient  30 0, h, w, bitmapWithReflection.getHeight()  31             + reflectionGap, paint);  32   33 return bitmapWithReflection;  34 }  

 

 三、Drawable1、Bitmap轉換成Drawable

1 Bitmap bm=xxx; //xxx根據你的情況擷取   2 BitmapDrawable bd= new BitmapDrawable(getResource(), bm);    3 因為BtimapDrawable是Drawable的子類，最終直接使用bd對象即可。

 

 

2、Drawable縮放

 1 public static Drawable zoomDrawable(Drawable drawable, int w, int h) {   2 int width = drawable.getIntrinsicWidth();   3 int height = drawable.getIntrinsicHeight();   4 // drawable轉換成bitmap   5     Bitmap oldbmp = drawableToBitmap(drawable);   6 // 建立操作圖片用的Matrix對象   7 new Matrix();   8 // 計算縮放比例   9 float sx = ((float) w / width);  10 float sy = ((float) h / height);  11 // 設定縮放比例  12     matrix.postScale(sx, sy);  13 // 建立新的bitmap，其內容是對原bitmap的縮放後的圖  14 0, 0, width, height,  15 true);  16 return new BitmapDrawable(newbmp);  

 

Android中Bitmap和Drawable