Android中Bitmap和Drawable，等相关内容

 一、相关概念

1、Drawable就是一个可画的对象，其可能是一张位图（BitmapDrawable），也可能是一个图形（ShapeDrawable），还有可能是一个图层（LayerDrawable），我们根据画图的需求，创建相应的可画对象

2、Canvas画布，绘图的目的区域，用于绘图

3、Bitmap位图，用于图的处理

4、Matrix矩阵

二、Bitmap

1、从资源中获取Bitmap

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

2、Bitmap → byte[]

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

3、byte[] → Bitmap

public Bitmap Bytes2Bimap(byte[] b) {
    if (b.length != 0) {
        return BitmapFactory.decodeByteArray(b, 0, b.length);
    } else {
        return null;
    }
}

4、Bitmap缩放

 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、将Drawable转化为Bitmap

 

 1 public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roun dPx) {  2 int w = bitmap.getWidth();  3 int h = bitmap.getHeight();  4 Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);  5 Canvas canvas = 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 paint.setAntiAlias(true); 11 canvas.drawARGB(0, 0, 0, 0); 12  paint.setColor(color); 13  canvas.drawRoundRect(rectF, roundPx, roundPx, paint); 14 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); 15  canvas.drawBitmap(bitmap, rect, rect, paint); 16 17 return output; 18 }

 

6、获得圆角图片 

 

 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 Canvas canvas = 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 paint.setAntiAlias(true); 11 canvas.drawARGB(0, 0, 0, 0); 12  paint.setColor(color); 13  canvas.drawRoundRect(rectF, roundPx, roundPx, paint); 14 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); 15  canvas.drawBitmap(bitmap, rect, rect, paint); 16 17 return output; 18 }

 

 7、获得带倒影的图片

 

 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 in 28 paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN)); 29 // Draw a rectangle using the paint with our linear gradient 30 canvas.drawRect(0, h, w, bitmapWithReflection.getHeight() 31 + reflectionGap, paint); 32 33 return bitmapWithReflection; 34 }

 

 三、Drawable

1、Bitmap转换成Drawable

1 Bitmap bm=xxx; //xxx根据你的情况获取 2 BitmapDrawable bd= new BitmapDrawable(getResource(), bm); 3 因为BtimapDrawable是Drawable的子类，最终直接使用bd对象即可。

 

2、Drawable缩放

 1 public static Drawable zoomDrawable(Drawable drawable, int w, int h) {  2 int width = drawable.getIntrinsicWidth();  3 int height = drawable.getIntrinsicHeight();  4 // drawable转换成bitmap  5 Bitmap oldbmp = drawableToBitmap(drawable);  6 // 创建操作图片用的Matrix对象  7 Matrix matrix = new Matrix();  8 // 计算缩放比例  9 float sx = ((float) w / width); 10 float sy = ((float) h / height); 11 // 设置缩放比例 12  matrix.postScale(sx, sy); 13 // 建立新的bitmap，其内容是对原bitmap的缩放后的图 14 Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height, 15 matrix, true); 16 return new BitmapDrawable(newbmp); 17 }

 

 1 // 获取bitmap占用的字节数  2 protected int sizeOf(Bitmap data) {  3 if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB_MR1) {  4 return data.getRowBytes() * data.getHeight();  5 } else {  6 return data.getByteCount();  7  }  8 }  9 10 // 3.以RGB_565方式读入图片 11 public Bitmap readBitMap(Context context, int resId) { 12 BitmapFactory.Options opt = new BitmapFactory.Options(); 13 opt.inPreferredConfig = Bitmap.Config.RGB_565; 14 opt.inPurgeable = true; 15 opt.inInputShareable = true; 16 // 获取资源图片 17 InputStream is = context.getResources().openRawResource(resId); 18 return BitmapFactory.decodeStream(is, null, opt); 19  } 20 21 // 4.获取ImageView和其中drawable的大小 22 // 获取ImageView和其中drawable大小需在onWindowFocusChanged获取，在oncreate中返回的结果是0 23 public void onWindowFocusChanged(boolean hasFocus) { 24 ImageView imageView = (ImageView) findViewById(R.id.test1); 25 Log.v("Testresult", "width= " + imageView.getWidth() + " height= " 26 + imageView.getHeight()); 27 Log.v("Testresult", "drawawidth= " 28 + imageView.getDrawable().getBounds().width() 29 + " drawableheight= " 30 + imageView.getDrawable().getBounds().height()); 31 }