fix: InWindowBlur reports error in gles2

  replacing glenable with glActiveTexture.
  using opengl's function to get sufface with.

src/private/dblitframebuffernode.cpp

@@ -133,7 +133,7 @@ class Q_DECL_HIDDEN GLRenderNode : public DBlitFramebufferNode {
             m_texture->subRect.setSize(QSizeF(sourceRect.width() / fbo->width(),
                                               sourceRect.height() / fbo->height()));
         }
-        const QSizeF ss = QOpenGLContext::currentContext()->surface()->size() * scale;
+        const QSizeF ss = surfaceSize() * scale;
         const QRectF transfromSR(sourceRect.x(), ss.height() - sourceRect.y(),
                                  sourceRect.width(), -sourceRect.height());
         QOpenGLFramebufferObject::blitFramebuffer(fbo.data(), QRect(QPoint(0, 0), textureSize),
@@ -142,6 +142,22 @@ class Q_DECL_HIDDEN GLRenderNode : public DBlitFramebufferNode {
         doRenderCallback();
     }
 
+    QSizeF surfaceSize() const
+    {
+        QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();
+        const GLuint InvalidFBOId = 0;
+        GLuint currentFBO = InvalidFBOId;
+        f->glGetIntegerv(GL_FRAMEBUFFER_BINDING, (GLint*)&currentFBO);
+        if (currentFBO != InvalidFBOId) {
+            int width, height;
+            f->glBindRenderbuffer(GL_RENDERBUFFER, currentFBO);
+            f->glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, (GLint*)&width);
+            f->glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, (GLint*)&height);
+            return QSizeF(width, height);
+        }
+        return QOpenGLContext::currentContext()->surface()->size();
+    }
+
 private:
     SharedCachedFBO fbo;
 };

src/private/dblurimagenode.cpp

@@ -633,12 +633,11 @@ void DOpenGLBlurEffectNode::applyDaulBlur(QOpenGLFramebufferObject *targetFBO, G
     shader->enableAttributeArray(1);
     m_sampleVbo->release();
 
-    glEnable(GL_TEXTURE_2D);
+    f->glActiveTexture(GL_TEXTURE0);
     f->glBindTexture(GL_TEXTURE_2D, sourceTexture);
     f->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     f->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     f->glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
-    glDisable(GL_TEXTURE_2D);
     shader->release();
     targetFBO->release();