Huw Davies : gdi32: Fix fractional scaling threshold.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: ff2f88cf08f47c6e2c17e0475d7f3364dae730b1
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=ff2f88cf08f47c6e2c17e0475d...

Author: Huw Davies 
Date:   Fri Feb 20 14:40:44 2009 +0000

gdi32: Fix fractional scaling threshold.

---

dlls/gdi32/freetype.c   |    6 ++++--
 dlls/gdi32/tests/font.c |    8 +++++---
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/dlls/gdi32/freetype.c b/dlls/gdi32/freetype.c
index 711f259..6ca35c3 100644
--- a/dlls/gdi32/freetype.c
+++ b/dlls/gdi32/freetype.c
@@ -3627,8 +3627,10 @@ found:

scale = (height + face->size.height - 1) / face->size.height;
         scaled_height = scale * face->size.height;
-        /* XP allows not more than 10% deviation */
-        if (scale > 1 && scaled_height - height > scaled_height / 10) scale--;
+        /* Only jump to the next height if the difference <= 25% original height */
+        if (scale > 2 && scaled_height - height > face->size.height / 4) scale--;
+        /* The jump between unscaled and doubled is delayed by 1 */
+        else if (scale == 2 && scaled_height - height > (face->size.height / 4 - 1)) scale--;
         ret->scale_y = scale;

width = face->size.x_ppem >> 6;
diff --git a/dlls/gdi32/tests/font.c b/dlls/gdi32/tests/font.c
index 92623dc..5b50a14 100644
--- a/dlls/gdi32/tests/font.c
+++ b/dlls/gdi32/tests/font.c
@@ -344,7 +344,7 @@ static void test_bitmap_font(void)
     bitmap_lf.lfWidth = lfWidth;

/* test fractional scaling */
-    for (i = 1; i <= height_orig * 3; i++)
+    for (i = 1; i <= height_orig * 6; i++)
     {
         INT nearest_height;

@@ -352,8 +352,10 @@ static void test_bitmap_font(void)
    hfont = create_font("fractional", &bitmap_lf);
         scale = (i + height_orig - 1) / height_orig;
         nearest_height = scale * height_orig;
-        /* XP allows not more than 10% deviation */
-        if (scale > 1 && nearest_height - i > nearest_height / 10) scale--;
+        /* Only jump to the next height if the difference <= 25% original height */
+        if (scale > 2 && nearest_height - i > height_orig / 4) scale--;
+        /* The jump between unscaled and doubled is delayed by 1 */
+        else if(scale == 2 && nearest_height - i > (height_orig / 4 - 1)) scale--;
         old_hfont = SelectObject(hdc, hfont);
         test_font_metrics(hdc, hfont, bitmap_lf.lfHeight, 0, test_str, sizeof(test_str), &tm_orig, &size_orig, width_orig, 1, scale);
         SelectObject(hdc, old_hfont);