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Zoom Image - Android Tutorial

Here we are going to see how to zoom an image in Imageview

Will see it through a sample

1. Create xml with an ImageView
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="200dp"
        android:layout_height="200dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:orientation="vertical">

        <LinearLayout
            android:id="@+id/progress_one"
            android:layout_width="match_parent"
            android:layout_height="200dp"
            android:visibility="visible">

            <ProgressBar
                android:layout_width="match_parent"
                android:layout_height="50dp"
                android:layout_gravity="center"
                android:indeterminateDrawable="@drawable/splash_loading">
            </ProgressBar>

        </LinearLayout>

        <ImageView
            android:id="@+id/id_imgview"
            android:layout_width="match_parent"
            android:layout_height="200dp"
            android:scaleType="fitXY"
            android:adjustViewBounds="true"/>

    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

2. MainActivity.java
public class MainActivity extends AppCompatActivity {

    ImageView imageView;
    LinearLayout progressll;
    String imgUrl = "https://i2.wp.com/allpicts.in/wp-content/uploads/2017/02/pictures-of-the-solar-system.jpg";


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = findViewById(R.id.id_imgview);
        progressll = findViewById(R.id.progress_one);

        //callSetImageFun
        setImage(imageView, imgUrl, progressll);
        //callImageviewClick
        imageView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                fullPreviewScreen(imgUrl, MainActivity.this);
            }
        });
    }

    private void setImage(ImageView ximageView, String imgUrl, final LinearLayout xllProgress) {
        RequestOptions options = new RequestOptions()
                .override(imageView.getMeasuredWidth(),200);

        Glide.with(getApplicationContext()).load(imgUrl).apply(options)
                .listener(new RequestListener<Drawable>() {
                    @Override
                    public boolean onLoadFailed(@Nullable GlideException e, Object model, Target<Drawable> target, boolean isFirstResource) {
                        xllProgress.setVisibility(View.GONE);
                        return false;
                    }

                    @Override
                    public boolean onResourceReady(Drawable resource, Object model, Target<Drawable> target, DataSource dataSource, boolean isFirstResource) {
                        xllProgress.setVisibility(View.GONE);
                        return false;
                    }
                })
                .into(ximageView);
    }

    private void fullPreviewScreen(String ximgurl, Context xcontext) {
        final Dialog dialog = new Dialog(xcontext);
        dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
        dialog.setContentView(R.layout.dialog_image);
        dialog.getWindow().setBackgroundDrawable(new ColorDrawable(xcontext.getResources().getColor(R.color.color_trans_semi)));
        WindowManager wm = (WindowManager)xcontext.getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();
        int width = display.getWidth();
        int height = display.getHeight() * 80 / 100;
        dialog.getWindow().setLayout(WindowManager.LayoutParams.MATCH_PARENT, height);

        ImageView imgClose = dialog.findViewById(R.id.idClose);
        TouchImageView imageView = dialog.findViewById(R.id.img);
        RequestOptions options = new RequestOptions()
                .override(imageView.getMeasuredWidth(),150);

        Glide.with(xcontext).load(ximgurl).apply(options).into(imageView);

        imgClose.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dialog.dismiss();
            }
        });

        dialog.show();
    }
}

3.dialog_image.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <com.mrbrown.zoomimage.TouchImageView
            android:id="@+id/img"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_gravity="center"
            android:adjustViewBounds="true"
            android:layout_marginLeft="5dp"
            android:layout_marginRight="5dp"
            android:gravity="center"/>

        <ImageView
            android:id="@+id/idClose"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|center"
            android:padding="10dp"
            android:src="@drawable/cancel"
            android:clickable="true"
            android:tint="#ffffff"/>

    </FrameLayout>

</LinearLayout>

4. TouchImageView
public class TouchImageView extends AppCompatImageView {

    Matrix matrix;
    // We can be in one of these 3 states
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;

    int mode = NONE;

    // Remember some things for zooming
    PointF last = new PointF();
    PointF start = new PointF();
    float minScale = 1f;
    float maxScale = 3f;
    float[] m;
    int viewWidth, viewHeight;

    static final int CLICK = 3;

    float saveScale = 1f;

    protected float origWidth, origHeight;

    int oldMeasuredWidth, oldMeasuredHeight;

    ScaleGestureDetector mScaleDetector;

    Context context;

    public TouchImageView(Context context) {
        super(context);
        sharedConstructing(context);
    }

    public TouchImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        sharedConstructing(context);
    }

    private void sharedConstructing(Context context) {

        super.setClickable(true);

        this.context = context;

        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());

        matrix = new Matrix();

        m = new float[9];

        setImageMatrix(matrix);

        setScaleType(ImageView.ScaleType.MATRIX);

        setOnTouchListener(new View.OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {

                mScaleDetector.onTouchEvent(event);

                PointF curr = new PointF(event.getX(), event.getY());

                switch (event.getAction()) {

                    case MotionEvent.ACTION_DOWN:

                        last.set(curr);

                        start.set(last);

                        mode = DRAG;

                        break;

                    case MotionEvent.ACTION_MOVE:

                        if (mode == DRAG) {

                            float deltaX = curr.x - last.x;

                            float deltaY = curr.y - last.y;

                            float fixTransX = getFixDragTrans(deltaX, viewWidth, origWidth * saveScale);

                            float fixTransY = getFixDragTrans(deltaY, viewHeight, origHeight * saveScale);

                            matrix.postTranslate(fixTransX, fixTransY);

                            fixTrans();

                            last.set(curr.x, curr.y);

                        }

                        break;

                    case MotionEvent.ACTION_UP:

                        mode = NONE;

                        int xDiff = (int) Math.abs(curr.x - start.x);

                        int yDiff = (int) Math.abs(curr.y - start.y);

                        if (xDiff < CLICK && yDiff < CLICK)

                            performClick();

                        break;

                    case MotionEvent.ACTION_POINTER_UP:

                        mode = NONE;

                        break;

                }

                setImageMatrix(matrix);

                invalidate();

                return true; // indicate event was handled

            }

        });
    }

    public void setMaxZoom(float x) {

        maxScale = x;

    }

    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {

        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector) {

            mode = ZOOM;

            return true;

        }

        @Override
        public boolean onScale(ScaleGestureDetector detector) {

            float mScaleFactor = detector.getScaleFactor();

            float origScale = saveScale;

            saveScale *= mScaleFactor;

            if (saveScale > maxScale) {

                saveScale = maxScale;

                mScaleFactor = maxScale / origScale;

            } else if (saveScale < minScale) {

                saveScale = minScale;

                mScaleFactor = minScale / origScale;

            }

            if (origWidth * saveScale <= viewWidth || origHeight * saveScale <= viewHeight)

                matrix.postScale(mScaleFactor, mScaleFactor, viewWidth / 2, viewHeight / 2);

            else

                matrix.postScale(mScaleFactor, mScaleFactor, detector.getFocusX(), detector.getFocusY());

            fixTrans();

            return true;

        }

    }

    void fixTrans() {

        matrix.getValues(m);

        float transX = m[Matrix.MTRANS_X];

        float transY = m[Matrix.MTRANS_Y];

        float fixTransX = getFixTrans(transX, viewWidth, origWidth * saveScale);

        float fixTransY = getFixTrans(transY, viewHeight, origHeight * saveScale);

        if (fixTransX != 0 || fixTransY != 0)

            matrix.postTranslate(fixTransX, fixTransY);

    }



    float getFixTrans(float trans, float viewSize, float contentSize) {

        float minTrans, maxTrans;

        if (contentSize <= viewSize) {

            minTrans = 0;

            maxTrans = viewSize - contentSize;

        } else {

            minTrans = viewSize - contentSize;

            maxTrans = 0;

        }

        if (trans < minTrans)

            return -trans + minTrans;

        if (trans > maxTrans)

            return -trans + maxTrans;

        return 0;

    }

    float getFixDragTrans(float delta, float viewSize, float contentSize) {

        if (contentSize <= viewSize) {

            return 0;

        }

        return delta;

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        viewWidth = View.MeasureSpec.getSize(widthMeasureSpec);

        viewHeight = View.MeasureSpec.getSize(heightMeasureSpec);

        //
        // Rescales image on rotation
        //
        if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight

                || viewWidth == 0 || viewHeight == 0)

            return;

        oldMeasuredHeight = viewHeight;

        oldMeasuredWidth = viewWidth;

        if (saveScale == 1) {

            //Fit to screen.

            float scale;

            Drawable drawable = getDrawable();

            if (drawable == null || drawable.getIntrinsicWidth() == 0 || drawable.getIntrinsicHeight() == 0)

                return;

            int bmWidth = drawable.getIntrinsicWidth();

            int bmHeight = drawable.getIntrinsicHeight();

            Log.d("bmSize", "bmWidth: " + bmWidth + " bmHeight : " + bmHeight);

            float scaleX = (float) viewWidth / (float) bmWidth;

            float scaleY = (float) viewHeight / (float) bmHeight;

            scale = Math.min(scaleX, scaleY);

            matrix.setScale(scale, scale);

            // Center the image

            float redundantYSpace = (float) viewHeight - (scale * (float) bmHeight);

            float redundantXSpace = (float) viewWidth - (scale * (float) bmWidth);

            redundantYSpace /= (float) 2;

            redundantXSpace /= (float) 2;

            matrix.postTranslate(redundantXSpace, redundantYSpace);

            origWidth = viewWidth - 2 * redundantXSpace;

            origHeight = viewHeight - 2 * redundantYSpace;

            setImageMatrix(matrix);

        }

        fixTrans();

    }
}

5. Don't forget to give Internet Permission in Manifest

________________________________________________________________________

Happy Coding...

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