我的远程数据库中有一个Base64字符串的位图，（encodedImage是用Base64表示图像的字符串）：
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
好的，但是我必须在我的ImageView布局上显示之前调整此图片的大小。我必须将其调整为120x120。
有人可以告诉我调整大小的代码吗？
我找到的示例无法应用于获得位图的base64字符串。
答案 0 :(得分：493)
变化：
profileImage.setImageBitmap(
BitmapFactory.decodeByteArray(imageAsBytes, 0, imageAsBytes.length)
要：
Bitmap b = BitmapFactory.decodeByteArray(imageAsBytes, 0, imageAsBytes.length)
profileImage.setImageBitmap(Bitmap.createScaledBitmap(b, 120, 120, false));
答案 1 :(得分：263)
public Bitmap getResizedBitmap(Bitmap bm, int newWidth, int newHeight) {
int width = bm.getWidth();
int height = bm.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// CREATE A MATRIX FOR THE MANIPULATION
Matrix matrix = new Matrix();
// RESIZE THE BIT MAP
matrix.postScale(scaleWidth, scaleHeight);
// "RECREATE" THE NEW BITMAP
Bitmap resizedBitmap = Bitmap.createBitmap(
bm, 0, 0, width, height, matrix, false);
bm.recycle();
return resizedBitmap;
}
编辑：正如@aveschini所建议的，我已经为内存泄漏添加了bm.recycle();。请注意，如果您将上一个对象用于其他目的，请相应处理。
答案 2 :(得分：107)
如果您已有位图，则可以使用以下代码调整大小：
Bitmap originalBitmap = <original initialization>;
Bitmap resizedBitmap = Bitmap.createScaledBitmap(
originalBitmap, newWidth, newHeight, false);
答案 3 :(得分：35)
根据宽高比进行缩放：
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height作为宽度变化的基本intead：
int height = 480;
int width = Math.round(height * aspectRatio);
答案 4 :(得分：22)
使用目标最大大小和宽度缩放位图，同时保持纵横比：
int maxHeight = 2000;
int maxWidth = 2000;
float scale = Math.min(((float)maxHeight / bitmap.getWidth()), ((float)maxWidth / bitmap.getHeight()));
Matrix matrix = new Matrix();
matrix.postScale(scale, scale);
bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
答案 5 :(得分：7)
试试这段代码：
BitmapDrawable drawable = (BitmapDrawable) imgview.getDrawable();
Bitmap bmp = drawable.getBitmap();
Bitmap b = Bitmap.createScaledBitmap(bmp, 120, 120, false);
我希望它有用。
答案 6 :(得分：7)
有人问过如何在这种情况下保持纵横比：
计算用于缩放的因子，并将其用于两个维度。 假设您希望图像高度为屏幕的20％
int scaleToUse = 20; // this will be our percentage
Bitmap bmp = BitmapFactory.decodeResource(
context.getResources(), R.drawable.mypng);
int sizeY = screenResolution.y * scaleToUse / 100;
int sizeX = bmp.getWidth() * sizeY / bmp.getHeight();
Bitmap scaled = Bitmap.createScaledBitmap(bmp, sizeX, sizeY, false);
获取屏幕分辨率，你有这个解决方案： Get screen dimensions in pixels
答案 7 :(得分：3)
profileImage.setImageBitmap(
Bitmap.createScaledBitmap(
BitmapFactory.decodeByteArray(imageAsBytes, 0, imageAsBytes.length),
80, 80, false
)
);
答案 8 :(得分：3)
试试这个：
此函数按比例调整位图大小。当最后一个参数设置为＆＃34; X＆＃34; newDimensionXorY被视为新的宽度，当设置为＆＃34; Y＆＃34;一个新的高度。
public Bitmap getProportionalBitmap(Bitmap bitmap,
int newDimensionXorY,
String XorY) {
if (bitmap == null) {
return null;
}
float xyRatio = 0;
int newWidth = 0;
int newHeight = 0;
if (XorY.toLowerCase().equals("x")) {
xyRatio = (float) newDimensionXorY / bitmap.getWidth();
newHeight = (int) (bitmap.getHeight() * xyRatio);
bitmap = Bitmap.createScaledBitmap(
bitmap, newDimensionXorY, newHeight, true);
} else if (XorY.toLowerCase().equals("y")) {
xyRatio = (float) newDimensionXorY / bitmap.getHeight();
newWidth = (int) (bitmap.getWidth() * xyRatio);
bitmap = Bitmap.createScaledBitmap(
bitmap, newWidth, newDimensionXorY, true);
}
return bitmap;
}
答案 9 :(得分：3)
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;
}
答案 10 :(得分：3)
public static Bitmap resizeBitmapByScale(
Bitmap bitmap, float scale, boolean recycle) {
int width = Math.round(bitmap.getWidth() * scale);
int height = Math.round(bitmap.getHeight() * scale);
if (width == bitmap.getWidth()
&& height == bitmap.getHeight()) return bitmap;
Bitmap target = Bitmap.createBitmap(width, height, getConfig(bitmap));
Canvas canvas = new Canvas(target);
canvas.scale(scale, scale);
Paint paint = new Paint(Paint.FILTER_BITMAP_FLAG | Paint.DITHER_FLAG);
canvas.drawBitmap(bitmap, 0, 0, paint);
if (recycle) bitmap.recycle();
return target;
}
private static Bitmap.Config getConfig(Bitmap bitmap) {
Bitmap.Config config = bitmap.getConfig();
if (config == null) {
config = Bitmap.Config.ARGB_8888;
}
return config;
}
答案 11 :(得分：2)
public Bitmap bitmapResize(Bitmap imageBitmap) {
Bitmap bitmap = imageBitmap;
float heightbmp = bitmap.getHeight();
float widthbmp = bitmap.getWidth();
// Get Screen width
DisplayMetrics displaymetrics = new DisplayMetrics();
this.getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
float height = displaymetrics.heightPixels / 3;
float width = displaymetrics.widthPixels / 3;
int convertHeight = (int) hight, convertWidth = (int) width;
// higher
if (heightbmp > height) {
convertHeight = (int) height - 20;
bitmap = Bitmap.createScaledBitmap(bitmap, convertWidth,
convertHighet, true);
}
// wider
if (widthbmp > width) {
convertWidth = (int) width - 20;
bitmap = Bitmap.createScaledBitmap(bitmap, convertWidth,
convertHeight, true);
}
return bitmap;
}
答案 12 :(得分：1)
从API 19开始，存在Bitmap setWidth（int width）和setHeight（int height）。 http://developer.android.com/reference/android/graphics/Bitmap.html
答案 13 :(得分：1)
保持长宽比，
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;
}
}
答案 14 :(得分：0)
/**
* Kotlin method for Bitmap scaling
* @param bitmap the bitmap to be scaled
* @param pixel the target pixel size
* @param width the width
* @param height the height
* @param max the max(height, width)
* @return the scaled bitmap
*/
fun scaleBitmap(bitmap:Bitmap, pixel:Float, width:Int, height:Int, max:Int):Bitmap {
val scale = px / max
val h = Math.round(scale * height)
val w = Math.round(scale * width)
return Bitmap.createScaledBitmap(bitmap, w, h, true)
}
答案 15 :(得分：0)
尽管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Bitmap的大小。如果您正在寻找一种通过保持相同的宽高比来调整Bitmap大小的方法，则可以使用以下实用程序功能。 this link中提供了用法的详细信息和功能说明。
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;
}
}
答案 16 :(得分：0)
虽然前面的答案确实缩放了图像并注意了纵横比，但应该完成重采样本身，以免出现锯齿。处理规模是正确修正论点的问题。有很多关于标准缩放调用输出图像质量的评论。要保持图像质量，应使用标准调用：
Bitmap resizedBitmap = Bitmap.createScaledBitmap(originalBitmap, newWidth, newHeight, true);
将最后一个参数设置为 true 因为它会对重采样进行双线性过滤以防止混叠。在此处阅读有关别名的更多信息：https://en.wikipedia.org/wiki/Aliasing
来自安卓文档：
public static Bitmap createScaledBitmap (Bitmap src,
int dstWidth,
int dstHeight,
boolean filter)
filter : boolean, 缩放位图时是否使用双线性过滤。如果这是真的，那么在缩放时将使用双线性过滤，以降低性能为代价获得更好的图像质量。如果这是错误的，则使用最近邻缩放代替，这将具有更差的图像质量但速度更快。推荐的默认设置是将过滤器设置为“true”，因为双线性过滤的成本通常很小，而且图像质量的改进非常显着。
答案 17 :(得分：0)
* For resize bitmap with width and height ratio.
public static Bitmap getResizedBitmap(Bitmap image, int maxSize) {
int width = image.getWidth();
int height = image.getHeight();
float bitmapRatio = (float) width / (float) height;
if (bitmapRatio > 1) {
width = maxSize;
height = (int) (width / bitmapRatio);
} else {
height = maxSize;
width = (int) (height * bitmapRatio);
}
return Bitmap.createScaledBitmap(image, width, height, true);
}