Android(安卓)Bitmap用法总结

16lz 2021-01-24

Bitmap用法总结
1、Drawable → Bitmap

Java代码 [java]view plaincopy

1、Drawable→Bitmap
publicstaticBitmapdrawableToBitmap(Drawabledrawable){
Bitmapbitmap=Bitmap
.createBitmap(
drawable.getIntrinsicWidth(),
drawable.getIntrinsicHeight(),
drawable.getOpacity()!=PixelFormat.OPAQUE?Bitmap.Config.ARGB_8888
:Bitmap.Config.RGB_565);
Canvascanvas=newCanvas(bitmap);
//canvas.setBitmap(bitmap);
drawable.setBounds(0,0,drawable.getIntrinsicWidth(),
drawable.getIntrinsicHeight());
drawable.draw(canvas);
returnbitmap;
}

2、从资源中获取Bitmap
Java代码

<span style="font-size: medium;">Resources res=getResources();
Bitmap bmp=BitmapFactory.decodeResource(res, R.drawable.pic);</span>

3、Bitmap → byte[]

Java代码

privatebyte[] Bitmap2Bytes(Bitmap bm){
ByteArrayOutputStream baos =newByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.PNG,100, baos);
returnbaos.toByteArray();</span>

4、byte[] → Bitmap
Java代码

privateBitmap Bytes2Bimap(byte[] b){
if(b.length!=0){
returnBitmapFactory.decodeByteArray(b,0, b.length);
}
else{
returnnull;
}
}</span>

5、保存bitmap

Java代码

staticbooleansaveBitmap2file(Bitmap bmp,String filename){
CompressFormat format= Bitmap.CompressFormat.JPEG;
intquality =100;
OutputStream stream =null;
try{
stream =newFileOutputStream("/sdcard/"+ filename);
}catch(FileNotFoundException e) {
// TODO Auto-generated catch block
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http://www.foxitsoftware.com For evaluation only.
e.printStackTrace();
}
returnbmp.compress(format, quality, stream);
}</span>

6、将图片按自己的要求缩放

Java代码

// 图片源
Bitmap bm = BitmapFactory.decodeStream(getResources()
.openRawResource(R.drawable.dog));
// 获得图片的宽高
intwidth = bm.getWidth();
intheight = bm.getHeight();
// 设置想要的大小
intnewWidth =320;
intnewHeight =480;
// 计算缩放比例
floatscaleWidth = ((float) newWidth) / width;
floatscaleHeight = ((float) newHeight) / height;
// 取得想要缩放的matrix参数
Matrix matrix =newMatrix();
matrix.postScale(scaleWidth, scaleHeight);
// 得到新的图片
Bitmap newbm = Bitmap.createBitmap(bm,0,0, width, height, matrix,
true);
// 放在画布上
canvas.drawBitmap(newbm,0,0, paint);</span>

相关知识链接：http://www.eoeandroid.com/thread-3162-1-1.html
7、bitmap的用法小结
Java代码

BitmapFactory.Options option =newBitmapFactory.Options();
option.inSampleSize =2;//将图片设为原来宽高的1/2，防止内存溢出
Bitmap bm = BitmapFactory.decodeFile("",option);//文件流
URL url =newURL("");
InputStream is = url.openStream();
Bitmap bm = BitmapFactory.decodeStream(is);
android:scaleType：
android:scaleType是控制图片如何resized/moved来匹对ImageView的size。ImageView.ScaleType /
android:scaleType值的意义区别：
CENTER /center 按图片的原来size居中显示，当图片长/宽超过View的长/宽，则截取图片的居中部分
显示
CENTER_CROP / centerCrop 按比例扩大图片的size居中显示，使得图片长(宽)等于或大于View的长
(宽)
CENTER_INSIDE / centerInside 将图片的内容完整居中显示，通过按比例缩小或原来的size使得图片
长/宽等于或小于View的长/宽
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http://www.foxitsoftware.com For evaluation only.
FIT_CENTER / fitCenter 把图片按比例扩大/缩小到View的宽度，居中显示
FIT_END / fitEnd 把图片按比例扩大/缩小到View的宽度，显示在View的下部分位置
FIT_START / fitStart 把图片按比例扩大/缩小到View的宽度，显示在View的上部分位置
FIT_XY / fitXY 把图片不按比例扩大/缩小到View的大小显示
MATRIX / matrix 用矩阵来绘制，动态缩小放大图片来显示。</span>

8. 放大缩小图片
Java代码

publicstaticBitmap zoomBitmap(Bitmap bitmap,intw,inth){
intwidth = bitmap.getWidth();
intheight = bitmap.getHeight();
Matrix matrix =newMatrix();
floatscaleWidht = ((float)w / width);
floatscaleHeight = ((float)h / height);
matrix.postScale(scaleWidht, scaleHeight);
Bitmap newbmp = Bitmap.createBitmap(bitmap,0,0, width, height, matrix,
true);
returnnewbmp;
}</span>

9. 将Drawable转化为Bitmap
Java代码

publicstaticBitmap drawableToBitmap(Drawable drawable){
intwidth = drawable.getIntrinsicWidth();
intheight = drawable.getIntrinsicHeight();
Bitmap bitmap = Bitmap.createBitmap(width, height,
drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
: Bitmap.Config.RGB_565);
Canvas canvas =newCanvas(bitmap);
drawable.setBounds(0,0,width,height);
drawable.draw(canvas);
returnbitmap;
Generated by Foxit PDF Creator © Foxit Software
http://www.foxitsoftware.com For evaluation only.
}</span>

10. 获得圆角图片的方法

Java代码

publicstaticBitmap getRoundedCornerBitmap(Bitmap bitmap,floatroundPx){
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap
.getHeight(), Config.ARGB_8888);
Canvas canvas =newCanvas(output);
finalintcolor =0xff424242;
finalPaint paint =newPaint();
finalRect rect =newRect(0,0, bitmap.getWidth(), bitmap.getHeight());
finalRectF rectF =newRectF(rect);
paint.setAntiAlias(true);
canvas.drawARGB(0,0,0,0);
paint.setColor(color);
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
paint.setXfermode(newPorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
returnoutput;
}</span>

11. 获得带倒影的图片方法
Java代码

publicstaticBitmap createReflectionImageWithOrigin(Bitmap bitmap){
finalintreflectionGap =4;
intwidth = bitmap.getWidth();
intheight = bitmap.getHeight();
Matrix matrix =newMatrix();
matrix.preScale(1, -1);
Bitmap reflectionImage = Bitmap.createBitmap(bitmap,
0, height/2, width, height/2, matrix,false);
Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height/2),
Config.ARGB_8888);
Canvas canvas =newCanvas(bitmapWithReflection);
canvas.drawBitmap(bitmap,0,0,null);
Paint deafalutPaint =newPaint();
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http://www.foxitsoftware.com For evaluation only.
canvas.drawRect(0, height,width,height + reflectionGap,
deafalutPaint);
canvas.drawBitmap(reflectionImage,0, height + reflectionGap,null);
Paint paint =newPaint();
LinearGradient shader =newLinearGradient(0,
bitmap.getHeight(),0, bitmapWithReflection.getHeight()
+ reflectionGap,0x70ffffff,0x00ffffff, TileMode.CLAMP);
paint.setShader(shader);
// Set the Transfer mode to be porter duff and destination in
paint.setXfermode(newPorterDuffXfermode(Mode.DST_IN));
// Draw a rectangle using the paint with our linear gradient
canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
+ reflectionGap, paint);
returnbitmapWithReflection;
}
}<

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