Limit the lower glyph texture cache size to 16x16 in GL.

The SGX chip has a limitation regarding FBOs in that it doesn't support
FBO sizes that are POT and less than 16 pixels in width/height.
Since the FBO we use in the GL glyph cache always mirrors the size
of the texture itself, we limit that instead to avoid creating
invalid FBOs.

Task-number: QTBUG-10645
Reviewed-by: Gunnar

1 files changed, 12 insertions, 0 deletions

diff --git a/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp b/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
index cc42c63..410cf21 100644
--- a/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
+++ b/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
@@ -91,6 +91,12 @@ void QGLTextureGlyphCache::createTextureData(int width, int height)
     if (ctx->d_ptr->workaround_brokenFBOReadBack && image().isNull())
         QImageTextureGlyphCache::createTextureData(width, height);
 
+    // Make the lower glyph texture size 16 x 16.
+    if (width < 16)
+        width = 16;
+    if (height < 16)
+        height = 16;
+
     glGenTextures(1, &m_texture);
     glBindTexture(GL_TEXTURE_2D, m_texture);
 
@@ -115,6 +121,12 @@ void QGLTextureGlyphCache::resizeTextureData(int width, int height)
     int oldWidth = m_width;
     int oldHeight = m_height;
 
+    // Make the lower glyph texture size 16 x 16.
+    if (width < 16)
+        width = 16;
+    if (height < 16)
+        height = 16;
+
     GLuint oldTexture = m_texture;
     createTextureData(width, height);