Add an eglReadBuffer function to read out pixel data.

2 files changed, 38 insertions, 0 deletions

diff --git a/eagle.h b/eagle.h
index a47a23b..bd2f2a9 100644
--- a/eagle.h
+++ b/eagle.h
@@ -235,6 +235,9 @@ extern EGLBoolean eglCopyNativeBuffers(EGLDisplay display,
 				       EGLSurface src, GLenum srcBuffer,
 				       int32_t x, int32_t y, int32_t width, int32_t height);
 
+extern void *eglReadBuffer(EGLDisplay display,
+			   EGLSurface surface, GLenum buffer, GLuint *stride);
+
 extern EGLBoolean eglDestroySurface(EGLDisplay display,
 				    EGLSurface surface);
 
diff --git a/intel.c b/intel.c
index 1cac601..d0af60e 100644
--- a/intel.c
+++ b/intel.c
@@ -373,6 +373,8 @@ eglCreateSurfaceForName(EGLDisplay display, EGLConfig config,
 	return &nativeSurface->base;
 }
 
+#ifdef __DRI_COPY_BUFFER
+
 EGLBoolean
 eglCopyNativeBuffers(EGLDisplay display,
 		     EGLSurface dst, GLenum dstBuffer, int32_t dst_x, int32_t dst_y,
@@ -405,3 +407,36 @@ eglCopyNativeBuffers(EGLDisplay display,
 						     srcDRIBuffer,
 						     x, y, width, height);
 }
+
+#endif
+
+void *
+eglReadBuffer(EGLDisplay display,
+	      EGLSurface surface, GLenum buffer, GLuint *stride)
+{
+	EGLSurfaceNative nativeSurface = (EGLSurfaceNative) surface;
+	struct drm_i915_gem_pread pread;
+	void *data;
+
+	*stride = surface->buffers[0].pitch;
+	pread.handle = nativeSurface->handles[0];
+	pread.pad = 0;
+	pread.offset = 0;
+	pread.size = *stride * nativeSurface->height;
+
+	data = malloc(pread.size);
+	if (data == NULL) {
+		fprintf(stderr, "swap buffers malloc failed\n");
+		return NULL;
+	}
+
+	pread.data_ptr = (long) data;
+
+	if (ioctl(display->fd, DRM_IOCTL_I915_GEM_PREAD, &pread)) {
+		fprintf(stderr, "gem pread failed\n");
+		free(data);
+		return NULL;
+	}
+
+	return data;
+}