skia2/example/HelloWorld.cpp

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/*
* Copyright 2017 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 "GrContext.h"
#include "SkCanvas.h"
#include "SkGradientShader.h"
#include "SkGraphics.h"
using namespace sk_app;
Application* Application::Create(int argc, char** argv, void* platformData) {
return new HelloWorld(argc, argv, platformData);
}
HelloWorld::HelloWorld(int argc, char** argv, void* platformData)
: fBackendType(Window::kNativeGL_BackendType)
, fRotationAngle(0) {
SkGraphics::Init();
fWindow = Window::CreateNativeWindow(platformData);
fWindow->setRequestedDisplayParams(DisplayParams());
// register callbacks
fWindow->pushLayer(this);
fWindow->attach(fBackendType);
}
HelloWorld::~HelloWorld() {
fWindow->detach();
delete fWindow;
}
void HelloWorld::updateTitle() {
if (!fWindow || fWindow->sampleCount() < 0) {
return;
}
SkString title("Hello World ");
title.append(Window::kRaster_BackendType == fBackendType ? "Raster" : "OpenGL");
fWindow->setTitle(title.c_str());
}
void HelloWorld::onBackendCreated() {
this->updateTitle();
fWindow->show();
fWindow->inval();
}
void HelloWorld::onPaint(SkCanvas* canvas) {
// Clear background
canvas->clear(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.setAntiAlias(true);
canvas->drawCircle(200, 200, 64, paint);
// Detach shader
paint.setShader(nullptr);
}
// Draw a message with a nice black paint
paint.setSubpixelText(true);
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 HelloWorld::onIdle() {
// Just re-paint continously
fWindow->inval();
}
bool HelloWorld::onChar(SkUnichar c, uint32_t modifiers) {
if (' ' == c) {
fBackendType = Window::kRaster_BackendType == fBackendType ? Window::kNativeGL_BackendType
: Window::kRaster_BackendType;
fWindow->detach();
fWindow->attach(fBackendType);
}
return true;
}