Viewport

import com.williamcallahan.tui4j.compat.bubbles.viewport.Viewport;
import com.williamcallahan.tui4j.compat.bubbletea.*;

public class App implements Model {

    private Viewport vp;

    public App() {
        String content = "Line 1\nLine 2\nLine 3\n…";
        vp = new Viewport(content, 80, 20);
    }

    @Override
    public Command init() { return null; }

    @Override
    public UpdateResult<App> update(Message msg) {
        if (msg instanceof KeyPressMessage kp && "q".equals(kp.key())) {
            return UpdateResult.from(this, QuitMessage::new);
        }
        UpdateResult<Viewport> result = vp.update(msg);
        vp = result.model();
        return UpdateResult.from(this, result.command());
    }

    @Override
    public String view() {
        return vp.view() + "\n" + scrollIndicator();
    }

    private String scrollIndicator() {
        return "Scroll: %.0f%%".formatted(vp.scrollPercent() * 100);
    }
}

// Replace all content — resets position if content shrinks above current scroll
vp.setContent("New content\nLine 2\nLine 3");

vp.setWidth(80);   // Width in terminal cells
vp.setHeight(20);  // Number of visible lines

int w = vp.getWidth();
int h = vp.getHeight();

vp.scrollDown(3);    // Scroll down by 3 lines
vp.scrollUp(3);      // Scroll up by 3 lines
vp.pageDown();       // Scroll down one full page
vp.pageUp();         // Scroll up one full page
vp.halfPageDown();   // Scroll down half a page
vp.halfPageUp();     // Scroll up half a page
vp.gotoTop();        // Jump to the first line
vp.gotoBottom();     // Jump to the last line

double pct   = vp.scrollPercent();           // 0.0–1.0
boolean top  = vp.atTop();                   // True when at the first line
boolean bot  = vp.atBottom();                // True when at the last line
int yOff     = vp.getYOffset();              // Current line offset
int maxYOff  = vp.getMaxYOffset();           // Maximum scroll offset
int total    = vp.totalLineCount();          // Total content lines
int visible  = vp.visibleLineCount();        // Lines currently shown

vp.setHorizontalStep(4);   // Cells to scroll per left/right key press
vp.setXOffset(10);         // Jump to a specific horizontal position
vp.scrollLeft(4);
vp.scrollRight(4);

double hPct = vp.horizontalScrollPercent(); // 0.0–1.0

import com.williamcallahan.tui4j.compat.lipgloss.Borders;
import com.williamcallahan.tui4j.compat.lipgloss.Style;

vp.setStyle(Style.newStyle().border(Borders.roundedBorder()));

vp.setMouseWheelEnabled(false); // Disable mouse wheel
vp.setMouseWheelDelta(5);       // 5 lines per wheel notch

vp.setHighPerformanceRendering(true);