qt结合Skia绘制图形在窗口上

QOpenGLWidget_Skia

//
// Created by WuXiangGuJun on 2023/6/18.
//
#pragma once

#include <iostream>
#include <QTime>
#include <QTimer>
#include <QOpenGLWidget>
#include <QOpenGLFunctions>
#include <QApplication>
#include <QMainWindow>
#include <QPaintEvent>
#include <QPainter>
#include "include/core/SkColorSpace.h"
#include <include/core/SkFont.h>
#include <include/core/SkStream.h>
#include "include/core/SkData.h"
#include <include/core/SkCanvas.h>
#include <include/core/SkPaint.h>
#include "include/core/SkImageInfo.h"
#include "include/core/SkPixmap.h"
#include "include/core/SkSurface.h"
#include "include/core/SkSurfaceProps.h"
#include "include/core/SkRect.h"
#include "include/encode/SkPngEncoder.h"
#include <include/gpu/GrDirectContext.h>
#include <include/gpu/GrBackendSurface.h>
#include <include/gpu/gl/GrGLInterface.h>


class LineNumberWidget : public QOpenGLWidget, protected QOpenGLFunctions {

private:
    sk_sp<GrDirectContext> grDirectContext = nullptr;
    sk_sp<SkSurface> skSurface = nullptr;
    SkImageInfo info;
public:
    explicit LineNumberWidget(QWidget *widget = nullptr) : QOpenGLWidget(widget) {
    }

protected:
    void initializeGL() override {
        initializeOpenGLFunctions();//初始化OPenGL功能函数
        glClearColor(0, 0, 0, 0);

        grDirectContext = makeContext();

        skSurface = createSurface(grDirectContext.get(), this->width(), this->height());

        if (skSurface == nullptr) abort();

    }

    sk_sp<GrDirectContext> makeContext() {
        auto grGLInterface = GrGLMakeNativeInterface();
        return GrDirectContext::MakeGL(grGLInterface);
    }

    sk_sp<SkSurface> createSurface(GrRecordingContext *grRecordingContext, int width, int height) {
        GrGLFramebufferInfo framebufferInfo;
        framebufferInfo.fFBOID = 0;
        framebufferInfo.fFormat = GL_RGBA8;

        SkColorType colorType = kRGBA_8888_SkColorType;

        GrBackendRenderTarget backendRenderTarget(width, height, 0, 0, framebufferInfo);
        return SkSurface::MakeFromBackendRenderTarget(grRecordingContext,
                                                      backendRenderTarget, kBottomLeft_GrSurfaceOrigin, colorType,
                                                      nullptr, nullptr);
    }


    void resizeGL(int w, int h) override {
        skSurface = createSurface(grDirectContext.get(), w, h);
        glViewport(0, 0, w, h);
        grDirectContext->resetContext();
        update();
    }

    void paintGL() override {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        auto canvas = skSurface->getCanvas();
        draw(canvas);
    }

    void draw(SkCanvas *canvas) {
        const SkScalar scale = 256.0f;
        const SkScalar R = 0.45f * scale;
        const SkScalar TAU = 6.2831853f;
        SkPath path;
        path.moveTo(R, 0.0f);
        for (int i = 1; i < 7; ++i) {
            SkScalar theta = 3 * i * TAU / 7;
            path.lineTo(R * cos(theta), R * sin(theta));
        }
        path.close();
        SkPaint p;
        p.setAntiAlias(true);
        canvas->clear(SK_ColorWHITE);
        canvas->save();
        canvas->translate(0.5f * scale, 0.5f * scale);
        canvas->drawPath(path, p);
        canvas->flush();
    }
};