core: Add GraphicsBuffer map flags

This allows to specify whether the graphics buffer will be read or
written. It's mainly needed to map our APIs to gbm APIs.

src/core/gbmgraphicsbufferallocator.cpp

@@ -117,14 +117,22 @@ const DmaBufAttributes *GbmGraphicsBuffer::dmabufAttributes() const
     return &m_dmabufAttributes;
 }
 
-void *GbmGraphicsBuffer::map()
+void *GbmGraphicsBuffer::map(MapFlags flags)
 {
     if (m_mapPtr) {
         return m_mapPtr;
     }
 
+    uint32_t access = 0;
+    if (flags & MapFlag::Read) {
+        access |= GBM_BO_TRANSFER_READ;
+    }
+    if (flags & MapFlag::Write) {
+        access |= GBM_BO_TRANSFER_WRITE;
+    }
+
     uint32_t stride = 0;
-    m_mapPtr = gbm_bo_map(m_bo, 0, 0, m_dmabufAttributes.width, m_dmabufAttributes.height, GBM_BO_TRANSFER_READ_WRITE, &stride, &m_mapData);
+    m_mapPtr = gbm_bo_map(m_bo, 0, 0, m_dmabufAttributes.width, m_dmabufAttributes.height, access, &stride, &m_mapData);
     return m_mapPtr;
 }
 

src/core/gbmgraphicsbufferallocator.h

@@ -23,13 +23,13 @@ public:
     GbmGraphicsBuffer(DmaBufAttributes attributes, gbm_bo *handle);
     ~GbmGraphicsBuffer() override;
 
+    void *map(MapFlags flags) override;
+    void unmap() override;
+
     QSize size() const override;
     bool hasAlphaChannel() const override;
     const DmaBufAttributes *dmabufAttributes() const override;
 
-    void *map() override;
-    void unmap() override;
-
 private:
     gbm_bo *m_bo;
     void *m_mapPtr = nullptr;

src/core/graphicsbuffer.cpp

@@ -53,7 +53,7 @@ void GraphicsBuffer::drop()
     }
 }
 
-void *GraphicsBuffer::map()
+void *GraphicsBuffer::map(MapFlags flags)
 {
     return nullptr;
 }

src/core/graphicsbuffer.h

@@ -58,7 +58,13 @@ public:
     void unref();
     void drop();
 
-    virtual void *map();
+    enum MapFlag {
+        Read = 0x1,
+        Write = 0x2,
+    };
+    Q_DECLARE_FLAGS(MapFlags, MapFlag)
+
+    virtual void *map(MapFlags flags);
     virtual void unmap();
 
     virtual QSize size() const = 0;
@@ -78,3 +84,5 @@ protected:
 };
 
 } // namespace KWin
+
+Q_DECLARE_OPERATORS_FOR_FLAGS(KWin::GraphicsBuffer::MapFlags)

src/core/graphicsbufferview.cpp

@@ -39,7 +39,7 @@ static QImage::Format drmFormatToQImageFormat(uint32_t drmFormat)
     }
 }
 
-GraphicsBufferView::GraphicsBufferView(GraphicsBuffer *buffer)
+GraphicsBufferView::GraphicsBufferView(GraphicsBuffer *buffer, GraphicsBuffer::MapFlags accessFlags)
     : m_buffer(buffer)
 {
     int width;
@@ -65,7 +65,7 @@ GraphicsBufferView::GraphicsBufferView(GraphicsBuffer *buffer)
         return;
     }
 
-    void *data = buffer->map();
+    void *data = buffer->map(accessFlags);
     if (data) {
         m_image = QImage(static_cast<uchar *>(data), width, height, stride, drmFormatToQImageFormat(format));
     }

src/core/graphicsbufferview.h

@@ -6,19 +6,17 @@
 
 #pragma once
 
-#include "kwin_export.h"
+#include "core/graphicsbuffer.h"
 
 #include <QImage>
 
 namespace KWin
 {
 
-class GraphicsBuffer;
-
 class KWIN_EXPORT GraphicsBufferView
 {
 public:
-    explicit GraphicsBufferView(GraphicsBuffer *buffer);
+    explicit GraphicsBufferView(GraphicsBuffer *buffer, GraphicsBuffer::MapFlags accessFlags = GraphicsBuffer::Read);
     ~GraphicsBufferView();
 
     QImage *image();

src/wayland/shmclientbuffer.cpp

@@ -233,7 +233,7 @@ static void sigbusHandler(int signum, siginfo_t *info, void *context)
     }
 }
 
-void *ShmClientBuffer::map()
+void *ShmClientBuffer::map(MapFlags flags)
 {
     if (!m_shmPool->sigbusImpossible) {
         // A SIGBUS signal may be emitted if the backing file is shrinked and we access now

src/wayland/shmclientbuffer_p.h

@@ -57,7 +57,7 @@ public:
     ShmClientBuffer(ShmPool *pool, KWin::ShmAttributes attributes, wl_client *client, uint32_t id);
     ~ShmClientBuffer() override;
 
-    void *map() override;
+    void *map(MapFlags flags) override;
     void unmap() override;
 
     QSize size() const override;