Customize PDFViewCtrl

You can change the color themes inside document viewers.

Android

Viewer theme customization in Xamarin.Android

Day and night themes Find out more about the sleek day and night themes available for the viewer UI.

Page Color mode Pages can be viewed in various color modes, find out more here.

iOS

Change color theme in Xamarin.iOS viewer

PDFViewCtrl has three special color modes: night mode, inverted color mode, and custom color mode. In night mode, colors are adjusted to improve reading at night, in inverted color mode, all colors are inverted, and in custom color mode, you can set a custom color for text and the background color.

Color modes from left to right: normal color mode, inverted color mode, night mode and custom color mode.

Set the color mode

To set the color mode:

1. Find the constant value of the color mode

Color mode	Constant value
Normal color mode	PDFRasterizer.ColorPostProcessMode.e_postprocess_none
Night mode	PDFRasterizer.ColorPostProcessMode.e_postprocess_night_mode
Inverted color mode	PDFRasterizer.ColorPostProcessMode.e_postprocess_invert
Custom color mode	PDFRasterizer.ColorPostProcessMode.e_postprocess_gradient_map

1. Call SetColorPostProcessMode.
2. Optionally, set the PDFViewCtrl background color for the best visual result. You can set background color by calling SetClientBackgroundColor (Xamarin.Android) or SetBackgroundColor (Xamarin.iOS).For example, set the background color to black for night mode:

// Xamarin.Android
mPdfViewCtrl.SetClientBackgroundColor(0, 0, 0, false);

// Xamarin.iOS
mPdfViewCtrl.SetBackgroundColor(0, 0, 0, false);

1. If you are using postprocess_gradient_map, call PDFViewCtrl.SetColorPostProcessColors to set the white and black points. For example, for a sepia effect, try:

// Xamarin.Android
var darkBrown = Android.Graphics.Color.Rgb(61, 38, 10);
var lightBrown = Android.Graphics.Color.Rgb(245, 224, 202);
mPdfViewCtrl.SetColorPostProcessColors(lightBrown, darkBrown);

// Xamarin.iOS
var darkBrown = new UIKit.UIColor(0.24f, 0.15f, 0.04f, 1.0f);
var lightBrown = new UIKit.UIColor(0.96f, 0.88f, 0.79f, 1.0f);
mPdfViewCtrl.SetColorPostProcessColors(lightBrown, darkBrown);

1. Update PDFViewCtrl to redraw the contents:Sample result when using postprocess_gradient_map and a light/dark brown for the white/black color:

mPdfViewCtrl.Update(true);