Android中Bitmap和Drawable

標籤：

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     }

 

 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         Matrix matrix = new Matrix(); 5         float scaleWidth = ((float) width / w); 6         float scaleHeight = ((float) height / h); 7         matrix.postScale(scaleWidth, scaleHeight); 8         Bitmap newbmp = Bitmap.createBitmap(bitmap, 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 bitmap10         Bitmap bitmap = Bitmap.createBitmap(w, h, config);11         // 建立對應 bitmap 的畫布12         Canvas canvas = new Canvas(bitmap);13         drawable.setBounds(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 

public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) {        int w = bitmap.getWidth();        int h = bitmap.getHeight();        Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);        Canvas canvas = new Canvas(output);        final int color = 0xff424242;        final Paint paint = new Paint();        final Rect rect = new Rect(0, 0, w, h);        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(Mode.SRC_IN));        canvas.drawBitmap(bitmap, rect, rect, paint);        return output;    }

 

 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         Matrix matrix = new Matrix(); 7         matrix.preScale(1, -1); 8  9         Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, h / 2, w,10                 h / 2, matrix, false);11 12         Bitmap bitmapWithReflection = Bitmap.createBitmap(w, (h + h / 2),13                 Config.ARGB_8888);14 15         Canvas canvas = new Canvas(bitmapWithReflection);16         canvas.drawBitmap(bitmap, 0, 0, null);17         Paint deafalutPaint = new Paint();18         canvas.drawRect(0, h, w, h + reflectionGap, deafalutPaint);19 20         canvas.drawBitmap(reflectionImage, 0, h + reflectionGap, null);21 22         Paint paint = new Paint();23         LinearGradient shader = new LinearGradient(0, bitmap.getHeight(), 0,24                 bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff,25                 0x00ffffff, TileMode.CLAMP);26         paint.setShader(shader);27         // Set the Transfer mode to be porter duff and destination in28         paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));29         // Draw a rectangle using the paint with our linear gradient30         canvas.drawRect(0, h, w, bitmapWithReflection.getHeight()31                 + reflectionGap, paint);32 33         return bitmapWithReflection;34     }

 

 三、Drawable1、Bitmap轉換成Drawable

Bitmap bm=xxx; //xxx根據你的情況擷取BitmapDrawable bd= new BitmapDrawable(getResource(), bm); 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         Matrix matrix = 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         Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height,15                 matrix, true);16         return new BitmapDrawable(newbmp);17     }

 

 

Android中Bitmap和Drawable