Android MathView Example

AndroidManifest.xml

<uses-permission android:name="android.permission.INTERNET" />

MainActivity.java

package com.mathviewandroid;

import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.webkit.JavascriptInterface;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    String tex = "This come from string. You can insert inline formula:" +
            " \\(ax^2 + bx + c = 0\\) " +
            "or displayed formula: $$\\sum_{i=0}^n i^2 = \\frac{(n^2+n)(2n+1)}{6}$$";

    private WebView webView;

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

        webView = (WebView) findViewById(R.id.webView1);
        webView.addJavascriptInterface(new WebAppInterface(this), "android");
        WebSettings ws = webView.getSettings();
        ws.setJavaScriptEnabled(true);
        webView.setWebViewClient(new WebViewClient() {

            public void onPageFinished(WebView view, String url){
                // do your stuff here

            }
        });

        webView.loadDataWithBaseURL(null, "<style type=text/css>img{display: inline;height: auto;max-width: 100%;} @font-face{font-family: \"chantelli_antiqua\";src: url('file:///android_asset/fonts/MavenPro-Regular.ttf');}body{font-family: \"Chantelli_Antiqua\";}\n</style> <script type=\"text/javascript\"\n" +
                "        src=\"http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_SVG\">\n" +
                "</script>" + tex, "text/html", "UTF-8", null);
    }

    public class WebAppInterface {
        Context mContext;

        /** Instantiate the interface and set the context */
        WebAppInterface(Context c) {
            mContext = c;
        }

        /** Show a toast from the web page */
        @JavascriptInterface
        public void showToast(String toast) {
            Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout 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="com.mathviewandroid.MainActivity">



    <WebView

        xmlns:android="http://schemas.android.com/apk/res/android"

        android:id="@+id/webView1"

        android:layout_width="fill_parent"

        android:layout_height="fill_parent"

        android:visibility="visible"

        android:layout_margin="10dp"/>



</LinearLayout>

import android.content.Context;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.webkit.JavascriptInterface;

import android.webkit.WebSettings;

import android.webkit.WebView;

import android.webkit.WebViewClient;

import android.widget.ProgressBar;

import android.widget.Toast;



public class PDFViewActivity extends AppCompatActivity {



    WebView webView;

    String pdf_file = "http://integrityinitiative.com/wp-content/uploads/2017/06/Lorem-Ipsum.pdf";



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_pdfview);



        webView = (WebView)findViewById(R.id.webView1);

        WebSettings ws = webView.getSettings();

        ws.setJavaScriptEnabled(true);

        webView.setWebViewClient(new WebViewClient() {



            public void onPageFinished(WebView view, String url){

                // do your stuff here

                webView.loadUrl("javascript:(function() { " +

                        "document.getElementsByClassName('ndfHFb-c4YZDc-GSQQnc-LgbsSe ndfHFb-c4YZDc-to915-LgbsSe VIpgJd-TzA9Ye-eEGnhe ndfHFb-c4YZDc-LgbsSe')[0].style.display='none'; })()");

            }

        });

        webView.loadUrl("http://docs.google.com/gview?embedded=true&url=" + pdf_file);

    }

}

Pinch To Zoom Android Tutorial

TouchImageView.java

package com.pinchtozoom;

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;

public class TouchImageView extends android.support.v7.widget.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(ScaleType.MATRIX);

        setOnTouchListener(new 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 = MeasureSpec.getSize(widthMeasureSpec);
        viewHeight = 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();
    }
}

activity_main.xml


<?xml version="1.0" encoding="utf-8"?><LinearLayout 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="com.pinchtozoom.MainActivity">

    <com.pinchtozoom.TouchImageView        android:layout_width="match_parent"        android:layout_height="fill_parent"        android:id="@+id/image"        android:src="@drawable/image_bg"/>

</LinearLayout>

MainActivity.java


package com.pinchtozoom;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    TouchImageView image;

    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        image = (TouchImageView)findViewById(R.id.image);
    }
}