mirror of https://github.com/BOINC/boinc.git
84 lines
3.1 KiB
C++
84 lines
3.1 KiB
C++
// This file is part of BOINC.
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// http://boinc.berkeley.edu
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// Copyright (C) 2008 University of California
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//
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// BOINC is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License
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// as published by the Free Software Foundation,
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// either version 3 of the License, or (at your option) any later version.
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//
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// BOINC is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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// See the GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with BOINC. If not, see <http://www.gnu.org/licenses/>.
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// The class GRAPHICS_DOUBLE_BUFFER provides a mechanism
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// for synchronizing the generation of graphics information
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// (done by the "science thread")
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// with the graphics rendering (done by the "GUI thread",
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// which periodically calls the application-supplied render() function)
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//
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// We assume that graphics info is generated incrementally
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// and displayed incrementally.
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// The scheme handles mismatches between generation and rendering rates:
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// - if generation is faster than display, data cycles will be skipped
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// - if display is faster than generation, the display will "linger"
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// on a cycle until the next cycle is available in its entirety.
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//
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// Here's what the application programmer does:
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// - subclass GRAPHICS_BUFFER, adding your application-specific data
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// - declare a GRAPHICS_DOUBLE_BUFFER object (call it gdb),
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// initializing it with pointers to two GRAPHICS_BUFFER structures.
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// - when the science thread wants to add an increment of data,
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// it calls gdb->get_generate_buffer(first)
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// ("first" indicates whether this is the first data increment of a cycle).
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// If this returns nonzero, it adds data to the buffer.
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// If this addition causes it to be full, it calls gdb->generate_done();
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// - render() calls gdb->get_render_buffer().
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// If this returns nonzero, it displays some or all the data.
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// If this completes the display of the data, it calls gdb->render_done().
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// Here's how it works:
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// There are two buffers, each with a "state" (see below).
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// In a given state, only one thread can access the data or change the state.
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//
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#ifndef GRAPHICS_DATA_H
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#define GRAPHICS_DATA_H
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#define GB_STATE_IDLE 0
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#define GB_STATE_GENERATING 1
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#define GB_STATE_GENERATED 2
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#define GB_STATE_RENDERING 3
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#define GB_STATE_RENDERED 4
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// subclass this for your applications
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//
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class GRAPHICS_BUFFER {
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public:
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virtual ~GRAPHICS_BUFFER() {}
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virtual void clear();
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int state;
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};
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class GRAPHICS_DOUBLE_BUFFER {
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GRAPHICS_BUFFER* b1, *b2;
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GRAPHICS_BUFFER* get_buffer(int state);
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public:
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void init(GRAPHICS_BUFFER*, GRAPHICS_BUFFER*);
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// the following called by app's render()
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//
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GRAPHICS_BUFFER* get_render_buffer();
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void render_done(GRAPHICS_BUFFER*);
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// the following called by app's science thread
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//
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GRAPHICS_BUFFER* get_generate_buffer(bool first);
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void generate_done(GRAPHICS_BUFFER*);
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};
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#endif
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