Add Grayscale8 and Alpha8 formats to QImage and drawing

Extend the QImage format with two 8-bit grayscale and alpha formats.
These formats have the advantage over Indexed8 that they have simpler
conversion and can be rendered to by the raster engine.

[ChangeLog][QtGui][QImage] Added support grayscale and alpha 8-bit
formats which can also be rendered to.

Change-Id: I4343c80a92a3dda196aa38d0c3ea251b094fc274
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

2 files changed, 6 insertions, 16 deletions

diff --git a/src/plugins/platforms/windows/qwindowsfontengine.cpp b/src/plugins/platforms/windows/qwindowsfontengine.cpp
index 35b7f13ea4..ff2cfe4745 100644
--- a/src/plugins/platforms/windows/qwindowsfontengine.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontengine.cpp
@@ -1168,19 +1168,13 @@ QImage QWindowsFontEngine::alphaMapForGlyph(glyph_t glyph, const QTransform &xfo
         return QImage();
     }
 
-    QImage indexed(mask->width(), mask->height(), QImage::Format_Indexed8);
+    QImage alphaMap(mask->width(), mask->height(), QImage::Format_Alpha8);
 
-    // ### This part is kinda pointless, but we'll crash later if we don't because some
-    // code paths expects there to be colortables for index8-bit...
-    QVector<QRgb> colors(256);
-    for (int i=0; i<256; ++i)
-        colors[i] = qRgba(0, 0, 0, i);
-    indexed.setColorTable(colors);
 
     // Copy data... Cannot use QPainter here as GDI has messed up the
     // Alpha channel of the ni.image pixels...
     for (int y=0; y<mask->height(); ++y) {
-        uchar *dest = indexed.scanLine(y);
+        uchar *dest = alphaMap.scanLine(y);
         if (mask->image().format() == QImage::Format_RGB16) {
             const qint16 *src = (qint16 *) ((const QImage &) mask->image()).scanLine(y);
             for (int x=0; x<mask->width(); ++x)
@@ -1202,7 +1196,7 @@ QImage QWindowsFontEngine::alphaMapForGlyph(glyph_t glyph, const QTransform &xfo
         DeleteObject(font);
     }
 
-    return indexed;
+    return alphaMap;
 }
 
 #define SPI_GETFONTSMOOTHINGCONTRAST           0x200C
diff --git a/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp b/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
index 15b14aff1a..9825653a62 100644
--- a/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
@@ -493,15 +493,11 @@ QImage QWindowsFontEngineDirectWrite::alphaMapForGlyph(glyph_t glyph, QFixed sub
 {
     QImage im = imageForGlyph(glyph, subPixelPosition, 0, QTransform());
 
-    QImage indexed(im.width(), im.height(), QImage::Format_Indexed8);
-    QVector<QRgb> colors(256);
-    for (int i=0; i<256; ++i)
-        colors[i] = qRgba(0, 0, 0, i);
-    indexed.setColorTable(colors);
+    QImage alphaMap(im.width(), im.height(), QImage::Format_Alpha8);
 
     for (int y=0; y<im.height(); ++y) {
         uint *src = (uint*) im.scanLine(y);
-        uchar *dst = indexed.scanLine(y);
+        uchar *dst = alphaMap.scanLine(y);
         for (int x=0; x<im.width(); ++x) {
             *dst = 255 - (m_fontEngineData->pow_gamma[qGray(0xffffffff - *src)] * 255. / 2047.);
             ++dst;
@@ -509,7 +505,7 @@ QImage QWindowsFontEngineDirectWrite::alphaMapForGlyph(glyph_t glyph, QFixed sub
         }
     }
 
-    return indexed;
+    return alphaMap;
 }
 
 bool QWindowsFontEngineDirectWrite::supportsSubPixelPositions() const