问题
I am using the following code to rotate a image in ImageView by an angle. Is there any simpler and less complex method available.
ImageView iv = (ImageView)findViewById(imageviewid);
TextView tv = (TextView)findViewById(txtViewsid);
Matrix mat = new Matrix();
Bitmap bMap = BitmapFactory.decodeResource(getResources(),imageid);
mat.postRotate(Integer.parseInt(degree));===>angle to be rotated
Bitmap bMapRotate = Bitmap.createBitmap(bMap, 0, 0,bMap.getWidth(),bMap.getHeight(), mat, true);
iv.setImageBitmap(bMapRotate);
回答1:
Another simple way to rotate an ImageView:
UPDATE:
Required imports:
import android.graphics.Matrix;
import android.widget.ImageView;
Code: (Assuming imageView, angle, pivotX & pivotY are already defined)
Matrix matrix = new Matrix();
imageView.setScaleType(ImageView.ScaleType.MATRIX); //required
matrix.postRotate((float) angle, pivotX, pivotY);
imageView.setImageMatrix(matrix);
This method does not require creating a new bitmap each time.
NOTE: To rotate an
ImageViewon ontouch at runtime you can set onTouchListener onImageView& rotate it by adding last two lines(i.e. postRotate matrix & set it on imageView) in above code section in your touch listener ACTION_MOVE part.
回答2:
mImageView.setRotation(angle) with API>=11
回答3:
If you're supporting API 11 or higher, you can just use the following XML attribute:
android:rotation="90"
It might not display correctly in Android Studio xml preview, but it works as expected.
回答4:
There are two ways to do that:
1 Using Matrix to create a new bitmap:
imageView = (ImageView) findViewById(R.id.imageView);
Bitmap myImg = BitmapFactory.decodeResource(getResources(), R.drawable.image);
Matrix matrix = new Matrix();
matrix.postRotate(30);
Bitmap rotated = Bitmap.createBitmap(myImg, 0, 0, myImg.getWidth(), myImg.getHeight(),
matrix, true);
imageView.setImageBitmap(rotated);
2 use RotateAnimation on the View you want to Rotate, and make sure the Animation set to fillAfter=true, duration=0, and fromDegrees=toDgrees
<?xml version="1.0" encoding="utf-8"?>
<rotate
xmlns:android="http://schemas.android.com/apk/res/android"
android:fromDegrees="45"
android:toDegrees="45"
android:pivotX="50%"
android:pivotY="50%"
android:duration="0"
android:startOffset="0"
/>
and Inflate the Animation in code:
Animation rotation = AnimationUtils.loadAnimation(this, R.anim.rotation);
myView.startAnimation(rotation);
回答5:
I know this is insanely late, but it was helpful for me so it may help others.
As of API 11, you can set the absolute rotation of an ImageView programmatically by using the imageView.setRotation(angleInDegrees); method.
By absolute, I mean you can repeatedly call this function without having to keep track of the current rotation. Meaning, if I rotate by passing 15F to the setRotation() method, and then call setRotation() again with 30F, the image's rotation with be 30 degrees, not 45 degrees.
Note: This actually works for any subclass of the View object, not just ImageView.
回答6:
This is my implementation of RotatableImageView. Usage is very easy: just copy attrs.xml and RotatableImageView.java into your project and add RotatableImageView to your layout. Set desired rotation angle using example:angle parameter.
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:example="http://schemas.android.com/apk/res/com.example"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<com.example.views.RotatableImageView
android:id="@+id/layout_example_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:src="@drawable/ic_layout_arrow"
example:angle="180" />
</FrameLayout>
If you have some problems with displaying image, try change code in RotatableImageView.onDraw() method or use draw() method instead.
回答7:
Also, if you want to rotate an ImageView by 180 degrees vertically or horizontally, you can use scaleY or scaleX properties and set them to -1f. Here is a Kotlin example:
imageView.scaleY = -1f
imageView.scaleX = -1f
1f value is used to return an ImageView to its normal state:
imageView.scaleY = 1f
imageView.scaleX = 1f
回答8:
I have a solution to this. Actually it is a solution to a problem that arises after rotation(Rectangular image doesn't fit ImagView) but it covers your problem too.. Although this Solution has Animation for better or for worse
int h,w;
Boolean safe=true;
Getting the parameters of imageView is not possible at initialisation of activity To do so please refer to this solution OR set the dimensions at onClick of a Button Like this
rotateButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(imageView.getRotation()/90%2==0){
h=imageView.getHeight();
w=imageView.getWidth();
}
.
.//Insert the code Snippet below here
}
And the code to be run when we want to rotate ImageView
if(safe)
imageView.animate().rotationBy(90).scaleX(imageView.getRotation()/90%2==0?(w*1.0f/h):1).scaleY(imageView.getRotation()/90%2==0?(w*1.0f/h):1).setDuration(2000).setInterpolator(new LinearInterpolator()).setListener(new Animator.AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
safe=false;
}
@Override
public void onAnimationEnd(Animator animation) {
safe=true;
}
@Override
public void onAnimationCancel(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
}).start();
}
});
This solution is sufficient for the Problem above.Although it will shrink the imageView even if it is not necessary(when height is smaller than Width).If it bothers you,you can add another ternary operator inside scaleX/scaleY.
回答9:
I think the best method :)
int angle = 0;
imageView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
angle = angle + 90;
imageView.setRotation(angle);
}
});
回答10:
Can also be done this way:-
imageView.animate().rotation(180).start();
got from here.
回答11:
Rotate an image in android with delay:
imgSplash.animate().rotationBy(360f).setDuration(3000).setInterpolator(new LinearInterpolator()).start();
回答12:
try this on a custom view
public class DrawView extends View {
public DrawView(Context context,AttributeSet attributeSet){
super(context, attributeSet);
}
@Override
public void onDraw(Canvas canvas) {
/*Canvas c=new Canvas(BitmapFactory.decodeResource(getResources(), R.drawable.new_minute1) );
c.rotate(45);*/
canvas.drawBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.new_minute1), 0, 0, null);
canvas.rotate(45);
}
}
回答13:
here's a nice solution for putting a rotated drawable for an imageView:
Drawable getRotateDrawable(final Bitmap b, final float angle) {
final BitmapDrawable drawable = new BitmapDrawable(getResources(), b) {
@Override
public void draw(final Canvas canvas) {
canvas.save();
canvas.rotate(angle, b.getWidth() / 2, b.getHeight() / 2);
super.draw(canvas);
canvas.restore();
}
};
return drawable;
}
usage:
Bitmap b=...
float angle=...
final Drawable rotatedDrawable = getRotateDrawable(b,angle);
root.setImageDrawable(rotatedDrawable);
another alternative:
private Drawable getRotateDrawable(final Drawable d, final float angle) {
final Drawable[] arD = { d };
return new LayerDrawable(arD) {
@Override
public void draw(final Canvas canvas) {
canvas.save();
canvas.rotate(angle, d.getBounds().width() / 2, d.getBounds().height() / 2);
super.draw(canvas);
canvas.restore();
}
};
}
also, if you wish to rotate the bitmap, but afraid of OOM, you can use an NDK solution i've made here
回答14:
If you only want to rotate the view visually you can use:
iv.setRotation(float)
回答15:
Sadly, I don't think there is. The Matrix class is responsible for all image manipulations, whether it's rotating, shrinking/growing, skewing, etc.
http://developer.android.com/reference/android/graphics/Matrix.html
My apologies, but I can't think of an alternative. Maybe someone else might be able to, but the times I've had to manipulate an image I've used a Matrix.
Best of luck!
回答16:
Another possible solution is to create your own custom Image view(say RotateableImageView extends ImageView )...and override the onDraw() to rotate either the canvas/bitmaps before redering on to the canvas.Don't forget to restore the canvas back.
But if you are going to rotate only a single instance of image view,your solution should be good enough.
回答17:
without matrix and animated:
{
img_view = (ImageView) findViewById(R.id.imageView);
rotate = new RotateAnimation(0 ,300);
rotate.setDuration(500);
img_view.startAnimation(rotate);
}
回答18:
just write this in your onactivityResult
Bitmap yourSelectedImage= BitmapFactory.decodeFile(filePath);
Matrix mat = new Matrix();
mat.postRotate((270)); //degree how much you rotate i rotate 270
Bitmap bMapRotate=Bitmap.createBitmap(yourSelectedImage, 0,0,yourSelectedImage.getWidth(),yourSelectedImage.getHeight(), mat, true);
image.setImageBitmap(bMapRotate);
Drawable d=new BitmapDrawable(yourSelectedImage);
image.setBackground(d);
回答19:
Try this code 100% working;
On rotate button click write this code:
@Override
public void onClick(View view) {
if(bitmap==null){
Toast.makeText(getApplicationContext(), "Image photo is not yet set", Toast.LENGTH_LONG).show();
}
else {
Matrix matrix = new Matrix();
ivImageProduct.setScaleType(ImageView.ScaleType.MATRIX); //required
matrix.postRotate(90,ivImageProduct.getDrawable().getBounds().width()/2,ivImageProduct.getDrawable().getBounds().height()/2);
Bitmap bmp=Bitmap.createBitmap(bitmap, 0, 0,bitmap.getWidth(), bitmap.getHeight(), matrix, true);
bitmap.recycle();
bitmap=bmp;
ivImageProduct.setImageBitmap(bitmap);
}
}
回答20:
Rather than convert image to bitmap and then rotate it try to rotate direct image view like below code.
ImageView myImageView = (ImageView)findViewById(R.id.my_imageview);
AnimationSet animSet = new AnimationSet(true);
animSet.setInterpolator(new DecelerateInterpolator());
animSet.setFillAfter(true);
animSet.setFillEnabled(true);
final RotateAnimation animRotate = new RotateAnimation(0.0f, -90.0f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
animRotate.setDuration(1500);
animRotate.setFillAfter(true);
animSet.addAnimation(animRotate);
myImageView.startAnimation(animSet);
回答21:
Follow the below answer for continuous rotation of an imageview
int i=0;
If rotate button clicked
imageView.setRotation(i+90);
i=i+90;
回答22:
if u want to rotate an image by 180 degrees then put these two value in imageview tag:-
android:scaleX="-1"
android:scaleY="-1"
Explanation:- scaleX = 1 and scaleY = 1 repesent it's normal state but if we put -1 on scaleX/scaleY property then it will be rotated by 180 degrees
回答23:
Matrix matrix = new Matrix();
imageView.setScaleType(ImageView.ScaleType.MATRIX); //required
matrix.postRotate((float) 20, imageView.getDrawable().getBounds().width()/2, imageView.getDrawable().getBounds().height()/2);
imageView.setImageMatrix(matrix);
how to use?
public class MainActivity extends AppCompatActivity {
int view = R.layout.activity_main;
TextView textChanger;
ImageView imageView;
@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(view);
textChanger = findViewById(R.id.textChanger);
imageView=findViewById(R.id.imageView);
textChanger.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
roateImage(imageView);
}
});
}
private void roateImage(ImageView imageView) {
Matrix matrix = new Matrix();
imageView.setScaleType(ImageView.ScaleType.MATRIX); //required
matrix.postRotate((float) 20, imageView.getDrawable().getBounds().width()/2, imageView.getDrawable().getBounds().height()/2);
imageView.setImageMatrix(matrix);
}
}
来源：https://stackoverflow.com/questions/8981845/android-rotate-image-in-imageview-by-an-angle