platforms/drm: refactor post processing bits

Putting the OpenGL post processing rotation into its own class cleans
the EglGbmBackend code up a bit and adds post processing rotation for
the EglStreamBackend

src/plugins/platforms/drm/CMakeLists.txt

@@ -14,6 +14,7 @@ set(DRM_SOURCES
     egl_multi_backend.cpp
     abstract_egl_drm_backend.cpp
     dumb_swapchain.cpp
+    shadowbuffer.cpp
 )
 
 if (HAVE_GBM)

src/plugins/platforms/drm/egl_gbm_backend.cpp

@@ -24,6 +24,7 @@
 #include "linux_dmabuf.h"
 #include "dumb_swapchain.h"
 #include "kwineglutils_p.h"
+#include "shadowbuffer.h"
 // kwin libs
 #include <kwinglplatform.h>
 #include <kwineglimagetexture.h>
@@ -60,21 +61,12 @@ void EglGbmBackend::cleanupSurfaces()
     m_outputs.clear();
 }
 
-void EglGbmBackend::cleanupFramebuffer(Output &output)
-{
-    if (!output.render.framebuffer) {
-        return;
-    }
-    makeContextCurrent(output);
-    glDeleteTextures(1, &output.render.texture);
-    output.render.texture = 0;
-    glDeleteFramebuffers(1, &output.render.framebuffer);
-    output.render.framebuffer = 0;
-}
-
 void EglGbmBackend::cleanupOutput(Output &output)
 {
-    cleanupFramebuffer(output);
+    if (output.shadowBuffer) {
+        makeContextCurrent(output);
+        output.shadowBuffer = nullptr;
+    }
 
     if (output.eglSurface != EGL_NO_SURFACE) {
         // gbm buffers have to be released before destroying the egl surface
@@ -205,7 +197,15 @@ bool EglGbmBackend::resetOutput(Output &output, DrmOutput *drmOutput)
     output.eglSurface = eglSurface;
     output.gbmSurface = gbmSurface;
 
-    resetFramebuffer(output);
+    if (output.output->hardwareTransforms()) {
+        output.shadowBuffer = nullptr;
+    } else {
+        makeContextCurrent(output);
+        output.shadowBuffer = QSharedPointer<ShadowBuffer>::create(output.output->pixelSize());
+        if (!output.shadowBuffer->isComplete()) {
+            return false;
+        }
+    }
     return true;
 }
 
@@ -393,138 +393,14 @@ void EglGbmBackend::importFramebuffer(Output &output) const
     // TODO turn off output?
 }
 
-const float vertices[] = {
-   -1.0f,  1.0f,
-   -1.0f, -1.0f,
-    1.0f, -1.0f,
-
-   -1.0f,  1.0f,
-    1.0f, -1.0f,
-    1.0f,  1.0f,
-};
-
-const float texCoords[] = {
-    0.0f,  1.0f,
-    0.0f,  0.0f,
-    1.0f,  0.0f,
-
-    0.0f,  1.0f,
-    1.0f,  0.0f,
-    1.0f,  1.0f
-};
-
-bool EglGbmBackend::resetFramebuffer(Output &output)
-{
-    cleanupFramebuffer(output);
-
-    if (output.output->hardwareTransforms()) {
-        // No need for an extra render target.
-        return true;
-    }
-
-    makeContextCurrent(output);
-
-    glGenFramebuffers(1, &output.render.framebuffer);
-    glBindFramebuffer(GL_FRAMEBUFFER, output.render.framebuffer);
-    GLRenderTarget::setKWinFramebuffer(output.render.framebuffer);
-
-    glGenTextures(1, &output.render.texture);
-    glBindTexture(GL_TEXTURE_2D, output.render.texture);
-
-    const QSize texSize = output.output->pixelSize();
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texSize.width(), texSize.height(),
-                 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-
-    glBindTexture(GL_TEXTURE_2D, 0);
-
-    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
-                           output.render.texture, 0);
-
-    if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
-        qCWarning(KWIN_DRM) << "Error: framebuffer not complete";
-        return false;
-    }
-
-    glBindFramebuffer(GL_FRAMEBUFFER, 0);
-    GLRenderTarget::setKWinFramebuffer(0);
-
-    return true;
-}
-
-void EglGbmBackend::initRenderTarget(Output &output)
-{
-    if (output.render.vbo) {
-        // Already initialized.
-        return;
-    }
-    QSharedPointer<GLVertexBuffer> vbo(new GLVertexBuffer(KWin::GLVertexBuffer::Static));
-    vbo->setData(6, 2, vertices, texCoords);
-    output.render.vbo = vbo;
-}
-
 void EglGbmBackend::renderFramebufferToSurface(Output &output)
 {
-    if (!output.render.framebuffer) {
+    if (!output.shadowBuffer) {
         // No additional render target.
         return;
     }
     makeContextCurrent(output);
-
-    const auto size = output.output->modeSize();
-    glViewport(0, 0, size.width(), size.height());
-
-    auto shader = ShaderManager::instance()->pushShader(ShaderTrait::MapTexture);
-
-    QMatrix4x4 mvpMatrix;
-
-    const DrmOutput *drmOutput = output.output;
-    switch (drmOutput->transform()) {
-    case DrmOutput::Transform::Normal:
-    case DrmOutput::Transform::Flipped:
-        break;
-    case DrmOutput::Transform::Rotated90:
-    case DrmOutput::Transform::Flipped90:
-        mvpMatrix.rotate(90, 0, 0, 1);
-        break;
-    case DrmOutput::Transform::Rotated180:
-    case DrmOutput::Transform::Flipped180:
-        mvpMatrix.rotate(180, 0, 0, 1);
-        break;
-    case DrmOutput::Transform::Rotated270:
-    case DrmOutput::Transform::Flipped270:
-        mvpMatrix.rotate(270, 0, 0, 1);
-        break;
-    }
-    switch (drmOutput->transform()) {
-    case DrmOutput::Transform::Flipped:
-    case DrmOutput::Transform::Flipped90:
-    case DrmOutput::Transform::Flipped180:
-    case DrmOutput::Transform::Flipped270:
-        mvpMatrix.scale(-1, 1);
-        break;
-    default:
-        break;
-    }
-
-    shader->setUniform(GLShader::ModelViewProjectionMatrix, mvpMatrix);
-
-    initRenderTarget(output);
-
-    glBindFramebuffer(GL_FRAMEBUFFER, 0);
-    GLRenderTarget::setKWinFramebuffer(0);
-    glBindTexture(GL_TEXTURE_2D, output.render.texture);
-    output.render.vbo->render(GL_TRIANGLES);
-    ShaderManager::instance()->popShader();
-    glBindTexture(GL_TEXTURE_2D, 0);
-}
-
-void EglGbmBackend::prepareRenderFramebuffer(const Output &output) const
-{
-    // When render.framebuffer is 0 we may just reset to the screen framebuffer.
-    glBindFramebuffer(GL_FRAMEBUFFER, output.render.framebuffer);
-    GLRenderTarget::setKWinFramebuffer(output.render.framebuffer);
+    output.shadowBuffer->render(output.output);
 }
 
 bool EglGbmBackend::makeContextCurrent(const Output &output) const
@@ -706,7 +582,9 @@ QRegion EglGbmBackend::beginFrame(int screenId)
 QRegion EglGbmBackend::prepareRenderingForOutput(Output &output) const
 {
     makeContextCurrent(output);
-    prepareRenderFramebuffer(output);
+    if (output.shadowBuffer) {
+        output.shadowBuffer->bind();
+    }
     setViewport(output);
 
     if (supportsBufferAge()) {
@@ -861,8 +739,8 @@ QSharedPointer<GLTexture> EglGbmBackend::textureForOutput(AbstractOutput *abstra
     }
 
     DrmOutput *drmOutput = itOutput->output;
-    if (!drmOutput->hardwareTransforms()) {
-        const auto glTexture = QSharedPointer<KWin::GLTexture>::create(itOutput->render.texture, GL_RGBA8, drmOutput->pixelSize());
+    if (itOutput->shadowBuffer) {
+        const auto glTexture = QSharedPointer<KWin::GLTexture>::create(itOutput->shadowBuffer->texture(), GL_RGBA8, drmOutput->pixelSize());
         glTexture->setYInverted(true);
         return glTexture;
     }

src/plugins/platforms/drm/egl_gbm_backend.h

@@ -32,6 +32,7 @@ class DrmOutput;
 class GbmSurface;
 class GbmBuffer;
 class DumbSwapchain;
+class ShadowBuffer;
 
 /**
  * @brief OpenGL Backend using Egl on a GBM surface.
@@ -91,11 +92,7 @@ private:
          */
         QList<QRegion> damageHistory;
 
-        struct {
-            GLuint framebuffer = 0;
-            GLuint texture = 0;
-            QSharedPointer<GLVertexBuffer> vbo;
-        } render;
+        QSharedPointer<ShadowBuffer> shadowBuffer;
 
         KWaylandServer::SurfaceInterface *surfaceInterface = nullptr;
         ImportMode importMode = ImportMode::Dmabuf;
@@ -108,9 +105,6 @@ private:
     bool makeContextCurrent(const Output &output) const;
     void setViewport(const Output &output) const;
 
-    bool resetFramebuffer(Output &output);
-    void initRenderTarget(Output &output);
-
     void prepareRenderFramebuffer(const Output &output) const;
     void renderFramebufferToSurface(Output &output);
     QRegion prepareRenderingForOutput(Output &output) const;

src/plugins/platforms/drm/egl_stream_backend.cpp

@@ -25,6 +25,7 @@
 #include "drm_gpu.h"
 #include "dumb_swapchain.h"
 #include "kwineglutils_p.h"
+#include "shadowbuffer.h"
 
 #include <QOpenGLContext>
 #include <KWaylandServer/buffer_interface.h>
@@ -88,13 +89,13 @@ EglStreamBackend::~EglStreamBackend()
 
 void EglStreamBackend::cleanupSurfaces()
 {
-    for (auto it = m_outputs.constBegin(); it != m_outputs.constEnd(); ++it) {
+    for (auto it = m_outputs.begin(); it != m_outputs.end(); ++it) {
         cleanupOutput(*it);
     }
     m_outputs.clear();
 }
 
-void EglStreamBackend::cleanupOutput(const Output &o)
+void EglStreamBackend::cleanupOutput(Output &o)
 {
     if (o.eglSurface != EGL_NO_SURFACE) {
         eglDestroySurface(eglDisplay(), o.eglSurface);
@@ -102,6 +103,7 @@ void EglStreamBackend::cleanupOutput(const Output &o)
     if (o.eglStream != EGL_NO_STREAM_KHR) {
         pEglDestroyStreamKHR(eglDisplay(), o.eglStream);
     }
+    o.shadowBuffer = nullptr;
 }
 
 bool EglStreamBackend::initializeEgl()
@@ -356,6 +358,15 @@ bool EglStreamBackend::resetOutput(Output &o, DrmOutput *drmOutput)
 
         o.eglStream = stream;
         o.eglSurface = eglSurface;
+
+        if (!drmOutput->hardwareTransforms()) {
+            makeContextCurrent(o);
+            o.shadowBuffer = QSharedPointer<ShadowBuffer>::create(o.output->pixelSize());
+            if (!o.shadowBuffer->isComplete()) {
+                cleanupOutput(o);
+                return false;
+            }
+        }
     } else {
         QSize size = drmOutput->hardwareTransforms() ? drmOutput->pixelSize() : drmOutput->modeSize();
         o.dumbSwapchain = QSharedPointer<DumbSwapchain>::create(m_gpu, size);
@@ -477,6 +488,9 @@ QRegion EglStreamBackend::beginFrame(int screenId)
     const Output &o = m_outputs.at(screenId);
     if (isPrimary()) {
         makeContextCurrent(o);
+        if (o.shadowBuffer) {
+            o.shadowBuffer->bind();
+        }
         return o.output->geometry();
     } else {
         return renderingBackend()->beginFrameForSecondaryGpu(o.output);
@@ -496,6 +510,9 @@ void EglStreamBackend::endFrame(int screenId, const QRegion &renderedRegion, con
     QSharedPointer<DrmDumbBuffer> buffer;
     if (isPrimary()) {
         buffer = renderOutput.buffer;
+        if (renderOutput.shadowBuffer) {
+            renderOutput.shadowBuffer->render(renderOutput.output);
+        }
         if (!eglSwapBuffers(eglDisplay(), renderOutput.eglSurface)) {
             qCCritical(KWIN_DRM) << "eglSwapBuffers() failed:" << getEglErrorString();
             frameFailed = true;

src/plugins/platforms/drm/egl_stream_backend.h

@@ -20,6 +20,7 @@ namespace KWin
 class DrmOutput;
 class DrmDumbBuffer;
 class DumbSwapchain;
+class ShadowBuffer;
 
 /**
  * @brief OpenGL Backend using Egl with an EGLDevice.
@@ -65,13 +66,14 @@ private:
         QSharedPointer<DrmDumbBuffer> buffer;
         EGLSurface eglSurface = EGL_NO_SURFACE;
         EGLStreamKHR eglStream = EGL_NO_STREAM_KHR;
+        QSharedPointer<ShadowBuffer> shadowBuffer;
 
         // for operation as secondary GPU
         QSharedPointer<DumbSwapchain> dumbSwapchain;
     };
     bool resetOutput(Output &output, DrmOutput *drmOutput);
     bool makeContextCurrent(const Output &output);
-    void cleanupOutput(const Output &output);
+    void cleanupOutput(Output &output);
 
     QVector<Output> m_outputs;
     KWaylandServer::EglStreamControllerInterface *m_eglStreamControllerInterface;

src/plugins/platforms/drm/shadowbuffer.cpp

@@ -0,0 +1,131 @@
+/*
+    KWin - the KDE window manager
+    This file is part of the KDE project.
+
+    SPDX-FileCopyrightText: 2021 Xaver Hugl <xaver.hugl@gmail.com>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+#include "shadowbuffer.h"
+
+#include "logging.h"
+#include "drm_output.h"
+
+namespace KWin
+{
+
+static const float vertices[] = {
+   -1.0f,  1.0f,
+   -1.0f, -1.0f,
+    1.0f, -1.0f,
+
+   -1.0f,  1.0f,
+    1.0f, -1.0f,
+    1.0f,  1.0f,
+};
+
+static const float texCoords[] = {
+    0.0f,  1.0f,
+    0.0f,  0.0f,
+    1.0f,  0.0f,
+
+    0.0f,  1.0f,
+    1.0f,  0.0f,
+    1.0f,  1.0f
+};
+
+ShadowBuffer::ShadowBuffer(const QSize &size)
+{
+    glGenFramebuffers(1, &m_framebuffer);
+    glBindFramebuffer(GL_FRAMEBUFFER, m_framebuffer);
+    GLRenderTarget::setKWinFramebuffer(m_framebuffer);
+
+    glGenTextures(1, &m_texture);
+    glBindTexture(GL_TEXTURE_2D, m_texture);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, size.width(), size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glBindTexture(GL_TEXTURE_2D, 0);
+
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_texture, 0);
+    if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
+        qCCritical(KWIN_DRM) << "Error: framebuffer not complete!";
+        return;
+    }
+
+    glBindFramebuffer(GL_FRAMEBUFFER, 0);
+    GLRenderTarget::setKWinFramebuffer(0);
+
+    m_vbo.reset(new GLVertexBuffer(KWin::GLVertexBuffer::Static));
+    m_vbo->setData(6, 2, vertices, texCoords);
+}
+
+ShadowBuffer::~ShadowBuffer()
+{
+    glDeleteTextures(1, &m_texture);
+    glDeleteFramebuffers(1, &m_framebuffer);
+}
+
+void ShadowBuffer::render(DrmOutput *output)
+{
+    const auto size = output->modeSize();
+    glViewport(0, 0, size.width(), size.height());
+    auto shader = ShaderManager::instance()->pushShader(ShaderTrait::MapTexture);
+
+    QMatrix4x4 mvpMatrix;
+
+    switch (output->transform()) {
+    case DrmOutput::Transform::Normal:
+    case DrmOutput::Transform::Flipped:
+        break;
+    case DrmOutput::Transform::Rotated90:
+    case DrmOutput::Transform::Flipped90:
+        mvpMatrix.rotate(90, 0, 0, 1);
+        break;
+    case DrmOutput::Transform::Rotated180:
+    case DrmOutput::Transform::Flipped180:
+        mvpMatrix.rotate(180, 0, 0, 1);
+        break;
+    case DrmOutput::Transform::Rotated270:
+    case DrmOutput::Transform::Flipped270:
+        mvpMatrix.rotate(270, 0, 0, 1);
+        break;
+    }
+    switch (output->transform()) {
+    case DrmOutput::Transform::Flipped:
+    case DrmOutput::Transform::Flipped90:
+    case DrmOutput::Transform::Flipped180:
+    case DrmOutput::Transform::Flipped270:
+        mvpMatrix.scale(-1, 1);
+        break;
+    default:
+        break;
+    }
+
+    shader->setUniform(GLShader::ModelViewProjectionMatrix, mvpMatrix);
+
+    glBindFramebuffer(GL_FRAMEBUFFER, 0);
+    GLRenderTarget::setKWinFramebuffer(0);
+    glBindTexture(GL_TEXTURE_2D, m_texture);
+    m_vbo->render(GL_TRIANGLES);
+    ShaderManager::instance()->popShader();
+    glBindTexture(GL_TEXTURE_2D, 0);
+}
+
+void ShadowBuffer::bind()
+{
+    glBindFramebuffer(GL_FRAMEBUFFER, m_framebuffer);
+    GLRenderTarget::setKWinFramebuffer(m_framebuffer);
+}
+
+bool ShadowBuffer::isComplete() const
+{
+    return m_texture && m_framebuffer && m_vbo;
+}
+
+int ShadowBuffer::texture() const
+{
+    return m_texture;
+}
+
+}

src/plugins/platforms/drm/shadowbuffer.h

@@ -0,0 +1,38 @@
+/*
+    KWin - the KDE window manager
+    This file is part of the KDE project.
+
+    SPDX-FileCopyrightText: 2021 Xaver Hugl <xaver.hugl@gmail.com>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+#pragma once
+
+#include <QSize>
+#include <kwinglutils.h>
+
+namespace KWin
+{
+
+class DrmOutput;
+
+class ShadowBuffer
+{
+public:
+    ShadowBuffer(const QSize &size);
+    ~ShadowBuffer();
+
+    bool isComplete() const;
+
+    void bind();
+    void render(DrmOutput *output);
+
+    int texture() const;
+
+private:
+    GLuint m_texture;
+    GLuint m_framebuffer;
+    QScopedPointer<GLVertexBuffer> m_vbo;
+};
+
+}