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>

1 files changed, 16 insertions, 0 deletions

diff --git a/src/gui/opengl/qopengltexturecache.cpp b/src/gui/opengl/qopengltexturecache.cpp
index 055974d5a4..f60d273361 100644
--- a/src/gui/opengl/qopengltexturecache.cpp
+++ b/src/gui/opengl/qopengltexturecache.cpp
@@ -281,6 +281,22 @@ GLuint QOpenGLTextureCache::bindTexture(QOpenGLContext *context, qint64 key, con
         pixelType = GL_UNSIGNED_BYTE;
         targetFormat = image.format();
         break;
+    case QImage::Format_Alpha8:
+        if (context->isOpenGLES() || context->format().profile() != QSurfaceFormat::CoreProfile) {
+            externalFormat = internalFormat = GL_ALPHA;
+            pixelType = GL_UNSIGNED_BYTE;
+            targetFormat = image.format();
+        }
+        // ### add support for core profiles.
+        break;
+    case QImage::Format_Grayscale8:
+        if (context->isOpenGLES() || context->format().profile() != QSurfaceFormat::CoreProfile) {
+            externalFormat = internalFormat = GL_LUMINANCE;
+            pixelType = GL_UNSIGNED_BYTE;
+            targetFormat = image.format();
+        }
+        // ### add support for core profiles.
+        break;
     default:
         break;
     }