opengl: Add GLTexture::update() overload that takes a region

This ensures a couple of things:

- avoid pointlessly binding and unbinding the texture
- if the image format needs to be changed, it will be done only once

src/opengl/gltexture.cpp

@@ -147,6 +147,11 @@ void GLTexture::setSize(const QSize &size)
 }
 
 void GLTexture::update(const QImage &image, const QPoint &offset, const QRect &src)
+{
+    update(image, src.isEmpty() ? image.rect() : src, offset);
+}
+
+void GLTexture::update(const QImage &image, const QRegion &region, const QPoint &offset)
 {
     if (image.isNull() || isNull()) {
         return;
@@ -188,25 +193,22 @@ void GLTexture::update(const QImage &image, const QPoint &offset, const QRect &s
         im.convertTo(uploadFormat);
     }
 
-    QRect rect = src;
-    if (rect.isEmpty()) {
-        rect = im.rect();
-    }
-
-    Q_ASSERT(im.depth() % 8 == 0);
-    glPixelStorei(GL_UNPACK_ROW_LENGTH, im.bytesPerLine() / (im.depth() / 8));
-    glPixelStorei(GL_UNPACK_SKIP_PIXELS, rect.x());
-    glPixelStorei(GL_UNPACK_SKIP_ROWS, rect.y());
-
     bind();
 
-    glTexSubImage2D(d->m_target, 0, offset.x(), offset.y(), rect.width(), rect.height(), glFormat, type, im.constBits());
+    for (const QRect &rect : region) {
+        Q_ASSERT(im.depth() % 8 == 0);
+        glPixelStorei(GL_UNPACK_ROW_LENGTH, im.bytesPerLine() / (im.depth() / 8));
+        glPixelStorei(GL_UNPACK_SKIP_PIXELS, rect.x());
+        glPixelStorei(GL_UNPACK_SKIP_ROWS, rect.y());
 
-    unbind();
+        glTexSubImage2D(d->m_target, 0, offset.x() + rect.x(), offset.y() + rect.y(), rect.width(), rect.height(), glFormat, type, im.constBits());
+    }
 
     glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
     glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
     glPixelStorei(GL_UNPACK_SKIP_ROWS, 0);
+
+    unbind();
 }
 
 void GLTexture::bind()

src/opengl/gltexture.h

@@ -85,6 +85,7 @@ public:
     QMatrix4x4 matrix(TextureCoordinateType type) const;
 
     void update(const QImage &image, const QPoint &offset = QPoint(0, 0), const QRect &src = QRect());
+    void update(const QImage &image, const QRegion &region, const QPoint &offset = QPoint());
     void bind();
     void unbind();
     void render(const QSizeF &size);

src/platformsupport/scenes/opengl/basiceglsurfacetexture_wayland.cpp

@@ -108,10 +108,7 @@ void BasicEGLSurfaceTextureWayland::updateShmTexture(GraphicsBuffer *buffer, con
         return;
     }
 
-    const QRegion simplifiedDamage = simplifyDamage(region);
+    m_texture.planes[0]->update(*view.image(), simplifyDamage(region));
-    for (const QRect &rect : simplifiedDamage) {
-        m_texture.planes[0]->update(*view.image(), rect.topLeft(), rect);
-    }
 }
 
 bool BasicEGLSurfaceTextureWayland::loadDmabufTexture(GraphicsBuffer *buffer)