[freetype2] master a3dd6d9: Fix multiple calls of `FT_Bitmap_Convert'.

[Werner LEMBERG]

branch: master
commit a3dd6d99a4c9f61667e5c996c0997cdd0207fc73
Author: Werner Lemberg <address@hidden>
Commit: Werner Lemberg <address@hidden>

    Fix multiple calls of `FT_Bitmap_Convert'.
    
    The documentation of `FT_Bitmap_Convert' says that multiple calls do
    proper reallocation of the target FT_Bitmap object.  However, this
    failed for the sequence
    
      non-empty bitmap
      empty bitmap
      non-empty bitmap
    
    Reason was that `FT_Bitmap_Convert' only reallocated the bitmap
    buffer if it became too small; it didn't make the buffer smaller.
    For an empty bitmap following a non-empty one, only the buffer
    dimension got set to zero, without deallocation.  If the next call
    was a non-empty buffer again, an assertion in `ft_mem_qrealloc' was
    triggered.
    
    * src/base/ftbitmap.c (FT_Bitmap_Convert): Always reallocate target
    buffer to the correct size.
    
    * docs/CHANGES: Document it.
---
 ChangeLog           | 24 ++++++++++++++++++++++++
 docs/CHANGES        |  4 ++++
 src/base/ftbitmap.c |  3 +--
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 6ae91dd..c697729 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,29 @@
 2017-09-05  Werner Lemberg  <address@hidden>
 
+       Fix multiple calls of `FT_Bitmap_Convert'.
+
+       The documentation of `FT_Bitmap_Convert' says that multiple calls do
+       proper reallocation of the target FT_Bitmap object.  However, this
+       failed for the sequence
+
+         non-empty bitmap
+         empty bitmap
+         non-empty bitmap
+
+       Reason was that `FT_Bitmap_Convert' only reallocated the bitmap
+       buffer if it became too small; it didn't make the buffer smaller.
+       For an empty bitmap following a non-empty one, only the buffer
+       dimension got set to zero, without deallocation.  If the next call
+       was a non-empty buffer again, an assertion in `ft_mem_qrealloc' was
+       triggered.
+
+       * src/base/ftbitmap.c (FT_Bitmap_Convert): Always reallocate target
+       buffer to the correct size.
+
+       * docs/CHANGES: Document it.
+
+2017-09-05  Werner Lemberg  <address@hidden>
+
        [bdf] Fix size and resolution handling.
 
        * src/bdf/bdfdrivr.c (BDF_Face_Init): Use `SIZE' values if
diff --git a/docs/CHANGES b/docs/CHANGES
index 7bb5fce..2bac995 100644
--- a/docs/CHANGES
+++ b/docs/CHANGES
@@ -54,6 +54,10 @@ CHANGES BETWEEN 2.8 and 2.8.1
       missing.   Previously,   `SIZE'  was  completely   ignored,  and
       FreeType used heuristic values instead.
 
+    - Multiple calls to `FT_Bitmap_Convert' do work now as advertised.
+      Previously,  they failed with an assertion error if there was an
+      empty bitmap between non-empty ones.
+
 
 ======================================================================
 
diff --git a/src/base/ftbitmap.c b/src/base/ftbitmap.c
index ee50c2f..e567a04 100644
--- a/src/base/ftbitmap.c
+++ b/src/base/ftbitmap.c
@@ -534,8 +534,7 @@
              (FT_ULong)target->rows > FT_ULONG_MAX / (FT_ULong)target_pitch )
           return FT_THROW( Invalid_Argument );
 
-        if ( target->rows * (FT_ULong)target_pitch > old_size              &&
-             FT_QREALLOC( target->buffer,
+        if ( FT_QREALLOC( target->buffer,
                           old_size, target->rows * (FT_UInt)target_pitch ) )
           return error;