render font glyphs at device resolution to fix pixelation

glyphs were rasterized at gui-space size and then magnified by the
gui scale with nearest-neighbour sampling, making every custom font
blocky. rasters are now built at font-size * gui-scale (one texel per
screen pixel) and drawn through a 1/scale pose, so text is 1:1 and
antialiased at any gui scale. measurements convert back to gui units
and a gui scale change re-rasterizes everything

src/main/java/cc/fros/util/render/FrosFont.java

@@ -82,6 +82,7 @@ public final class FrosFont {
     private static FontMetrics metrics;
     private static String loadedName;
     private static float loadedSize = Float.NaN;
+    private static int loadedScale = 1;
     private static long lastAttempt;
     private static int glyphCounter;
 
@@ -92,7 +93,7 @@ public final class FrosFont {
         if (text == null || text.isEmpty()) return 0;
         sync();
         if (awtFont == null) return mc.font.width(text);
-        return metrics.stringWidth(stripCodes(text));
+        return toGui(metrics.stringWidth(stripCodes(text)));
     }
 
     public static int width(Component component) {
@@ -104,7 +105,20 @@ public final class FrosFont {
 
     public static int lineHeight() {
         sync();
-        return awtFont == null ? mc.font.lineHeight : metrics.getHeight();
+        return awtFont == null ? mc.font.lineHeight : toGui(metrics.getHeight());
+    }
+
+    /** converts a raster pixel measurement to gui units */
+    private static int toGui(int pixels) {
+        return (pixels + loadedScale - 1) / loadedScale;
+    }
+
+    private static int currentScale() {
+        try {
+            return Math.max(1, (int) Math.round(mc.getWindow().getGuiScale()));
+        } catch (Exception e) {
+            return 1;
+        }
     }
 
     public static void draw(GuiGraphics context, String text, int x, int y, int color) {
@@ -140,20 +154,22 @@ public final class FrosFont {
         String name = gui == null || vanilla ? "" : gui.font.getValue();
         int size = gui == null ? 10 : gui.fontSize.getValue();
         if (name == null) name = "";
+        int scale = currentScale();
 
-        boolean changed = !Objects.equals(name, loadedName) || size != loadedSize;
+        boolean changed = !Objects.equals(name, loadedName) || size != loadedSize || scale != loadedScale;
         if (!changed) {
             boolean missing = awtFont == null && !name.isBlank();
             // retry a missing file every couple of seconds so dropping one
             // into the folder loads without touching the setting again
             if (!missing || System.currentTimeMillis() - lastAttempt < 2000) return;
         }
-        reset(name, size, changed);
+        reset(name, size, scale, changed);
     }
 
-    private static void reset(String name, float size, boolean verbose) {
+    private static void reset(String name, float size, int scale, boolean verbose) {
         loadedName = name;
         loadedSize = size;
+        loadedScale = scale;
         lastAttempt = System.currentTimeMillis();
         awtFont = null;
         metrics = null;
@@ -170,13 +186,13 @@ public final class FrosFont {
             Path file = resolveFontFile(name);
             if (file != null) {
                 applyFont(java.awt.Font.createFont(java.awt.Font.TRUETYPE_FONT, file.toFile()),
-                        size, "Loaded font " + file.getFileName(), verbose);
+                        size * scale, "Loaded font " + file.getFileName(), verbose);
                 return;
             }
 
             java.awt.Font installed = installedFont(name);
             if (installed != null) {
-                applyFont(installed, size, "Using system font '" + name + "'", verbose);
+                applyFont(installed, size * scale, "Using system font '" + name + "'", verbose);
                 return;
             }
 
@@ -279,18 +295,28 @@ public final class FrosFont {
             if (glyph == null) return;
             GLYPHS.put(key, glyph);
         }
+
+        // the bitmap is rasterized at device resolution (one texel per screen
+        // pixel); scale the pose down into gui space so the gpu never has to
+        // magnify it with nearest-neighbour sampling
+        float scale = loadedScale;
+        context.pose().pushMatrix();
+        context.pose().scale(1f / scale, 1f / scale);
+        context.pose().translate((x - 1) * scale, (y - 1) * scale);
         context.blit(RenderPipelines.GUI_TEXTURED, glyph.id(),
-                x - 1, y - 1, 0.0f, 0.0f, glyph.width(), glyph.height(), glyph.width(), glyph.height());
+                0, 0, 0.0f, 0.0f, glyph.width(), glyph.height(), glyph.width(), glyph.height());
+        context.pose().popMatrix();
     }
 
     private static Glyph createGlyph(String text, int baseColor) {
         String plain = stripCodes(text);
         if (plain.isEmpty()) return null;
 
+        int pad = loadedScale;
         int width = Math.max(1, metrics.stringWidth(plain));
         int height = metrics.getHeight();
-        int imageWidth = width + 2;
-        int imageHeight = height + 2;
+        int imageWidth = width + 2 * pad;
+        int imageHeight = height + 2 * pad;
 
         BufferedImage image = new BufferedImage(imageWidth, imageHeight, BufferedImage.TYPE_INT_ARGB);
         Graphics2D graphics = image.createGraphics();
@@ -319,7 +345,7 @@ public final class FrosFont {
     }
 
     private static void drawSegments(Graphics2D graphics, String text, int baseColor) {
-        int baseline = metrics.getAscent() + 1;
+        int baseline = metrics.getAscent() + loadedScale;
         int cursor = 1;
         int current = baseColor;
         int segmentStart = 0;