Fix ARGB image glyphs on Open GL ES2 or big endian

Change Ie891665ad66e31692b69db02d34be8d303a7d631 accidentially removed
the condition that would ensure ARGB glyphs would get swizzled on OpenGL
ES2.

This patch readds a condition to check that, and also fixes the same on
big endian hosts by reusing the OpenGL ES2 code path.

Change-Id: I55615c498261a43c50e5a6902a7e2e24cddc4f4b
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

src/gui/opengl/qopengltextureglyphcache.cpp

@@ -43,6 +43,8 @@
 #include "qopenglpaintengine_p.h"
 #include "private/qopenglengineshadersource_p.h"
 #include "qopenglextensions_p.h"
+#include <qrgb.h>
+#include <private/qdrawhelper_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -316,24 +318,27 @@ void QOpenGLTextureGlyphCache::fillTexture(const Coord &c, glyph_t glyph, QFixed
         if (mask.format() == QImage::Format_RGB32
             // We need to make the alpha component equal to the average of the RGB values.
             // This is needed when drawing sub-pixel antialiased text on translucent targets.
+#if defined(QT_OPENGL_ES_2) || Q_BYTE_ORDER == Q_BIG_ENDIAN
+            || mask.format() == QImage::Format_ARGB32_Premultiplied
+#endif
             ) {
             for (int y = 0; y < maskHeight; ++y) {
-                quint32 *src = (quint32 *) mask.scanLine(y);
+                QRgb *src = (QRgb *) mask.scanLine(y);
                 for (int x = 0; x < maskWidth; ++x) {
-                    uchar r = src[x] >> 16;
-                    uchar g = src[x] >> 8;
-                    uchar b = src[x];
-                    quint32 avg;
+                    int r = qRed(src[x]);
+                    int g = qGreen(src[x]);
+                    int b = qBlue(src[x]);
+                    int avg;
                     if (mask.format() == QImage::Format_RGB32)
-                        avg = (quint32(r) + quint32(g) + quint32(b) + 1) / 3; // "+1" for rounding.
+                        avg = (r + g + b + 1) / 3; // "+1" for rounding.
                     else // Format_ARGB_Premultiplied
-                        avg = src[x] >> 24;
+                        avg = qAlpha(src[x]);
 
-#if defined(QT_OPENGL_ES_2)
+                    src[x] = qRgba(r, g, b, avg);
+#if defined(QT_OPENGL_ES_2) || Q_BYTE_ORDER == Q_BIG_ENDIAN
                     // swizzle the bits to accommodate for the GL_RGBA upload.
-                    src[x] = (avg << 24) | (quint32(r) << 0) | (quint32(g) << 8) | (quint32(b) << 16);
+                    src[x] = ARGB2RGBA(src[x]);
 #endif
-                    src[x] = (src[x] & 0x00ffffff) | (avg << 24);
                 }
             }
         }
@@ -341,7 +346,7 @@ void QOpenGLTextureGlyphCache::fillTexture(const Coord &c, glyph_t glyph, QFixed
 
     glBindTexture(GL_TEXTURE_2D, m_textureResource->m_texture);
     if (mask.depth() == 32) {
-#if defined(QT_OPENGL_ES_2)
+#if defined(QT_OPENGL_ES_2) || Q_BYTE_ORDER == Q_BIG_ENDIAN
         glTexSubImage2D(GL_TEXTURE_2D, 0, c.x, c.y, maskWidth, maskHeight, GL_RGBA, GL_UNSIGNED_BYTE, mask.bits());
 #else
         glTexSubImage2D(GL_TEXTURE_2D, 0, c.x, c.y, maskWidth, maskHeight, GL_BGRA, GL_UNSIGNED_BYTE, mask.bits());