// Copyright 2019 The MediaPipe Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef MEDIAPIPE_GPU_GL_SIMPLE_CALCULATOR_H_
#define MEDIAPIPE_GPU_GL_SIMPLE_CALCULATOR_H_
#include <utility> // for declval
#include "mediapipe/framework/calculator_framework.h"
#include "mediapipe/framework/port/status.h"
#include "mediapipe/gpu/gl_calculator_helper.h"
namespace mediapipe {
// This class saves some boilerplate for the common case of processing one
// input stream of frames and outputting it as one output stream of frames,
// processed using OpenGL.
//
// If you use tags, both input and output streams should be tagged as VIDEO.
// Otherwise, this will use the first input and output.
//
// Subclasses should define at least:
// - GlSetup(), which is called once (on the first frame) and should set up any
// GL objects the calculator will reuse throughout its life.
// - GlRender(), which is called for each frame.
// - A destructor, to destroy the objects created in GlSetup.
// Note that when GlSetup and GlRender are called, the GL context has already
// been set, but in the destructor it has not. The destructor should use the
// RunInGlContext() helper to make sure it is doing the destruction in the right
// GL context.
//
// Additionally, you can define a GlBind() method, which will be called to
// enable shader programs, bind any additional textures you may need, etc.
// If your calculator shares a context with other calculators, GlBind() will be
// called before each GlRender(); if it has its own context, it will be called
// only once.
class GlSimpleCalculator : public CalculatorBase {
public:
GlSimpleCalculator() : initialized_(false) {}
GlSimpleCalculator(const GlSimpleCalculator&) = delete;
GlSimpleCalculator& operator=(const GlSimpleCalculator&) = delete;
~GlSimpleCalculator() override = default;
static absl::Status GetContract(CalculatorContract* cc);
absl::Status Open(CalculatorContext* cc) override;
absl::Status Process(CalculatorContext* cc) override;
absl::Status Close(CalculatorContext* cc) override;
// This method is called once on the first frame. Use it to setup any objects
// that will be reused throughout the calculator's life.
virtual absl::Status GlSetup() = 0;
// You can use this optional method to do any pre-rendering setup that needs
// to be redone after the context has been used by another calculator.
// If your context is not shared, it will only be called once.
virtual absl::Status GlBind() { return absl::OkStatus(); }
// Do your rendering here. The source and destination textures have already
// been created and bound for you.
// - src: source texture (contains input frame); already bound to GL_TEXTURE1.
// - dst: destination texture (write output frame here); already bound to
// GL_TEXTURE0 and attached to the framebuffer.
virtual absl::Status GlRender(const GlTexture& src, const GlTexture& dst) = 0;
// The method is called to delete all the programs.
virtual absl::Status GlTeardown() = 0;
// You can override this method to compute the size of the destination
// texture. By default, it will take the same size as the source texture.
virtual void GetOutputDimensions(int src_width, int src_height,
int* dst_width, int* dst_height) {
*dst_width = src_width;
*dst_height = src_height;
}
// Override this to output a different type of buffer.
virtual GpuBufferFormat GetOutputFormat() { return GpuBufferFormat::kBGRA32; }
protected:
// Forward invocations of RunInGlContext to the helper.
// The decltype part just says that this method returns whatever type the
// helper method invocation returns. In C++14 we could remove it and use
// return type deduction, i.e.:
// template <typename F> auto RunInGlContext(F&& f) { ... }
template <typename F>
auto RunInGlContext(F&& f)
-> decltype(std::declval<GlCalculatorHelper>().RunInGlContext(f)) {
return helper_.RunInGlContext(std::forward<F>(f));
}
GlCalculatorHelper helper_;
bool initialized_;
};
} // namespace mediapipe
#endif // MEDIAPIPE_GPU_GL_SIMPLE_CALCULATOR_H_