Texture glyph cache: Use a vbo

It is not going to work with core profile otherwise.

This fixes one of the several problems that make native
text rendering in Quick impossible with OpenGL core profile.

The GL2 paint engine path is not changed, that continues to use
client side pointers.

Task-number: QTBUG-36993
Change-Id: Icfbd6efc894a79a3a84568fb792c1cb6692469cb
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>

1 files changed, 17 insertions, 3 deletions

diff --git a/src/gui/opengl/qopengltextureglyphcache.cpp b/src/gui/opengl/qopengltextureglyphcache.cpp
index ba1fa8f486..f1bf944d7b 100644
--- a/src/gui/opengl/qopengltextureglyphcache.cpp
+++ b/src/gui/opengl/qopengltextureglyphcache.cpp
@@ -58,6 +58,7 @@ QOpenGLTextureGlyphCache::QOpenGLTextureGlyphCache(QFontEngine::GlyphFormat form
     , m_blitProgram(0)
     , m_filterMode(Nearest)
     , m_serialNumber(qopengltextureglyphcache_serial_number.fetchAndAddRelaxed(1))
+    , m_buffer(QOpenGLBuffer::VertexBuffer)
 {
 #ifdef QT_GL_TEXTURE_GLYPH_CACHE_DEBUG
     qDebug(" -> QOpenGLTextureGlyphCache() %p for context %p.", this, QOpenGLContext::currentContext());
@@ -139,6 +140,18 @@ void QOpenGLTextureGlyphCache::createTextureData(int width, int height)
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     m_filterMode = Nearest;
+
+    if (!m_buffer.isCreated()) {
+        m_buffer.create();
+        m_buffer.bind();
+        static GLfloat buf[sizeof(m_vertexCoordinateArray) + sizeof(m_textureCoordinateArray)];
+        memcpy(buf, m_vertexCoordinateArray, sizeof(m_vertexCoordinateArray));
+        memcpy(buf + (sizeof(m_vertexCoordinateArray) / sizeof(GLfloat)),
+               m_textureCoordinateArray,
+               sizeof(m_textureCoordinateArray));
+        m_buffer.allocate(buf, sizeof(buf));
+        m_buffer.release();
+    }
 }
 
 void QOpenGLTextureGlyphCache::resizeTextureData(int width, int height)
@@ -239,10 +252,10 @@ void QOpenGLTextureGlyphCache::resizeTextureData(int width, int height)
             m_blitProgram->link();
         }
 
-        funcs.glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, m_vertexCoordinateArray);
-        funcs.glVertexAttribPointer(QT_TEXTURE_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, m_textureCoordinateArray);
-
+        m_buffer.bind();
         m_blitProgram->bind();
+        m_blitProgram->setAttributeBuffer(int(QT_VERTEX_COORDS_ATTR), GL_FLOAT, 0, 2);
+        m_blitProgram->setAttributeBuffer(int(QT_TEXTURE_COORDS_ATTR), GL_FLOAT, sizeof(m_vertexCoordinateArray), 2);
         m_blitProgram->enableAttributeArray(int(QT_VERTEX_COORDS_ATTR));
         m_blitProgram->enableAttributeArray(int(QT_TEXTURE_COORDS_ATTR));
         m_blitProgram->disableAttributeArray(int(QT_OPACITY_ATTR));
@@ -278,6 +291,7 @@ void QOpenGLTextureGlyphCache::resizeTextureData(int width, int height)
     } else {
         m_blitProgram->disableAttributeArray(int(QT_VERTEX_COORDS_ATTR));
         m_blitProgram->disableAttributeArray(int(QT_TEXTURE_COORDS_ATTR));
+        m_buffer.release();
     }
 }