include "wx/module.h" for wxModule

[wxWidgets.git] / src / common / imagpng.cpp

diff --git a/src/common/imagpng.cpp b/src/common/imagpng.cpp
index 1b8e2017189f27a9ed42cc7f0c1b2dd6e26baf46..bdbe0c5267e22894de8b155cf7bcd1a58c6ee0e7 100644 (file)
--- a/src/common/imagpng.cpp
+++ b/src/common/imagpng.cpp
@@ -75,7 +75,8 @@ enum Transparency
 // have transparent pixels, i.e. either Transparency_Alpha or Transparency_Mask
 static Transparency
 CheckTransparency(const unsigned char *ptr,
 // have transparent pixels, i.e. either Transparency_Alpha or Transparency_Mask
 static Transparency
 CheckTransparency(const unsigned char *ptr,

-                  png_uint_32 x, png_uint_32 y, png_uint_32 w, png_uint_32 h);
+                  png_uint_32 x, png_uint_32 y, png_uint_32 w, png_uint_32 h,
+                  size_t numColBytes);

 
 // init the alpha channel for the image and fill it with 1s up to (x, y)
 static unsigned char *InitAlpha(wxImage *image, png_uint_32 x, png_uint_32 y);
 
 // init the alpha channel for the image and fill it with 1s up to (x, y)
 static unsigned char *InitAlpha(wxImage *image, png_uint_32 x, png_uint_32 y);


@@ -85,6 +86,20 @@ static void
 FindMaskColour(unsigned char **lines, png_uint_32 width, png_uint_32 height,
                unsigned char& rMask, unsigned char& gMask, unsigned char& bMask);
 
 FindMaskColour(unsigned char **lines, png_uint_32 width, png_uint_32 height,
                unsigned char& rMask, unsigned char& gMask, unsigned char& bMask);
 

+// is the pixel with this value of alpha a fully opaque one?
+static inline
+bool IsOpaque(unsigned char a)
+{
+    return a == 0xff;
+}
+
+// is the pixel with this value of alpha a fully transparent one?
+static inline
+bool IsTransparent(unsigned char a)
+{
+    return !a;
+}
+

 // ============================================================================
 // wxPNGHandler implementation
 // ============================================================================
 // ============================================================================
 // wxPNGHandler implementation
 // ============================================================================


@@ -189,41 +204,50 @@ PNGLINKAGEMODE wx_png_warning(png_structp png_ptr, png_const_charp message)
 // LoadFile() helpers
 // ----------------------------------------------------------------------------
 
 // LoadFile() helpers
 // ----------------------------------------------------------------------------
 

+// determine the kind of transparency we need for this image: if the only alpha
+// values it has are 0 (transparent) and 0xff (opaque) then we can simply
+// create a mask for it, we should be ok with a simple mask but otherwise we
+// need a full blown alpha channel in wxImage
+//
+// parameters:
+//      ptr             the start of the data to examine
+//      x, y            starting position
+//      w, h            size of the image
+//      numColBytes     number of colour bytes (1 for grey scale, 3 for RGB)
+//                      (NB: alpha always follows the colour bytes)

 Transparency
 CheckTransparency(const unsigned char *ptr,
 Transparency
 CheckTransparency(const unsigned char *ptr,

-                  png_uint_32 x, png_uint_32 y, png_uint_32 w, png_uint_32 h)
+                  png_uint_32 x, png_uint_32 y, png_uint_32 w, png_uint_32 h,
+                  size_t numColBytes)

 {
 {

-    // suppose that a mask will suffice
-    Transparency transparency = Transparency_Mask;
+    // we start from (x + 1, y)
+    x++;

 
 

-    // and check all the remaining alpha values to see if it does
-    unsigned char a2;
+    // suppose that a mask will suffice and check all the remaining alpha
+    // values to see if it does

     unsigned const char *ptr2 = ptr;
     for ( png_uint_32 y2 = y; y2 < h; y2++ )
     {
     unsigned const char *ptr2 = ptr;
     for ( png_uint_32 y2 = y; y2 < h; y2++ )
     {

-        for ( png_uint_32 x2 = x + 1; x2 < w; x2++ )
+        for ( png_uint_32 x2 = x; x2 < w; x2++ )

         {
         {

-            // skip the grey byte
-            a2 = *++ptr2;
+            // skip the grey or colour byte(s)
+            ptr2 += numColBytes;

 
 

-            if ( a2 && a2 != 0xff )
+            unsigned char a2 = *ptr2++;
+
+            if ( !IsTransparent(a2) && !IsOpaque(a2) )

             {
             {

-                // not fully opeaque nor fully transparent, hence need alpha
-                transparency = Transparency_Alpha;
-                break;
+                // not fully opaque nor fully transparent, hence need alpha
+                return Transparency_Alpha;

             }
             }

-
-            ++ptr2;

         }
 
         }
 

-        if ( transparency == Transparency_Alpha )
-        {
-            // no need to continue
-            break;
-        }
+        // during the next loop iteration check all the pixels in the row
+        x = 0;

     }
 
     }
 

-    return transparency;
+    // mask will be enough
+    return Transparency_Mask;

 }
 
 unsigned char *InitAlpha(wxImage *image, png_uint_32 x, png_uint_32 y)
 }
 
 unsigned char *InitAlpha(wxImage *image, png_uint_32 x, png_uint_32 y)


@@ -234,13 +258,11 @@ unsigned char *InitAlpha(wxImage *image, png_uint_32 x, png_uint_32 y)
     unsigned char *alpha = image->GetAlpha();
 
     // set alpha for the pixels we had so far
     unsigned char *alpha = image->GetAlpha();
 
     // set alpha for the pixels we had so far

-    for ( png_uint_32 y2 = 0; y2 <= y; y2++ )
+    png_uint_32 end = y * image->GetWidth() + x;
+    for ( png_uint_32 i = 0; i < end; i++ )

     {
     {

-        for ( png_uint_32 x2 = 0; x2 < x; x2++ )
-        {
-            // all the previous pixels were opaque
-            *alpha++ = 0xff;
-        }
+        // all the previous pixels were opaque
+        *alpha++ = 0xff;

     }
 
     return alpha;
     }
 
     return alpha;


@@ -335,14 +357,19 @@ void CopyDataFromPNG(wxImage *image,
 
                 // the first time we encounter a transparent pixel we must
                 // decide about what to do about them
 
                 // the first time we encounter a transparent pixel we must
                 // decide about what to do about them

-                if ( a != 0xff && transparency == Transparency_None )
+                if ( !IsOpaque(a) && transparency == Transparency_None )

                 {
                     // we'll need at least the mask for this image and
                     // maybe even full alpha channel info: the former is
                     // only enough if we have alpha values of 0 and 0xff
                     // only, otherwisewe need the latter
                 {
                     // we'll need at least the mask for this image and
                     // maybe even full alpha channel info: the former is
                     // only enough if we have alpha values of 0 and 0xff
                     // only, otherwisewe need the latter

-                    transparency = CheckTransparency(ptrSrc, x, y,
-                                                     width, height);
+                    transparency = CheckTransparency
+                                   (
+                                        ptrSrc,
+                                        x, y,
+                                        width, height,
+                                        1
+                                   );

 
                     if ( transparency == Transparency_Mask )
                     {
 
                     if ( transparency == Transparency_Mask )
                     {


@@ -362,8 +389,25 @@ void CopyDataFromPNG(wxImage *image,
 
                 switch ( transparency )
                 {
 
                 switch ( transparency )
                 {

+                    case Transparency_Mask:
+                        if ( IsTransparent(a) )
+                        {
+                            *ptrDst++ = rMask;
+                            *ptrDst++ = bMask;
+                            *ptrDst++ = gMask;
+                            break;
+                        }
+                        // else: !transparent
+
+                        // must be opaque then as otherwise we shouldn't be
+                        // using the mask at all
+                        wxASSERT_MSG( IsOpaque(a), _T("logic error") );
+
+                        // fall through
+

                     case Transparency_Alpha:
                     case Transparency_Alpha:

-                        *alpha++ = a;
+                        if ( alpha )
+                            *alpha++ = a;

                         // fall through
 
                     case Transparency_None:
                         // fall through
 
                     case Transparency_None:


@@ -371,11 +415,6 @@ void CopyDataFromPNG(wxImage *image,
                         *ptrDst++ = g;
                         *ptrDst++ = g;
                         break;
                         *ptrDst++ = g;
                         *ptrDst++ = g;
                         break;

-
-                    case Transparency_Mask:
-                        *ptrDst++ = rMask;
-                        *ptrDst++ = bMask;
-                        *ptrDst++ = gMask;

                 }
             }
         }
                 }
             }
         }


@@ -394,10 +433,15 @@ void CopyDataFromPNG(wxImage *image,
 
                 // the logic here is the same as for the grey case except
                 // where noted
 
                 // the logic here is the same as for the grey case except
                 // where noted

-                if ( a != 0xff && transparency == Transparency_None )
+                if ( !IsOpaque(a) && transparency == Transparency_None )

                 {
                 {

-                    transparency = CheckTransparency(ptrSrc, x, y,
-                                                     width, height);
+                    transparency = CheckTransparency
+                                   (
+                                        ptrSrc,
+                                        x, y,
+                                        width, height,
+                                        3
+                                   );

 
                     if ( transparency == Transparency_Mask )
                     {
 
                     if ( transparency == Transparency_Mask )
                     {


@@ -413,8 +457,34 @@ void CopyDataFromPNG(wxImage *image,
 
                 switch ( transparency )
                 {
 
                 switch ( transparency )
                 {

+                    case Transparency_Mask:
+                        if ( IsTransparent(a) )
+                        {
+                            // if we couldn't find a unique colour for the mask, we
+                            // can have real pixels with the same value as the mask
+                            // and it's better to slightly change their colour than
+                            // to make them transparent
+                            if ( r == rMask && g == gMask && b == bMask )
+                            {
+                                r++;
+                            }
+
+                            *ptrDst++ = rMask;
+                            *ptrDst++ = bMask;
+                            *ptrDst++ = gMask;
+                            break;
+                        }
+                        // else: !transparent
+
+                        // must be opaque then as otherwise we shouldn't be
+                        // using the mask at all
+                        wxASSERT_MSG( IsOpaque(a), _T("logic error") );
+
+                        // fall through
+

                     case Transparency_Alpha:
                     case Transparency_Alpha:

-                        *alpha++ = a;
+                        if ( alpha )
+                            *alpha++ = a;

                         // fall through
 
                     case Transparency_None:
                         // fall through
 
                     case Transparency_None:


@@ -422,20 +492,6 @@ void CopyDataFromPNG(wxImage *image,
                         *ptrDst++ = g;
                         *ptrDst++ = b;
                         break;
                         *ptrDst++ = g;
                         *ptrDst++ = b;
                         break;

-
-                    case Transparency_Mask:
-                        // if we couldn't find a unique colour for the mask, we
-                        // can have real pixels with the same value as the mask
-                        // and it's better to slightly change their colour than
-                        // to make them transparent
-                        if ( r == rMask && g == gMask && b == bMask )
-                        {
-                            r++;
-                        }
-
-                        *ptrDst++ = rMask;
-                        *ptrDst++ = bMask;
-                        *ptrDst++ = gMask;

                 }
             }
         }
                 }
             }
         }