我有一个位图采取的Base64字符串从我的远程数据库，(encodedImage是字符串表示图像与Base64):
profileImage = (ImageView)findViewById(R.id.profileImage);
byte[] imageAsBytes=null;
try {
imageAsBytes = Base64.decode(encodedImage.getBytes());
} catch (IOException e) {e.printStackTrace();}
profileImage.setImageBitmap(
BitmapFactory.decodeByteArray(imageAsBytes, 0, imageAsBytes.length)
);
profileImage是我的ImageView
但在显示在布局的ImageView中之前，我需要调整图像的大小。我得把它调整到120x120。
有人能告诉我调整大小的代码吗?
我发现的例子不能应用于base64字符串获得位图。
当前回答
基于纵横比的规模:
float aspectRatio = yourSelectedImage.getWidth() /
(float) yourSelectedImage.getHeight();
int width = 480;
int height = Math.round(width / aspectRatio);
yourSelectedImage = Bitmap.createScaledBitmap(
yourSelectedImage, width, height, false);
使用高度作为基础而不是宽度更改为:
int height = 480;
int width = Math.round(height * aspectRatio);
其他回答
public Bitmap scaleBitmap(Bitmap mBitmap) {
int ScaleSize = 250;//max Height or width to Scale
int width = mBitmap.getWidth();
int height = mBitmap.getHeight();
float excessSizeRatio = width > height ? width / ScaleSize : height / ScaleSize;
Bitmap bitmap = Bitmap.createBitmap(
mBitmap, 0, 0,(int) (width/excessSizeRatio),(int) (height/excessSizeRatio));
//mBitmap.recycle(); if you are not using mBitmap Obj
return bitmap;
}
保持纵横比，
public Bitmap resizeBitmap(Bitmap source, int width,int height) {
if(source.getHeight() == height && source.getWidth() == width) return source;
int maxLength=Math.min(width,height);
try {
source=source.copy(source.getConfig(),true);
if (source.getHeight() <= source.getWidth()) {
if (source.getHeight() <= maxLength) { // if image already smaller than the required height
return source;
}
double aspectRatio = (double) source.getWidth() / (double) source.getHeight();
int targetWidth = (int) (maxLength * aspectRatio);
return Bitmap.createScaledBitmap(source, targetWidth, maxLength, false);
} else {
if (source.getWidth() <= maxLength) { // if image already smaller than the required height
return source;
}
double aspectRatio = ((double) source.getHeight()) / ((double) source.getWidth());
int targetHeight = (int) (maxLength * aspectRatio);
return Bitmap.createScaledBitmap(source, maxLength, targetHeight, false);
}
}
catch (Exception e)
{
return source;
}
}
虽然接受的答案是正确的，但它不会通过保持相同的纵横比来调整位图的大小。如果你正在寻找一种方法来调整位图的大小保持相同的纵横比，你可以使用下面的实用函数。该功能的使用细节和解释在此链接中。
public static Bitmap resizeBitmap(Bitmap source, int maxLength) {
try {
if (source.getHeight() >= source.getWidth()) {
int targetHeight = maxLength;
if (source.getHeight() <= targetHeight) { // if image already smaller than the required height
return source;
}
double aspectRatio = (double) source.getWidth() / (double) source.getHeight();
int targetWidth = (int) (targetHeight * aspectRatio);
Bitmap result = Bitmap.createScaledBitmap(source, targetWidth, targetHeight, false);
if (result != source) {
}
return result;
} else {
int targetWidth = maxLength;
if (source.getWidth() <= targetWidth) { // if image already smaller than the required height
return source;
}
double aspectRatio = ((double) source.getHeight()) / ((double) source.getWidth());
int targetHeight = (int) (targetWidth * aspectRatio);
Bitmap result = Bitmap.createScaledBitmap(source, targetWidth, targetHeight, false);
if (result != source) {
}
return result;
}
}
catch (Exception e)
{
return source;
}
}
虽然前面的答案确实缩放了图像并考虑了纵横比，但重新采样本身应该这样做，这样就不会出现混叠。注意尺度是一个正确修正参数的问题。有许多关于标准缩放调用输出图像质量的评论。为了保持图像的质量，应该使用标准调用:
位图resizedBitmap =位图。createScaledBitmap(originalBitmap, newWidth, newHeight, true);
最后一个参数设置为true，因为它将对重采样进行双线性过滤，以防止混叠。在这里阅读更多关于别名的信息:https://en.wikipedia.org/wiki/Aliasing
来自android文档:
https://developer.android.com/reference/android/graphics/Bitmap createScaledBitmap (android.graphics.Bitmap % 20 int, int % 20, % 20布尔)
public static Bitmap createScaledBitmap (Bitmap src,
int dstWidth,
int dstHeight,
boolean filter)
filter: boolean，当缩放位图时是否应该使用双线性过滤。如果这是真的，那么在缩放时将使用双线性滤波，它以更差的性能为代价，具有更好的图像质量。如果这是假的，那么使用最近邻缩放，这将有较差的图像质量，但更快。推荐的默认值是将filter设置为'true'，因为双线性过滤的成本通常是最小的，并且图像质量的改善是显著的。
基于纵横比的规模:
float aspectRatio = yourSelectedImage.getWidth() /
(float) yourSelectedImage.getHeight();
int width = 480;
int height = Math.round(width / aspectRatio);
yourSelectedImage = Bitmap.createScaledBitmap(
yourSelectedImage, width, height, false);
使用高度作为基础而不是宽度更改为:
int height = 480;
int width = Math.round(height * aspectRatio);
