加载大图片到内存
public class MainActivity extends Activity {
private ImageView iv_img;
private int windowHeight;
private int windowWidth;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this.iv_img = (ImageView) this.findViewById(R.id.iv_img);
WindowManager manager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
// 第一种获取手机屏幕宽高的方法
this.windowHeight = manager.getDefaultDisplay().getHeight();
this.windowWidth = manager.getDefaultDisplay().getWidth();
System.out.println("手机宽 ：" + this.windowWidth);
System.out.println("手机高 ：" + this.windowHeight);
// 第二种获取手机屏幕宽高的方法，但是getSize()是从 API Level 13才有的方法
// Point outSize = new Point();
// manager.getDefaultDisplay().getSize(outSize );
// this.windowWidth = outSize.x;
// this.windowHeight = outSize.y;
}
public void load1(View view) {
String src = "mnt/sdcard/DSC.jpg";
Bitmap bitmap = BitmapFactory.decodeFile(src);
this.iv_img.setImageBitmap(bitmap);
}
public void load2(View view) {
String src = "mnt/sdcard/DSC.jpg";
// 图片解析的配置
Options options = new Options();
// 不去真正解析图片，只是获取图片的宽高
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(src, options);
int imageWidth = options.outWidth;
int imageHeight = options.outHeight;
System.out.println("图片宽 :" + imageWidth);
System.out.println("图片高 :" + imageHeight);
int scaleX = imageWidth / this.windowWidth;
int scaleY = imageHeight / this.windowHeight;
int scale = 1;
if (scaleX >= scaleY && scaleX >= 1) {
// 水平方向的缩放比例比竖直方向的缩放比例大，同时图片的宽要比手机屏幕要大,就按水平方向比例缩放
System.out.println("按宽比例缩放");
scale = scaleX;
} else if (scaleY >= scaleX && scaleY >= 1) {
// 竖直方向的缩放比例比水平方向的缩放比例大，同时图片的高要比手机屏幕要大，就按竖直方向比例缩放
System.out.println("按高比例缩放");
scale = scaleY;
}
System.out.println("缩放比例：" + scale);
// 真正解析图片
options.inJustDecodeBounds = false;
// 设置采样率
options.inSampleSize = scale;
Bitmap bitmap = BitmapFactory.decodeFile(src,options);
this.iv_img.setImageBitmap(bitmap);
}
}
获取图片exif信息
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void read(View view) {
try {
/*
* ExifInterface.TAG_APERTURE：光圈
* ExifInterface.TAG_DATETIME:拍摄日期
* ExifInterface.TAG_EXPOSURE_TIME:曝光时间
* ExifInterface.TAG_FLASH:闪光灯
* ExifInterface.TAG_FOCAL_LENGTH:焦距
* ExifInterface.TAG_GPS_ALTITUDE:海拔
* ExifInterface.TAG_GPS_ALTITUDE_REF:海拔参数
* ExifInterface.TAG_GPS_DATESTAMP
*/
String src = "mnt/sdcard/DCIM/Camera/IMG_20130718_164129.jpg";
// src = "mnt/sdcard/dog.jpg";
ExifInterface exif = new ExifInterface(src);
// String make = exif. getAttribute(ExifInterface.TAG_MAKE);
// String model = exif.getAttribute(ExifInterface.TAG_MODEL);
// String datetime = exif.getAttribute(ExifInterface.TAG_DATETIME);
// Toast.makeText(this, "制造商： " + make, 0).show();
// Toast.makeText(this, "相机类型： " + model, 0).show();
// Toast.makeText(this, "拍摄日期：" + datetime, 0).show();
// System.out.println(exif.getAttribute(ExifInterface.TAG_APERTURE));
System.out.println(exif.getAttribute(ExifInterface.TAG_DATETIME));
// System.out.println(exif.getAttribute(ExifInterface.TAG_EXPOSURE_TIME));
System.out.println(exif.getAttribute(ExifInterface.TAG_FLASH));
System.out.println(exif.getAttribute(ExifInterface.TAG_FOCAL_LENGTH));
// System.out.println(exif.getAttribute(ExifInterface.TAG_GPS_ALTITUDE));
// System.out.println(exif.getAttribute(ExifInterface.TAG_GPS_ALTITUDE_REF));
System.out.println(exif.getAttribute(ExifInterface.TAG_GPS_DATESTAMP));
System.out.println(exif.getAttribute(ExifInterface.TAG_GPS_LATITUDE));
System.out.println(exif.getAttribute(ExifInterface.TAG_GPS_LATITUDE_REF));
System.out.println(exif.getAttribute(ExifInterface.TAG_GPS_LONGITUDE));
System.out.println(exif.getAttribute(ExifInterface.TAG_GPS_LONGITUDE_REF));
System.out.println(exif.getAttribute(ExifInterface.TAG_IMAGE_LENGTH));
System.out.println(exif.getAttribute(ExifInterface.TAG_IMAGE_WIDTH));
// System.out.println(exif.getAttribute(ExifInterface.TAG_ISO));
System.out.println(exif.getAttribute(ExifInterface.TAG_MAKE));
System.out.println(exif.getAttribute(ExifInterface.TAG_MODEL));
System.out.println(exif.getAttribute(ExifInterface.TAG_ORIENTATION));
System.out.println(exif.getAttribute(ExifInterface.TAG_WHITE_BALANCE));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
从gallery获取图片
查看系统gallery应用的源码：
在清单文件中,我们发现可以通过android.intent.action.PICK这个action来从图库选择一张图片
<activity android:name="com.android.camera.ImageGallery"
android:label="@string/gallery_label"
android:configChanges="orientation|keyboardHidden"
android:icon="@drawable/ic_launcher_gallery">
.......
<intent-filter>
<action android:name="android.intent.action.PICK" />
<category android:name="android.intent.category.DEFAULT" />
<data android:mimeType="image/*" />
<data android:mimeType="video/*" />
</intent-filter>
.......
</activity>
再查看com.android.camera.ImageGallery类发现，图库会返回图片的全路径和图片的缩略图给我们
Intent result = new Intent(null, img.fullSizeImageUri());
if (myExtras != null && myExtras.getBoolean("return-data")) {
// The size of a transaction should be below 100K.
Bitmap bitmap = img.fullSizeBitmap(
IImage.UNCONSTRAINED, 100 * 1024);
if (bitmap != null) {
result.putExtra("data", bitmap);
}
根据上边的信息，我们可以编写一下代码来获取图库的某种图片
public class MainActivity extends Activity {
private ImageView iv_image;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this.iv_image = (ImageView) this.findViewById(R.id.iv_image);
}
public void load(View view) {
// 激活系统图库，选择一张图片
Intent intent = new Intent();
intent.setAction(Intent.ACTION_PICK);
intent.setType("image/*");
startActivityForResult(intent, 0);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (data != null) {
// 得到图片的全路径
Uri uri = data.getData();
// 通过路径加载图片
// this.iv_image.setImageURI(uri);
try {
InputStream is = getContentResolver().openInputStream(uri);
Bitmap bitmap = BitmapFactory.decodeStream(is);
this.iv_image.setImageBitmap(bitmap);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// 获取图片的缩略图，可能为空！
// Bitmap bitmap = data.getParcelableExtra("data");
// this.iv_image.setImageBitmap(bitmap);
}
super.onActivityResult(requestCode, resultCode, data);
}
}