Customizing thumbnail slider in Android

ThumbnailSlider is a LinearLayout that contains an AppCompatSeekBar to change pages, and two AppCompatImageButton on the left and right side. When sliding the seekbar, it displays a small page preview on top of the thumbnail slider.

Show thumbnail slider

To set up your layout with the thumbnail slider, add a <ThumbnailSlider> element to your XML layout. For example, your layout may look like this:

XML

<com.pdftron.pdf.controls.ThumbnailSlider android:id="@+id/thumbnailSlider" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true"/>

Then, attach a PDFViewCtrl to the thumbnail slider. If PDFViewCtrl is in the same layout, you can set it by adding the app:pdfviewctrlId attribute:

XML

<com.pdftron.pdf.controls.ThumbnailSlider android:id="@+id/thumbnailSlider" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" app:pdfviewctrlId="@id/pdfviewctrl"/>

If PDFViewCtrl is not in the same layout, you can programmatically set it to a thumbnail slider by calling setPdfViewCtrl(PDFViewCtrl):

Java

ThumbnailSlider thumbnailSlider = findViewById(R.id.thumbnailSlider);
thumbnailSlider.setPdfViewCtrl(mPdfViewCtrl);

Kotlin

val thumbnailSlider = findViewById(R.id.thumbnailSlider)
thumbnailSlider.setPdfViewCtrl(mPdfViewCtrl)

Change thumbnail slider buttons

You can change the image drawable of the left menu item and right menu item buttons by adding the app:leftMenuItemDrawable and app:rightMenuItemDrawable attributes in your xml layout.

Example

XML

<com.pdftron.pdf.controls.ThumbnailSlider android:id="@+id/thumbnailSlider" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" app:leftMenuItemDrawable="@drawable/left_icon" app:rightMenuItemDrawable="@drawable/right_icon"/>

Additionally, you can remove the left and right slider buttons by setting the drawables to null:

XML

<com.pdftron.pdf.controls.ThumbnailSlider android:id="@+id/thumbnailSlider" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" app:leftMenuItemDrawable="@null" app:rightMenuItemDrawable="@null"/>

You can also change the buttons programmatically by calling setMenuItem(@DrawableRes int, @MenuItemPosition int). The second parameter determines the position of the button which is either POSITION_LEFT or POSITION_RIGHT.

Example

Java

thumbnailSlider.setMenuItem(R.drawable.left_icon, ThumbnailSlider.POSITION_LEFT);

Kotlin

thumbnailSlider.setMenuItem(R.drawable.left_icon, ThumbnailSlider.POSITION_LEFT)

Thumbnail slider listeners

Buttons listener

You can add a menu item clicked event listener by calling setOnMenuItemClickedListener to be notified when one of the left or right buttons is clicked.

Java

thumbnailSlider.setOnMenuItemClickedListener(new ThumbnailSlider.OnMenuItemClickedListener(){
    @Override
    public void onMenuItemClicked(int menuItemPosition) {
        if (menuItemPosition == ThumbnailSlider.POSITION_LEFT) {
            // The left button was clicked.
        } else {
            // The right button was clicked.
        }
    }
});

Kotlin

thumbnailSlider!!.setOnMenuItemClickedListener { menuItemPosition ->
    if (menuItemPosition == ThumbnailSlider.POSITION_LEFT) {
        // The left button was clicked.
    } else {
        // The right button was clicked.
    }
}

Seekbar listener

You can set a thumbnail slider seekbar event listener by calling setThumbSliderListener to be notified when thumbnail slider touch tracking has started/stopped:

Java

thumbnailSlider.setThumbSliderListener(new ThumbnailSlider.OnThumbnailSliderTrackingListener() {
    @Override
    public void onThumbSliderStartTrackingTouch() {
        // Called when tracking on the seekbar has started
    }

    @Override
    public void onThumbSliderStopTrackingTouch(int pageNum) {
        // Called when tracking on the seekbar has stopped
    }
});

Kotlin

thumbnailSlider!!.setThumbSliderListener(object : ThumbnailSlider.OnThumbnailSliderTrackingListener {
    override fun onThumbSliderStartTrackingTouch() {
        // Called when tracking on the seekbar has started
    }

    override fun onThumbSliderStopTrackingTouch(pageNum: Int) {
        // Called when tracking on the seekbar has stopped
    }
})

Appearance style

Customize slider colors

You can customize the color of the left and right menu buttons as well as the seekbar by setting a custom style to the thumbnail_slider attribute in your apps's theme. The custom style must extend ThumbnailSliderStyle. For example:

XML

<style name="PDFTronAppTheme" parent="PDFTronAppThemeBase"> <item name="colorPrimary">@color/app_color_primary_day</item> <item name="colorPrimaryDark">@color/app_color_primary_dark_day</item> <item name="colorAccent">@color/app_color_accent</item> <!-- Set your custom style in your app theme --> <item name="thumbnail_slider">@style/CustomThumbnailSliderStyle</item> </style>

<style name="CustomThumbnailSliderStyle" parent="ThumbnailSliderStyle"> <!-- Change the background color of the slider--> <item name="colorBackground">@android:color/red</item> <!-- Change the color of the seekbar and seekbar icon in the slider--> <item name="seekbarColor">@android:color/black</item> <!-- Change the color of the menu button left of the slider --> <item name="leftMenuItemColor">@android:color/black</item> <!-- Change the color of the menu button right of the slider --> <item name="rightMenuItemColor">@android:color/black</item> <!-- Change the description of the menu button left of the slider --> <item name="leftMenuItemContentDescription">"LeftDescription"</item> <!-- Change the color of the menu button right of the slider --> <item name="rightMenuItemContentDescription">"RightDescription"</item> <!-- Change the icon of the menu button left of the slider --> <item name="leftMenuItemDrawable">@drawable/ic_thumbnails_grid_black_24dp</item> <!-- Change the icon of the menu button right of the slider --> <item name="rightMenuItemDrawable">@drawable/ic_list_white_24dp</item> </style>

Customize seekbar attributes

If you want to further customize the seekbar's layout attributes and appearance, such as padding and height, you can override the default seekbar style R.style.ThumbnailSliderStyle.Seekbar by declaring the following in res/values/styles.xml:

Example

For API < 21:

Java

<style name="ThumbnailSliderStyle.Seekbar" parent="Widget.AppCompat.SeekBar" > <!-- add paddingTop and paddingBottom for api < 21 here for avoiding seekbar becomes too thick--> <item name="android:paddingTop">16dp</item> <item name="android:paddingBottom">16dp</item> <item name="android:minHeight">2dp</item> <item name="android:maxHeight">2dp</item> <item name="android:layout_gravity">center</item> </style>

For API >= 21:

XML

<style name="ThumbnailSliderStyle.Seekbar" parent="Widget.AppCompat.SeekBar"> <item name="android:progressTint">?attr/colorPrimary</item> <item name="android:progressBackgroundTint">?attr/colorPrimary</item> <item name="android:colorControlActivated">?attr/colorPrimary</item> <item name="android:colorControlHighlight">?attr/colorPrimary</item> <item name="android:minHeight">2dp</item> <item name="android:maxHeight">2dp</item> <item name="android:layout_gravity">center</item> </style>

Customize the thumb and progress bar

The seekbar progress bar drawable can be customized by overriding the seek_track_material.xml drawable file. Similarly, the seekbar thumbnail drawable can be changed by overriding the seek_thumb.xml drawable file. For reference, the source code for these drawables can be found in the lib\src\PDFViewCtrlTools\res\drawable folder of the SDK package.

XML attributes

Attribute	Description	Format
app:pdfviewctrlId	Specifies the PDFViewCtrl view id	Reference
app:leftMenuItemContentDescription	Specifies the content description of left menu item.	String
app:rightMenuItemContentDescription	Specifies the content description of right menu item.	String
app:leftMenuItemDrawable	Specifies left menu item drawable resource.	Reference
app:rightMenuItemDrawable	Specifies right menu item drawable resource.	Reference
app:colorBackground	Specifies background color. Uses default system background color if not defined.	Color
app:seekbarColor	Specifies seekbar progress bar and thumb color. Default value: ?attr/colorPrimary in day mode and @android:color/white in night mode.	Color
app:leftMenuItemColor	Specifies left menu item color. Default value: ?attr/colorPrimary in day mode and @android:color/white in night mode.	Color
app:rightMenuItemColor	Specifies right menu item color. Default value: ?attr/colorPrimary in day mode and @android:color/white in night mode.	Color
app:shadowEnabled	Specifies whether the shadow will appear. Default value: true.	Boolean