Avoid image copy in toTexture() on GLES 3.0 as well

The default backingstore implementation is now cleaned for ES_2 ifdefs.
All the checks are now done at runtime and ES 3.0+ is included as well
for the efficient, QImage::copy()-less path.

For embedded a customized backingstore is used so the change has to be
done separately there.

This should result in a slight improvement for QOpenGLWidget/QQuickWidget
when running on GLES 3.x.

Task-number: QTBUG-37624
Change-Id: I107330c25a993c5cdcd92e4ebdc17ae172a03da8
Reviewed-by: Paul Olav Tvete <paul.tvete@theqtcompany.com>

1 files changed, 36 insertions, 22 deletions

diff --git a/src/platformsupport/platformcompositor/qopenglcompositorbackingstore.cpp b/src/platformsupport/platformcompositor/qopenglcompositorbackingstore.cpp
index 8ce1ed2d2b..bb3ea6981a 100644
--- a/src/platformsupport/platformcompositor/qopenglcompositorbackingstore.cpp
+++ b/src/platformsupport/platformcompositor/qopenglcompositorbackingstore.cpp
@@ -39,6 +39,10 @@
 #include "qopenglcompositorbackingstore_p.h"
 #include "qopenglcompositor_p.h"
 
+#ifndef GL_UNPACK_ROW_LENGTH
+#define GL_UNPACK_ROW_LENGTH              0x0CF2
+#endif
+
 QT_BEGIN_NAMESPACE
 
 /*!
@@ -100,29 +104,39 @@ void QOpenGLCompositorBackingStore::updateTexture()
         QRegion fixed;
         QRect imageRect = m_image.rect();
 
-        foreach (const QRect &rect, m_dirty.rects()) {
-            // intersect with image rect to be sure
-            QRect r = imageRect & rect;
-
-            // if the rect is wide enough it's cheaper to just
-            // extend it instead of doing an image copy
-            if (r.width() >= imageRect.width() / 2) {
-                r.setX(0);
-                r.setWidth(imageRect.width());
+        QOpenGLContext *ctx = QOpenGLContext::currentContext();
+        if (!ctx->isOpenGLES() || ctx->format().majorVersion() >= 3) {
+            foreach (const QRect &rect, m_dirty.rects()) {
+                QRect r = imageRect & rect;
+                glPixelStorei(GL_UNPACK_ROW_LENGTH, m_image.width());
+                glTexSubImage2D(GL_TEXTURE_2D, 0, r.x(), r.y(), r.width(), r.height(), GL_RGBA, GL_UNSIGNED_BYTE,
+                                m_image.constScanLine(r.y()) + r.x() * 4);
+                glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
             }
-
-            fixed |= r;
-        }
-
-        foreach (const QRect &rect, fixed.rects()) {
-            // if the sub-rect is full-width we can pass the image data directly to
-            // OpenGL instead of copying, since there's no gap between scanlines
-            if (rect.width() == imageRect.width()) {
-                glTexSubImage2D(GL_TEXTURE_2D, 0, 0, rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
-                                m_image.constScanLine(rect.y()));
-            } else {
-                glTexSubImage2D(GL_TEXTURE_2D, 0, rect.x(), rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
-                    m_image.copy(rect).constBits());
+        } else {
+            foreach (const QRect &rect, m_dirty.rects()) {
+                // intersect with image rect to be sure
+                QRect r = imageRect & rect;
+
+                // if the rect is wide enough it's cheaper to just
+                // extend it instead of doing an image copy
+                if (r.width() >= imageRect.width() / 2) {
+                    r.setX(0);
+                    r.setWidth(imageRect.width());
+                }
+
+                fixed |= r;
+            }
+            foreach (const QRect &rect, fixed.rects()) {
+                // if the sub-rect is full-width we can pass the image data directly to
+                // OpenGL instead of copying, since there's no gap between scanlines
+                if (rect.width() == imageRect.width()) {
+                    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
+                                    m_image.constScanLine(rect.y()));
+                } else {
+                    glTexSubImage2D(GL_TEXTURE_2D, 0, rect.x(), rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
+                                    m_image.copy(rect).constBits());
+                }
             }
         }