feat: add text selection to browse example

Author: franzos

litehtml/examples/browse.rs

@@ -1,15 +1,18 @@
-/// Fetch and render a web page by URL in a window with scrolling.
+/// Fetch and render a web page by URL in a window with scrolling and text selection.
 ///
 /// Usage: cargo run --example browse --features pixbuf -p litehtml -- <url> [width] [--height N] [--scale N] [--fullscreen]
+///
+/// Click and drag to select text. Selected text is printed on exit.
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::time::Instant;
 use std::{env, process};
 
-use minifb::{Key, Window, WindowOptions};
+use minifb::{Key, MouseButton, MouseMode, Window, WindowOptions};
 use url::Url;
 
 use litehtml::pixbuf::PixbufContainer;
+use litehtml::selection::Selection;
 use litehtml::{
     BackgroundLayer, BorderRadiuses, Borders, Color, ConicGradient, DocumentContainer,
     FontDescription, FontMetrics, LinearGradient, ListMarker, MediaFeatures, Position,
@@ -18,6 +21,15 @@ use litehtml::{
 
 const USER_AGENT: &str = "Mozilla/5.0 (X11; Linux x86_64; rv:122.0) Gecko/20100101 Firefox/122.0";
 
+/// Minimum drag distance (px) before selection starts.
+const DRAG_THRESHOLD: f32 = 4.0;
+
+/// Auto-scroll edge zone (px from top/bottom).
+const SCROLL_EDGE: f32 = 20.0;
+
+/// Max auto-scroll speed (px/frame).
+const SCROLL_SPEED_MAX: f32 = 12.0;
+
 struct BrowseContainer {
     inner: PixbufContainer,
     base_url: Url,
@@ -223,6 +235,36 @@ fn premul_to_rgb(pixels: &[u8]) -> Vec<u32> {
         .collect()
 }
 
+/// Overlay a semi-transparent blue rectangle onto the visible framebuffer.
+fn overlay_selection_rect(
+    buf: &mut [u32],
+    buf_width: u32,
+    scroll_y: u32,
+    win_height: u32,
+    rect: &Position,
+) {
+    let x0 = (rect.x.max(0.0) as u32).min(buf_width);
+    let x1 = ((rect.x + rect.width).max(0.0) as u32).min(buf_width);
+    let y0 = (rect.y as i32 - scroll_y as i32).max(0) as u32;
+    let y1 = ((rect.y + rect.height) as i32 - scroll_y as i32).clamp(0, win_height as i32) as u32;
+
+    for y in y0..y1 {
+        for x in x0..x1 {
+            let idx = (y * buf_width + x) as usize;
+            if idx < buf.len() {
+                let pixel = buf[idx];
+                let r = (pixel >> 16) & 0xFF;
+                let g = (pixel >> 8) & 0xFF;
+                let b = pixel & 0xFF;
+                let r = (r * 70 + 100 * 30) / 100;
+                let g = (g * 70 + 150 * 30) / 100;
+                let b = (b * 70 + 255 * 30) / 100;
+                buf[idx] = (r.min(255) << 16) | (g.min(255) << 8) | b.min(255);
+            }
+        }
+    }
+}
+
 fn main() {
     let args: Vec<String> = env::args().collect();
 
@@ -370,6 +412,26 @@ fn main() {
 
     let base_framebuffer = premul_to_rgb(container.inner.pixels());
 
+    // Create document for interactive selection (layout only, no draw)
+    let measure = container.inner.text_measure_fn();
+    let doc = match litehtml::Document::from_html(&html, &mut container, None, None) {
+        Ok(mut d) => {
+            let _ = d.render(width as f32);
+            d
+        }
+        Err(e) => {
+            eprintln!("Failed to create selection document: {:?}", e);
+            process::exit(1);
+        }
+    };
+
+    let mut selection = Selection::for_document(&doc);
+    let mut selection_rects: Vec<Position> = Vec::new();
+    let mut mouse_was_down = false;
+    let mut drag_origin: Option<(f32, f32)> = None;
+    let mut drag_active = false;
+    let mut last_mouse: Option<(f32, f32)> = None;
+
     // Window
     let title = format!("browse - {}", raw_url);
     let mut window = Window::new(
@@ -390,7 +452,7 @@ fn main() {
     let max_scroll = content_height.saturating_sub(win_height);
     let mut scroll_y: u32 = 0;
 
-    eprintln!("Ready. Scroll with mouse wheel or arrow keys. ESC to quit.");
+    eprintln!("Ready. Scroll with mouse wheel or arrow keys. Click+drag to select. ESC to quit.");
 
     while window.is_open() && !window.is_key_down(Key::Escape) {
         if let Some((_, dy)) = window.get_scroll_wheel() {
@@ -416,13 +478,88 @@ fn main() {
             scroll_y = max_scroll;
         }
 
+        // Mouse selection
+        let mouse_down = window.get_mouse_down(MouseButton::Left);
+        if let Some((mx_phys, my_phys)) = window.get_mouse_pos(MouseMode::Clamp) {
+            let mx = mx_phys / scale;
+            let my = my_phys / scale;
+            let doc_x = mx;
+            let doc_y = my + scroll_y as f32;
+
+            if mouse_down && !mouse_was_down {
+                drag_origin = Some((mx, my));
+                drag_active = false;
+                selection.clear();
+                selection_rects.clear();
+                last_mouse = Some((mx, my));
+            } else if mouse_down {
+                let moved = last_mouse.map_or(true, |(lx, ly)| {
+                    (mx - lx).abs() > 0.5 || (my - ly).abs() > 0.5
+                });
+
+                if moved {
+                    last_mouse = Some((mx, my));
+
+                    if !drag_active {
+                        if let Some((ox, oy)) = drag_origin {
+                            let dist = ((mx - ox).powi(2) + (my - oy).powi(2)).sqrt();
+                            if dist >= DRAG_THRESHOLD {
+                                drag_active = true;
+                                let origin_doc_y = oy + scroll_y as f32;
+                                selection.start_at(&doc, &measure, ox, origin_doc_y, ox, oy);
+                            }
+                        }
+                    }
+
+                    if drag_active {
+                        selection.extend_to(&doc, &measure, doc_x, doc_y, mx, my);
+                        selection_rects = selection.rectangles().to_vec();
+
+                        if my < SCROLL_EDGE {
+                            let factor = 1.0 - (my / SCROLL_EDGE).max(0.0);
+                            let speed = (factor * SCROLL_SPEED_MAX).ceil() as u32;
+                            scroll_y = scroll_y.saturating_sub(speed);
+                        } else if my > win_height as f32 - SCROLL_EDGE {
+                            let over = my - (win_height as f32 - SCROLL_EDGE);
+                            let factor = (over / SCROLL_EDGE).min(1.0);
+                            let speed = (factor * SCROLL_SPEED_MAX).ceil() as u32;
+                            scroll_y = (scroll_y + speed).min(max_scroll);
+                        }
+                    }
+                }
+            } else {
+                if drag_active {
+                    drag_active = false;
+                }
+                drag_origin = None;
+            }
+        }
+        mouse_was_down = mouse_down;
+
         // Build visible slice
         let phys_scroll_y = ((scroll_y as f32) * scale).ceil() as u32;
         let row_start = phys_scroll_y as usize * phys_width as usize;
         let row_end = (row_start + phys_win_height as usize * phys_width as usize)
             .min(base_framebuffer.len());
         let mut visible: Vec<u32> = base_framebuffer[row_start..row_end].to_vec();
 
+        // Overlay selection highlight
+        for rect in &selection_rects {
+            let phys_rect = Position {
+                x: rect.x * scale,
+                y: rect.y * scale,
+                width: rect.width * scale,
+                height: rect.height * scale,
+            };
+            overlay_selection_rect(
+                &mut visible,
+                phys_width,
+                phys_scroll_y,
+                phys_win_height,
+                &phys_rect,
+            );
+        }
+
         let expected = phys_win_height as usize * phys_width as usize;
         if visible.len() < expected {
             visible.resize(expected, 0x00FFFFFF);
@@ -432,4 +569,11 @@ fn main() {
             .update_with_buffer(&visible, phys_width as usize, phys_win_height as usize)
             .unwrap();
     }
+
+    // Print selected text on exit
+    if let Some(text) = selection.selected_text() {
+        if !text.is_empty() {
+            println!("Selected: {}", text);
+        }
+    }
 }