问题
In Android, I defined an ImageView\'s layout_width to be fill_parent (which takes up the full width of the phone).
If the image I put to ImageView is bigger than the layout_width, Android will scale it, right? But what about the height? When Android scales the image, will it keep the aspect ratio?
What I find out is that there is some white space at the top and bottom of the ImageView when Android scales an image which is bigger than the ImageView. Is that true? If yes, how can I eliminate that white space?
回答1:
Yes, by default Android will scale your image down to fit the ImageView, maintaining the aspect ratio. However, make sure you're setting the image to the ImageView using
android:src="..."rather thanandroid:background="...".src=makes it scale the image maintaining aspect ratio, butbackground=makes it scale and distort the image to make it fit exactly to the size of the ImageView. (You can use a background and a source at the same time though, which can be useful for things like displaying a frame around the main image, using just one ImageView.)You should also see
android:adjustViewBoundsto make the ImageView resize itself to fit the rescaled image. For example, if you have a rectangular image in what would normally be a square ImageView, adjustViewBounds=true will make it resize the ImageView to be rectangular as well. This then affects how other Views are laid out around the ImageView.Then as Samuh wrote, you can change the way it default scales images using the
android:scaleTypeparameter. By the way, the easiest way to discover how this works would simply have been to experiment a bit yourself! Just remember to look at the layouts in the emulator itself (or an actual phone) as the preview in Eclipse is usually wrong.
回答2:
See android:adjustViewBounds.
Set this to true if you want the ImageView to adjust its bounds to preserve the aspect ratio of its drawable.
回答3:
To anyone else having this particular issue. You have an ImageView (or other View) that you want to have a width of fill_parent and a height scaled proportionately:
Add these two attributes to your ImageView:
android:adjustViewBounds="true"
android:scaleType="centerCrop"
And set the ImageView width to fill_parent and height to wrap_content.
Also, if you don't want your image to be cropped, try this:
android:adjustViewBounds="true"
android:layout_centerInParent="true"
回答4:
If you want an ImageView that both scales up and down while keeping the proper aspect ratio, add this to your XML:
android:adjustViewBounds="true"
android:scaleType="fitCenter"
Add this to your code:
// We need to adjust the height if the width of the bitmap is
// smaller than the view width, otherwise the image will be boxed.
final double viewWidthToBitmapWidthRatio = (double)image.getWidth() / (double)bitmap.getWidth();
image.getLayoutParams().height = (int) (bitmap.getHeight() * viewWidthToBitmapWidthRatio);
It took me a while to get this working, but this appears to work in the cases both where the image is smaller than the screen width and larger than the screen width, and it does not box the image.
回答5:
This worked for me:
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:maxWidth="39dip"
android:scaleType="centerCrop"
android:adjustViewBounds ="true"
回答6:
Below code Working for scale image as aspect ratio:
Bitmap bitmapImage = BitmapFactory.decodeFile("Your path");
int nh = (int) ( bitmapImage.getHeight() * (512.0 / bitmapImage.getWidth()) );
Bitmap scaled = Bitmap.createScaledBitmap(bitmapImage, 512, nh, true);
your_imageview.setImageBitmap(scaled);
回答7:
this solved my problem
android:adjustViewBounds="true"
android:scaleType="fitXY"
回答8:
Take a look at ImageView.ScaleType to control and understand the way resizing happens in an ImageView. When the image is resized (while maintaining its aspect ratio), chances are that either the image's height or width becomes smaller than ImageView's dimensions.
回答9:
Use these properties in ImageView to keep aspect ratio:
android:adjustViewBounds="true"
android:scaleType="fitXY"
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:scaleType="fitXY"
/>
回答10:
I have an image smaller than the screen. To have it stretched proportionally to the max and centered in the view I had to use the following code:
<ImageView
android:id="@+id/my_image"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_centerInParent="true"
android:adjustViewBounds="true"
android:layout_weight="1"
android:scaleType="fitCenter" />
Have in mind though, that if you have a relative layout and have some elements set to be above or below the ImageView, they will be most likely overlapped by the image.
回答11:
For anyone of you who wants the image to fit exact the imageview with proper scaling and no cropping use
imageView.setScaleType(ScaleType.FIT_XY);
where imageView is the view representing your ImageView
回答12:
You can calculate screen width. And you can scale bitmap.
public static float getScreenWidth(Activity activity) {
Display display = activity.getWindowManager().getDefaultDisplay();
DisplayMetrics outMetrics = new DisplayMetrics();
display.getMetrics(outMetrics);
float pxWidth = outMetrics.widthPixels;
return pxWidth;
}
calculate screen width and scaled image height by screen width.
float screenWidth=getScreenWidth(act)
float newHeight = screenWidth;
if (bitmap.getWidth() != 0 && bitmap.getHeight() != 0) {
newHeight = (screenWidth * bitmap.getHeight()) / bitmap.getWidth();
}
After you can scale bitmap.
Bitmap scaledBitmap=Bitmap.createScaledBitmap(bitmap, (int) screenWidth, (int) newHeight, true);
回答13:
When doing this programmatically, be sure to call the setters in the correct order:
imageView.setAdjustViewBounds(true)
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP)
回答14:
If image quality decreases in: use
android:adjustViewBounds="true"
instead of
android:adjustViewBounds="true"
android:scaleType="fitXY"
回答15:
This is how it worked for me inside a ConstraintLayout:
<ImageView
android:id="@+id/myImg"
android:layout_width="300dp"
android:layout_height="300dp"
android:scaleType="fitCenter"
android:adjustViewBounds="true"/>
Then in code, I set the drawable as:
ImageView imgView = findViewById(R.id.myImg);
imgView.setImageDrawable(ResourcesCompat.getDrawable(getResources(), R.drawable.image_to_show, null));
This fits the image nicely according to its aspect ratio and keeps it in centre.
回答16:
If you want your image occupy the maximum possible space then the best option would be
android:layout_weight="1"
android:scaleType="fitCenter"
回答17:
Try using android:layout_gravity for ImageView:
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_gravity="center_vertical|center_horizontal"
android:layout_weight="1"
The example above worked for me.
回答18:
I have an algorithm to scale a bitmap to bestFit the container dimensions, maintaining its aspect ratio. Please find my solution here
Hope this helps someone down the lane!
回答19:
Yo don't need any java code. You just have to :
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:adjustViewBounds="true"
android:scaleType="centerCrop" />
The key is in the match parent for width and height
回答20:
I use this:
<ImageView
android:id="@+id/logo"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_centerInParent="true"
android:scaleType="centerInside"
android:src="@drawable/logo" />
回答21:
in case of using cardviewfor rounding imageview and fixed android:layout_height for header this worked for me to load image with Glide
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="220dp"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
>
<android.support.v7.widget.CardView
android:id="@+id/card_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center|top"
card_view:cardBackgroundColor="@color/colorPrimary"
card_view:cardCornerRadius="10dp"
card_view:cardElevation="10dp"
card_view:cardPreventCornerOverlap="false"
card_view:cardUseCompatPadding="true">
<ImageView
android:adjustViewBounds="true"
android:maxHeight="220dp"
android:id="@+id/iv_full"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scaleType="fitCenter"/>
</android.support.v7.widget.CardView>
</FrameLayout>
回答22:
You can scale image that will also reduce the size of your image. There is a library for it you can download and use it. https://github.com/niraj124124/Images-Files-scale-and-compress.git
How to use 1)Import the compressor-v1.0. jar to your project. 2)Add the below sample code to test. ResizeLimiter resize = ImageResizer.build(); resize.scale("inputImagePath", "outputImagePath",imageWidth, imageHeight); Many more methods are there according to your requirement
回答23:
Pass your ImageView and based on screen height and width you can make it
public void setScaleImage(EventAssetValueListenerView view){
// Get the ImageView and its bitmap
Drawable drawing = view.getDrawable();
Bitmap bitmap = ((BitmapDrawable)drawing).getBitmap();
// Get current dimensions
int width = bitmap.getWidth();
int height = bitmap.getHeight();
float xScale = ((float) 4) / width;
float yScale = ((float) 4) / height;
float scale = (xScale <= yScale) ? xScale : yScale;
Matrix matrix = new Matrix();
matrix.postScale(scale, scale);
Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
BitmapDrawable result = new BitmapDrawable(scaledBitmap);
width = scaledBitmap.getWidth();
height = scaledBitmap.getHeight();
view.setImageDrawable(result);
LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) view.getLayoutParams();
params.width = width;
params.height = height;
view.setLayoutParams(params);
}
回答24:
myImageView.setAdjustViewBounds(true);
回答25:
imageView.setImageBitmap(Bitmap.createScaledBitmap(bitmap, 130, 110, false));
来源：https://stackoverflow.com/questions/2521959/how-to-scale-an-image-in-imageview-to-keep-the-aspect-ratio