scenes/opengl: Port lanczos filter to ShaderManager::generateShaderFromFile()

src/scenes/opengl/lanczosfilter.cpp

@@ -76,14 +76,8 @@ void LanczosFilter::init()
             return;
         }
     }
-    QFile ff(gl->glslVersion() >= kVersionNumber(1, 40) ?
-             QStringLiteral(":/scenes/opengl/shaders/1.40/lanczos-fragment.glsl") :
-             QStringLiteral(":/scenes/opengl/shaders/1.10/lanczos-fragment.glsl"));
-    if (!ff.open(QIODevice::ReadOnly)) {
-        qCDebug(KWIN_OPENGL) << "Failed to open lanczos shader";
-        return;
-    }
-    m_shader.reset(ShaderManager::instance()->generateCustomShader(ShaderTrait::MapTexture, QByteArray(), ff.readAll()));
+
+    m_shader.reset(ShaderManager::instance()->generateShaderFromFile(ShaderTrait::MapTexture, QString(), QStringLiteral(":/scenes/opengl/shaders/lanczos.frag")));
     if (m_shader->isValid()) {
         ShaderBinder binder(m_shader.data());
         m_uKernel     = m_shader->uniformLocation("kernel");

src/scenes/opengl/lanczosresources.qrc

@@ -1,6 +1,6 @@
 <!DOCTYPE RCC><RCC version="1.0">
 <qresource prefix="/scenes/opengl">
-  <file>shaders/1.10/lanczos-fragment.glsl</file>
-  <file>shaders/1.40/lanczos-fragment.glsl</file>
+  <file>shaders/lanczos.frag</file>
+  <file>shaders/lanczos_core.frag</file>
 </qresource>
 </RCC>