Android中Bitmap和Drawable

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

Java代码  

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

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

 

2、Bitmap → byte[]

Java代码  

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

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

 3、byte[] → Bitmap

Java代码  

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. }  

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

4、Bitmap缩放

Java代码  

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. }  

public static Bitmap zoomBitmap(Bitmap bitmap, int width, int height) {int w = bitmap.getWidth();int h = bitmap.getHeight();Matrix matrix = new Matrix();float scaleWidth = ((float) width / w);float scaleHeight = ((float) height / h);matrix.postScale(scaleWidth, scaleHeight);Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);return newbmp;}

  5、将Drawable转化为Bitmap

Java代码  

1. public static Bitmap drawableToBitmap(Drawable drawable) {   
2.         // 取 drawable 的长宽   
3.         int w = drawable.getIntrinsicWidth();   
4.         int h = drawable.getIntrinsicHeight();   
5.   
6.         // 取 drawable 的颜色格式   
7.         Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888   
8.                 : Bitmap.Config.RGB_565;   
9.         // 建立对应 bitmap   
10.         Bitmap bitmap = Bitmap.createBitmap(w, h, config);   
11.         // 建立对应 bitmap 的画布   
12.         Canvas canvas = new Canvas(bitmap);   
13.         drawable.setBounds(0, 0, w, h);   
14.         // 把 drawable 内容画到画布中   
15.         drawable.draw(canvas);   
16.         return bitmap;   
17.     }  

public static Bitmap drawableToBitmap(Drawable drawable) {// 取 drawable 的长宽int w = drawable.getIntrinsicWidth();int h = drawable.getIntrinsicHeight();// 取 drawable 的颜色格式Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888: Bitmap.Config.RGB_565;// 建立对应 bitmapBitmap bitmap = Bitmap.createBitmap(w, h, config);// 建立对应 bitmap 的画布Canvas canvas = new Canvas(bitmap);                  //图片显示区域，相当于setSize 

drawable.setBounds(0, 0, w, h);// 把 drawable 内容画到画布中drawable.draw(canvas);return bitmap;}

6、获得圆角图片 

Java代码  

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. }  

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、获得带倒影的图片

Java代码  

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. }  

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),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, TileMode.CLAMP);paint.setShader(shader);// Set the Transfer mode to be porter duff and destination inpaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));// Draw a rectangle using the paint with our linear gradientcanvas.drawRect(0, h, w, bitmapWithReflection.getHeight()+ reflectionGap, paint);return bitmapWithReflection;}

 三、Drawable

1、Bitmap转换成Drawable

Java代码  

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。  

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

2、Drawable缩放

Java代码  

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. }  

public static Drawable zoomDrawable(Drawable drawable, int w, int h) {int width = drawable.getIntrinsicWidth();int height = drawable.getIntrinsicHeight();// drawable转换成bitmapBitmap 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);}

 

转自 http://dyh7077063.iteye.com/blog/970672