[libcamera-devel] [PATCH v5 3/4] qcam: add viewfinderGL class to accelerate the format convert

Show Liu show.liu at linaro.org
Thu Sep 10 11:38:31 CEST 2020


Hi Laurent,

On Mon, Sep 7, 2020 at 7:10 AM Laurent Pinchart <
laurent.pinchart at ideasonboard.com> wrote:

> On Sun, Sep 06, 2020 at 07:18:07PM +0300, Laurent Pinchart wrote:
> > Hi Show,
> >
> > Thank you for the patch.
> >
> > On Fri, Sep 04, 2020 at 04:43:15PM +0800, Show Liu wrote:
> > > the viewfinderGL accelerates the format conversion by
> > > using OpenGL ES shader
> > >
> > > Signed-off-by: Show Liu <show.liu at linaro.org>
> > > ---
> > >  src/qcam/meson.build       |   2 +
> > >  src/qcam/viewfinder_gl.cpp | 441 +++++++++++++++++++++++++++++++++++++
> > >  src/qcam/viewfinder_gl.h   |  97 ++++++++
> > >  3 files changed, 540 insertions(+)
> > >  create mode 100644 src/qcam/viewfinder_gl.cpp
> > >  create mode 100644 src/qcam/viewfinder_gl.h
> > >
> > > diff --git a/src/qcam/meson.build b/src/qcam/meson.build
> > > index a4bad0a..32c0fc3 100644
> > > --- a/src/qcam/meson.build
> > > +++ b/src/qcam/meson.build
> > > @@ -7,11 +7,13 @@ qcam_sources = files([
> > >      'main.cpp',
> > >      'main_window.cpp',
> > >      'viewfinder_qt.cpp',
> > > +    'viewfinder_gl.cpp',
> >
> > Let's keep files alphabetically sorted.
> >
> > >  ])
> > >
> > >  qcam_moc_headers = files([
> > >      'main_window.h',
> > >      'viewfinder_qt.h',
> > > +    'viewfinder_gl.h',
> >
> > Here too.
> >
> > >  ])
> > >
> > >  qcam_resources = files([
> >
> > You need to set the minimum Qt version to 5.4, as QOpenGLWidget wasn't
> > available before that.
> >
> > diff --git a/src/qcam/meson.build b/src/qcam/meson.build
> > index 32c0fc3e0f6b..9d3f189a896b 100644
> > --- a/src/qcam/meson.build
> > +++ b/src/qcam/meson.build
> > @@ -25,7 +25,8 @@ qt5 = import('qt5')
> >  qt5_dep = dependency('qt5',
> >                       method : 'pkg-config',
> >                       modules : ['Core', 'Gui', 'Widgets'],
> > -                     required : get_option('qcam'))
> > +                     required : get_option('qcam'),
> > +                     version : '>=5.4')
> >
> >  if qt5_dep.found()
> >      qcam_deps = [
> >
> > Furthermore, Qt can be compiled without OpenGL support, in which case
> > this patch will fail to compile. The following change should address it.
> >
> > diff --git a/meson.build b/meson.build
> > index b6c99ba8e0eb..5f7d619a79d0 100644
> > --- a/meson.build
> > +++ b/meson.build
> > @@ -26,6 +26,7 @@ libcamera_version = libcamera_git_version.split('+')[0]
> >
> >  # Configure the build environment.
> >  cc = meson.get_compiler('c')
> > +cxx = meson.get_compiler('cpp')
> >  config_h = configuration_data()
> >
> >  if cc.has_header_symbol('execinfo.h', 'backtrace')
> > diff --git a/src/qcam/meson.build b/src/qcam/meson.build
> > index 32c0fc3e0f6b..9bb48c0d06c5 100644
> > --- a/src/qcam/meson.build
> > +++ b/src/qcam/meson.build
> > @@ -7,18 +7,15 @@ qcam_sources = files([
> >      'main.cpp',
> >      'main_window.cpp',
> >      'viewfinder_qt.cpp',
> > -    'viewfinder_gl.cpp',
> >  ])
> >
> >  qcam_moc_headers = files([
> >      'main_window.h',
> >      'viewfinder_qt.h',
> > -    'viewfinder_gl.h',
> >  ])
> >
> >  qcam_resources = files([
> >      'assets/feathericons/feathericons.qrc',
> > -    'assets/shader/shaders.qrc'
> >  ])
> >
> >  qt5 = import('qt5')
> > @@ -44,6 +42,19 @@ if qt5_dep.found()
> >          ])
> >      endif
> >
> > +    if cxx.has_header_symbol('QOpenGLWidget', 'QOpenGLWidget',
> > +                             dependencies : qt5_dep, args : '-fPIC')
> > +        qcam_sources += files([
> > +            'viewfinder_gl.cpp',
> > +        ])
> > +        qcam_moc_headers += files([
> > +            'viewfinder_gl.h',
> > +        ])
> > +        qcam_resources += files([
> > +            'assets/shader/shaders.qrc'
> > +        ])
> > +    endif
> > +
> >      # gcc 9 introduced a deprecated-copy warning that is triggered by
> Qt until
> >      # Qt 5.13. clang 10 introduced the same warning, but detects more
> issues
> >      # that are not fixed in Qt yet. Disable the warning manually in
> both cases.
> >
> > Patch 4/4 will need to be updated to with conditional compilation on
> > QT_NO_OPENGL.
> >
> > > diff --git a/src/qcam/viewfinder_gl.cpp b/src/qcam/viewfinder_gl.cpp
> > > new file mode 100644
> > > index 0000000..5591916
> > > --- /dev/null
> > > +++ b/src/qcam/viewfinder_gl.cpp
> > > @@ -0,0 +1,441 @@
> > > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > > +/*
> > > + * Copyright (C) 2020, Linaro
> > > + *
> > > + * viewfinderGL.cpp - Render YUV format frame by OpenGL shader
> > > + */
> > > +
> > > +#include "viewfinder_gl.h"
> > > +
> > > +#include <QImage>
> > > +
> > > +#include <libcamera/formats.h>
> > > +
> > > +#define ATTRIB_VERTEX 0
> > > +#define ATTRIB_TEXTURE 1
> >
> > Is there a guarantee that attribute locations match the declaration
> > order in the shader program ? Wouldn't it be better to use
> > shaderProgram.attributeLocation() to retrieve the attribute locations by
> > name (before linking), or shaderProgram.bindAttributeLocation() to set
> > them explicitly (after linking) ?
> >
> > > +
> > > +static const QList<libcamera::PixelFormat> supportFormats{
> >
> > s/supportFormats/supportedFormats/
> >
> > > +   libcamera::formats::NV12,
> > > +   libcamera::formats::NV21,
> > > +   libcamera::formats::NV16,
> > > +   libcamera::formats::NV61,
> > > +   libcamera::formats::NV24,
> > > +   libcamera::formats::NV42,
> > > +   libcamera::formats::YUV420,
> > > +   libcamera::formats::YVU420
> > > +};
> > > +
> > > +ViewFinderGL::ViewFinderGL(QWidget *parent)
> > > +   : QOpenGLWidget(parent),
> > > +     buffer_(nullptr),
> > > +     pFShader_(nullptr),
> > > +     pVShader_(nullptr),
> > > +     vbuf_(QOpenGLBuffer::VertexBuffer),
> > > +     yuvDataPtr_(nullptr),
> > > +     textureU_(QOpenGLTexture::Target2D),
> > > +     textureV_(QOpenGLTexture::Target2D),
> > > +     textureY_(QOpenGLTexture::Target2D)
> >
> > Feel free to have multiple members per line if desired.
> >
> > > +{
> > > +}
> > > +
> > > +ViewFinderGL::~ViewFinderGL()
> > > +{
> > > +   removeShader();
> > > +
> > > +   if (textureY_.isCreated())
> > > +           textureY_.destroy();
> > > +
> > > +   if (textureU_.isCreated())
> > > +           textureU_.destroy();
> > > +
> > > +   if (textureV_.isCreated())
> > > +           textureV_.destroy();
> >
> > Are these needed, or does the QOpenGLTexture destructor destroy the
> > textures ?
> >
> > > +
> > > +   vbuf_.destroy();
> >
> > Same question for vbuf_.
> >
> > > +}
> > > +
> > > +const QList<libcamera::PixelFormat> &ViewFinderGL::nativeFormats()
> const
> > > +{
> > > +   return (::supportFormats);
> >
> > No need for parentheses or an explicit namespace.
> >
> >       return supportedFormats;
> >
> > > +}
> > > +
> > > +int ViewFinderGL::setFormat(const libcamera::PixelFormat &format,
> > > +                       const QSize &size)
> > > +{
> > > +   int ret = 0;
> > > +
> > > +   if (isFormatSupport(format)) {
> > > +           format_ = format;
> > > +           size_ = size;
> > > +   } else {
> > > +           ret = -1;
> > > +   }
> > > +   updateGeometry();
> >
> > When the format change, don't you need to recreate the shaders ?
> >
> > > +   return ret;
> > > +}
> > > +
> > > +void ViewFinderGL::stop()
> > > +{
> > > +   if (buffer_) {
> > > +           renderComplete(buffer_);
> > > +           buffer_ = nullptr;
> > > +   }
> > > +}
> > > +
> > > +QImage ViewFinderGL::getCurrentImage()
> > > +{
> > > +   QMutexLocker locker(&mutex_);
> > > +
> > > +   return (grabFramebuffer());
> >
> >       return grabFrameBuffer();
> >
> > > +}
> > > +
> > > +void ViewFinderGL::render(libcamera::FrameBuffer *buffer,
> MappedBuffer *map)
> > > +{
> > > +   if (buffer->planes().size() != 1) {
> > > +           qWarning() << "Multi-planar buffers are not supported";
> > > +           return;
> > > +   }
> > > +
> > > +   if (buffer_)
> > > +           renderComplete(buffer_);
> > > +
> > > +   unsigned char *memory = static_cast<unsigned char *>(map->memory);
> > > +   if (memory) {
> >
> > Can memory be null ?
> >
> > > +           yuvDataPtr_ = memory;
> > > +           update();
> > > +           buffer_ = buffer;
> > > +   }
> > > +}
> > > +
> > > +bool ViewFinderGL::isFormatSupport(const libcamera::PixelFormat
> &format)
> > > +{
> >
> > As this function sets internal members based on the format, I would call
> > it selectFormat(), it does more than just checking if the format is
> > supported.
> >
> > > +   bool ret = true;
> > > +   switch (format) {
> > > +   case libcamera::formats::NV12:
> > > +           horzSubSample_ = 2;
> > > +           vertSubSample_ = 2;
> > > +           vsrc_ = ":NV_vertex_shader.glsl";
> > > +           fsrc_ = ":NV_2_planes_UV_f.glsl";
> > > +           break;
> > > +   case libcamera::formats::NV21:
> > > +           horzSubSample_ = 2;
> > > +           vertSubSample_ = 2;
> > > +           vsrc_ = ":NV_vertex_shader.glsl";
> > > +           fsrc_ = ":NV_2_planes_VU_f.glsl";
> > > +           break;
> > > +   case libcamera::formats::NV16:
> > > +           horzSubSample_ = 2;
> > > +           vertSubSample_ = 1;
> > > +           vsrc_ = ":NV_vertex_shader.glsl";
> > > +           fsrc_ = ":NV_2_planes_UV_f.glsl";
> > > +           break;
> > > +   case libcamera::formats::NV61:
> > > +           horzSubSample_ = 2;
> > > +           vertSubSample_ = 1;
> > > +           vsrc_ = ":NV_vertex_shader.glsl";
> > > +           fsrc_ = ":NV_2_planes_VU_f.glsl";
> > > +           break;
> > > +   case libcamera::formats::NV24:
> > > +           horzSubSample_ = 1;
> > > +           vertSubSample_ = 1;
> > > +           vsrc_ = ":NV_vertex_shader.glsl";
> > > +           fsrc_ = ":NV_2_planes_UV_f.glsl";
> > > +           break;
> > > +   case libcamera::formats::NV42:
> > > +           horzSubSample_ = 1;
> > > +           vertSubSample_ = 1;
> > > +           vsrc_ = ":NV_vertex_shader.glsl";
> > > +           fsrc_ = ":NV_2_planes_VU_f.glsl";
> > > +           break;
> > > +   case libcamera::formats::YUV420:
> > > +           horzSubSample_ = 2;
> > > +           vertSubSample_ = 2;
> > > +           vsrc_ = ":NV_vertex_shader.glsl";
> > > +           fsrc_ = ":NV_3_planes_UV_f.glsl";
> > > +           break;
> > > +   case libcamera::formats::YVU420:
> > > +           horzSubSample_ = 2;
> > > +           vertSubSample_ = 2;
> > > +           vsrc_ = ":NV_vertex_shader.glsl";
> > > +           fsrc_ = ":NV_3_planes_VU_f.glsl";
> > > +           break;
> > > +   default:
> > > +           ret = false;
> > > +           qWarning() << "[ViewFinderGL]:"
> > > +                      << "format not support yet.";
> >
> > s/support yet./supported/
> >
> > > +           break;
> > > +   };
> > > +
> > > +   return ret;
> > > +}
> > > +
> > > +void ViewFinderGL::createVertexShader()
> > > +{
> > > +   bool bCompile;
> >
> > No need to prefix variables with the type name.
> >
> > > +   /* Create Vertex Shader */
> > > +   pVShader_ = new QOpenGLShader(QOpenGLShader::Vertex, this);
> > > +
> > > +   bCompile = pVShader_->compileSourceFile(vsrc_);
> > > +   if (!bCompile) {
> > > +           qWarning() << "[ViewFinderGL]:" << pVShader_->log();
> > > +   }
> >
> > This can simply be written
> >
> >       if (!pVShader_->compileSourceFile(vsrc_))
> >               qWarning() << "[ViewFinderGL]:" << pVShader_->log();
> >
> > > +
> > > +   shaderProgram_.addShader(pVShader_);
> >
> > Won't this crash if shader compilation failed ? I think
> > createVertexShader() should return a status as a bool.
> >
> > > +}
> > > +
> > > +bool ViewFinderGL::createFragmentShader()
> > > +{
> > > +   bool bCompile;
> > > +
> > > +   /* Create Fragment Shader */
> > > +   pFShader_ = new QOpenGLShader(QOpenGLShader::Fragment, this);
> > > +
> > > +   bCompile = pFShader_->compileSourceFile(fsrc_);
> > > +   if (!bCompile) {
> >
> >       if (!pFShader_->compileSourceFile(fsrc_)) {
> >
> > > +           qWarning() << "[ViewFinderGL]:" << pFShader_->log();
> > > +           return bCompile;
> >
> >               return false;
> >
> > > +   }
> > > +
> > > +   shaderProgram_.addShader(pFShader_);
> > > +
> > > +   /* Link shader pipeline */
> > > +   if (!shaderProgram_.link()) {
> > > +           qWarning() << "[ViewFinderGL]:" << shaderProgram_.log();
> > > +           close();
> > > +   }
> > > +
> > > +   /* Bind shader pipeline for use */
> > > +   if (!shaderProgram_.bind()) {
> > > +           qWarning() << "[ViewFinderGL]:" << shaderProgram_.log();
> > > +           close();
> > > +   }
> > > +
> > > +   shaderProgram_.enableAttributeArray(ATTRIB_VERTEX);
> > > +   shaderProgram_.enableAttributeArray(ATTRIB_TEXTURE);
> > > +
> > > +   shaderProgram_.setAttributeBuffer(ATTRIB_VERTEX,
> > > +                                     GL_FLOAT,
> > > +                                     0,
> > > +                                     2,
> > > +                                     2 * sizeof(GLfloat));
> > > +   shaderProgram_.setAttributeBuffer(ATTRIB_TEXTURE,
> > > +                                     GL_FLOAT,
> > > +                                     8 * sizeof(GLfloat),
> > > +                                     2,
> > > +                                     2 * sizeof(GLfloat));
> > > +
> > > +   textureUniformY_ = shaderProgram_.uniformLocation("tex_y");
> > > +   textureUniformU_ = shaderProgram_.uniformLocation("tex_u");
> > > +   textureUniformV_ = shaderProgram_.uniformLocation("tex_v");
> > > +
> > > +   if (!textureY_.isCreated())
> > > +           textureY_.create();
> > > +
> > > +   if (!textureU_.isCreated())
> > > +           textureU_.create();
> > > +
> > > +   if (!textureV_.isCreated())
> > > +           textureV_.create();
> > > +
> > > +   id_y_ = textureY_.textureId();
> > > +   id_u_ = textureU_.textureId();
> > > +   id_v_ = textureV_.textureId();
> > > +   return true;
> > > +}
> > > +
> > > +void ViewFinderGL::configureTexture(unsigned int id)
> > > +{
> > > +   glBindTexture(GL_TEXTURE_2D, id);
> > > +   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
> > > +   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
> > > +   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,
> GL_CLAMP_TO_EDGE);
> > > +   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,
> GL_CLAMP_TO_EDGE);
> > > +}
> > > +
> > > +void ViewFinderGL::removeShader()
> > > +{
> > > +   if (shaderProgram_.isLinked()) {
> > > +           shaderProgram_.release();
> > > +           shaderProgram_.removeAllShaders();
> > > +   }
> > > +
> > > +   if (pFShader_)
> > > +           delete pFShader_;
> > > +
> > > +   if (pVShader_)
> > > +           delete pVShader_;
> > > +}
> > > +
> > > +void ViewFinderGL::initializeGL()
> > > +{
> > > +   initializeOpenGLFunctions();
> > > +   glEnable(GL_TEXTURE_2D);
> > > +   glDisable(GL_DEPTH_TEST);
> > > +
> > > +   static const GLfloat vertices[]{
> > > +           -1.0f, -1.0f, -1.0f, +1.0f,
> > > +           +1.0f, +1.0f, +1.0f, -1.0f,
> > > +           0.0f, 1.0f, 0.0f, 0.0f,
> > > +           1.0f, 0.0f, 1.0f, 1.0f
> > > +   };
> >
> > This is vertex and texture coordinates, not just vertices. How about
> > writing it as follows ?
> >
> >       static const GLfloat coordinates[2][4][2] {
> >               {
> >                       /* Vertex coordinates */
> >                       { -1.0f, -1.0f },
> >                       { -1.0f, +1.0f },
> >                       { +1.0f, +1.0f },
> >                       { +1.0f, -1.0f },
> >               }, {
> >                       /* Texture coordinates */
> >                       { 0.0f, 1.0f },
> >                       { 0.0f, 0.0f },
> >                       { 1.0f, 0.0f },
> >                       { 1.0f, 1.0f },
> >               },
> >       };
> >
> > There's something I don't get though, maybe you can help me understand
> > it. The vertex coordinates are copied directly to gl_Position in the
> > vertex shader, so they're essentially expressed in clip space, which I
> > understand has X pointing towards the right and Y pointing towards the
> > top. The texture coordinates, if my understand is correct again, have
> > their origin at the bottom-left corner too. The first vertex, (-1.0,
> > -1.0), which is at the bottom-left, then maps to texture coordinate
> > (0.0, 1.0), which is the top-left pixel of the texture. The image should
> > thus be flipped vertically. Why isn't it ? I'm sure I'm missing
> > somethign simple.
>
> I figured it out. The texture created with glTexImage2D() has (0,0) at
> byte 0. As the camera captures the image with the top line at the
> beginning of the buffer, the texture is stored with the top line on row
> 0. texture coordinate (0.0, 1.0) is thus the bottom-left corner of the
> texture, not the top-left corner.
>

You definitely are an OpenGL expert...:-)
The original coordinate mapping is for my camera usage on rockpi4b.
And in my case the camera module is vertical flipped.
So...anyway I am now change the coordinate mapping as default below

+       static const GLfloat coordinates[2][4][2] {
+               {
+                       /* Vertex coordinates */
+                       { -1.0f, -1.0f },
+                       { -1.0f, +1.0f },
+                       { +1.0f, +1.0f },
+                       { +1.0f, -1.0f },
+               }, {
+                       /* Texture coordinates */
+                       { 1.0f, 0.0f },
+                       { 1.0f, 1.0f },
+                       { 0.0f, 1.0f },
+                       { 0.0f, 0.0f },
+               },
Please let me know if you have any concern.

Thanks,
Show

>
> > > +
> > > +   vbuf_.create();
> > > +   vbuf_.bind();
> > > +   vbuf_.allocate(vertices, sizeof(vertices));
> > > +
> > > +   /* Create Vertex Shader */
> > > +   createVertexShader();
> > > +
> > > +   glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
> > > +}
> > > +
> > > +void ViewFinderGL::doRender()
> > > +{
> > > +   switch (format_) {
> > > +   case libcamera::formats::NV12:
> > > +   case libcamera::formats::NV21:
> > > +   case libcamera::formats::NV16:
> > > +   case libcamera::formats::NV61:
> > > +   case libcamera::formats::NV24:
> > > +   case libcamera::formats::NV42:
> > > +           /* activate texture 0 */
> > > +           glActiveTexture(GL_TEXTURE0);
> > > +           configureTexture(id_y_);
> > > +           glTexImage2D(GL_TEXTURE_2D,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        size_.width(),
> > > +                        size_.height(),
> > > +                        0,
> > > +                        GL_RED,
> > > +                        GL_UNSIGNED_BYTE,
> > > +                        yuvDataPtr_);
> > > +           glUniform1i(textureUniformY_, 0);
> >
> > Would it make sense to use
> >
> >               shaderProgram_.setUniformValue(textureUniformY_, 0);
> >
> > (and similarly below) ?
> >
> > > +
> > > +           /* activate texture 1 */
> > > +           glActiveTexture(GL_TEXTURE1);
> > > +           configureTexture(id_u_);
> > > +           glTexImage2D(GL_TEXTURE_2D,
> > > +                        0,
> > > +                        GL_RG,
> > > +                        size_.width() / horzSubSample_,
> > > +                        size_.height() / vertSubSample_,
> > > +                        0,
> > > +                        GL_RG,
> > > +                        GL_UNSIGNED_BYTE,
> > > +                        (char *)yuvDataPtr_ + size_.width() *
> size_.height());
> > > +           glUniform1i(textureUniformU_, 1);
> > > +           break;
> >
> > A blank line here would increase readability. Same below.
> >
> > > +   case libcamera::formats::YUV420:
> > > +           /* activate texture 0 */
> > > +           glActiveTexture(GL_TEXTURE0);
> > > +           configureTexture(id_y_);
> > > +           glTexImage2D(GL_TEXTURE_2D,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        size_.width(),
> > > +                        size_.height(),
> > > +                        0,
> > > +                        GL_RED,
> > > +                        GL_UNSIGNED_BYTE,
> > > +                        yuvDataPtr_);
> > > +           glUniform1i(textureUniformY_, 0);
> > > +
> > > +           /* activate texture 1 */
> > > +           glActiveTexture(GL_TEXTURE1);
> > > +           configureTexture(id_u_);
> > > +           glTexImage2D(GL_TEXTURE_2D,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        size_.width() / horzSubSample_,
> > > +                        size_.height() / vertSubSample_,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        GL_UNSIGNED_BYTE,
> > > +                        (char *)yuvDataPtr_ + size_.width() *
> size_.height());
> > > +           glUniform1i(textureUniformU_, 1);
> > > +
> > > +           /* activate texture 2 */
> > > +           glActiveTexture(GL_TEXTURE2);
> > > +           configureTexture(id_v_);
> > > +           glTexImage2D(GL_TEXTURE_2D,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        size_.width() / horzSubSample_,
> > > +                        size_.height() / vertSubSample_,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        GL_UNSIGNED_BYTE,
> > > +                        (char *)yuvDataPtr_ + size_.width() *
> size_.height() * 5 / 4);
> > > +           glUniform1i(textureUniformV_, 2);
> > > +           break;
> > > +   case libcamera::formats::YVU420:
> > > +           /* activate texture 0 */
> > > +           glActiveTexture(GL_TEXTURE0);
> > > +           configureTexture(id_y_);
> > > +           glTexImage2D(GL_TEXTURE_2D,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        size_.width(),
> > > +                        size_.height(),
> > > +                        0,
> > > +                        GL_RED,
> > > +                        GL_UNSIGNED_BYTE,
> > > +                        yuvDataPtr_);
> > > +           glUniform1i(textureUniformY_, 0);
> > > +
> > > +           /* activate texture 1 */
> > > +           glActiveTexture(GL_TEXTURE2);
> > > +           configureTexture(id_v_);
> > > +           glTexImage2D(GL_TEXTURE_2D,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        size_.width() / horzSubSample_,
> > > +                        size_.height() / vertSubSample_,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        GL_UNSIGNED_BYTE,
> > > +                        (char *)yuvDataPtr_ + size_.width() *
> size_.height());
> > > +           glUniform1i(textureUniformV_, 1);
> >
> > OK, now I understand why the NV_3_planes_UV_f.glsl and
> > NV_3_planes_VU_f.glsl shaders are identical, you switch the U and V
> > planes here. I think we should then merge the two files into
> > NV_3_planes_f_glsl. The above line should become
> >
> >               glUniform1i(textureUniformU_, 2);
> >
> > as you deal with texture 2 here (and a similar change is needed below),
> > and the two blocks should be swapped as the comments are incorrect (the
> > comment above refers to texture 1 while the code deals with texture 2).
> >
> > > +
> > > +           /* activate texture 2 */
> > > +           glActiveTexture(GL_TEXTURE1);
> > > +           configureTexture(id_u_);
> > > +           glTexImage2D(GL_TEXTURE_2D,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        size_.width() / horzSubSample_,
> > > +                        size_.height() / vertSubSample_,
> > > +                        0,
> > > +                        GL_RED,
> > > +                        GL_UNSIGNED_BYTE,
> > > +                        (char *)yuvDataPtr_ + size_.width() *
> size_.height() * 5 / 4);
> > > +           glUniform1i(textureUniformU_, 2);
> >
> > Please add a break here, let's not rely on implicit fall-through.
> >
> > > +   default:
> > > +           break;
> > > +   };
> > > +}
> > > +
> > > +void ViewFinderGL::paintGL()
> > > +{
> > > +   if (pFShader_ == nullptr)
> >
> >       if (!pfShader_)
> >
> > > +           createFragmentShader();
> > > +
> > > +   if (yuvDataPtr_) {
> > > +           glClearColor(0.0, 0.0, 0.0, 1.0);
> > > +           glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
> > > +
> > > +           doRender();
> > > +           glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
> > > +   }
> > > +}
> > > +
> > > +void ViewFinderGL::resizeGL(int w, int h)
> > > +{
> > > +   glViewport(0, 0, w, h);
> > > +}
> > > +
> > > +QSize ViewFinderGL::sizeHint() const
> > > +{
> > > +   return size_.isValid() ? size_ : QSize(640, 480);
> > > +}
> > > diff --git a/src/qcam/viewfinder_gl.h b/src/qcam/viewfinder_gl.h
> > > new file mode 100644
> > > index 0000000..e708c32
> > > --- /dev/null
> > > +++ b/src/qcam/viewfinder_gl.h
> > > @@ -0,0 +1,97 @@
> > > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > > +/*
> > > + * Copyright (C) 2020, Linaro
> > > + *
> > > + * viewfinder_GL.h - OpenGL Viewfinder for rendering by OpenGL shader
> > > + *
> > > + */
> > > +#ifndef __VIEWFINDER_GL_H__
> > > +#define __VIEWFINDER_GL_H__
> > > +
> > > +#include <QImage>
> > > +#include <QMutex>
> > > +#include <QObject>
> >
> > This header shouldn't be needed.
> >
> > > +#include <QOpenGLBuffer>
> > > +#include <QOpenGLFunctions>
> > > +#include <QOpenGLShader>
> > > +#include <QOpenGLShaderProgram>
> > > +#include <QOpenGLTexture>
> > > +#include <QOpenGLWidget>
> > > +#include <QSize>
> > > +
> > > +#include <libcamera/buffer.h>
> > > +#include <libcamera/formats.h>
> >
> > Missing blank line.
> >
> > > +#include "viewfinder.h"
> > > +
> > > +class ViewFinderGL : public QOpenGLWidget,
> > > +                public ViewFinder,
> > > +                protected QOpenGLFunctions
> > > +{
> > > +   Q_OBJECT
> > > +
> > > +public:
> > > +   ViewFinderGL(QWidget *parent = 0);
> >
> >  = nullptr
> >
> > > +   ~ViewFinderGL();
> > > +
> > > +   const QList<libcamera::PixelFormat> &nativeFormats() const
> override;
> > > +
> > > +   int setFormat(const libcamera::PixelFormat &format, const QSize
> &size) override;
> > > +   void render(libcamera::FrameBuffer *buffer, MappedBuffer *map)
> override;
> > > +   void stop() override;
> > > +
> > > +   QImage getCurrentImage() override;
> > > +
> > > +Q_SIGNALS:
> > > +   void renderComplete(libcamera::FrameBuffer *buffer);
> > > +
> > > +protected:
> > > +   void initializeGL() override;
> > > +   void paintGL() override;
> > > +   void resizeGL(int w, int h) override;
> > > +   QSize sizeHint() const override;
> > > +
> > > +private:
> > > +   bool isFormatSupport(const libcamera::PixelFormat &format);
> >
> > s/isFormatSupport/isFormatSupported/
> >
> > > +
> > > +   void configureTexture(unsigned int id);
> > > +   bool createFragmentShader();
> > > +   void createVertexShader();
> > > +   void removeShader();
> > > +   void doRender();
> > > +
> > > +   /* Captured image size, format and buffer */
> > > +   libcamera::FrameBuffer *buffer_;
> > > +   libcamera::PixelFormat format_;
> > > +   QSize size_;
> > > +
> > > +   /* OpenGL components for render */
> >
> > s/render/rendering/
> >
> > > +   QOpenGLShader *pFShader_;
> >
> > No need to prefix pointers with 'p'. I'd name this fragmentShader_.
> >
> > > +   QOpenGLShader *pVShader_;
> >
> > Same here, vertexShader_.
> >
> > > +   QOpenGLShaderProgram shaderProgram_;
> >
> > Is there a specific reason why pFShader_ and pVShader_ are pointers,
> > while shaderProgram_ is embedded directly in ViewFinderGL ?
> >
> > > +
> > > +   /* Vertex buffer */
> > > +   QOpenGLBuffer vbuf_;
> > > +
> > > +   /* Fragment and Vertex shader file name */
> > > +   QString fsrc_;
> >
> > fragmentShaderSrc_ ?
> >
> > > +   QString vsrc_;
> >
> > And vertexShaderSrc_.
> >
> > > +
> > > +   unsigned char *yuvDataPtr_;
> >
> > And no need for a Ptr suffix either :-)
> >
> > > +
> > > +   /* YUV texture planars and parameters */
> > > +   GLuint id_u_;
> > > +   GLuint id_v_;
> > > +   GLuint id_y_;
> > > +   GLuint textureUniformU_;
> > > +   GLuint textureUniformV_;
> > > +   GLuint textureUniformY_;
> > > +   QOpenGLTexture textureU_;
> > > +   QOpenGLTexture textureV_;
> > > +   QOpenGLTexture textureY_;
> > > +   unsigned int horzSubSample_;
> > > +   unsigned int vertSubSample_;
> > > +
> > > +   QImage image_;
> >
> > This is never used.
> >
> > > +   QMutex mutex_; /* Prevent concurrent access to image_ */
> > > +};
> > > +#endif /* __VIEWFINDER_GL_H__ */
>
> --
> Regards,
>
> Laurent Pinchart
>
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