From 68780da673e7b5971245c15a1837ef661ecd67cf Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Mon, 21 Jul 2025 13:35:21 -0700
Subject: [PATCH] Pass scale factor transform to glyph analysis when computing
 bounds

rather than simply multiplying every rect field by the scale factor.
This fixes clipping of glyphs and removes the need for magic numbers
expanding the bounds vertically.

Co-authored-by: Julia Ryan <juliaryan3.14@gmail.com>
---
 .../gpui/src/platform/windows/direct_write.rs | 39 +++++++------------
 1 file changed, 13 insertions(+), 26 deletions(-)

diff --git a/crates/gpui/src/platform/windows/direct_write.rs b/crates/gpui/src/platform/windows/direct_write.rs
index 82b9058b808bb1b4d826165c90bc10d2694b573d..a86c6d5d6866544bb1c38a9dd209bb35f396665b 100644
--- a/crates/gpui/src/platform/windows/direct_write.rs
+++ b/crates/gpui/src/platform/windows/direct_write.rs
@@ -759,10 +759,19 @@ impl DirectWriteState {
         let baseline_origin_x = 0.0;
         let baseline_origin_y = 0.0;
 
+        let transform = DWRITE_MATRIX {
+            m11: params.scale_factor,
+            m12: 0.0,
+            m21: 0.0,
+            m22: params.scale_factor,
+            dx: 0.0,
+            dy: 0.0,
+        };
+
         let glyph_analysis = unsafe {
             self.components.factory.CreateGlyphRunAnalysis(
                 &glyph_run,
-                None,
+                Some(&transform),
                 rendering_mode,
                 measuring_mode,
                 DWRITE_GRID_FIT_MODE_DEFAULT,
@@ -775,19 +784,6 @@ impl DirectWriteState {
         let texture_type = DWRITE_TEXTURE_CLEARTYPE_3x1;
         let bounds = unsafe { glyph_analysis.GetAlphaTextureBounds(texture_type)? };
 
-        // todo(windows)
-        // This is a walkaround, deleted when figured out.
-        let y_offset;
-        let extra_height;
-        if params.is_emoji {
-            y_offset = 0;
-            extra_height = 0;
-        } else {
-            // make some room for scaler.
-            y_offset = -1;
-            extra_height = 2;
-        }
-
         if bounds.right < bounds.left {
             Ok(Bounds {
                 origin: point(0.into(), 0.into()),
@@ -795,16 +791,10 @@ impl DirectWriteState {
             })
         } else {
             Ok(Bounds {
-                origin: point(
-                    ((bounds.left as f32 * params.scale_factor).ceil() as i32).into(),
-                    ((bounds.top as f32 * params.scale_factor).ceil() as i32 + y_offset).into(),
-                ),
+                origin: point((bounds.left as i32).into(), (bounds.top as i32).into()),
                 size: size(
-                    (((bounds.right - bounds.left) as f32 * params.scale_factor).ceil() as i32)
-                        .into(),
-                    (((bounds.bottom - bounds.top) as f32 * params.scale_factor).ceil() as i32
-                        + extra_height)
-                        .into(),
+                    (bounds.right - bounds.left).into(),
+                    (bounds.bottom - bounds.top).into(),
                 ),
             })
         }
@@ -922,7 +912,6 @@ impl DirectWriteState {
                 &transform,
                 point(baseline_origin_x, baseline_origin_y),
                 bitmap_size,
-                size(texture_width, texture_height),
             ) {
                 bitmap_data = color;
             } else {
@@ -960,7 +949,6 @@ impl DirectWriteState {
 
         let mut alpha_data = vec![0u8; (texture_size.width * texture_size.height * 3) as usize];
 
-        // todo: this should just use the 1x1 format without manual converison as it's kinda useless here
         unsafe {
             glyph_analysis.CreateAlphaTexture(
                 DWRITE_TEXTURE_CLEARTYPE_3x1,
@@ -1006,7 +994,6 @@ impl DirectWriteState {
         transform: &DWRITE_MATRIX,
         baseline_origin: Point<f32>,
         bitmap_size: Size<DevicePixels>,
-        texture_size: Size<u32>,
     ) -> Result<Vec<u8>> {
         // todo: support formats other than COLR
         let color_enumerator = unsafe {