我正在开发一个应用程序,需要从SD卡
中选择一个图像并显示在图像视图中。现在我想让用户通过点击按钮来增加/减少其宽度,然后将其保存回SD卡。
我已经完成了图片的选择和在UI上显示的部分,但是无法找到如何调整大小的方法。请有经验的开发者给予建议。
就在昨天我做了这件事
File dir=Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM);
Bitmap b= BitmapFactory.decodeFile(PATH_ORIGINAL_IMAGE);
Bitmap out = Bitmap.createScaledBitmap(b, 320, 480, false);
File file = new File(dir, "resize.png");
FileOutputStream fOut;
try {
fOut = new FileOutputStream(file);
out.compress(Bitmap.CompressFormat.PNG, 100, fOut);
fOut.flush();
fOut.close();
b.recycle();
out.recycle();
} catch (Exception e) {}
同时不要忘记回收你的位图
:这将节省内存。
您还可以获取新创建文件的路径字符串:newPath = file.getAbsolutePath();
Kotlin中避免OutOfMemoryException
的解决方案
fun resizeImage(file: File, scaleTo: Int = 1024) {
val bmOptions = BitmapFactory.Options()
bmOptions.inJustDecodeBounds = true
BitmapFactory.decodeFile(file.absolutePath, bmOptions)
val photoW = bmOptions.outWidth
val photoH = bmOptions.outHeight
// Determine how much to scale down the image
val scaleFactor = Math.min(photoW / scaleTo, photoH / scaleTo)
bmOptions.inJustDecodeBounds = false
bmOptions.inSampleSize = scaleFactor
val resized = BitmapFactory.decodeFile(file.absolutePath, bmOptions) ?: return
file.outputStream().use {
resized.compress(Bitmap.CompressFormat.JPEG, 75, it)
resized.recycle()
}
}
尝试使用这个方法:
public static Bitmap scaleBitmap(Bitmap bitmapToScale, float newWidth, float newHeight) {
if(bitmapToScale == null)
return null;
//get the original width and height
int width = bitmapToScale.getWidth();
int height = bitmapToScale.getHeight();
// create a matrix for the manipulation
Matrix matrix = new Matrix();
// resize the bit map
matrix.postScale(newWidth / width, newHeight / height);
// recreate the new Bitmap and set it back
return Bitmap.createBitmap(bitmapToScale, 0, 0, bitmapToScale.getWidth(), bitmapToScale.getHeight(), matrix, true);
}
这里是我的静态方法:
public static void resizeImageFile(File originalImageFile, File resizedImageFile, int maxSize) {
Bitmap bitmap = BitmapFactory.decodeFile(originalImageFile.getAbsolutePath());
Bitmap resizedBitmap;
if (bitmap.getWidth() > bitmap.getHeight()) {
resizedBitmap = Bitmap.createScaledBitmap(bitmap, maxSize, maxSize * bitmap.getHeight() / bitmap.getWidth(), false);
} else {
resizedBitmap = Bitmap.createScaledBitmap(bitmap, maxSize * bitmap.getWidth() / bitmap.getHeight(), maxSize, false);
}
FileOutputStream fileOutputStream;
try {
fileOutputStream = new FileOutputStream(resizedImageFile);
resizedBitmap.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream);
fileOutputStream.flush();
fileOutputStream.close();
bitmap.recycle();
resizedBitmap.recycle();
} catch (Exception e) {
e.printStackTrace();
}
}