ZoomHelper will make any view to be zoomable just like the Instagram pinch-to-zoom. :wink:

Installation

ZoomHelper is available in the mavenCentral(), so you just need to add it as a dependency (Module gradle)

Gradle

implementation 'io.github.aghajari:ZoomHelper:1.1.0'

Maven

<dependency>
    <groupId>io.github.aghajari</groupId>
    <artifactId>ZoomHelper</artifactId>
    <version>1.1.0</version>
    <type>pom</type>
</dependency>

Usage (Kotlin)

just override dispatchTouchEvent in your Activity and pass all touch events to ZoomHelper!

override fun dispatchTouchEvent(ev: MotionEvent?): Boolean {
    return ZoomHelper.getInstance().dispatchTouchEvent(ev!!,this) || super.dispatchTouchEvent(ev)
}

And set View to be zoomable :

ZoomHelper.addZoomableView(view)
//ZoomHelper.addZoomableView(view,tag)

Or make a zoomable View by using xml layout :

<ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <tag android:id="@+id/zoomable" android:value="ZoomableViewTag" />
</ImageView>

Note: \ is only used in API level 21 and higher

And we are Done! :smiley:

Usage (Java)

Installation: you have to add kotlin as a dependency! (Module gradle)

implementation 'com.aghajari.zoomhelper:ZoomHelper:1.0.1'
implementation 'org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion' //1.4.0-rc

and just override dispatchTouchEvent in your Activity and pass all touch events to ZoomHelper!

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    return ZoomHelper.Companion.getInstance().dispatchTouchEvent(ev,this) || super.dispatchTouchEvent(ev);
}

And set View to be zoomable :

ZoomHelper.Companion.addZoomableView(view);
//ZoomHelper.Companion.addZoomableView(view,tag);

Or make a zoomable View by using xml layout :

<ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <tag android:id="@+id/zoomable" android:value="ZoomableViewTag" />
</ImageView>

Note: \ is only used in API level 21 and higher

And we are Done! :smiley:

Customization

Kotlin:

ZoomHelper.getInstance().minScale = 1f
ZoomHelper.getInstance().maxScale = Float.MAX_VALUE
ZoomHelper.getInstance().shadowColor = Color.BLACK
ZoomHelper.getInstance().maxShadowAlpha = 0.6f
ZoomHelper.getInstance().shadowAlphaFactory = 4
ZoomHelper.getInstance().dismissDuration = 200
ZoomHelper.getInstance().layoutTheme = android.R.style.Theme_Translucent_NoTitleBar_Fullscreen
ZoomHelper.getInstance().isEnabled = true

Java:

ZoomHelper zoomHelper = ZoomHelper.Companion.getInstance();
zoomHelper.setMinScale(1f);
zoomHelper.setMaxScale(Float.MAX_VALUE);
zoomHelper.setShadowColor(Color.BLACK);
zoomHelper.setMaxShadowAlpha(0.6f);
zoomHelper.setShadowAlphaFactory(4);
zoomHelper.setDismissDuration(200);
zoomHelper.setLayoutTheme(android.R.style.Theme_Translucent_NoTitleBar_Fullscreen);
zoomHelper.setEnabled(true);

you can disable a zoomable view by using this code :

ZoomHelper.removeZoomableView(view)

Or skip a View or a ViewGroup and all its children :

ZoomHelper.skipLayout(view,true)

And also you can disable ZoomHelper by using this code :

ZoomHelper.getInstance().isEnabled = false

Check the layout is zooming currently :

if (ZoomHelper.getInstance().isZooming)

Listeners :

You can add callbacks to listen for specific events.

ZoomHelper.getInstance().addOnZoomStateChangedListener(object : ZoomHelper.OnZoomStateChangedListener{
    override fun onZoomStateChanged(zoomHelper: ZoomHelper, zoomableView: View, isZooming: Boolean) {
       Toast.makeText(zoomableView.context,if (isZooming) "Zooming started" else "Zooming ended", Toast.LENGTH_SHORT).show()
       // you can also get zoomableView Tag
       val tag = ZoomHelper.getZoomableViewTag(zoomableView) 
    }
})

ZoomHelper.getInstance().addOnZoomScaleChangedListener(object : ZoomHelper.OnZoomScaleChangedListener{
    override fun onZoomScaleChanged(zoomHelper: ZoomHelper, zoomableView: View, scale: Float, event: MotionEvent?) {
       // called when zoom scale changed
    }
})

ZoomHelper.getInstance().addOnZoomLayoutCreatorListener(object : ZoomHelper.OnZoomLayoutCreatorListener{
    override fun onZoomLayoutCreated(zoomHelper: ZoomHelper, zoomableView: View, zoomLayout: FrameLayout) {
       // called when zoomlayout created (zoom started)
    }
})

Also the default view listeners (onClick,onLongClick,onTouch) will work as well!

Author

Amir Hossein Aghajari

Inspired by ImageZoom library.

License

Copyright 2020 Amir Hossein Aghajari
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.