最近学习Android开发,发现图片处理很常用,特依据下载的各类代码,提取了几个不错的图片处理函数。
读取本地资源的图片的方法如下:
public static Bitmap ReadBitmapById(Context context, int resId) {
BitmapFactory.Options opt = new BitmapFactory.Options();
opt.inPreferredConfig = Bitmap.Config.RGB_565;
opt.inPurgeable = true;
opt.inInputShareable = true;
// 获取资源图片
InputStream is = context.getResources().openRawResource(resId);
return BitmapFactory.decodeStream(is, null, opt);
}
等比例压缩图片的函数封装如下:
public static Bitmap getBitmap(Bitmap bitmap, int screenWidth,
int screenHight) {
int w = bitmap.getWidth();
int h = bitmap.getHeight();
Log.e("jj", "图片宽度" + w + ",screenWidth=" + screenWidth);
Matrix matrix = new Matrix();
float scale = (float) screenWidth / w;
float scale2 = (float) screenHight / h;
// scale = scale < scale2 ? scale : scale2;
// 保证图片不变形.
matrix.postScale(scale, scale);
// w,h是原图的属性.
return Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
}
保存图片至SD卡的代码:
private static int FREE_SD_SPACE_NEEDED_TO_CACHE = 1;
private static int MB = 1024 * 1024;
public final static String DIR = "/sdcard/hypers";
public static void saveBmpToSd(Bitmap bm, String url, int quantity) {
// 判断sdcard上的空间
if (FREE_SD_SPACE_NEEDED_TO_CACHE > freeSpaceOnSd()) {
return;
}
if (!Environment.MEDIA_MOUNTED.equals(Environment
.getExternalStorageState()))
return;
String filename = url;
// 目录不存在就创建
File dirPath = new File(DIR);
if (!dirPath.exists()) {
dirPath.mkdirs();
}
File file = new File(DIR + "/" + filename);
try {
file.createNewFile();
OutputStream outStream = new FileOutputStream(file);
bm.compress(Bitmap.CompressFormat.PNG, quantity, outStream);
outStream.flush();
outStream.close();
} catch (FileNotFoundException e) {
} catch (IOException e) {
e.printStackTrace();
}
}
获取SD卡图片的方法如下:
public static Bitmap GetBitmap(String url, int quantity) {
InputStream inputStream = null;
String filename = "";
Bitmap map = null;
URL url_Image = null;
String LOCALURL = "";
if (url == null)
return null;
try {
filename = url;
} catch (Exception err) {
}
LOCALURL = URLEncoder.encode(filename);
if (Exist(DIR + "/" + LOCALURL)) {
map = BitmapFactory.decodeFile(DIR + "/" + LOCALURL);
} else {
try {
url_Image = new URL(url);
inputStream = url_Image.openStream();
map = BitmapFactory.decodeStream(inputStream);
// url = URLEncoder.encode(url, "UTF-8");
if (map != null) {
saveBmpToSd(map, LOCALURL, quantity);
}
inputStream.close();
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
return map;
}
头文件引入如下:
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLEncoder;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Environment;
import android.os.StatFs;
import android.util.Log;