offscreen rendering

meson.build

@@ -12,6 +12,7 @@ executable('somebar',
   'src/main.cpp',
   'src/shm_buffer.cpp',
   'src/bar.cpp',
+  'src/bar_widget.cpp',
   wayland_sources,
   #moc,
   dependencies: [qt5_dep, wayland_dep])

src/bar.cpp

@@ -1,8 +1,7 @@
 // somebar - dwl bar
 // See LICENSE file for copyright and license details.
 
-#include <cstdio>
-#include <cstring>
+#include <QImage>
 #include "bar.hpp"
 #include "config.hpp"
 
@@ -34,11 +33,25 @@ Bar::~Bar()
 void Bar::layerSurfaceConfigure(uint32_t serial, uint32_t width, uint32_t height)
 {
     zwlr_layer_surface_v1_ack_configure(_layerSurface, serial);
-    printf("configure: %d x %d\n", width, height);
-
     _bufs.emplace(width, height, WL_SHM_FORMAT_XRGB8888);
-    memset(_bufs->data(), 0xff, _bufs->stride*_bufs->height);
+    auto root = _widget.root();
+    root->setFixedSize(width, height);
+    render();
+}
+
+void Bar::render()
+{
+    auto img = QImage {
+        _bufs->data(),
+        _bufs->width,
+        _bufs->height,
+        _bufs->stride,
+        QImage::Format_RGBX8888
+    };
+    auto root = _widget.root();
+    root->render(&img);
     wl_surface_attach(_surface, _bufs->buffer(), 0, 0);
     wl_surface_commit(_surface);
+    _bufs->flip();
     waylandFlush();
 }

src/bar.hpp

@@ -7,6 +7,7 @@
 #include "wlr-layer-shell-unstable-v1-client-protocol.h"
 #include "common.hpp"
 #include "shm_buffer.hpp"
+#include "bar_widget.hpp"
 
 class Bar {
     static const zwlr_layer_surface_v1_listener _layerSurfaceListener;
@@ -14,8 +15,10 @@ class Bar {
     wl_surface *_surface {nullptr};
     zwlr_layer_surface_v1 *_layerSurface {nullptr};
     std::optional<ShmBuffer> _bufs;
+    BarWidget _widget;
 
     void layerSurfaceConfigure(uint32_t serial, uint32_t width, uint32_t height);
+    void render();
 public:
     explicit Bar(const wl_output *output);
     ~Bar();

src/bar_widget.cpp

@@ -0,0 +1,18 @@
+// somebar - dwl bar
+// See LICENSE file for copyright and license details.
+
+#include "bar_widget.hpp"
+
+BarWidget::BarWidget()
+    : _box {QBoxLayout::LeftToRight, &_root}
+    , _label {&_root}
+{
+    _root.setAttribute(Qt::WA_DontShowOnScreen);
+    _label.setText("somebar");
+}
+
+BarWidget::~BarWidget()
+{
+}
+
+QWidget* BarWidget::root() { return &_root; }

src/bar_widget.hpp

@@ -0,0 +1,17 @@
+// somebar - dwl bar
+// See LICENSE file for copyright and license details.
+
+#pragma once
+#include <QBoxLayout>
+#include <QLabel>
+#include <QWidget>
+
+class BarWidget {
+    QWidget _root;
+    QBoxLayout _box;
+    QLabel _label;
+public:
+    explicit BarWidget();
+    ~BarWidget();
+    QWidget* root();
+};

src/main.cpp

@@ -5,7 +5,7 @@
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <unistd.h>
-#include <QCoreApplication>
+#include <QApplication>
 #include <QSocketNotifier>
 #include <wayland-client.h>
 #include "qnamespace.h"
@@ -69,7 +69,7 @@ static const struct wl_registry_listener registry_listener = { registryHandleGlo
 
 int main(int argc, char **argv)
 {
-    QCoreApplication app(argc, argv);
+    QApplication app(argc, argv);
     QCoreApplication::setOrganizationName("tape software");
     QCoreApplication::setOrganizationDomain("tapesoftware.net");
     QCoreApplication::setApplicationName("somebar");

src/shm_buffer.cpp

@@ -18,7 +18,7 @@ ShmBuffer::ShmBuffer(int w, int h, wl_shm_format format)
     auto fd = memfd_create("wl_shm", MFD_CLOEXEC);
     ftruncate(fd, _totalSize);
     auto pool = wl_shm_create_pool(shm, fd, _totalSize);
-    auto ptr = reinterpret_cast<char*>(mmap(nullptr, _totalSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0));
+    auto ptr = reinterpret_cast<uint8_t*>(mmap(nullptr, _totalSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0));
     close(fd);
     for (auto i=0; i<n; i++) {
         auto offset = oneSize*i;
@@ -37,6 +37,6 @@ ShmBuffer::~ShmBuffer()
     waylandFlush();
 }
 
-char* ShmBuffer::data() const { return _buffers[_current].data; }
+uint8_t* ShmBuffer::data() const { return _buffers[_current].data; }
 wl_buffer* ShmBuffer::buffer() const { return _buffers[_current].buffer; }
 void ShmBuffer::flip() { _current = 1-_current; }

src/shm_buffer.hpp

@@ -9,7 +9,7 @@
 // format is must be 32-bit
 class ShmBuffer {
     struct Buf {
-        char *data {nullptr};
+        uint8_t *data {nullptr};
         wl_buffer *buffer {nullptr};
     };
     std::array<Buf, 2> _buffers;
@@ -18,7 +18,7 @@ class ShmBuffer {
 public:
     int width, height, stride;
     explicit ShmBuffer(int width, int height, wl_shm_format format);
-    char* data() const;
+    uint8_t* data() const;
     wl_buffer* buffer() const;
     void flip();
     ~ShmBuffer();