Transitions¶

gSlapper supports smooth fade transitions between static images, providing a polished wallpaper switching experience.

Enabling Transitions¶

Transitions are enabled via command-line options:

gslapper --transition-type fade --transition-duration 2.0 -I /tmp/gslapper.sock DP-1 image.jpg

Options¶

--transition-type TYPE - Transition effect type
none (default) - No transition
fade - Smooth fade between images
--transition-duration SECS - Transition duration in seconds (default: 0.5)

Requirements¶

IPC must be enabled - Transitions require the -I or --ipc-socket option
Static images only - Transitions work between images, not videos
Same or different aspect ratios - Both images will correctly fill the screen

Usage¶

Basic Fade Transition¶

# Start with first image
gslapper --transition-type fade --transition-duration 2.0 -I /tmp/gslapper.sock DP-1 image1.jpg

# Switch to second image (transition happens automatically)
echo "change /path/to/image2.jpg" | nc -U /tmp/gslapper.sock

Different Aspect Ratios¶

Transitions handle images with different aspect ratios correctly:

# 4:3 image -> 16:9 image
gslapper --transition-type fade --transition-duration 1.5 -I /tmp/gslapper.sock DP-1 4x3_image.jpg
echo "change /path/to/16x9_image.jpg" | nc -U /tmp/gslapper.sock

Both images will fill the screen properly during the transition, with no letterboxing.

How It Works¶

Capture - When a transition starts, the current image is captured
Load - The new image is loaded asynchronously
Resize - Both images are resized to display resolution with fill mode
Blend - Images are blended pixel-by-pixel using CPU-based alpha blending
Complete - Transition completes when duration is reached

Supported Formats¶

Transitions work with all supported image formats: - JPEG (.jpg, .jpeg) - PNG (.png) - WebP (.webp) - GIF (.gif) - First frame only

Performance¶

CPU-based blending - Uses efficient pixel blending similar to swww
Display resolution - Blends at logical display resolution for optimal performance
Smooth animation - Frame rate capped to ensure smooth transitions

Limitations¶

Transitions only work between static images
Video wallpapers do not support transitions
IPC socket must be enabled
Rapid transitions (multiple changes in quick succession) may cancel previous transitions

Examples¶

Slideshow Script¶

#!/bin/bash
SOCKET="/tmp/gslapper.sock"
IMAGES=(
    "/path/to/image1.jpg"
    "/path/to/image2.png"
    "/path/to/image3.webp"
)

# Start with first image
gslapper --transition-type fade --transition-duration 2.0 -I "$SOCKET" DP-1 "${IMAGES[0]}" &
sleep 3

# Cycle through images
for img in "${IMAGES[@]:1}"; do
    echo "change $img" | nc -U "$SOCKET"
    sleep 3
done

Random Wallpaper with Transition¶

#!/bin/bash
SOCKET="/tmp/gslapper.sock"
WALLPAPER_DIR="/home/user/Pictures/wallpapers"

# Get random image
RANDOM_IMG=$(find "$WALLPAPER_DIR" -type f \( -iname "*.jpg" -o -iname "*.png" -o -iname "*.webp" \) | shuf -n 1)

# Start or change wallpaper
if pgrep -x gslapper > /dev/null; then
    echo "change $RANDOM_IMG" | nc -U "$SOCKET"
else
    gslapper --transition-type fade --transition-duration 1.5 -I "$SOCKET" DP-1 "$RANDOM_IMG"
fi