skia2/example/HelloWorld.cpp

/*
 * Copyright 2015 Google Inc.
 *
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 *
 */

#include "HelloWorld.h"

#include "gl/GrGLInterface.h"
#include "GrContext.h"
#include "SkApplication.h"
#include "SkCanvas.h"
#include "SkGradientShader.h"
#include "SkGraphics.h"
#include "SkGr.h"

void application_init() {
    SkGraphics::Init();
    SkEvent::Init();
}

void application_term() {
    SkEvent::Term();
}

HelloWorldWindow::HelloWorldWindow(void* hwnd)
    : INHERITED(hwnd) {
    fType = kGPU_DeviceType;
    fRotationAngle = 0;
    this->setTitle();
    this->setUpBackend();
}

HelloWorldWindow::~HelloWorldWindow() {
    tearDownBackend();
}

void HelloWorldWindow::tearDownBackend() {
    SkSafeUnref(fContext);
    fContext = NULL;

    SkSafeUnref(fInterface);
    fInterface = NULL;

    fGpuSurface = nullptr;

    INHERITED::release();
}

void HelloWorldWindow::setTitle() {
    SkString title("Hello World ");
    title.appendf(fType == kRaster_DeviceType ? "raster" : "opengl");
    INHERITED::setTitle(title.c_str());
}

bool HelloWorldWindow::setUpBackend() {
    this->setVisibleP(true);
    this->setClipToBounds(false);

    bool result = attach(kNativeGL_BackEndType, 0 /*msaa*/, false, &fAttachmentInfo);
    if (false == result) {
        SkDebugf("Not possible to create backend.\n");
        release();
        return false;
    }

    fInterface = GrGLCreateNativeInterface();
    SkASSERT(NULL != fInterface);

    fContext = GrContext::Create(kOpenGL_GrBackend, (GrBackendContext)fInterface);
    SkASSERT(NULL != fContext);

    this->setUpGpuBackedSurface();
    return true;
}

void HelloWorldWindow::setUpGpuBackedSurface() {
    fGpuSurface = this->makeGpuBackedSurface(fAttachmentInfo, fInterface, fContext);
}

void HelloWorldWindow::drawContents(SkCanvas* canvas) {
    // Clear background
    canvas->drawColor(SK_ColorWHITE);

    SkPaint paint;
    paint.setColor(SK_ColorRED);

    // Draw a rectangle with red paint
    SkRect rect = SkRect::MakeXYWH(10, 10, 128, 128);
    canvas->drawRect(rect, paint);

    // Set up a linear gradient and draw a circle
    {
        SkPoint linearPoints[] = {
                {0, 0},
                {300, 300}
        };
        SkColor linearColors[] = {SK_ColorGREEN, SK_ColorBLACK};

        paint.setShader(SkGradientShader::MakeLinear(
                linearPoints, linearColors, nullptr, 2,
                SkShader::kMirror_TileMode));
        paint.setFlags(SkPaint::kAntiAlias_Flag);

        canvas->drawCircle(200, 200, 64, paint);

        // Detach shader
        paint.setShader(nullptr);
    }

    // Draw a message with a nice black paint.
    paint.setFlags(
            SkPaint::kAntiAlias_Flag |
            SkPaint::kSubpixelText_Flag |  // ... avoid waggly text when rotating.
            SkPaint::kUnderlineText_Flag);
    paint.setColor(SK_ColorBLACK);
    paint.setTextSize(20);

    canvas->save();

    static const char message[] = "Hello World";

    // Translate and rotate
    canvas->translate(300, 300);
    fRotationAngle += 0.2f;
    if (fRotationAngle > 360) {
        fRotationAngle -= 360;
    }
    canvas->rotate(fRotationAngle);

    // Draw the text:
    canvas->drawText(message, strlen(message), 0, 0, paint);

    canvas->restore();
}

void HelloWorldWindow::draw(SkCanvas* canvas) {
    this->drawContents(canvas);
    // Invalidate the window to force a redraw. Poor man's animation mechanism.
    this->inval(NULL);

    if (kRaster_DeviceType == fType) {
        fRasterSurface->draw(fGpuSurface->getCanvas(), 0, 0, nullptr);
    }
    fGpuSurface->getCanvas()->flush();
    INHERITED::present();
}

void HelloWorldWindow::onSizeChange() {
    this->setUpGpuBackedSurface();
}

bool HelloWorldWindow::onHandleChar(SkUnichar unichar) {
    if (' ' == unichar) {
        fType = fType == kRaster_DeviceType ? kGPU_DeviceType: kRaster_DeviceType;
        tearDownBackend();
        setUpBackend();
        this->setTitle();
        this->inval(NULL);
    }
    return true;
}

SkOSWindow* create_sk_window(void* hwnd, int , char** ) {
    return new HelloWorldWindow(hwnd);
}