Android中Bit地图和Drawable(转)

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

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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);??

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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. }??

?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. }??

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. }??

??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. ????}??

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. }??

?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. }??

?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。??

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. } ?