Replace int flags with struct FXDIB_ResampleOptions.

Using bit values in an int may not be reliable, since different parts of
the code can interpret the bits differently. e.g. FXDIB_DOWNSAMPLE and
RENDER_FORCE_DOWNSAMPLE are defined in different places, but can be used
interchangeably because they just happen to have the same value. It
works but is rather fragile.

Instead, use a struct of bools to explicitly define what different bits
mean. Remove FXDIB_DOWNSAMPLE and friends.

Change-Id: I9cf0c8f94d1ed27edf8dba22b0ab0ee67f2722cc
Reviewed-on: https://pdfium-review.googlesource.com/c/44650
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/core/fxge/dib/cfx_dibitmap.cpp b/core/fxge/dib/cfx_dibitmap.cpp
index dcf5fdc7ab..011270494c 100644
--- a/core/fxge/dib/cfx_dibitmap.cpp
+++ b/core/fxge/dib/cfx_dibitmap.cpp
@@ -329,7 +329,8 @@ bool CFX_DIBitmap::LoadChannelFromAlpha(
     if (pSrcClone->GetWidth() != m_Width ||
         pSrcClone->GetHeight() != m_Height) {
       if (pAlphaMask) {
-        pAlphaMask = pAlphaMask->StretchTo(m_Width, m_Height, 0, nullptr);
+        pAlphaMask = pAlphaMask->StretchTo(m_Width, m_Height,
+                                           FXDIB_ResampleOptions(), nullptr);
         if (!pAlphaMask)
           return false;
       }
@@ -338,8 +339,8 @@ bool CFX_DIBitmap::LoadChannelFromAlpha(
     srcOffset = 0;
   } else if (pSrcClone->GetWidth() != m_Width ||
              pSrcClone->GetHeight() != m_Height) {
-    RetainPtr<CFX_DIBitmap> pSrcMatched =
-        pSrcClone->StretchTo(m_Width, m_Height, 0, nullptr);
+    RetainPtr<CFX_DIBitmap> pSrcMatched = pSrcClone->StretchTo(
+        m_Width, m_Height, FXDIB_ResampleOptions(), nullptr);
     if (!pSrcMatched)
       return false;
 
@@ -437,7 +438,8 @@ bool CFX_DIBitmap::MultiplyAlpha(const RetainPtr<CFX_DIBBase>& pSrcBitmap) {
   RetainPtr<CFX_DIBitmap> pSrcClone = pSrcBitmap.As<CFX_DIBitmap>();
   if (pSrcBitmap->GetWidth() != m_Width ||
       pSrcBitmap->GetHeight() != m_Height) {
-    pSrcClone = pSrcBitmap->StretchTo(m_Width, m_Height, 0, nullptr);
+    pSrcClone = pSrcBitmap->StretchTo(m_Width, m_Height,
+                                      FXDIB_ResampleOptions(), nullptr);
     if (!pSrcClone)
       return false;
   }