Cards that reflow

package dev.cf.recipe;

import dev.cf.Tones;

import dev.crossfly.ui.*;
import dev.crossfly.ui.color.*;
import dev.crossfly.ui.graphics.*;
import dev.crossfly.ui.layout.*;
import dev.crossfly.ui.style.*;

import static dev.crossfly.ui.Widgets.*;

/**
 * Cards that reflow, and the width check you do not write.
 *
 * <p>Resize the window: one column becomes two, then three. There is no listener here, no
 * {@code if (width > 600)}, and no phone/tablet branch. {@link CardGrid} is told the width a card
 * <i>wants</i> and the column range it may use, and it works the rest out — which means the same
 * code is right on a phone, a tablet, a split-screen window and a desktop nobody tested on.</p>
 *
 * <p>{@link Screen#sizeClass()} exists for the decisions a layout genuinely cannot make: whether to
 * show a second pane at all, whether a table is worth offering. Reach for it there, and not for
 * spacing.</p>
 */
public class R14Reflow extends Recipe
{
   private static final String[] NAME = { "Bearings", "Fasteners", "Seals", "Hydraulics",
      "Electrical", "Tooling", "Adhesives", "Abrasives" };
   private static final int[] COUNT = { 128, 412, 96, 55, 210, 74, 31, 88 };

   private Label sizeLine;

   public String title()
   {
      return "Cards that reflow";
   }

   public String note()
   {
      return "Tell CardGrid the width a card wants, not how many columns to use. Resize the window"
         + " — the reflow is the framework's, not yours.";
   }

   public void build(Component body) throws Exception
   {
      sizeLine = label("", 1f, false, Styles.captionColor, Position.START);
      body.add(LAY_AUTO, outgap(sizeLine, 0, 0, 0, .8f));
      updateSizeLine();
      // Re-read on restyle: a resize repositions, which restyles, so this line follows the window
      // without a resize listener of its own.
      onRestyle(this::updateSizeLine);

      CardGrid grid = new CardGrid().columns(1, 3)
         .cardWidth(13f)
         .gap(.6f);
      grid.testTag("recipe.reflow");
      for (int i = 0; i < NAME.length; i++)
         grid.card(tile(NAME[i], COUNT[i], i));
      body.add(LAY_AUTO, grid);
   }

   private Component tile(String name, int count, int i) throws Exception
   {
      // A grid of cards is exactly where a rotating tone earns its keep: the reflow is the thing
      // being demonstrated, and identical grey tiles make it hard to see that anything moved.
      Card c = Tones.card(Tones.cycle(i));
      c.add(LAY_AUTO, label(name, 1.2f, true, Styles.textColor, Position.START));
      c.add(LAY_AUTO, outgap(label(count + " in stock", 1f, true, Tones.cycle(i),
         Position.START), 0, .2f, 0, 0));
      return c;
   }

   private void updateSizeLine()
   {
      sizeLine.setText("This window is " + Screen.sizeClass() + " — the grid decided the columns,"
         + " nothing here did.");
      sizeLine.setValidLayout(false);
   }
}

package dev.cf.recipe;

import dev.cf.*;
import dev.crossfly.ui.*;
import dev.crossfly.ui.graphics.*;
import dev.crossfly.ui.layout.*;
import dev.crossfly.ui.skin.*;
import dev.crossfly.ui.style.*;

import static dev.crossfly.ui.Widgets.*;

/**
 * Base of a <b>recipe</b>: one screen that shows one thing, and nothing else.
 *
 * <p>A recipe is not a sample. A sample shows a component with all its knobs; a recipe answers a
 * question somebody actually has — "how do I put a filter sheet over a list?", "how do I make this
 * follow the theme?" — in as few lines as it takes, so the answer can be read in one screen and
 * copied without editing.</p>
 *
 * <p>That is the whole design constraint: <b>the boilerplate lives here, the substance lives in the
 * subclass.</b> A recipe that spends twenty lines building a title bar teaches the title bar.</p>
 *
 * <p>Write one as:</p>
 *
 * <pre>
 * public class MyRecipe extends Recipe
 * {
 *    public String title() { return "What this shows"; }
 *    public String note()  { return "The one sentence worth knowing."; }
 *
 *    public void build(Component body) throws Exception
 *    {
 *       body.add(LAY_AUTO, new Button("Tap"));
 *    }
 * }
 * </pre>
 */
public abstract class Recipe extends SampleWindow implements Described
{
   @Override
   public abstract String title();

   /**
    * The one thing a reader should take away — printed above the recipe, in caption tone.
    *
    * @return the note, or null for none
    */
   @Override
   public String note()
   {
      return null;
   }

   /**
    * Builds the recipe.
    *
    * @param body a vertical, scrollable container with sensible padding — add to it and stop
    * @throws Exception when building fails
    */
   public abstract void build(Component body) throws Exception;

   @Override
   public void onAdd(boolean firstTime) throws Exception
   {
      addTopBar(title());

      // The page, not the surface. addTopBar just set fullscreenColor to the surface,
      // and on a white page a white card has no edges — see Tones.page(). Re-derived on restyle so
      // a dark-mode flip does not leave the light page behind.
      fullscreenColor = Tones.page();
      onRestyle(() -> fullscreenColor = Tones.page());

      contents.setLayout(new VerticalLayout(Position.START, Position.START));
      contents.getStyle()
         .ingap(Gap.ofFont(1f, 1f, 1f, 1f));

      String n = note();
      if (n != null)
         contents.add(LAY_AUTO, outgap(nota(n), 0, 0, 0, 1f));

      Component body = new Component();
      body.setLayout(new VerticalLayout(Position.START, Position.START));
      body.setScrollable(ScrollDirection.VERTICAL);
      body.testTag("recipe.body");
      contents.add(LAY_FILL, body);
      build(body);
      if (pinned != null)
      {
         // Measured again once its labels have sizes: the band's AUTO height is taken in the first
         // layout, before them, and on the iPhone it showed only its first line - the odometer's
         // "No text recognizer on this device." was set and never seen (17/10/2026).
         final Component band = pinned;
         onUI(band::invalidateMeasure);
      }
      if (pinned != null)
         body.add(LAY_AUTO, new Component()
         {
            @Override
            public int getAutoHeight()
            {
               // Room for the last row to scroll clear of the floating band.
               return pinned.getAutoHeight();
            }
         });
   }

   /**
    * The note, as a tinted band rather than three lines of grey.
    *
    * <p>It is the one sentence the reader is meant to leave with, and it used to be the least
    * legible thing on the screen: caption-coloured, caption-sized, indistinguishable from the
    * captions further down that are only labels. A tone and a glyph cost nothing here — nobody has
    * to read the band to know what it is.</p>
    *
    * @param n the note text
    * @return the band
    * @throws Exception when building fails
    */
   /**
    * Pins {@code c} to the bottom of the screen, in a band that FLOATS over the scrolling body: it
    * stays on screen however far the body is scrolled, and the body scrolls underneath it. That is the
    * place a recipe says what just happened. An answer at the top of the body went out of view as soon
    * as the person scrolled down to the button that produced it (14/10/2026).
    * <p>
    * The band is 80% OPAQUE (the surface at alpha 0xCC), as the user asked; it floats rather than
    * sitting below the body because a transparency with nothing behind it cannot be seen -- the first
    * version had the band under the body, and the person saw a plain bar. The body gets a spacer as
    * tall as the band at its end, so its last row can still scroll clear of it.
    *
    * @param c the component to pin, usually the answer label
    * @return {@code c}, to chain
    * @throws Exception if the layout refuses
    */
   protected <T extends Component> T pin(T c) throws Exception
   {
      Component band = new Component();
      band.setLayout(new VerticalLayout(Position.START, Position.START));
      band.style(Skin.get()
         .card()
         .backColor(Styles.backColor.withAlpha(0xCC))
         .borderColor(Styles.borderColor.withAlpha(0x33))
         .borderRadius(0)
         .shadow(0, 0, 0, 0)
         .ingap(Gap.ofFont(1f, 1f, 1f, 1.2f))
         .outgap(Gap.ofFont(0)));
      band.add(LAY_AUTO, c);
      // Floated: positioned at the bottom, full width, over whatever the body has there.
      band.setRelativeBounds(Relative.START, Relative.END, Relative.FULL, Relative.AUTO);
      contents.add(LAY_AUTO, band);
      pinned = band;
      return c;
   }

   /** The floating band {@link #pin} made, or null; the body ends in a spacer as tall as it. */
   private Component pinned;

   private Component nota(String n) throws Exception
   {
      Component band = new Component();
      band.setLayout(new GridLayout(Position.START, Position.START));
      band.style(Skin.get()
         .card()
         .backColor(Tones.accent().withAlpha(0x16))
         .borderColor(Tones.accent().withAlpha(0x4A))
         .shadow(0, 0, 0, 0)
         .outgap(Gap.ofFont(0)));
      // 0xE88E is the outlined "info". The glyph column hugs; the text takes the rest and wraps.
      // The weights are GridLayout's own — 0f hugs, 1f takes what is left. LAY_FILL belongs to the
      // vertical and horizontal layouts and means nothing here: it collapsed the text to nothing.
      band.add(LAY_AUTO, 1f, matglyph(0xE88E, Tones.accent(), 1.05f),
         outgap(label(n, 1f, false, secondary(), Position.START), .5f, 0, 0, 0));
      return band;
   }
}

package dev.cf;

import dev.crossfly.ui.*;
import dev.crossfly.ui.graphics.*;
import dev.crossfly.ui.layout.*;
import dev.crossfly.ui.style.*;

import static dev.cf.sample.CrossFlySamplesColors.*;

/**
 * Base class for all CrossFly sample windows.
 * <p>
 * Provides common infrastructure:
 * <ul>
 *   <li>Shared color palette and styles from {@link dev.cf.sample.CrossFlySamplesColors}</li>
 *   <li>{@link #addTopBar(String, Button...)} — standard deep-indigo top bar with back button</li>
 *   <li>{@link #barButton(String, Runnable)} — helper to create icon buttons for the bar</li>
 * </ul>
 *
 * <h3>Usage</h3>
 * <pre>
 * public class MySample extends SampleWindow {
 *     public void onAdd(boolean firstTime) throws Exception {
 *         if (!firstTime) return;
 *         initWindow();
 *         addTopBar("My Sample");
 *         // ... add content
 *     }
 * }
 * </pre>
 */
public abstract class SampleWindow extends Window
{
   /** The main content area of the window, added by {@link #addTopBar(String, Button...)}, for subclasses to add their content into. */
   protected Component contents;

   // ─── Top bar ─────────────────────────────────────────────────────────────

   /**
    * Builds and adds a standard top bar with a back (←) button on the left,
    * a centered title, and any optional extra buttons on the right.
    *
    * @param title        the text shown in the bar
    * @param rightButtons zero or more icon buttons placed aligned to the right
    * @throws Exception if component construction fails
    */
   protected void addTopBar(String title, Button... rightButtons) throws Exception
   {
      fullscreenColor = Styles.backColor.color();
      setLayout(new VerticalLayout());
      add(0f, buildTopBar(title, rightButtons));
      add(LAY_FILL, contents = new Component());
      contents.getStyle()
         .ingap(Gap.ofFont(0, .5f, 0, .5f));
   }

   /**
    * Same as {@link #addTopBar(String, Button...)}, but returns the bar component
    * instead of adding it, for callers that need to position it manually.
    *
    * @param title        the bar title
    * @param rightButtons optional right-side icon buttons
    * @return the assembled top-bar {@link Component}
    * @throws Exception if component construction fails
    */
   protected Component buildTopBar(String title, Button... rightButtons) throws Exception
   {
      Button btBack = barButton("\ue5c4", this::hide);   // arrow_back
      btBack.testTag("sample.back");
      // Padded on every side, like the bar's right buttons: with none above and below, the target
      // was the arrow itself, too small to hit on a small phone (iPhone 5s, 17/10/2026).
      btBack.getStyle()
         .ingap(Gap.ofFont(.75f))
         .outgap(Gap.ofFont(0, 0, .25f, 0));

      Component bar = new Component().style(barStyle);
      bar.setLayout(new GridLayout(Position.START, Position.CENTER));

      int n = 2 + rightButtons.length;
      Object[] params = new Object[n * 2];
      params[0] = 0f;
      params[1] = 1f;
      for (int i = 0; i < rightButtons.length; i++)
         params[2 + i] = 0f;
      params[n] = btBack;
      params[n + 1] = new Label(title).style(barTitleStyle);
      for (int i = 0; i < rightButtons.length; i++)
      {
         params[n + 2 + i] = rightButtons[i];
         rightButtons[i].getStyle()
            .ingap(Gap.ofFont(.75f));
      }

      bar.add(params);
      return bar;
   }

   /**
    * Creates a standard bar icon button (transparent, white icon, pressed feedback).
    *
    * @param materialIcon the Material Icon unicode codepoint string
    * @param action       the action to run when the button is tapped
    * @return the configured {@link Button}
    */
   protected Button barButton(String materialIcon, Runnable action)
   {
      return new Button(new MaterialIcon(materialIcon)).style(barButtonNormal)
         .pressedStyle(barButtonPressed)
         .onAction(e -> action.run());
   }
}